Fastener Retention Requirements and Practices in Spaceflight Hardware

NASA Technical Reports Server (NTRS)

Dasgupta, Rajib

2004-01-01

This presentation reviews the requirements for safety critical fasteners in spaceflight hardware. Included in the presentation are design guidelines and information for Locking Helicoils, key locked inserts and thinwalled inserts, self locking screws and bolts. locknuts, and a locking adhesives, Loctite and Vibratite.

Random Vibration and Torque Tests of Fasteners Secured With Locking Cable, Room Temperature Vulcanized (RTV) Rubber, and Closed Cell Foam to Support the Launch of STS-82

NASA Technical Reports Server (NTRS)

Yost, V. H.

1997-01-01

During a walkdown of the Space Transportation System (STS) orbiter for the 82nd Space Shuttle flight (STS-82), technicians found several safety cables for bolts with missing or loose ferrules. Typically, two or three bolts are secured with a cable which passes through one of the holes in the head of each bolt and a ferrule is crimped on each end of the cable to prevent it from coming out of the holes. The purpose of the cable is to prevent bolts from rotating should they become untightened. Other bolts are secured with either a locking cable or wire which is covered with RTV and foam. The RTV and foam would have to be removed to inspect for missing or loose ferrules. To determine whether this was necessary, vibration and torque test fixtures and tests were made to determine whether or not bolts with missing or loose ferrules would unloosen. These tests showed they would not, and the RTV and foam was not removed.

A microprocessor based portable bolt tension monitor

NASA Technical Reports Server (NTRS)

Perey, D. F.

1991-01-01

A bolt tension monitor (BTM) which uses ultrasonics and a pulsed phase locked loop circuit to measure load-induced acoustic phase shifts which are independent of friction is described. The BTM makes it possible to measure the load in a bolt that was tightened at some time in the past. This capability to recertify a load after-the-fact will help to insure the integrity of a bolted joint.

Impact extractive fracture of jointed steel plates of a bolted joint

NASA Astrophysics Data System (ADS)

Daimaruya, M.; Fujiki, H.; Ambarita, H.

2012-08-01

This study is concerned with the development of a fracture criterion for the impact fracture of jointed steel plates of a bolted joint used in a car body. For the accurate prediction of crash characteristics of car bodies by computer-aided engineering (CAE), it is also necessary to examine the behavior and fracture of jointed steel plates subjected to impact loads. Although the actual impact fracture of jointed steel plates of a bolted joint used in cars is complicated, for simplifying the problem it might be classified into the shear fracture and the extractive fracture of jointed steel plates. Attention is given to the extractive fracture of jointed steel plates in this study. The extractive behavior and fracture of three kinds of steel plates used for cars are examined in experiments and numerical simulations. The impact extraction test of steel plates jointed by a bolt is performed using the one-bar method, together with the static test. In order to understand the mechanism of extractive fracture process of jointed steel plates, numerical simulations by a FEM code LS-DYNA are also carried out. The obtained results suggest that a stress-based fracture criterion may be developed for the impact extractive fracture of jointed steel plates of a bolted joint used in a car body.

Testing and evaluation of Vespel up to 450 deg F when used in nuts and bolts as a self-locking element

NASA Technical Reports Server (NTRS)

Wood, C. M.

1984-01-01

The object of this investigation was to evaluate Vespel for potential application on the Solid Rocket Booster to replace all-metal deformed self-locking nuts and anchor nuts and be used as self-locking elements for bolts and screws. The Vespel self-locking elements were tested for prevailing torque retention at room temperature, after heating to 450 F and exposure for 3 hr, breakaway torque at 450 F and for vibration at a level consistent with the maximum expected on the SRB at lift-off and reentry. The investigation revealed Vespel has properties that can provide a self-locking capability for threaded fasteners up to 450 F and it can be used in nuts and anchor nuts for installation on the SRB. Vespel elements in bolts did not meet all our SRB requirements for reuse, however, we have defined a design for Vespel elements in nuts/anchor nuts that fully meets all requirements. It is recommended that No. 1, 1/4 in. and 5/16 in. nuts/anchor nuts be procured for use on the SRB. This system will eliminate the galling problems now encountered and achieve a much higher reuse life than the present deformed nut design.

Discussion about effecting of stiffener in four bolts in a row end plate connection for long span and heavy load steel structures in Vietnam

NASA Astrophysics Data System (ADS)

Huong, Khang T.; Nguyen, Cung H.

2018-04-01

Nowadays, steel structure industry in Vietnam is in strong development. The construction of steel structure becomes larger span and heavier load. The issue spawned a number of issues arise from optimizing connections. Typical of steel connections in prefabricated steel structure that is an end plate (face plate) bolted connection. When the connection carried a heavy load, then the number of bolts is required much more. Increasing the number of rows bolts will less effective because can still not enough strength requirements, the bolts in row near rotational center will level arm reduction, then it cannot carry heavy loads. The current solution is doing multiple bolts in a row. Current standards such as EN [1], AISC [2] are no specific guidelines for calculating the connection four bolts in a row that primarily assumes the way works like a T-stub of the two bolts a row. Some articles studied T-stub four bolts in a row [3], [4], [5], [6] by component method but it has some components which weren’t considered. In this paper, in order to provide a contribution to improve the T-stub four bolts in a row, the stiffener component in T-stub will be added and compared with T-stub without stiffener by the finite element model to demonstrate effectiveness in reducing stress and displacement of T-stub. It gives ideas for the economic design of four bolts in a row end plate connection in Vietnam for future.

Preload Loss in a Spacecraft Fastener via Vibration-Induced Unwinding

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher; Howard, S. Adam; Hess, Daniel P.

2018-01-01

Sound engineering practice requires that fasteners and bolted joints maintain preload in service. NASA recently concluded a series of vibration tests of a multicomponent structure intended to simulate an upper stage section of a launch vehicle. The stacked components were joined through six circumferentially placed bolted cup-cone-style pyrotechnic joint mechanisms designed to share spacecraft structural loads and then enable separation during ascent. Over the course of the vibration test campaign, all six bolted cup-cone mechanisms experienced some degree of preload loss with two mechanisms losing half of their original bolt preload. A subsequent forensic anomaly investigation concluded that vibration-induced unwinding of the preload nut-and-bolt assemblies occurred despite the use of safety wire and high levels of thread friction. A series of experiments were done to better understand how large, heavily preloaded fasteners could unwind. Additionally, thread friction torque was measured and the fastener locking capability of safety wire was evaluated. The friction coefficient between the clamped cup-cone components was characterized and finally a highly instrumented mechanism-level vibration test was done to reproduce the unwinding phenomenon to better understand the mechanism's behavior. The conclusion drawn was that vibration and structural forces led to relative motion (sliding) of the clamped components, resulting in self-loosening and unwinding effects on the nut-and-bolt assembly. To counter this phenomenon, more effective fastener locking methodologies were recommended and a follow-on effort was initiated to quantify the relationship between preload, component motion, and resulting unwinding forces. It is hoped that elucidation of these effects can be used to design more effective fastener locking features.

Metallurgical failure analysis of MH-1A reactor core hold-down bolts. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hawthorne, J.R.; Watson, H.E.

1976-11-01

The Naval Research Laboratory has performed a failure analysis on two MH-1A reactor core hold-down bolts that broke in service. Adherence to fabrication specifications, post-service properties and possible causes of bolt failure were investigated. The bolt material was verified as 17-4PH precipitation hardening stainless steel. Measured bolt dimensions also were in accordance with fabrication drawing specifications. Bolt failure occurred in the region of a locking pin hole which reduced the bolt net section by 47 percent. The failure analysis indicates that the probable cause of failure was net section overloading resulting from a lateral bending force on the bolt. Themore » analysis indicates that net section overloading could also have resulted from combined tensile stresses (bolt preloading plus differential thermal expansion). Recommendations are made for improved bolting.« less

Delayed unlatching mechanism

DOEpatents

Bzorgi, Fariborz M.

2015-05-19

In various embodiments an apparatus is presented for securing a structure such as a door, window, hatch, or gate that moves between an open and a closed position relative to a fixed structure to provide or deny access to a compartment, a room, an outdoor area, or a facility. Various embodiments provide a delay in opening the closure of sufficient duration to frustrate a rapid activation that might be desired by a person who is attempting to pass through the closure for some illicit purpose. Typically, hydraulics are used to activate the apparatus and no electrical energy or electronic signals are employed. In one embodiment, a plurality of actuations of a hand lever operates a hydraulic pump that moves a locking bolt from a first position in which a locking bolt is engaged with a recess in the fixed structure (preventing opening of a gate) to a second position in which the locking bolt is disengaged from the recess to permit opening of the gate.

Eddy-Current Detection of Weak Bolt Heads

NASA Technical Reports Server (NTRS)

Messina, C. P.

1987-01-01

Electronic test identifies flawed units passing hardness tests. Eddy-current test detects weakness in head-to-shank junctions of 1/4-28 cup-washer lock bolts. Developed for alloy A286 steel bolts in Space Shuttle main engine fuel turbo-pump. Test examines full volume of head, including head-to-shank transition and nondestructively screens out potentially defective units. Test adapts to any other alloys.

Development of a Unified Rock Bolt Model in Discontinuous Deformation Analysis

NASA Astrophysics Data System (ADS)

He, L.; An, X. M.; Zhao, X. B.; Zhao, Z. Y.; Zhao, J.

2018-03-01

In this paper, a unified rock bolt model is proposed and incorporated into the two-dimensional discontinuous deformation analysis. In the model, the bolt shank is discretized into a finite number of (modified) Euler-Bernoulli beam elements with the degrees of freedom represented at the end nodes, while the face plate is treated as solid blocks. The rock mass and the bolt shank deform independently, but interact with each other through a few anchored points. The interactions between the rock mass and the face plate are handled via general contact algorithm. Different types of rock bolts (e.g., Expansion Shell, fully grouted rebar, Split Set, cone bolt, Roofex, Garford and D-bolt) can be realized by specifying the corresponding constitutive model for the tangential behavior of the anchored points. Four failure modes, namely tensile failure and shear failure of the bolt shank, debonding along the bolt/rock interface and loss of the face plate, are available in the analysis procedure. The performance of a typical conventional rock bolt (fully grouted rebar) and a typical energy-absorbing rock bolt (D-bolt) under the scenarios of suspending loosened blocks and rock dilation is investigated using the proposed model. The reliability of the proposed model is verified by comparing the simulation results with theoretical predictions and experimental observations. The proposed model could be used to reveal the mechanism of each type of rock bolt in realistic scenarios and to provide a numerical way for presenting the detailed profile about the behavior of bolts, in particular at intermediate loading stages.

Parametric Study of Single Bolted Composite Bolted Joint Subjected to Static Tensile Loading

NASA Astrophysics Data System (ADS)

Awadhani, L. V.; Bewoor, Anand, Dr.

2017-08-01

The use of composites is increasing in the engineering applications in order to reduce the weight, building energy efficient systems, designing a suitable material according to the requirements of the application. But at the same time, building a structure is possible only by bonding or bolting or combination of them. There are limitations for the bonding methods and problems with the bolting such as stress concentration near the neighborhood of the bolt hole, tensile or shear failure, delamination etc. Hence the design of a composite bolted structure needs a special attention. This paper focuses on the performance of the composite bolted joint under static tensile loading and the effect of variation in the parameters such as the bolt pitch, plate width, thickness, bolt tightening torque, composite material, coefficient of friction between the bolt and plate etc. A simple spring mass model is used to study the single bolted composite bolted joint. The influencing parameters are identified through the developed model and compared with the results from the literature. The best geometric parameters for the applied load are identified for the composite bolted joints.

Automatic, computerized testing of bolts

NASA Technical Reports Server (NTRS)

Carlucci, J., Jr.; Lobb, V. B.; Stoller, F. W.

1970-01-01

System for testing bolts with various platings, lubricants, nuts, and tightening procedures tests 200 fasteners, and processes and summarizes the results, within one month. System measures input torque, nut rotation, bolt clamping force, bolt shank twist, and bolt elongation, data is printed in report form. Test apparatus is described.

Fibular fixation as an adjuvant to tibial intramedullary nailing in the treatment of combined distal third tibia and fibula fractures: a biomechanical investigation.

PubMed

Morin, Paul M; Reindl, Rudolf; Harvey, Edward J; Beckman, Lorne; Steffen, Thomas

2008-02-01

Distal third tibia fractures have classically been treated with standard plating, but intramedullary (IM) nailing has gained popularity. Owing to the lack of interference fit of the nail in the metaphyseal bone of the distal tibia, it may be beneficial to add rigid plating of the fibula to augment the overall stability of fracture fixation in this area. This study sought to assess the biomechanical effect of adding a fibular plate to standard IM nailing in the treatment of distal third tibia and fibula fractures. Eight cadaveric tibia specimens were used. Tibial fixation consisted of a solid titanium nail locked with 3 screws distally and 2 proximally, and fibular fixation consisted of a 3.5 mm low-contact dynamic compression plate. A section of tibia and fibula was removed. Testing was accomplished with an MTS machine. Each leg was tested 3 times; with and without a fibular plate and with a repetition of the initial test condition. Vertical displacements were tested with an axial load up to 500 N, and angular rotation was tested with torques up to 5 N*m. The difference in axial rotation was the only statistically significant finding (p = 0.003), with fibular fixation resulting in 1.1 degrees less rotation through the osteotomy site (17.96 degrees v. 19.10 degrees ). Over 35% of this rotational displacement occurred at the nail-locking bolt interface with the application of small torsional forces. Fibular plating in addition to tibial IM fixation of distal third tibia and fibula fractures leads to slightly increased resistance to torsional forces. This small improvement may not be clinically relevant.

Monitoring of Pre-Load on Rock Bolt Using Piezoceramic-Transducer Enabled Time Reversal Method.

PubMed

Huo, Linsheng; Wang, Bo; Chen, Dongdong; Song, Gangbing

2017-10-27

Rock bolts ensure structural stability for tunnels and many other underground structures. The pre-load on a rock bolt plays an important role in the structural reinforcement and it is vital to monitor the pre-load status of rock bolts. In this paper, a rock bolt pre-load monitoring method based on the piezoceramic enabled time reversal method is proposed. A lead zirconate titanate (PZT) patch transducer, which works as an actuator to generate stress waves, is bonded onto the anchor plate of the rock bolt. A smart washer, which is fabricated by sandwiching a PZT patch between two metal rings, is installed between the hex nut and the anchor plate along the rock bolt. The smart washer functions as a sensor to detect the stress wave. With the increase of the pre-load values on the rock bolt, the effective contact surface area between the smart washer and the anchor plate, benefiting the stress wave propagation crossing the contact surface. With the help of time reversal technique, experimental results reveal that the magnitude of focused signal clearly increases with the increase of the pre-load on a rock bolt before the saturation which happens beyond a relatively high value of the pre-load. The proposed method provides an innovative and real time means to monitor the pre-load level of a rock bolt. By employing this method, the pre-load degradation process on a rock bolt can be clearly monitored. Please note that, currently, the proposed method applies to only new rock bolts, on which it is possible to install the PZT smart washer.

A New Tool for Industry

NASA Technical Reports Server (NTRS)

1981-01-01

Ultrasonic P2L2 bolt monitor is a new industrial tool, developed at Langley Research Laboratory, which is lightweight, portable, extremely accurate because it is not subject to friction error, and it is cost-competitive with the least expensive of other types of accurate strain monitors. P2L2 is an acronym for Pulse Phase Locked Loop. The ultrasound system which measures the stress that occurs when a bolt becomes elongated in the process of tightening, transmits sound waves to the bolt being fastened and receives a return signal indicating changes in bolt stress. Results are translated into a digital reading of the actual stress on the bolt. Device monitors the bolt tensioning process on mine roof bolts that provide increased safety within the mine. Also has utility in industrial applications.

Locking mechanism

DOEpatents

Williams, Gary L.; Goin, Jr., Jesse L.; Kirby, Patrick G.; McKenna, John P.

1997-01-01

The invention is a motorized linkage for operating a door strike. A six volt power source, controlled by a security code, rotates a small electric motor when a proper security code is given. The motor rotates a shaft which engages a coil spring. This moves a locking cam. When a catch on the locking cam separates from the locking lever catch, the latch bolt keeper may be manipulated by a user.

Experimental analysis of thread movement in bolted connections due to vibrations

NASA Technical Reports Server (NTRS)

Ramey, G. ED; Jenkins, Robert C.

1994-01-01

The objective of this study was to identify the main design parameters contributing to loosening of bolts due to vibration and to identify their relative importance and degree of contribution to bolt loosening. Vibration testing was conducted on a shaketable with a controlled-random input in the dynamic testing laboratory of the Structural Test Division of MSFC. Test specimens which contained one test bolt were vibrated for a fixed amount of time and percentage of pre-load loss was measured. Each specimen tested implemented some combination of eleven design parameters as dictated by the design of experiment methodology employed. The eleven design parameters were: bolt size (diameter), lubrication on bolt, hole tolerance, initial pre-load, nut locking device, grip length, thread pitch, lubrication between mating materials, class of fit, joint configuration and mass of configuration. These parameters were chosen for this experiment because they are believed to be the design parameters having the greatest impact on bolt loosening. Two values of each design parameter were used and each combination of parameters tested was subjected to two different directions of vibration and two different g-levels of vibration. One replication was made for each test to gain some indication of experimental error and repeatability and to give some degree of statistical credibility to the data, resulting in a total of 96 tests being performed. The results of the investigation indicated that nut locking devices, joint configuration, fastener size, and mass of configuration were significant in bolt loosening due to vibration. The results of this test can be utilized to further research the complex problem of bolt loosening due to vibration.

Real time bolt preload monitoring using piezoceramic transducers and time reversal technique—a numerical study with experimental verification

NASA Astrophysics Data System (ADS)

Parvasi, Seyed Mohammad; Ho, Siu Chun Michael; Kong, Qingzhao; Mousavi, Reza; Song, Gangbing

2016-08-01

Bolted joints are ubiquitous structural elements, and form critical connections in mechanical and civil structures. As such, loosened bolted joints may lead to catastrophic failures of these structures, thus inspiring a growing interest in monitoring of bolted joints. A novel energy based wave method is proposed in this study to monitor the axial load of bolted joint connections. In this method, the time reversal technique was used to focus the energy of a piezoelectric (PZT)-generated ultrasound wave from one side of the interface to be measured as a signal peak by another PZT transducer on the other side of the interface. A tightness index (TI) was defined and used to correlate the peak amplitude to the bolt axial load. The TI bypasses the need for more complex signal processing required in other energy-based methods. A coupled, electro-mechanical analysis with elasto-plastic finite element method was used to simulate and analyze the PZT based ultrasonic wave propagation through the interface of two steel plates connected by a single nut and bolt connection. Numerical results, backed by experimental results from testing on a bolted connection between two steel plates, revealed that the peak amplitude of the focused signal increases as the bolt preload (torque level) increases due to the enlarging true contact area of the steel plates. The amplitude of the focused peak saturates and the TI reaches unity as the bolt axial load reaches a threshold value. These conditions are associated with the maximum possible true contact area between the surfaces of the bolted connection.

Experimental and numerical analysis of clamped joints in front motorbike suspensions

NASA Astrophysics Data System (ADS)

Croccolo, D.; de Agostinis, M.; Vincenzi, N.

2010-06-01

Clamped joints are shaft-hub connections used, as an instance, in front motorbike suspensions to lock the steering plates with the legs and the legs with the wheel pin, by means of one or two bolts. The preloading force, produced during the tightening process, should be evaluated accurately, since it must lock safely the shaft, without overcoming the yielding point of the hub. Firstly, friction coefficients have been evaluated on “ad-hoc designed” specimens, by applying the Design of Experiment approach: the applied tightening torque has been precisely related to the imposed preloading force. Then, the tensile state of clamps have been evaluated both via FEM and by leveraging some design formulae proposed by the Authors as function of the preloading force and of the clamp geometry. Finally, the results have been compared to those given by some strain gauges applied on the tested clamps: the discrepancies between numerical analyses, the design formulae and the experimental results remains under a threshold of 10%.

Steel shear strength of anchors with stand-off base plates.

DOT National Transportation Integrated Search

2013-09-01

Sign and signal structures are often connected to concrete foundations through a stand-off annular base plate with a double-nut anchor bolt connection, which leaves exposed anchor bolt lengths below leveling nuts used in these connections. Cantilever...

Hexavalent Chrome Free Coatings for Electronics Electromagnetic Interference (EMI) Shielding Effectiveness (SE) Interim Test Report

NASA Technical Reports Server (NTRS)

Kessel, Kurt R.

2015-01-01

Test specimen configuration was provided by Parker Chomerics. The EMI gasket used in this project was Cho-Seal 6503E. Black oxide alloy steel socket head bolts were used to hold the plates together. Non-conductive spacers were used to control the amount of compression on the gaskets. The following test fixture specifications were provided by Parker Chomerics. The CHO-TP09 test plate sets selected for this project consist of two aluminum plates manufactured to the specifications detailed in CHO­-TP09. The first plate, referred to as the test frame, is illustrated in Figure 1. The test frame is designed with a cutout in the center and two alternating bolt patterns. One pattern is used to bolt the test frame to the corresponding test cover plate (Figure 2), forming a test plate set. The second pattern accepts the hardware used to mount the fully assembled test plate set to the main adapter plate (Figure 3).

Application of Long Expansion Rock Bolt Support in the Underground Mines of Legnica-Głogów Copper District

NASA Astrophysics Data System (ADS)

Skrzypkowski, Krzysztof; Korzeniowski, Waldemar; Zagórski, Krzysztof; Dudek, Piotr

2017-09-01

In the underground mines of the Legnica-Głogów Copper District (LGOM) the main way to protect the room excavation is the use of a rock bolt support. For many years, it has proven to be an efficient security measure in excavations which met all safety standards and requirements. The article presents the consumption of the rock bolt support in the Mining Department "Polkowice-Sieroszowice" in the years 2010-2015 as well as the number of bolt supports that were used to secure the excavations. In addition, it shows the percentage of bolt supports that were used to conduct rebuilding work and cover the surface of exposed roofs. One of the factors contributing to the loss of the functionality of bolt supports is corrosion whose occurrence may lead directly to a reduction in the diameter of rock bolt support parts, in particular rods, bearing plates and nuts. The phenomenon of the corrosion of the bolt support and its elements in underground mining is an extremely common phenomenon due to the favorable conditions for its development in mines, namely high temperature and humidity, as well as the presence of highly aggressive water. This involves primarily a decrease in the capacity of bolt support construction, which entails the need for its strengthening, and often the need to perform the reconstruction of the excavation. The article presents an alternative for steel bearing plates, namely plates made using the spatial 3D printing technology. Prototype bearing plates were printed on a 3D printer Formiga P100 using the "Precymit" material. The used printing technology was SLS (Selective Laser Sintering), which is one of the most widely used technologies among all the methods of 3D printing for the short series production of the technical parts of the final product. The article presents the stress-strain characteristic of the long expansion connected rock bolt support OB25 with a length of 3.65 m. A rock bolt support longer than 2.6 m is an additional bolt support in excavations, and it is increasingly frequently used to reinforce roofs and in rebuilding the underground mines of KGHM Polish Copper S.A. In order to conduct the laboratory tests that are most suitable for the mine conditions, and yet are carried out on a laboratory test facility, the Authors used a steel cylinder with an external diameter of 102 mm and a length of 600 mm, which was filled with a core of rock (dolomite) from the roofs of the mine workings. In addition the maximum load that took over the bolt support made of rods and connected with sleeves was determined. For the initial tension, the elastic and plastic range of the maximal displacements, which were measured by the rope encoder, were determined. The statical tests of the expansion rock bolt support were carried out at the laboratory of the Department of Underground Mining in simulated mine conditions. The test facility enables the study of the long bolt rods on a geometric scale of 1:1 for the different ways of fixing. The aim of the laboratory research was to obtain the stress-strain characteristics, of the long expansion rock bolt support with a steel bearing plate and a plate printed on a 3D printer.

Shape memory alloy-based moment connections with superior self-centering properties

NASA Astrophysics Data System (ADS)

Farmani, Mohammad Amin; Ghassemieh, Mehdi

2016-07-01

Superelastic shape memory alloys (SMAs) have the potential to create a spontaneous recentering mechanism on the connections of a structural system under seismic actions, which results in mitigation of the damage in the main structural members. In this article, innovative types of steel beam-to-column moment connections incorporating SMA bolts and plates are introduced and studied through a numerical approach. First, SMA bolted end-plate connection model is produced and analyzed by means of the finite element method to validate the numerical analysis against the prior experimental results. Then, the performance of eleven different end-plate moment connection models subjected to cyclic loading is investigated. By selecting the lower values for the moment capacity based on bolts strength in comparison to the flexural resistance of the beam, the plastic hinge is transferred from the beam section to the beam-column interface. Hence, employing superelastic materials at the connection interface could be potentially effective in providing the desired self-centering effect in the connection. To this end, the impact of utilizing superelastic SMA bolts and end-plates instead of using the conventional structural steel on the overall cyclic response of the connections is evaluated in this study. Results show that extended end-plate connections equipped with SMA bolts and end-plates, if properly proportioned and detailed, not only exhibit a clear reduction in the residual drifts after a seismic event, but also can meet the ductility requirements with good energy dissipation and sufficient stiffness.

Safe-haven locking device

DOEpatents

Williams, J.V.

1984-04-26

Disclosed is a locking device for eliminating external control of a secured space formed by fixed and movable barriers. The locking device uses externally and internally controlled locksets and a movable strike, operable from the secured side of the movable barrier, to selectively engage either lockset. A disengagement device, for preventing forces from being applied to the lock bolts is also disclosed. In this manner, a secured space can be controlled from the secured side as a safe-haven. 4 figures.

Bolt and nut evaluator

NASA Technical Reports Server (NTRS)

Kerley, James J. (Inventor); Burkhardt, Raymond (Inventor); White, Steven (Inventor)

1994-01-01

A device for testing fasteners such as nuts and bolts is described which consists of a fixed base plate having a number of threaded and unthreaded holes of varying size for receiving the fasteners to be tested, a torque marking paper taped on top the fixed base plate for marking torque-angle indicia, a torque wrench for applying torque to the fasteners being tested, and an indicator for showing the torque applied to the fastener. These elements provide a low cost, nondestructive device for verifying the strength of bolts and nuts.

Experimental analysis of thread movement in bolted connections due to vibrations

NASA Technical Reports Server (NTRS)

Ramsey, G. ED; Jenkins, Robert C.

1995-01-01

This is the final report of research project NAS8-39131 #33 sponsored by NASA's George C. Marshall Space Flight Center (MSFC) and carried out by the Civil Engineering Department of Auburn University (Auburn, Alabama) and personnel of MSFC. The objective of this study was to identify the main design parameters contributing to the loosening of bolts due to vibration and to identify their relative importance and degree of contribution to bolt loosening. Vibration testing was conducted on a shaketable with a controlled-random input in the dynamic testing laboratory of the Structural Test Division of MSFC. Test specimens which contained one test bolt were vibrated for a fixed amount of time and a percentage of pre-load loss was measured. Each specimen tested implemented some combination of eleven design parameters as dictated by the design of experiment methodology employed. The eleven design parameters were: bolt size (diameter), lubrication on bolt, hole tolerance, initial pre-load, nut locking device, grip length, thread pitch, lubrication between mating materials, class of fit, joint configuration, and mass of configuration. These parameters were chosen for this experiment because they are believed to be the design parameters having the greatest impact on bolt loosening. Two values of each design parameter were used and each combination of parameters tested was subjected to two different directions of vibration and two different g-levels of vibration. One replication was made for each test to gain some indication of experimental error and repeatability and to give some degree of statistical credibility to the data, resulting in a total of 96 tests being performed. The results of the investigation indicated that nut locking devices, joint configuration, fastener size, and mass of configuration were significant in bolt loosening due to vibration. The results of this test can be utilized to further research the complex problem of bolt loosening due to vibration.

Distal tibia fractures: locked or non-locked plating? A systematic review of outcomes.

PubMed

Khalsa, Amrit S; Toossi, Nader; Tabb, Loni P; Amin, Nirav H; Donohue, Kenneth W; Cerynik, Douglas L

2014-06-01

Although plating is considered to be the treatment of choice in distal tibia fractures, controversies abound regarding the type of plating for optimal fixation. We conducted a systematic review to evaluate and compare the outcomes of locked plating and non-locked plating in treatment of distal tibia fractures. A systematic review was conducted using PubMed to identify articles on the outcomes of plating in distal tibia fractures that were published up to June 2012. We included English language articles involving a minimum of 10 adult cases with acute fractures treated using single-plate, minimally invasive techniques. Study-level binomial regression on the pooled data was conducted to determine the effect of locking status on different outcomes, adjusted for age, sex, and other independent variables. 27 studies met the inclusion criteria and were included in the final analysis of 764 cases (499 locking, 265 non-locking). Based on descriptive analysis only, delayed union was reported in 6% of cases with locked plating and in 4% of cases with non-locked plating. Non-union was reported in 2% of cases with locked plating and 3% of cases with non-locked plating. Comparing locked and non-locked plating, the odds ratio (OR) for reoperation was 0.13 (95% CI: 0.03-0.57) and for malalignment it was 0.10 (95% CI: 0.02-0.42). Both values were statistically significant. This study showed that locked plating reduces the odds of reoperation and malalignment after treatment for acute distal tibia fracture. Future studies should accurately assess causality and the clinical and economic impact of these findings.

PWR integral tie plate and locking mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flora, B.S.; Osborne, J.L.

1980-08-26

A locking mechanism for securing an upper tie plate to the tie rods of a nuclear fuel bundle is described. The mechanism includes an upper tie plate assembly and locking sleeves fixed to the ends of the tie rods. The tie plate is part of the upper tie plate assembly and is secured to the fuel bundle by securing the entire upper tie plate assembly to the locking sleeves fixed to the tie rods. The assembly includes, in addition to the tie plate, locking nuts for engaging the locking sleeves, retaining sleeves to operably connect the locking nuts to themore » assembly, a spring biased reaction plate to restrain the locking nuts in the locked position and a means to facilitate the removal of the entire assembly as a unit from the fuel bundle.« less

Nondestructive ultrasonic measurement of bolt preload using the pulsed-phase locked-loop interferometer

NASA Technical Reports Server (NTRS)

Allison, S. G.; Heyman, J. S.

1985-01-01

Achieving accurate preload in threaded fasteners is an important and often critical problem which is encountered in nearly all sectors of government and industry. Conventional tensioning methods which rely on torque carry with them the disadvantage of requiring constant friction in the fastener in order to accurately correlate torque to preload. Since most of the applied torque typically overcomes friction rather than tensioning the fastener, small variations in friction can cause large variations in preload. An instrument called a pulsed phase locked loop interferometer, which was recently developed at NASA Langley, has found widespread use for measurement of stress as well as material properties. When used to measure bolt preload, this system detects changes in the fastener length and sound velocity which are independent of friction. The system is therefore capable of accurately establishing the correct change in bolt tension. This high resolution instrument has been used for precision measurement of preload in critical fasteners for numerous applications such as the space shuttle landing gear and helicopter main rotors.

Biomechanical comparison of locked versus non-locked symphyseal plating of unstable pelvic ring injuries.

PubMed

Godinsky, R J; Vrabec, G A; Guseila, L M; Filipkowski, D E; Elias, J J

2018-04-01

Locked symphyseal plates are utilized to provide higher levels of construct stiffness than non-locked plates. The current biomechanical study was performed to compare stiffness at the pubic symphysis between locked and non-locked plating systems. Synthetic models were utilized to represent injury to the pelvis and symphyseal plating combined with a sacro-iliac screw. Seven models were evaluated with plates and locking screws, and seven were evaluated with non-locking screws. Single limb stance was simulated, with all models loaded for 1000 cycles with 350 N applied at the sacrum. Two pairs of markers crossing the symphysis were tracked with a video-based tracking system. A coordinate system was developed to quantify motion between the pairs in three directions: medial-lateral gap, anterior-posterior shear translation, and superior-inferior shear translation. Significant differences between the plating systems were identified with t tests (p < 0.05). Anterior-posterior shear translation varied significantly between the two plating systems. From cycles 100 to 1000, average shear translation for the non-locked and locked systems was ~0.7 and 0.3 mm, respectively, at the markers closest to the plate and 2.2 and 1.4 mm, respectively, at the markers further from the plate. Motion in the other two directions did not differ significantly between locked and non-locked models. Locked symphyseal plating systems can provide better stability than non-locked systems for anterior-posterior shear translation. More stability could potentially reduce the risk of failure of the plate or screws.

Comparative evaluation of 2.3 mm locking plate system vs conventional 2.0 mm non locking plate system for mandibular condyle fracture fixation: a seven year retrospective study.

PubMed

Zhang, J; Wang, X; Wu, R-H; Zhuang, Q-W; Gu, Q P; Meng, J

2015-01-01

This retrospective study evaluated the efficacy of a 2.3 mm locking plate/screw system compared with a 2.0-mm non-locking plate/screw system in fixation of isolated non comminuted mandibular condyle fractures. Surgical records of 101 patients who received either a 2.3 mm locking plate (group A, n = 51) or 2.0 mm non locking plate (group B, n = 50) were analyzed. All patients were followed up to a minimum of 6 months postoperatively and evaluated for hardware related complications, occlusal stability, need for and duration of MMF and mandibular functional results. Four complications occurred in the locking group and eighteen in the non locking group with complication rates equalling 8% and 36% respectively. When comparing the overall results according to plates used, the χ2 test showed a statistically significant difference between the locking and non locking plates (p < 0.001). Fewer patients required postoperative MMF in group A. Mandibular condyle fractures treated with a 2.3 mm locking plate exhibited stable osteosynthesis, were associated with minimal complications and resulted in acceptable mandibular range of motion compared with a 2.0 mm non locking plate.

Distal tibia fractures: locked or non-locked plating?

PubMed Central

Khalsa, Amrit S; Toossi, Nader; Tabb, Loni P; Amin, Nirav H; Donohue, Kenneth W; Cerynik, Douglas L

2014-01-01

Background and purpose Although plating is considered to be the treatment of choice in distal tibia fractures, controversies abound regarding the type of plating for optimal fixation. We conducted a systematic review to evaluate and compare the outcomes of locked plating and non-locked plating in treatment of distal tibia fractures. Patients and methods A systematic review was conducted using PubMed to identify articles on the outcomes of plating in distal tibia fractures that were published up to June 2012. We included English language articles involving a minimum of 10 adult cases with acute fractures treated using single-plate, minimally invasive techniques. Study-level binomial regression on the pooled data was conducted to determine the effect of locking status on different outcomes, adjusted for age, sex, and other independent variables. Results 27 studies met the inclusion criteria and were included in the final analysis of 764 cases (499 locking, 265 non-locking). Based on descriptive analysis only, delayed union was reported in 6% of cases with locked plating and in 4% of cases with non-locked plating. Non-union was reported in 2% of cases with locked plating and 3% of cases with non-locked plating. Comparing locked and non-locked plating, the odds ratio (OR) for reoperation was 0.13 (95% CI: 0.03–0.57) and for malalignment it was 0.10 (95% CI: 0.02–0.42). Both values were statistically significant. Interpretation This study showed that locked plating reduces the odds of reoperation and malalignment after treatment for acute distal tibia fracture. Future studies should accurately assess causality and the clinical and economic impact of these findings. PMID:24758325

Biomechanical comparison of double-row locking plates versus single- and double-row non-locking plates in a comminuted metacarpal fracture model.

PubMed

Gajendran, Varun K; Szabo, Robert M; Myo, George K; Curtiss, Shane B

2009-12-01

Open or unstable metacarpal fractures frequently require open reduction and internal fixation. Locking plate technology has improved fixation of unstable fractures in certain settings. In this study, we hypothesized that there would be a difference in strength of fixation using double-row locking plates compared with single- and double-row non-locking plates in comminuted metacarpal fractures. We tested our hypothesis in a gap metacarpal fracture model simulating comminution using fourth-generation, biomechanical testing-grade composite sawbones. The metacarpals were divided into 6 groups of 15 bones each. Groups 1 and 4 were plated with a standard 6-hole, 2.3-mm plate in AO fashion. Groups 2 and 5 were plated with a 6-hole double-row 3-dimensional non-locking plate with bicortical screws aimed for convergence. Groups 3 and 6 were plated with a 6-hole double-row 3-dimensional locking plate with unicortical screws. The plated metacarpals were then tested to failure against cantilever apex dorsal bending (groups 1-3) and torsion (groups 4-6). The loads to failure in groups 1 to 3 were 198 +/- 18, 223 +/- 29, and 203 +/- 19 N, respectively. The torques to failure in groups 4 to 6 were 2,033 +/- 155, 3,190 +/- 235, and 3,161 +/- 268 N mm, respectively. Group 2 had the highest load to failure, whereas groups 5 and 6 shared the highest torques to failure (p < .05). Locking and non-locking double-row plates had equivalent bending and torsional stiffness, significantly higher than observed for the single-row non-locking plate. No other statistical differences were noted between groups. When subjected to the physiologically relevant forces of apex dorsal bending and torsion in a comminuted metacarpal fracture model, double-row 3-dimensional non-locking plates provided superior stability in bending and equivalent stability in torsion compared with double-row 3-dimensional locking plates, whereas single-row non-locking plates provided the least stability.

Update on slip and wear in multi-layer azimuth track systems

NASA Astrophysics Data System (ADS)

Juneja, Gunjeet; Kan, Frank W.; Antebi, Joseph

2006-06-01

Many antennas, such as the 100-m Green Bank Telescope, use a wheel-on-track systems in which the track segments consist of wear plates mounted on base plates. The wear plates are typically 2 to 3 inches thick and are case hardened or through hardened. The base plates are usually 3 to 4 times thicker than the wear plates and are not hardened. The wear plates are typically connected to the base plates using bolts. The base plates are supported on grout and anchored to the underlying concrete foundation. For some antennas, slip has been observed between the wear plate and base plate, and between the base plate and the grout, with the migration in the wheel rolling direction. In addition, there has been wear at the wear plate/base plate interface. This paper is an update on the evaluation of GBT track retrofit. The paper describes the use of three-dimensional non-linear finite element analyses to understand and evaluate the behavior of (1) the existing GBT wheel-on-track system with mitered joints, and (2) the various proposed modifications. The modifications include welding of the base plate joints, staggering of the wear plate joints from the base plate joints, changing thickness of the wear plate, and increasing bolt diameter and length. Parameters included in the evaluation were contact pressure, relative slip, wear at the wear plate/base plate interface, and bolt shears and moments.

78 FR 69595 - Airworthiness Directives; AgustaWestland S.p.A. (Type Certificate Formerly Held by Agusta S.p.A...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-20

... require recurring visual inspections of the tail rotor (T/R) blade retaining bolts (bolts) for a crack, corrosion, damage, or missing cadmium plating in the central part of the bolt. If a crack is not detected by.... Replacing a cracked or damaged bolt would be required before further flight. This proposed AD is prompted by...

Fatigue-Arrestor Bolts

NASA Technical Reports Server (NTRS)

Onstott, Joseph W.; Gilster, Mark; Rodriguez, Sergio; Larson, John E.; Wickham, Mark D.; Schoonover, Kevin E.

1995-01-01

Bolts that arrest (or, more precisely, retard) onset of fatigue cracking caused by inelastic strains developed. Specifically developed to be installed in flange holes of unrestrained rocket engine nozzle. Fanges sometimes used to bolt nozzle to test stand; however, when rocket engine operated without this restraint, region around bolt holes experience severe inelastic strains causing fatigue cracking. Interference fits introduce compressive preloads that retard fatigue by reducing ranges of strains. Principle of these fatigue-arrestor bolts also applicable to holes in plates made of other materials and/or used for different purposes.

Full-Scale Evaluation of DuraDeck (registered trademark) and MegaDeck (trademark) Matting Systems

DTIC Science & Technology

2013-07-01

plates studded with threaded bolts were placed ERDC/GSL TR-13-27 10 underneath two pre-drilled corners of the panel. The plates were positioned so...metal plates studded with threaded ERDC/GSL TR-13-27 4 Figure 1. DuraDeck® mat panel, top surface. Figure 2. DuraDeck® mat panel, bottom surface...ERDC/GSL TR-13-27 5 bolts , as shown in Figure 3, underneath the mat corners and then installing special connector nuts from the top surface

Improved Direct Methanol Fuel Cell Stack

DOEpatents

Wilson, Mahlon S.; Ramsey, John C.

2005-03-08

A stack of direct methanol fuel cells exhibiting a circular footprint. A cathode and anode manifold, tie-bolt penetrations and tie-bolts are located within the circular footprint. Each fuel cell uses two graphite-based plates. One plate includes a cathode active area that is defined by serpentine channels connecting the inlet and outlet cathode manifold. The other plate includes an anode active area defined by serpentine channels connecting the inlet and outlet of the anode manifold, where the serpentine channels of the anode are orthogonal to the serpentine channels of the cathode. Located between the two plates is the fuel cell active region.

Development of Anti-Loosening Performance of Hyper Lock Nut

NASA Astrophysics Data System (ADS)

Nishiyama, Shuji; Migita, Hiroaki; Kataoka, Mitumasa; Nakasaki, Nobuyuki; Murano, Kohshi

Bolted joints are widely used in mechanical structures as they allow easy disassembly for maintenance without high cost. However, vibration-induced loosening due to dynamic loading remains a long-unresolved issue. We have developed a new type of nut named the hyper lock nut (HLN) that offers anti-loosening performance without a complicated tightening process and tools. In this study, we investigated the mechanisms of joints bolted with the HLN, and tightening behavior was analyzed using the three-dimensional finite element method. The analytical results were compared with the experimental results for the HLN, and close qualitative agreement was observed between the two with respect to displacement, tightening force and tightening torque. We found a number of new aspects and plus points for joints bolted with the HLN in comparison to those fastened with JIS standard nuts. It was found that the tightening torque of the HLN is higher than that of JIS standard nuts, and that satisfactory anti-loosening performance can be realized through the thread contact force at the slit region and the angular face of the bearing surface.

Jam proof closure assembly for lidded pressure vessels

DOEpatents

Cioletti, Olisse C.

1992-01-01

An expendable closure assembly is provided for use (in multiple units) with a lockable pressure vessel cover along its rim, such as of an autoclave. This assembly is suited to variable compressive contact and locking with the vessel lid sealing gasket. The closure assembly consists of a thick walled sleeve insert for retention in the under bores fabricated in the cover periphery and the sleeve is provided with internal threading only. A snap serves as a retainer on the underside of the sleeve, locking it into an under bore retention channel. Finally, a standard elongate externally threaded bolt is sized for mating cooperation with the so positioned sleeve, whereby the location of the bolt shaft in the cover bore hole determines its compressive contact on the underlying gasket.

Pressure-welded flange assembly provides leaktight seal at reduced bolt loads

NASA Technical Reports Server (NTRS)

Martenson, A. J.

1966-01-01

Vibration resistant flange-connector assembly provides a leaktight seal under reduced bolt loads. The assembly consists of ductile metal plates that are pressure welded between dies mounted in recessed flanges.

Failure analysis of single-bolted joint for lightweight composite laminates and metal plate

NASA Astrophysics Data System (ADS)

Li, Linjie; Qu, Junli; Liu, Xiangdong

2018-01-01

A three-dimensional progressive damage model was developed in ANSYS to predict the damage accumulation of single bolted joint in composite laminates under in-plane tensile loading. First, we describe the formulation and algorithm of this model. Second, we calculate the failure loads of the joint in fibre reinforced epoxy laminated composite plates and compare it with the experiment results, which validates that our model can appropriately simulate the ultimate tensile strength of the joints and the whole process of failure of structure. Finally, this model is applied to study the failure process of the light-weight composite material (USN125). The study also has a great potential to provide a strong basis for bolted joints design in composite Laminates as well as a simple tool for comparing different laminate geometries and bolt arrangements.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muresan, Ioana Cristina; Balc, Roxana

Beam-to-column end-plate bolted connections are usually used as moment-resistant connections in steel framed structures. For this joint type, the deformability is governed by the deformation capacity of the column flange and end-plate under tension and elongation of the bolts. All these elements around the beam tension flange form the tension region of the joint, which can be modeled by means of equivalent T-stubs. In this paper a beam-to-column end-plate bolted connection is substituted with a T-stub of appropriate effective length and it is analyzed using the commercially available finite element software ABAQUS. The performance of the model is validated bymore » comparing the behavior of the T-stub from the numerical simulation with the behavior of the connection as a whole. The moment-rotation curve of the T-stub obtained from the numerical simulation is compared with the behavior of the whole extended end-plate connection, obtained by numerical simulation, experimental tests and analytical approach.« less

ACES. Accelerated Corrosion Expert Simulator

DTIC Science & Technology

2010-02-01

Composites Coating Systems Organic Inorganic Ceramic Materials 22 Inputs and Dimensions Xi Thickness Hardness Strength Ductility Abrasion Resistance...GPU 25 T-Handle Latch 10-Year ACT Material/ Coating Configuration Die Cast Zinc T-Handle Carbon Steel Pin CS Shank CS T-Washer Carbon Steel Dish E- coat ...CARC Zinc Plating Cadmium Plated BoltE- coat /CARC CS Panel CS Panel O-Ring E- coat /CARC Original (10-year ACT) Design Green Flag Color Qualitative

46 CFR 56.20-9 - Valve construction.

Code of Federal Regulations, 2010 CFR

2010-10-01

... closed. (b) Valves of Class I piping systems (for restrictions in other classes refer to sections on low temperature service), having diameters exceeding 2 inches must have bolted, pressure seal, or breech lock...

Randomised controlled trial of the sliding hip screw versus X-Bolt Dynamic Hip Plating System for the fixation of trochanteric fractures of the hip in adults: a protocol study for WHiTE 4 (WHiTE4).

PubMed

Griffin, Xavier L; Achten, Juul; Sones, William; Cook, Jonathan; Costa, Matthew L

2018-01-26

Sliding hip screw fixation is well established in the treatment of trochanteric fractures of the hip. The X-Bolt Dynamic Hip Plating System builds on the successful design features of the sliding hip screw but differs in the nature of the fixation in the femoral head. A randomised pilot study suggested that the X-bolt Dynamic Hip Plating System might provide similar health-related quality of life while reducing the risk of revision surgery when compared with the sliding hip screw. This is the protocol for a multicentre randomised trial of sliding hip screw versus X-Bolt Dynamic Hip Plating System for patients 60 years and over treated for a trochanteric fracture of the hip. Multicentre, multisurgeon, parallel, two-arm, randomised controlled trial. Patients aged 60 years and older with a trochanteric hip fracture are potentially eligible. Participants will be randomly allocated on a 1:1 basis to either sliding hip screw or X-Bolt Dynamic Hip Plating System. Otherwise, all care will be in accordance with National Institute for Health and Care Excellence guidance. A minimum of 1128 patients will be recruited to obtain 90% power to detect a 0.075-point difference in EuroQol-5D health-related quality of life at 4 months postrandomisation. Secondary outcomes include mortality, residential status, revision surgery and radiographic measures. The treatment effect will be estimated using a two-sided t-test adjusted for age, gender and cognitive impairment based on an intention-to-treat analysis. National Research Ethics Committee approved this study on 5 February 2016 (16/WM/0001). The study is sponsored by the University of Oxford and funded through an investigator initiated grant by X-Bolt Orthopaedics. A manuscript for a high-impact peer-reviewed journal will be prepared, and the results will be disseminated to patients through local mechanisms at participating centres. ISRCTN92825709. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Angular stable lateral plating is a valid alternative to conventional plate fixation in the proximal phalanx. A biomechanical study.

PubMed

Shanmugam, R; Ernst, M; Stoffel, K; Fischer, M F; Wahl, D; Richards, R G; Gueorguiev, B

2015-06-01

Dorsal plating is commonly used in proximal phalanx fractures but it bears the risk of interfering with the extensor apparatus. In this study, dorsal and lateral plating fixation methods are compared to assess biomechanical differences using conventional 1.5mm non-locking plates and novel 1.3mm lateral locking plates. Twenty-four fresh frozen human cadaveric proximal phalanges were equally divided into four groups. An osteotomy was set at the proximal metaphyseal-diaphyseal junction and fixed with either dorsal (group A) or lateral (group B) plating using a 1.5mm non-locking plate, or lateral plating with a novel 1.3mm locking plate with bicortical (group C) or unicortical (group D) screws. The specimens were loaded in axial, dorsovolar and mediolateral direction to assess fixation stiffness followed by a cyclic destructive test in dorsovolar loading direction. Axial stiffness was highest in group D (mean 321.02, SEM 21.47N/mm) with a significant difference between groups D and B (P=0.033). Locking plates (groups C and D) were stiffer than non-locking plates under mediolateral loading (P=0.007), no significant differences were noted under dorsovolar loading. Furthermore, no significant differences were observed under cyclic loading to failure between any of the study groups. No considerable biomechanical advantage of using a conventional 1.5mm dorsal non-locking plate was identified over the novel 1.3mm lateral locking plate in the treatment of proximal phalanx fractures. Since the novel low-profile plate is less disruptive to the extensor mechanism, it should be considered as a valid alternative. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluation of Bone Atrophy After Treatment of Forearm Fracture Using Nonlinear Finite Element Analysis: A Comparative Study of Locking Plates and Conventional Plates.

PubMed

Matsuura, Yusuke; Rokkaku, Tomoyuki; Suzuki, Takane; Thoreson, Andrew Ryan; An, Kai-Nan; Kuniyoshi, Kazuki

2017-08-01

Forearm diaphysis fractures are usually managed by open reduction internal fixation. Recently, locking plates have been used for treatment. In the long-term period after surgery, some patients present with bone atrophy adjacent to the plate. However, a comparison of locking and conventional plates as a cause of atrophy has not been reported. The aim of this study was to investigate long-term bone atrophy associated with use of locking and conventional plates for forearm fracture treatment. In this study we included 15 patients with forearm fracture managed by either locking or conventional plates and with more than 5 years of follow-up. Computed tomographic imaging of both forearms was performed to assess bone thickness and local bone mineral density and to predict bone strength without plate reinforcement based on finite element analysis. Mean patient age at surgery was 48.0 years. Eight patients underwent reduction with fixed locking plates and were followed up for a mean of 79.5 months; the remaining 7 patients were treated with conventional plates and were followed up for a mean of 105.0 months. Compared with the conventional plate group, the locking plate group had the same fractured limb-contralateral limb ratio of cortex bone thickness, but had significantly lower ratios of mineral density adjacent to the plate and adjusted bone strength. This study demonstrated bone atrophy after locking plate fixation for forearm fractures. Treatment plans for forearm fracture should take into consideration the impact of bone atrophy long after plate fixation. Therapeutic IV. Copyright © 2017 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

LagLoc - a new surgical technique for locking plate systems.

PubMed

Triana, Miguel; Gueorguiev, Boyko; Sommer, Christoph; Stoffel, Karl; Agarwal, Yash; Zderic, Ivan; Helfen, Tobias; Krieg, James C; Krause, Fabian; Knobe, Matthias; Richards, R Geoff; Lenz, Mark

2018-06-19

Treatment of oblique and spiral fractures remains challenging. The aim of this study was to introduce and investigate the new LagLoc technique for locked plating with generation of interfragmentary compression, combining the advantages of lag-screw and locking-head-screw techniques. Oblique fracture was simulated in artificial diaphyseal bones, assigned to three groups for plating with a 7-hole locking compression plate. Group I was plated with three locking screws in holes 1, 4 and 7. The central screw crossed the fracture line. In group II the central hole was occupied with a lag screw perpendicular to fracture line. Group III was instrumented applying the LagLoc technique as follows. Hole 4 was predrilled perpendicularly to the plate, followed by overdrilling of the near cortex and insertion of a locking screw whose head was covered by a holding sleeve to prevent temporarily the locking in the plate hole and generate interfragmentary compression. Subsequently, the screw head was released and locked in the plate hole. Holes 1 and 7 were occupied with locking screws. Interfragmentary compression in the fracture gap was measured using pressure sensors. All screws in the three groups were tightened with 4Nm torque. Interfragmentary compression in group I (167 ± 25N) was significantly lower in comparison to groups II (431 ± 21N) and III (379 ± 59N), p≤0.005. The difference in compression between groups II and III remained not significant (p = 0.999). The new LagLoc technique offers an alternative tool to generate interfragmentary compression with the application of locking plates by combining the biomechanical advantages of lag screw and locking screw fixations. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Rotation Capacity of Bolted Flush End-Plate Stiffened Beam-to-Column Connection

NASA Astrophysics Data System (ADS)

Ostrowski, Krzysztof; Kozłowski, Aleksander

2017-06-01

One of the flexibility parameters of semi-rigid joints is rotation capacity. Plastic rotation capacity is especially important in plastic design of framed structures. Current design codes, including Eurocode 3, do not posses procedures enabling designers to obtain value of rotation capacity. In the paper the calculation procedure of the rotation capacity for stiffened bolted flush end-plate beam-to-column connections has been proposed. Theory of experiment design was applied with the use of Hartley's PS/DS-P:Ha3 plan. The analysis was performed with the use of finite element method (ANSYS), based on the numerical experiment plan. The determination of maximal rotation angle was carried out with the use of regression analysis. The main variables analyzed in parametric study were: pitch of the bolt "w" (120-180 mm), the distance between the bolt axis and the beam upper edge cg1 (50-90 mm) and the thickness of the end-plate tp (10-20 mm). Power function was proposed to describe available rotation capacity of the joint. Influence of the particular components on the rotation capacity was also investigated. In the paper a general procedure for determination of rotation capacity was proposed.

Sobol's sensitivity analysis for a fuel cell stack assembly model with the aid of structure-selection techniques

NASA Astrophysics Data System (ADS)

Zhang, Wei; Cho, Chongdu; Piao, Changhao; Choi, Hojoon

2016-01-01

This paper presents a novel method for identifying the main parameters affecting the stress distribution of the components used in assembly modeling of proton exchange membrane fuel cell (PEMFC) stack. This method is a combination of an approximation model and Sobol's method, which allows a fast global sensitivity analysis for a set of uncertain parameters using only a limited number of calculations. Seven major parameters, i.e., Young's modulus of the end plate and the membrane electrode assembly (MEA), the contact stiffness between the MEA and bipolar plate (BPP), the X and Y positions of the bolts, the pressure of each bolt, and the thickness of the end plate, are investigated regarding their effect on four metrics, i.e., the maximum stresses of the MEA, BPP, and end plate, and the stress distribution percentage of the MEA. The analysis reveals the individual effects of each parameter and its interactions with the other parameters. The results show that the X position of a bolt has a major influence on the maximum stresses of the BPP and end plate, whereas the thickness of the end plate has the strongest effect on both the maximum stress and the stress distribution percentage of the MEA.

Design of a Combined Ballistic Simulator and Primer Force Experimental Fixture

DTIC Science & Technology

2015-08-01

preload bolt and breech, and between the breech and chamber, were found to be too loose. When heavy grease or Teflon tape was used to tighten the...increase the difficulty of removing and tightening the breech. The preload bolt does not have to be removed between firing and in future designs could use... tightened it could loosen the primer plate, so left-handed threads were machined on the primer plate. The ballistic simulator fixture was occasionally

High voltage feedthrough bushing

DOEpatents

Brucker, John P.

1993-01-01

A feedthrough bushing for a high voltage diode provides for using compression sealing for all sealing surfaces. A diode assembly includes a central conductor extending through the bushing and a grading ring assembly circumferentially surrounding and coaxial with the central conductor. A flexible conductive plate extends between and compressively seals against the central conductor and the grading ring assembly, wherein the flexibility of the plate allows inner and outer portions of the plate to axially translate for compression sealing against the central conductor and the grading ring assembly, respectively. The inner portion of the plate is bolted to the central conductor for affecting sealing. A compression beam is also bolted to the central conductor and engages the outer portion of the plate to urge the outer portion toward the grading ring assembly to obtain compression sealing therebetween.

Low-Thermal-Resistance Baseplate Mounting

NASA Technical Reports Server (NTRS)

Perreault, W. T.

1984-01-01

Low-thermal-resistance mounting achieved by preloading baseplate to slight convexity with screws threaded through beam. As mounting bolts around edge of base-place tightened, baseplate and cold plate contact first in center, with region of intimate contact spreading outward as bolts tightened.

Orthodontic skeletal anchorage using a palatal external plate.

PubMed

Kobayashi, Masaru; Fushima, Kenji

2014-03-01

We have developed the Anchor-Lock external plate system, which is fitted on the palate for the purpose of orthodontic skeletal anchorage. The aim of this study was to introduce the Anchor-Lock and assess its success rate. The Anchor-Lock is composed of titanium screws of 2·0-mm diameter and a titanium plate of 1·0-mm thickness. The external plate is rigidly interlocked with the heads of the screws, which are implanted trans-mucosally into palatal bone. Three types of Anchor-Lock are available. These were applied to 137 orthodontic patients (104 females and 33 males) aged 10-54 years. Two types of plate were used, a straight-shaped plate applied to the hard palate and to the anterior palate and a double-Y-shaped plate applied after tooth-borne rapid maxillary expansion. Success rate of the Anchor-Lock was 92·0% overall. No significant difference in success rate was found by age or sex of patients. Type or screw length of the Anchor-Lock did not affect success rate significantly. Success rate was significantly increased by the use of the surgical stent. The Anchor-Lock was effectively applied to distalize and/or intrude the upper molars. The Anchor-Lock system appears suitable for clinical use as an alternative to conventional screw- and plate-type orthodontic implants.

Comparison of modern locked plating and antiglide plating for fixation of osteoporotic distal fibular fractures.

PubMed

Switaj, Paul J; Wetzel, Robert J; Jain, Neel P; Weatherford, Brian M; Ren, Yupeng; Zhang, Li-Qun; Merk, Bradley R

2016-09-01

Fractures in osteoporotic patients can be difficult to treat because of poor bone quality and inability to gain screw purchase. The purpose of this study is to compare modern lateral periarticular distal fibula locked plating to antiglide plating in the setting of an osteoporotic, unstable distal fibula fracture. AO/OTA 44-B2 distal fibula fractures were created in sixteen paired fresh frozen cadaveric ankles and fixed with a lateral locking plate and an independent lag screw or an antiglide plate with a lag screw through the plate. The specimens underwent stiffness, cyclic loading, and load to failure testing. The energy absorbed until failure, torque to failure, construct stiffness, angle at failure, and energy at failure was recorded. The lateral locking construct had a higher torque to failure (p=0.02) and construct stiffness (p=0.04). The locking construct showed a trend toward increased angle at failure, but did not reach statistical significance (p=0.07). Seven of the eight lateral locking plate specimens failed through the distal locking screws, while the antiglide plating construct failed with pullout of the distal screws and displacement of the fracture in six of the eight specimens. In our study, the newly designed distal fibula periarticular locking plate with increased distal fixation is biomechanically stronger than a non-locking one third tubular plate applied in antiglide fashion for the treatment of AO/OTA 44-B2 osteoporotic distal fibula fractures. V: This is an ex-vivo study performed on cadavers and is not a study performed on live patients. Therefore, this is considered Level V evidence. Copyright © 2015. Published by Elsevier Ltd.

Dynamic Locked Plating of Distal Femur Fractures.

PubMed

Linn, Michael S; McAndrew, Christopher M; Prusaczyk, Beth; Brimmo, Olubusola; Ricci, William M; Gardner, Michael J

2015-10-01

Nonunion after locked bridge plating of comminuted distal femur fractures is not uncommon. "Dynamic" locked plating may create an improved mechanical environment, thereby achieving higher union rates than standard locked plating constructs. Academic Level 1 Trauma Center. Twenty-eight patients with comminuted supracondylar femur fractures treated with either dynamic or standard locked plating. Dynamic plating was achieved using an overdrilling technique of the near cortex to allow for a 0.5-mm "halo" around the screw shaft at the near cortex. Standard locked plating was done based on manufacturer's suggested technique. The patients treated with dynamic plating were matched 1:1 with those treated with standard locked plating based on OTA classification and working length. Three blinded observers made callus measurements on 6-week radiographs using a 4-point ordinal scale. The results were analyzed using a 2-tailed t test and 2-way intraclass correlations. The dynamic plating group had significantly greater callus (2.0; SD, 0.7) compared with the control group (1.3: SD, 0.8, P = 0.048) with substantial agreement amongst observers in both consistency (0.724) and absolute score (0.734). With dynamic plating group, 1 patient failed to unite, versus three in the control group (P = 0.59). The dynamic group had a mean change in coronal plane alignment of 0.5 degrees (SD, 2.6) compared with 0.6 (SD, 3.0) for the control group (P = 0.9) without fixation failure in either group. Overdrilling the near cortex in metaphyseal bridge plating can be adapted to standard implants to create a dynamic construct and increase axial motion. This technique seems to be safe and leads to increased callus formation, which may decrease nonunion rates seen with standard locked plating. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Biomechanical effect of the configuration of screw hole style on locking plate fixation in proximal humerus fracture with a simulated gap: A finite element analysis.

PubMed

Zhang, Ya-Kui; Wei, Hung-Wen; Lin, Kang-Ping; Chen, Wen-Chuan; Tsai, Cheng-Lun; Lin, Kun-Jhih

2016-06-01

Locking plate fixation for proximal humeral fractures is a commonly used device. Recently, plate breakages were continuously reported that the implants all have a mixture of holes allowing placement of both locking and non-locking screws (so-called combi plates). In commercialized proximal humeral plates, there still are two screw hole styles included "locking and dynamic holes separated" and "locking hole only" configurations. It is important to understand the biomechanical effect of different screw hole style on the stress distribution in bone plate. Finite element method was employed to conduct a computational investigation. Three proximal humeral plate models with different screw hole configurations were reconstructed depended upon an identical commercialized implant. A three-dimensional model of a humerus was created using process of thresholding based on the grayscale values of the CT scanning of an intact humerus. A "virtual" subcapital osteotomy was performed. Simulations were performed under an increasing axial load. The von Mises stresses around the screw holes of the plate shaft, the construct stiffness and the directional displacement within the fracture gap were calculated for comparison. The mean value of the peak von Mises stresses around the screw holes in the plate shaft was the highest for combi hole design while it was smallest for the locking and dynamic holes separated design. The stiffness of the plate-bone construct was 15% higher in the locking screw only design (132.6N/mm) compared with the combi design (115.0N/mm), and it was 4% higher than the combi design for the locking and dynamic holes separated design (119.5N/mm). The displacement within the fracture gap was greatest in the combi hole design, whereas it was smallest for the locking hole only design. The computed results provide a possible explanation for the breakages of combi plates revealed in clinical reports. The locking and dynamic holes separated design may be a better configuration to reduce the risk of plate fracture. Copyright © 2016 Elsevier Ltd. All rights reserved.

The strength of polyaxial locking interfaces of distal radius plates.

PubMed

Hoffmeier, Konrad L; Hofmann, Gunther O; Mückley, Thomas

2009-10-01

Currently available polyaxial locking plates represent the consequent enhancement of fixed-angle, first-generation locking plates. In contrast to fixed-angle locking plates which are sufficiently investigated, the strength of the new polyaxial locking options has not yet been evaluated biomechanically. This study investigates the mechanical strength of single polyaxial interfaces of different volar radius plates. Single screw-plate interfaces of the implants Palmar 2.7 (Königsee Implantate und Instrumente zur Osteosynthese GmbH, Allendorf, Germany), VariAx (Stryker Leibinger GmbH & Co. KG, Freiburg, Germany) und Viper (Integra LifeSciences Corporation, Plainsboro, NJ, USA) were tested by cantilever bending. The strength of 0 degrees, 10 degrees and 20 degrees screw locking angle was obtained during static and dynamic loading. The Palmar 2.7 interfaces showed greater ultimate strength and fatigue strength than the interfaces of the other implants. The strength of the VariAx interfaces was about 60% of Palmar 2.7 in both, static and dynamic loading. No dynamic testing was applied to the Viper plate because of its low ultimate strength. By static loading, an increase in screw locking angle caused a reduction of strength for the Palmar 2.7 and Viper locking interfaces. No influence was observed for the VariAx locking interfaces. During dynamic loading; angulation had no influence on the locking strength of Palmar 2.7. However, reduction of locking strength with increasing screw angulation was observed for VariAx. The strength of the polyaxial locking interfaces differs remarkably between the examined implants. Depending on the implant an increase of the screw locking angle causes a reduction of ultimate or fatigue strength, but not in all cases a significant impact was observed.

Vane segment support and alignment device

DOEpatents

McLaurin, L.D.; Sizemore, J.D.

1999-07-13

A support and alignment assembly for supporting and aligning a vane segment is provided. The support and alignment assembly comprises a torque plate which defines an opening for receiving an eccentric pin and a locking end member for receiving a lock socket member. An eccentric pin adjustably supported by the torque plate opening for supporting and aligning a vane segment is provided. A lock socket member adapted to securely receive the eccentric pin and rotated therewith, and adjustably engage the torque plate locking end is provided. The lock socket member receives the eccentric pin, such that when the eccentric pin is adjusted to align the vane segment, the lock socket member engages the torque plate locking end to secure the vane segment in the desired position. 5 figs.

Vane segment support and alignment device

DOEpatents

McLaurin, Leroy Dixon; Sizemore, John Derek

1999-01-01

A support and alignment assembly for supporting and aligning a vane segment is provided. The support and alignment assembly comprises a torque plate which defines an opening for receiving an eccentric pin and a locking end member for receiving a lock socket member. An eccentric pin adjustably supported by the torque plate opening for supporting and aligning a vane segment is provided. A lock socket member adapted to securely receive the eccentric pin and rotated therewith, and adjustably engage the torque plate locking end is provided. The lock socket member receives the eccentric pin, such that when the eccentric pin is adjusted to align the vane segment, the lock socket member engages the torque plate locking end to secure the vane segment in the desired position.

Percutaneous insertion of a proximal humeral locking plate: an anatomic study.

PubMed

Smith, Jason; Berry, Greg; Laflamme, Yves; Blain-Pare, Etienne; Reindl, Rudy; Harvey, Edward

2007-02-01

This cadaveric study sought to evaluate the feasibility of applying a locking proximal humerus plate with a novel minimally invasive technique. A unique pre-contoured locking plate was placed on cadaveric proximal humeri through a described minimally invasive approach. Proximity of the plate and screws to the axillary nerve and their respective surgical tracks were quantified. Safe screw hole placement with respect to the axillary nerve was determined. Risk of entrapment of the nerve beneath the plate was evaluated. Three of the holes near the middle of the locking plate consistently intersected the course of the axillary nerve and were unsafe for percutaneous placement of the screws. The axillary nerve could be palpated during the course of surgery and easily protected from injury. No entrapment of the axillary nerve occurred using this minimally invasive technique. The screw-in locking guide cannot be used with this technique as it caused tenting of the axillary nerve. Placement of a locking proximal humerus plate via a minimally invasive lateral trans-deltoid approach is safe if the locking screws are limited to superior and inferior holes. This can be done safely without entrapment of the axillary beneath the plate. Plate fixation of proximal humerus fractures may now be more desirable with the use of this approach.

Structural Analysis of the Redesigned Ice/Frost Ramp Bracket

NASA Technical Reports Server (NTRS)

Phillips, D. R.; Dawicke, D. S.; Gentz, S. J.; Roberts, P. W.; Raju, I. S.

2007-01-01

This paper describes the interim structural analysis of a redesigned Ice/Frost Ramp bracket for the Space Shuttle External Tank (ET). The proposed redesigned bracket consists of mounts for attachment to the ET wall, supports for the electronic/instrument cables and propellant repressurization lines that run along the ET, an upper plate, a lower plate, and complex bolted connections. The eight nominal bolted connections are considered critical in the summarized structural analysis. Each bolted connection contains a bolt, a nut, four washers, and a non-metallic spacer and block that are designed for thermal insulation. A three-dimensional (3D) finite element model of the bracket is developed using solid 10-node tetrahedral elements. The loading provided by the ET Project is used in the analysis. Because of the complexities associated with accurately modeling the bolted connections in the bracket, the analysis is performed using a global/local analysis procedure. The finite element analysis of the bracket identifies one of the eight bolted connections as having high stress concentrations. A local area of the bracket surrounding this bolted connection is extracted from the global model and used as a local model. Within the local model, the various components of the bolted connection are refined, and contact is introduced along the appropriate interfaces determined by the analysts. The deformations from the global model are applied as boundary conditions to the local model. The results from the global/local analysis show that while the stresses in the bolts are well within yield, the spacers fail due to compression. The primary objective of the interim structural analysis is to show concept viability for static thermal testing. The proposed design concept would undergo continued design optimization to address the identified analytical assumptions and concept shortcomings, assuming successful thermal testing.

[Comparative study on the strength of different mechanisms of operation of multidirectionally angle-stable distal radius plates].

PubMed

Rausch, S; Hoffmeier, K; Gueorguiev, B G; Klos, K; Gras, F; Hofmann, G O; Mückley, T

2011-12-01

Polyaxial angle-stable plating is thought to be particularly beneficial in the management of complex intra-articular fractures of the distal radius. The present study was performed to investigate the strength of polyaxial locking interfaces of distal radius plates. We tested the polyaxial interfaces of 3 different distal radius plates (2.4 mm Variable Angle LCP Two-Column Volar Distal Radius Plate, Synthes, Palmar Classic, Königsee Implantate and VariAx Plate Stryker). The strength of 0° and 10° screw locking angle was obtained during static loading. The strength of Palmar Classic with a 0° locking angle is significantly the best of all tested systems. With a 10° locking angle there is no significant difference between Palmar Classic, Two column Plate and VariAx Plate. The strength of polyaxial interfaces differs between the tested systems. A reduction of ultimate strength is due to increases of screw locking angle. The design of polyaxial locking interfaces should be investigated in human bone models. © Georg Thieme Verlag KG Stuttgart · New York.

Adult periarticular locking plates for the treatment of pediatric and adolescent subtrochanteric hip fractures.

PubMed

Sanders, Samuel; Egol, Kenneth A

2009-01-01

Two cases are presented in which adult, precontoured, lower-extremity periarticular locking plates were utilized for fixation of subtrochanteric femur fractures in pediatric patients. Recognition of the fact that a distal tibial locking plate in a small child and a proximal tibial locking plate in an adolescent anatomically ft the proximal femur in each case may provide a surgeon treating subtrochanteric hip fractures in this population increased options for operative stabilization.

Conduit grinding apparatus

DOEpatents

Nachbar, Henry D.; Korytkowski, Alfred S.

1991-01-01

A grinding apparatus for grinding the interior portion of a valve stem receiving area of a valve. The apparatus comprises a faceplate, a plurality of cams mounted to an interior face of the faceplate, a locking bolt to lock the faceplate at a predetermined position on the valve, a movable grinder and a guide tube for positioning an optical viewer proximate the area to be grinded. The apparatus can either be rotated about the valve for grinding an area of the inner diameter of a valve stem receiving area or locked at a predetermined position to grind a specific point in the receiving area.

Vane segment support and alignment device

DOE Office of Scientific and Technical Information (OSTI.GOV)

McLaurin, L.D.; Sizemore, J.D.

1999-07-13

A support and alignment assembly for supporting and aligning a vane segment is provided. The support and alignment assembly comprises a torque plate which defines an opening for receiving an eccentric pin and a locking end member for receiving a lock socket member. An eccentric pin adjustably supported by the torque plate opening for supporting and aligning a vane segment is provided. A lock socket member adapted to securely receive the eccentric pin and rotated therewith, and adjustably engage the torque plate locking end is provided. The lock socket member receives the eccentric pin, such that when the eccentric pinmore » is adjusted to align the vane segment, the lock socket member engages the torque plate locking end to secure the vane segment in the desired position. 5 figs.« less

49 CFR 236.329 - Bolt lock.

Code of Federal Regulations, 2010 CFR

2010-10-01

... TRANSPORTATION RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Interlocking Rules and Instructions... derail and displaying an aspect indicating stop cannot be operated to display a less restrictive aspect...

Biomechanical Analysis of the Efficacy of Locking Plates during Cyclic Loading in Metacarpal Fractures

PubMed Central

Meffert, Rainer H.; Raschke, Michael J.; Blunk, Torsten; Ochman, Sabine

2014-01-01

Purpose. To analyse the biomechanical characteristics of locking plates under cyclic loading compared to a nonlocking plate in a diaphyseal metacarpal fracture. Methods. Oblique diaphyseal shaft fractures in porcine metacarpal bones were created in a biomechanical fracture model. An anatomical reduction and stabilization with a nonlocking and a comparable locking plate in mono- or bicortical screw fixation followed. Under cyclic loading, the displacement, and in subsequent load-to-failure tests, the maximum load and stiffness were measured. Results. For the monocortical screw fixation of the locking plate, a similar displacement, maximum load, and stiffness could be demonstrated compared to the bicortical screw fixation of the nonlocking plate. Conclusions. Locking plates in monocortical configuration may function as a useful alternative to the currently common treatment with bicortical fixations. Thereby, irritation of the flexor tendons would be avoided without compromising the stability, thus enabling the necessary early functional rehabilitation. PMID:24757429

Ballistics Analysis of Orion Crew Module Separation Bolt Cover

NASA Technical Reports Server (NTRS)

Howard, Samuel A.; Konno, Kevin E.; Carney, Kelly S.; Pereira, J. Michael

2013-01-01

NASA is currently developing a new crew module to replace capabilities of the retired Space Shuttles and to provide a crewed vehicle for exploring beyond low earth orbit. The crew module is a capsule-type design, which is designed to separate from the launch vehicle during launch ascent once the launch vehicle fuel is expended. The separation is achieved using pyrotechnic separation bolts, wherein a section of the bolt is propelled clear of the joint at high velocity by an explosive charge. The resulting projectile must be contained within the fairing structure by a containment plate. This paper describes an analytical effort completed to augment testing of various containment plate materials and thicknesses. The results help guide the design and have potential benefit for future similar applications.

Effect of Off-Axis Screw Insertion, Insertion Torque, and Plate Contouring on Locked Screw Strength

PubMed Central

Gallagher, Bethany; Silva, Matthew J.; Ricci, William M.

2015-01-01

Objectives This study quantifies the effects of insertion torque, off-axis screw angulation, and plate contouring on the strength of locking plate constructs. Methods Groups of locking screws (n = 6–11 screws) were inserted at 50%, 100%, 150%, and 200% of the manufacturer-recommended torque (3.2 Nm) into locking compression plates at various angles: orthogonal (control), 5-degree angle off-axis, and 10-degree angle off-axis. Screws were loaded to failure by a transverse force (parallel to the plate) either in the same (“+”) or opposite direction (“−”) of the initial screw angulation. Separately, locking plates were bent to 5 and 10-degree angles, with the bend apex at a screw hole. Locking screws inserted orthogonally into the apex hole at 100% torque were loaded to failure. Results Orthogonal insertion resulted in the highest average load to failure, 2577 ± 141 N (range, 2413–2778 N), whereas any off-axis insertion significantly weakened constructs (165–1285 N, at 100% torque) (P < 0.05). For “+” loading, torque beyond 100% did not increase strength, but 50% torque reduced screw strength (P < 0.05). Loading in the “−” direction consistently resulted in higher strengths than “+” loading (P < 0.05). Plate contouring of 5-degree angle did not significantly change screw strength compared with straight plates but contouring of 10-degree angle significantly reduced load to failure (P < 0.05). Conclusions To maximize the screw plate interface strength, locking screws should be inserted without cross-threading. The mechanical stability of locked screws is significantly compromised by loose insertion, off-axis insertion, or severe distortion of the locking mechanism. PMID:24343255

External fixation versus open reduction with locked volar plating for geriatric distal radius fractures.

PubMed

Lee, Daniel J; Elfar, John C

2014-09-01

The optimal management of displaced dorsal radius fractures (DRFs) in older patients remains an issue of debate. Bridging external fixation is a well-accepted treatment modality for severely comminuted DRFs, while open reduction and internal fixation with locked volar plating has emerged as a promising alternative in recent years. The current body of randomized trials supports the trend toward locked volar plating, as it allows for quicker improvement in subjective and functional outcomes. There is no clear evidence to suggest that one technique carries significantly less complications than the other. Locked volar plating should be considered in patients for whom an accelerated functional recovery would be advantageous. Otherwise, both external fixation and locked volar plating provide good long-term clinical outcomes.

Safety lock-out device for electrical appliances

DOEpatents

Cliff, Jr., Paul L.

1996-01-01

A safety lock-out device prevents the insertion of an electrical power cord into an electrical power cord receptacle of an electrical appliance. The devise comprises a mounting plate fastened to the appliance and a cover plate hingedly attached to the appliance. The cover plate is movable between a first position and a second position such that, in the first position, the cover plate covers and prevents insertion of a power cord into the appliance receptacle. In said second position, the appliance receptacle is uncovered to permit insertion of a power cord into the receptacle. Extending a lock shank through aligned openings formed in flange members extending from the mounting plate and the cover plate locks the cover plate in the first position.

Safety lock-out device for electrical appliances

DOEpatents

Cliff, P.L. Jr.

1996-07-09

A safety lock-out device prevents the insertion of an electrical power cord into an electrical power cord receptacle of an electrical appliance. The device comprises a mounting plate fastened to the appliance and a hinged cover plate attached to the appliance. The cover plate is movable between a first position and a second position such that, in the first position, the cover plate covers and prevents insertion of a power cord into the appliance receptacle. In said second position, the appliance receptacle is uncovered to permit insertion of a power cord into the receptacle. Extending a lock shank through aligned openings formed in flange members extending from the mounting plate, the cover plate locks the cover plate in the first position. 15 figs.

Outcomes of proximal humeral fracture fixation with locked CFR-PEEK plating.

PubMed

Katthagen, Jan Christoph; Ellwein, Alexander; Lutz, Olga; Voigt, Christine; Lill, Helmut

2017-04-01

To investigate the outcomes of proximal humeral fracture (PHF) fixation with a novel carbon-fiber-reinforced (CFR)-PEEK plate and to compare results with outcomes after conventional locked titanium plating. Twenty-one patients (7 male, 14 female) with operative treatment of unilateral displaced PHFs (mean age, 66.8 ± 9.9 years) with a novel CRF-PEEK plate were prospectively enrolled. Patients were followed up clinically (Constant Score, Simple Shoulder Test and Simple Shoulder Value) and radiologically 3 months postoperative and again clinically 12 months postoperative. Implant-related complications were evaluated after 3 and 12 months. Results at 1-year follow-up were compared with results of 21 patients (7 male, 14 female; mean age, 67.4 ± 9.7 years) with conventional titanium locked plating by matched case-control analysis. All functional outcomes improved after CFR-PEEK plating (p < 0.05). Twelve months postoperatively, the mean age- and gender-related Constant Score was 99.8 ± 21.2%. All fractures healed by the 3-month follow-up without evidence of secondary screw perforation, fragment displacement or loss of fixation. There were no significant differences between the functional outcomes of patients with the CF-PEEK plate and patients with locked titanium plating (p > 0.05). Patients with locked titanium plating were significantly more likely to require revision surgery related to articular screw perforations (p = 0.048). Fracture fixation of displaced PHFs with a novel CFR-PEEK plate resulted in good to excellent 1-year functional outcomes which were similar to outcomes of conventional locked titanium plating. The stiffer locked titanium plating was associated with a higher risk of articular screw perforations than the more elastic CFR-PEEK plate.

High specific power, direct methanol fuel cell stack

DOEpatents

Ramsey, John C [Los Alamos, NM; Wilson, Mahlon S [Los Alamos, NM

2007-05-08

The present invention is a fuel cell stack including at least one direct methanol fuel cell. A cathode manifold is used to convey ambient air to each fuel cell, and an anode manifold is used to convey liquid methanol fuel to each fuel cell. Tie-bolt penetrations and tie-bolts are spaced evenly around the perimeter to hold the fuel cell stack together. Each fuel cell uses two graphite-based plates. One plate includes a cathode active area that is defined by serpentine channels connecting the inlet manifold with an integral flow restrictor to the outlet manifold. The other plate includes an anode active area defined by serpentine channels connecting the inlet and outlet of the anode manifold. Located between the two plates is the fuel cell active region.

Parametric study of extended end-plate connection using finite element modeling

NASA Astrophysics Data System (ADS)

Mureşan, Ioana Cristina; Bâlc, Roxana

2017-07-01

End-plate connections with preloaded high strength bolts represent a convenient, fast and accurate solution for beam-to-column joints. The behavior of framework joints build up with this type of connection are sensitive dependent on geometrical and material characteristics of the elements connected. This paper presents results of parametric analyses on the behavior of a bolted extended end-plate connection using finite element modeling program Abaqus. This connection was experimentally tested in the Laboratory of Faculty of Civil Engineering from Cluj-Napoca and the results are briefly reviewed in this paper. The numerical model of the studied connection was described in detail in [1] and provides data for this parametric study.

Dynamic Fixation of Humeral Shaft Fractures Using Active Locking Plates: A Prospective Observational Study.

PubMed

Madey, Steven M; Tsai, Stanley; Fitzpatrick, Daniel C; Earley, Kathleen; Lutsch, Michael; Bottlang, Michael

2017-01-01

Rigid locked plating constructs can suppress fracture healing by inhibiting interfragmentary motion required to stimulate natural bone healing by callus formation. Dynamic fixation with active locking plates reduces construct stiffness, enables controlled interfragmentary motion, and has been shown to induce faster and stronger bone healing in vivo compared to rigid locking plates. This prospective observational study represents the first clinical use of active locking plates. It documents our early clinical experience with active plates for stabilization of humeral shaft fractures to assess their durability and understand potential complications. Eleven consecutive patients with humeral shaft fractures (AO/OTA types 12 A-C) were prospectively enrolled at a level I and a level II trauma center. Fractures were stabilized by using active locking plates without supplemental bone graft or bone morphogenic proteins. The screw holes of active locking plates are elastically suspended in elastomer envelopes inside the plate, enabling up to 1.5 mm of controlled interfragmentary motion. Progression of fracture healing and integrity of implant fixation was assessed radiographically at 3, 6, 12, and 24 weeks post surgery. Patient-reported functional outcome measures were obtained at 6, 12, and 24 weeks post surgery. The primary endpoint of this study was plate durability in absence of plate bending or breakage, or failure of the elastically suspended locking hole mechanism. Secondary endpoints included fracture healing, complications requiring revision surgery, and functional outcome scores. The eleven patients had six simple AO/ OTA type 12A fractures, three wedge type 12B fractures, and two comminuted type 12C fracture, including one open fracture. All active locking plates endured the 6-month loading period without any signs of fatigue or failure. Ten of eleven fractures healed at 10.9 ± 5.2 weeks, as evident by bridging callus and pain-free function. One fracture required revision surgery 37 weeks post surgery due to late fixation failure at the screwbone interface in the presence of a atrophic delayed union. The average Disability of the Arm, Shoulder and Hand (DASH) score improved from 31 ± 22 at week 6 to 13 ± 15 by week 24, approaching that of the normal, healthy population (DASH = 10.1). By week 12, the difference between Constant shoulder scores, expressed as the difference between the affected and contralateral arm (8 ± 8), was considered excellent. By week 24, the SF-12 physical health score (44 ± 9) and mental health score (48 ± 11) approached the mean value of 50 that represents the norm for the general U.S. population. Absence of failure of the plate and locking holes suggests that dynamic fixation of humeral shaft fractures with active plates provides safe and effective fixation. Moreover, early callus bridging and excellent functional outcome scores suggest that dynamic fixation with active locking plates may promote increased fracture healing over standard locked plating.

Dual mini-fragment plating for midshaft clavicle fractures: a clinical and biomechanical investigation.

PubMed

Prasarn, Mark L; Meyers, Kathleen N; Wilkin, Geoffrey; Wellman, David S; Chan, Daniel B; Ahn, Jaimo; Lorich, Dean G; Helfet, David L

2015-12-01

We sought to evaluate clinical and biomechanical outcomes of dual mini-fragment plate fixation for clavicle fractures. We hypothesized that this technique would produce an anatomical reduction with good clinical outcomes, be well tolerated by patients, and demonstrate equivalent biomechanics to single plating. Dual mini-fragment plating was performed for 17 isolated, displaced midshaft clavicle fractures. Functional outcomes and complications were retrospectively reviewed. A sawbones model compared dual plating biomechanics to a (1) superior 3.5-mm locking reconstruction plate, or (2) antero-inferior 3.5-mm locking reconstruction plate. On biomechanical testing, with anterior loading, dual plating was significantly more rigid than single locked anterior-plating (p = 0.02) but less rigid than single locked superior-plating (p = 0.001). With superior loading, dual plating trended toward higher rigidity versus single locked superior-plating (p = 0.07) but was less rigid than single locked anterior-plating (p = 0.03). No statistically significant differences in axial loading (p = 0.27) or torsion (p = 0.23) were detected. Average patient follow-up was 16.1 months (12-38). Anatomic reduction was achieved and maintained through final healing (average 14.7 weeks). No patient underwent hardware removal. Average 1-year DASH score was 4.0 (completed in 88 %). Displaced midshaft clavicle fractures can be effectively managed with dual mini-fragment plating. This technique results in high union rates and excellent clinical outcomes. Compared to single plating, dual plating is biomechanically equivalent in axial loading and torsion, yet offers better multi-planar bending stiffness despite the use of smaller plates. This technique may decrease the need for secondary surgery due to implant prominence and may aid in fracture reduction by buttressing butterfly fragments in two planes.

Ex vivo biomechanical evaluation of pigeon (Columba livia) cadaver intact humeri and ostectomized humeri stabilized with caudally applied titanium locking plate or stainless steel nonlocking plate constructs.

PubMed

Darrow, Brett G; Biskup, Jeffrey J; Weigel, Joseph P; Jones, Michael P; Xie, Xie; Liaw, Peter K; Tharpe, Josh L; Sharma, Aashish; Penumadu, Dayakar

2017-05-01

OBJECTIVE To evaluate mechanical properties of pigeon (Columba livia) cadaver intact humeri versus ostectomized humeri stabilized with a locking or nonlocking plate. SAMPLE 30 humeri from pigeon cadavers. PROCEDURES Specimens were allocated into 3 groups and tested in bending and torsion. Results for intact pigeon humeri were compared with results for ostectomized humeri repaired with a titanium 1.6-mm screw locking plate or a stainless steel 1.5-mm dynamic compression plate; the ostectomized humeri mimicked a fracture in a thin cortical bone. Locking plates were secured with locking screws (2 bicortical and 4 monocortical), and nonlocking plates were secured with bicortical nonlocking screws. Constructs were cyclically tested nondestructively in 4-point bending and then tested to failure in bending. A second set of constructs were cyclically tested non-destructively and then to failure in torsion. Stiffness, strength, and strain energy of each construct were compared. RESULTS Intact specimens were stiffer and stronger than the repair groups for all testing methods, except for nonlocking constructs, which were significantly stiffer than intact specimens under cyclic bending. Intact bones had significantly higher strain energies than locking plates in both bending and torsion. Locking and nonlocking plates were of equal strength and strain energy, but not stiffness, in bending and were of equal strength, stiffness, and strain energy in torsion. CONCLUSIONS AND CLINICAL RELEVANCE Results for this study suggested that increased torsional strength may be needed before bone plate repair can be considered as the sole fixation method for avian species.

Trends in mechanical fasteners. [considering optimum metric fastener system

NASA Technical Reports Server (NTRS)

Levy, J. B.

1972-01-01

Some of the specialty fasteners which are enjoying increasing usage are: thread rolling screws, self drilling and tapping screws, locking screws, tamperproof fasteners, and flanged bolts and nuts. The development of an optimum metric fastener system is recommended for future fastener manufacturing.

Small-Bolt Torque-Tension Tester

NASA Technical Reports Server (NTRS)

Posey, Alan J.

2009-01-01

The device described here measures the torque-tension relationship for fasteners as small as #0. The small-bolt tester consists of a plate of high-strength steel into which three miniature load cells are recessed. The depth of the recess is sized so that the three load cells can be shimmed, the optimum height depending upon the test hardware. The three miniature load cells are arranged in an equilateral triangular configuration with the test bolt aligned with the centroid of the three. This is a kinematic arrangement.

Torque vs. induced load of A-286, and MP35N nuts and bolts with cadmium, dry film, and cetyl alcohol lubricants

NASA Technical Reports Server (NTRS)

Crispell, C.

1978-01-01

Data for specific joint design, utilizing various combinations of bolt, nut and lubricants in typical structure of the shuttle booster rocket is obtained. Requirements of the structure performance criteria were to withstand temperatures of 260 C (500 F) and to provide a nut lubricant which would be compatible with sealants used in the joint. Cadmium plating and dry film lubricant meeting the requirements of MIL-L-8937 were the lubricants specified. In a follow up effort, cadmium plating and cetyl alcohol were further specified The materials for the bolt and nut combinations were MP35N and A-286. These materials demand a lubricant to be used to prevent galling of the thread when tightened and also to help reduce the scatter of clamping load in application.

Steel shear strength of anchors with stand-off base plates : [technical summary].

DOT National Transportation Integrated Search

2013-09-01

Sign and signal structures are often connected : to concrete foundations through an annular base : plate set on anchor bolts. The plate is leveled : with nuts beneath it and secured with nuts : above it a double-nut connection. In many : in...

Locking support for nuclear fuel assemblies

DOEpatents

Ledin, Eric

1980-01-01

A locking device for supporting and locking a nuclear fuel assembly within a cylindrical bore formed by a support plate, the locking device including a support and locking sleeve having upwardly extending fingers forming wedge shaped contact portions arranged for interaction between an annular tapered surface on the fuel assembly and the support plate bore as well as downwardly extending fingers having wedge shaped contact portions arranged for interaction between an annularly tapered surface on the support plate bore and the fuel assembly whereby the sleeve tends to support and lock the fuel assembly in place within the bore by its own weight while facilitating removal and/or replacement of the fuel assembly.

[Unidirectional versus multidirectional palmar locking osteosynthesis of unstable distal radius fractures: comparative analysis with LDR 2.4 mm versus 2.7 mm matrix-Smartlock].

PubMed

Hakimi, M; Jungbluth, P; Gehrmann, S; Nowak, J; Windolf, J; Wild, M

2010-03-01

Due to advances in the development of the unidirectional locking plates there is now an increased use of multidirectional palmar locking plates in the treatment of distal radius factures. The purpose of this study was to evaluate a possible improvement of the treatment and results. This prospective cohort study investigated 40 patients with C1 and C2 Colles' fractures who had been treated with unidirectional and multidirectional locking plates. The average time for the follow-up examinations was 12.3 months (range 12-15 months) after surgery. The intra-operative functional (neutral-zero method), radiological and subjective (DASH score, VAS) results were evaluated. The intra-operative fluoroscopy time of the unidirectional group was 58 s shorter compared to the multidirectional group. All fractures healed without any complication. The radiological, subjective (DASH score) and objective results for both groups were good and showed no differences. Unidirectional palmar locking plates are equally suited for the therapy of C1 and C2 fractures as multidirectional palmar locking plates but multidirectional plates require a longer fluoroscopy time.

Structural health monitoring using a hybrid network of self-powered accelerometer and strain sensors

NASA Astrophysics Data System (ADS)

Alavi, Amir H.; Hasni, Hassene; Jiao, Pengcheng; Lajnef, Nizar

2017-04-01

This paper presents a structural damage identification approach based on the analysis of the data from a hybrid network of self-powered accelerometer and strain sensors. Numerical and experimental studies are conducted on a plate with bolted connections to verify the method. Piezoelectric ceramic Lead Zirconate Titanate (PZT)-5A ceramic discs and PZT-5H bimorph accelerometers are placed on the surface of the plate to measure the voltage changes due to damage progression. Damage is defined by loosening or removing one bolt at a time from the plate. The results show that the PZT accelerometers provide a fairly more consistent behavior than the PZT strain sensors. While some of the PZT strain sensors are not sensitive to the changes of the boundary condition, the bimorph accelerometers capture the mode changes from undamaged to missing bolt conditions. The results corresponding to the strain sensors are better indicator to the location of damage compared to the accelerometers. The characteristics of the overall structure can be monitored with even one accelerometer. On the other hand, several PZT strain sensors might be needed to localize the damage.

Biomechanical strength of the Peri-Loc proximal tibial plate: a comparison of all-locked versus hybrid locked/nonlocked screw configurations.

PubMed

Estes, Chris; Rhee, Peter; Shrader, M Wade; Csavina, Kristine; Jacofsky, Marc C; Jacofsky, David J

2008-01-01

The purpose of this study was to compare the biomechanical properties of a contoured locking plate instrumented with either an all-locked or hybrid locked/nonlocked screw construct in a proximal metaphyseal fracture of the tibia (AO 41-A3.2). A standardized proximal metaphyseal wedge osteotomy (AO 41-A3.2) was created in five pairs of cadaveric tibia. Each pair was randomly instrumented with either an all-locked or combination locked/nonlocked screw construct using a locked contoured periarticular plate (Peri-Loc periarticular locked plating system, Smith & Nephew, Memphis, TN). Vertical subsidence (irreversible deformation) and deflection (reversible deformation) in each pair were analyzed and compared. Load to failure, defined by complete fracture gap closure, was also determined. There was no statistically significant difference in vertical subsidence (P = 0.19) or deflection (P = 0.19) of the proximal tibia between the all-locked and combination locked/nonlocked screw construct with increasing levels of cyclical axial load from 200 to 1200 N. Failure occurred at a mean value of 2160 N in the locked group and 1760 N in the hybrid group (P = 0.19); the failure mode was plate bending in all specimens. The results indicate that the use of compression screws with locked screws in this particular construct allows a similar amount of irreversible and reversible deformation in response to an axial load when compared to an all-locked screw construct. This suggests that there is no statistically significant difference in the stability in fixation between the two methods, allowing the surgeon the freedom to choose the appropriate screw combination unique to each fracture.

49 CFR 236.756 - Lock, bolt.

Code of Federal Regulations, 2010 CFR

2010-10-01

... TRANSPORTATION RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR... a train movement, the signal governing that movement cannot display an aspect to proceed; and that will prevent a movement of the switch, derail or movable-point frog unless the signal displays its most...

Screw Loosening and Pelvic Canal Narrowing After Lateral Plating of Feline Ilial Fractures With Locking and Nonlocking Plates.

PubMed

Schmierer, Philipp A; Kircher, Patrick R; Hartnack, Sonja; Knell, Sebastian C

2015-10-01

To compare the frequency of complications, including screw loosening and pelvic canal narrowing, associated with dynamic compression plating, locking plating, and double locking plating of ilial fractures in cats. Historical cohort study. The radiographs and medical records of cats with pelvic fractures that were presented between 2004 and 2013 were reviewed. The cases were categorized based on the plate type and number as dynamic compression plate (DCP), single locking plate (LPS) and double locking plates (dLPS). The frequency of screw loosening was compared across categories using a Fisher's exact test. The change in pelvic alignment, described by the change in sacral index (postoperative sacral index-followup sacral index), was compared across plate categories using ANOVA. The frequency of screw loosening for DCP (5/10) was significantly higher than LPS (1/13) and dLPS (0/11) (P = .05, P = .012, respectively). There was no significant difference in the SI change across plate categories. The mean change in sacral index for DCP was -0.11 (95%CI -0.25 to 0.03), for LPS was 0.0007 (95%CI -0.07 to 0.08), and for dLPS was -0.01 (95%CI -0.04 to 0.02). None of the cats showed constipation postoperatively. Screw loosening occurred less often but the change in pelvic canal alignment was not significantly different in ilial fractures repaired with LPS or dLPS compared to ilial fractures repaired with DCP. Locking plating of ilial fractures in cats may offer advantages compared to nonlocking plating. © Copyright 2015 by The American College of Veterinary Surgeons.

Addition of a Medial Locking Plate to an In Situ Lateral Locking Plate Results in Healing of Distal Femoral Nonunions.

PubMed

Holzman, Michael A; Hanus, Bryan D; Munz, John W; O'Connor, Daniel P; Brinker, Mark R

2016-06-01

Nonunion of the distal femur after lateral plating is associated with axial malalignment, chronic pain, loss of ambulatory function, and decreased knee ROM. The addition of a medial locking plate with autogenous bone grafting can provide greater stability to allow bone healing and may be used to achieve union in these challenging cases. We wished to determine (1) the proportion of patients who achieve radiographic signs of osseous union for distal femoral nonunions with an in situ lateral plate after treatment with addition of a medial locking plate and autogenous bone grafting, and (2) the frequency and types of complications associated with this treatment. Between 2007 and 2013, we treated 22 patients for 23 distal femoral nonunions, defined as an unhealed fracture with no radiographic signs of osseous union at a mean of 16 months (SD, 13 months) after injury. During that time, we used a treatment algorithm consisting of treatment in one or two stages. The single-stage procedure performed in 16 aseptic nonunions with a stable lateral plate involved addition of a medial locking plate and autogenous bone graft. A two-stage treatment performed in seven nonunions with lateral plate failure involved placement of a new lateral locking plate followed by addition of a medial locking plate with autogenous bone graft at least 2 months after the first procedure. Of the 22 patients treated, 20 had a median followup of 18 months (SD, 6-94 months). We defined osseous union by bridging bone on three of four cortices with absence of a radiolucent line or more than 25% cross-sectional area of bridging bone via CT. Twenty of the 21 nonunions attained radiographic signs of osseous union by 12 months. Six of the 20 patients experienced complications: one patient had a persistent nonunion; four patients underwent removal of symptomatic hardware; and one patient experienced skin breakdown at the bone graft harvest site. A very high proportion of patients achieve union when using medial locking plates to treat distal femoral nonunions after lateral plating of the original injury. Addition of bone graft, staged reconstruction, and revision of the initial lateral plate is indicated when the nonunion is associated with fatigue failure of the initial lateral plate. Level IV, therapeutic study.

Importance of a moderate plate-to-bone distance for the functioning of the far cortical locking system.

PubMed

Yang, Jesse Chieh-Szu; Lin, Kang-Ping; Wei, Hung-Wen; Chen, Wen-Chuan; Chiang, Chao-Ching; Chang, Ming-Chau; Tsai, Cheng-Lun; Lin, Kun-Jhih

2018-06-01

The far cortical locking (FCL) system, a novel bridge-plating technique, aims to deliver controlled and symmetric interfragmentary motion for a potential uniform callus distribution. However, clinical data for the practical use of this system are limited. The current study investigated the biomechanical effect of a locking plate/far cortical locking construct on a simulated comminuted diaphyseal fracture of the synthetic bones at different distance between the plate and the bone. Biomechanical in vitro experiments were performed using composite sawbones as bone models. A 10-mm osteotomy gap was created and bridged with FCL constructs to determine the construct stiffness, strength, and interfragmentary movement under axial compression, which comprised one of three methods: locking plates applied flush to bone, at 2 mm, or at 4 mm from the bone. The plate applied flush to the bone exhibited higher stiffness than those at 2 mm and 4 mm plate elevation. A homogeneous interfragmentary motion at the near and far cortices was observed for the plate at 2 mm, whereas a relatively large movement was observed at the far cortex for the plate applied at 4 mm. A plate-to-bone distance of 2 mm had the advantages of reducing axial stiffness and providing nearly parallel interfragmentary motion. The plate flush to the bone prohibits the dynamic function of the far cortical locking mechanism, and the 4-mm offset was too unstable for fracture healing. Copyright © 2018 IPEM. Published by Elsevier Ltd. All rights reserved.

Easy and Inexpensive Technique for Removal of Round Headed, Jammed Locking Screws in Distal Tibial Interlocking Plate.

PubMed

Singh, Harpreet; Sharma, Rohit; Gupta, Sachin; Singh, Narinderjit; Singh, Simarpreet

2015-01-01

The advent of locking plates has brought new problems in implant removal. Difficulty in removing screws from a locking plate is well-known. These difficulties include cold welding between the screw head and locking screw hole, stripping of the recess of the screw head for the screwdriver, and cross-threading between threads in the screw head and screw hole. However, there are cases in which removal is difficult. We describe a new technique for removing a round headed, jammed locking screws from a locking plate. 55 years old male patient received a locking distal tibial plate along with distal fibular plate 3years back from UAE. Now patient came with complaint of non-healing ulcer over medial aspect of lower 1/3rd of right leg from past 1 year. Non operative management did not improve the symptoms. The patient consented to implant removal, with the express understanding that implant removal might be impossible because already one failed attempt had been performed at some other hospital six months back. We then decided to proceed with the new technique. The rest of the proximal screws were removed using a technique not previously described. We used stainless steel metal cutting blades that are used to cut door locks or pad locks to cut the remaining stripped headed screws. This technique is very quick, easy to perform and inexpensive because the metal cutting blades which are used to cut the screws are very cheap. Yet it is very effective technique to remove the stripped headed or jammed locking screws. It is also very less destructive because of very less heat production during the procedure there is no problem of thermal necrosis to the bone or the surrounding soft tissue.

Image Registration-Based Bolt Loosening Detection of Steel Joints

PubMed Central

2018-01-01

Self-loosening of bolts caused by repetitive loads and vibrations is one of the common defects that can weaken the structural integrity of bolted steel joints in civil structures. Many existing approaches for detecting loosening bolts are based on physical sensors and, hence, require extensive sensor deployment, which limit their abilities to cost-effectively detect loosened bolts in a large number of steel joints. Recently, computer vision-based structural health monitoring (SHM) technologies have demonstrated great potential for damage detection due to the benefits of being low cost, easy to deploy, and contactless. In this study, we propose a vision-based non-contact bolt loosening detection method that uses a consumer-grade digital camera. Two images of the monitored steel joint are first collected during different inspection periods and then aligned through two image registration processes. If the bolt experiences rotation between inspections, it will introduce differential features in the registration errors, serving as a good indicator for bolt loosening detection. The performance and robustness of this approach have been validated through a series of experimental investigations using three laboratory setups including a gusset plate on a cross frame, a column flange, and a girder web. The bolt loosening detection results are presented for easy interpretation such that informed decisions can be made about the detected loosened bolts. PMID:29597264

Image Registration-Based Bolt Loosening Detection of Steel Joints.

PubMed

Kong, Xiangxiong; Li, Jian

2018-03-28

Self-loosening of bolts caused by repetitive loads and vibrations is one of the common defects that can weaken the structural integrity of bolted steel joints in civil structures. Many existing approaches for detecting loosening bolts are based on physical sensors and, hence, require extensive sensor deployment, which limit their abilities to cost-effectively detect loosened bolts in a large number of steel joints. Recently, computer vision-based structural health monitoring (SHM) technologies have demonstrated great potential for damage detection due to the benefits of being low cost, easy to deploy, and contactless. In this study, we propose a vision-based non-contact bolt loosening detection method that uses a consumer-grade digital camera. Two images of the monitored steel joint are first collected during different inspection periods and then aligned through two image registration processes. If the bolt experiences rotation between inspections, it will introduce differential features in the registration errors, serving as a good indicator for bolt loosening detection. The performance and robustness of this approach have been validated through a series of experimental investigations using three laboratory setups including a gusset plate on a cross frame, a column flange, and a girder web. The bolt loosening detection results are presented for easy interpretation such that informed decisions can be made about the detected loosened bolts.

Development of a Titanium Plate for Mandibular Angle Fractures with a Bone Defect in the Lower Border: Finite Element Analysis and Mechanical Test

PubMed Central

Goulart, Douglas Rangel; Kemmoku, Daniel Takanori; Noritomi, Pedro Yoshito

2015-01-01

ABSTRACT Objectives The aim of the present study was to develop a plate to treat mandibular angle fractures using the finite element method and mechanical testing. Material and Methods A three-dimensional model of a fractured mandible was generated using Rhinoceros 4.0 software. The models were exported to ANSYS®, in which a static application of displacement (3 mm) was performed in the first molar region. Three groups were assessed according to the method of internal fixation (2 mm system): two non-locking plates; two locking plates and a new design locking plate. The computational model was transferred to an in vitro experiment with polyurethane mandibles. Each group contained five samples and was subjected to a linear loading test in a universal testing machine. Results A balanced distribution of stress was associated with the new plate design. This plate modified the mechanical behavior of the fractured region, with less displacement between the fractured segments. In the mechanical test, the group with two locking plates exhibited greater resistance to the 3 mm displacement, with a statistically significant difference when compared with the new plate group (ANOVA, P = 0.016). Conclusions The new plate exhibited a more balanced distribution of stress. However, the group with two locking plates exhibited greater mechanical resistance. PMID:26539287

49 CFR 236.779 - Plate, top.

Code of Federal Regulations, 2010 CFR

2010-10-01

... OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Definitions § 236.779 Plate, top. A metal plate secured to a locking bracket to prevent the cross locking from being forced out of the...

Thermal conductance measurements of bolted copper joints for SuperCDMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmitt, R.; Tatkowski, Greg; Ruschman, M.

2015-09-01

Joint thermal conductance testing has been undertaken for bolted copper to copper connections from 60 mK to 26 K. This testing was performed to validate an initial design basis for the SuperCDMS experiment, where a dilution refrigerator will be coupled to a cryostat via multiple bolted connections. Copper used during testing was either gold plated or passivated with citric acid to prevent surface oxidation. Results obtained are well fit by a power law regression of joint thermal conductance to temperature and match well with data collected during a literature review.

Notch sensitivity jeopardizes titanium locking plate fatigue strength.

PubMed

Tseng, Wo-Jan; Chao, Ching-Kong; Wang, Chun-Chin; Lin, Jinn

2016-12-01

Notch sensitivity may compromise titanium-alloy plate fatigue strength. However, no studies providing head-to-head comparisons of stainless-steel or titanium-alloy locking plates exist. Custom-designed identically structured locking plates were made from stainless steel (F138 and F1314) or titanium alloy. Three screw-hole designs were compared: threaded screw-holes with angle edges (type I); threaded screw-holes with chamfered edges (type II); and non-threaded screw-holes with chamfered edges (type III). The plates' bending stiffness, bending strength, and fatigue life, were investigated. The stress concentration at the screw threads was assessed using finite element analyses (FEA). The titanium plates had higher bending strength than the F1314 and F138 plates (2.95:1.56:1) in static loading tests. For all metals, the type-III plate fatigue life was highest, followed by type-II and type-I. The type-III titanium plates had longer fatigue lives than their F138 counterparts, but the type-I and type-II titanium plates had significantly shorter fatigue lives. All F1314 plate types had longer fatigue lives than the type-III titanium plates. The FEA showed minimal stress difference (0.4%) between types II and III, but the stress for types II and III was lower (11.9% and 12.4%) than that for type I. The screw threads did not cause stress concentration in the locking plates in FEA, but may have jeopardized the fatigue strength, especially in the notch-sensitive titanium plates. Improvement to the locking plate design is necessary. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Novel RFID-Based Sensing Method for Low-Cost Bolt Loosening Monitoring.

PubMed

Wu, Jian; Cui, Xingmei; Xu, Yunpeng

2016-01-28

In coal mines, bolt loosening in the cage guide is affected by the harsh environmental factors and cage hoist vibration, leading to significant threats to work safety. It is crucial, to this effect, to successfully detect the status of multipoint bolts of guide structures. This paper proposes a system to monitor bolt status in harsh environments established based on the RFID technique. A proof-of-concept model was demonstrated consisting of a bolt gearing system, passive UHF RFID tags, a reader, and monitoring software. A tinfoil metal film is fixed on the retaining plate and an RFID tag bonded to a large gear, with the bolt to be detected fixed in the center of a smaller gear. The radio-frequency signal cannot be received by the reader if the tag is completely obscured by the tinfoil, and if the bolt is loose, the tag's antenna is exposed when the gear revolves. A radio-frequency signal that carries corresponding bolt's information is transmitted by the RFID tag to the RFID reader due to coil coupling, identifying loose bolt location and reporting them in the software. Confirmatory test results revealed that the system indeed successfully detects bolt loosening and comparative test results (based on a reed switch multipoint bolt loosening monitor system) provided valuable information regarding the strengths and weaknesses of the proposed system.

Monolithic Flexure Pre-Stressed Ultrasonic Horns

NASA Technical Reports Server (NTRS)

Sherrit, Stewart; Bao, Xiaoqi; Badescu, Mircea; Bar-Cohen, Yoseph; Allen, Phillip Grant

2011-01-01

High-power ultrasonic actuators are generally assembled with a horn, backing, stress bolt, piezoelectric rings, and electrodes. The manufacturing process is complex, expensive, difficult, and time-consuming. The internal stress bolt needs to be insulated and presents a potential internal discharge point, which can decrease actuator life. Also, the introduction of a center hole for the bolt causes many failures, reducing the throughput of the manufactured actuators. A new design has been developed for producing ultrasonic horn actuators. This design consists of using flexures rather than stress bolts, allowing one to apply pre-load to the piezoelectric material. It also allows one to manufacture them from a single material/plate, rapid prototype them, or make an array in a plate or 3D structure. The actuator is easily assembled, and application of pre-stress greater than 25 MPa was demonstrated. The horn consists of external flexures that eliminate the need for the conventional stress bolt internal to the piezoelectric, and reduces the related complexity. The stress bolts are required in existing horns to provide prestress on piezoelectric stacks when driven at high power levels. In addition, the manufacturing process benefits from the amenability to produce horn structures with internal cavities. The removal of the pre-stress bolt removes a potential internal electric discharge point in the actuator. In addition, it significantly reduces the chances of mechanical failure in the piezoelectric stacks that result from the hole surface in conventional piezoelectric actuators. The novel features of this disclosure are: 1. A design that can be manufactured from a single piece of metal using EDM, precision machining, or rapid prototyping. 2. Increased electromechanical coupling of the horn actuator. 3. Higher energy density. 4. A monolithic structure of a horn that consists of an external flexure or flexures that can be used to pre-stress a solid piezoelectric structure rather than a bolt, which requires a through hole in the piezoelectric material. 5. A flexure system with low stiffness that accommodates mechanical creep with minor reduction in pre-stress.

Fixture for environmental exposure of structural materials under compression load

NASA Technical Reports Server (NTRS)

Clark, R. K.; Lisagor, W. B. (Inventor)

1983-01-01

A device for stressing a deformable material specimen consists of top plate and a bottom plate sandwiching a guide cylinder. The specimen is positioned on the bottom plate and attached to a load piston. Force is applied through the top plate into the guide cylinder. Once the specimen is loaded, the stress is maintained by tightening tie bolt nuts.

The influence of distal locking on the need for fibular plating in intramedullary nailing of distal metaphyseal tibiofibular fractures.

PubMed

Attal, R; Maestri, V; Doshi, H K; Onder, U; Smekal, V; Blauth, M; Schmoelz, W

2014-03-01

Using human cadaver specimens, we investigated the role of supplementary fibular plating in the treatment of distal tibial fractures using an intramedullary nail. Fibular plating is thought to improve stability in these situations, but has been reported to have increased soft-tissue complications and to impair union of the fracture. We proposed that multidirectional locking screws provide adequate stability, making additional fibular plating unnecessary. A distal tibiofibular osteotomy model performed on matched fresh-frozen lower limb specimens was stabilised with reamed nails using conventional biplanar distal locking (CDL) or multidirectional distal locking (MDL) options with and without fibular plating. Rotational stiffness was assessed under a constant axial force of 150 N and a superimposed torque of ± 5 Nm. Total movement, and neutral zone and fracture gap movement were analysed. In the CDL group, fibular plating improved stiffness at the tibial fracture site, albeit to a small degree (p = 0.013). In the MDL group additional fibular plating did not increase the stiffness. The MDL nail without fibular plating was significantly more stable than the CDL nail with an additional fibular plate (p = 0.008). These findings suggest that additional fibular plating does not improve stability if a multidirectional distal locking intramedullary nail is used, and is therefore unnecessary if not needed to aid reduction.

30 CFR 75.204 - Roof bolting.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) Bearing plates used directly against the mine roof shall be at least 6 inches square or the equivalent... or the equivalent may be used. (3) Bearing plates used with wood or metal materials shall be at least 4 inches square or the equivalent. (4) Wooden materials that are used between a bearing plate and...

30 CFR 75.204 - Roof bolting.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Bearing plates used directly against the mine roof shall be at least 6 inches square or the equivalent... or the equivalent may be used. (3) Bearing plates used with wood or metal materials shall be at least 4 inches square or the equivalent. (4) Wooden materials that are used between a bearing plate and...

30 CFR 75.204 - Roof bolting.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) Bearing plates used directly against the mine roof shall be at least 6 inches square or the equivalent... or the equivalent may be used. (3) Bearing plates used with wood or metal materials shall be at least 4 inches square or the equivalent. (4) Wooden materials that are used between a bearing plate and...

30 CFR 75.204 - Roof bolting.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) Bearing plates used directly against the mine roof shall be at least 6 inches square or the equivalent... or the equivalent may be used. (3) Bearing plates used with wood or metal materials shall be at least 4 inches square or the equivalent. (4) Wooden materials that are used between a bearing plate and...

Biomechanical testing of locking and nonlocking plates in the canine scapula.

PubMed

Acquaviva, Anthony E; Miller, Emily I; Eisenmann, David J; Stone, Rick T; Kraus, Karl H

2012-01-01

Locking plates have been shown to offer improved fixation in fractures involving either osteoporotic bone or bone with lesser screw pullout strength, such as thin and flat bones. Fractures of the scapular body are one type of fracture where the screw pullout strength using conventional plate fixation may not be sufficient to overcome physiologic forces. The purpose of this study was to compare the pullout strengths of locking plates to conventional nonlocking plates in the canine scapula. A 2.7 mm string of pearls plate (SOP) and a 2.7 mm limited contact dynamic compression plate (LC-DCP) were applied with similar divergent screws to the supraspinatus fossa of the scapula. Forces perpendicular to the plates were applied and both the loads at failure and modes of failure were recorded. No differences were noted in loads at failure between the two plating systems. Although the modes of failure were not significantly different, the SOP constructs tended to fail more often by bone slicing and coring, whereas the LC-DCP constructs failed primarily by screw stripping. Neither of the plate systems used in this study demonstrated a distinct mechanical advantage. The application and limitations of locking plate systems in various clinical situations require further study.

Device for measuring hole elongation in a bolted joint

NASA Technical Reports Server (NTRS)

Wichorek, Gregory R. (Inventor)

1987-01-01

A device to determine the operable failure mode of mechanically fastened lightweight composite joints by measuring the hole elongation of a bolted joint is disclosed. The double-lap joint test apparatus comprises a stud, a test specimen having a hole, two load transfer plates, and linear displacement measuring instruments. The test specimen is sandwiched between the two load transfer plates and clamped together with the stud. Spacer washers are placed between the test specimen and each load transfer plate to provide a known, controllable area for the determination of clamping forces around the hole of the specimen attributable to bolt torque. The spacer washers also provide a gap for the mounting of reference angles on each side of the test specimen. Under tensile loading, elongation of the hole of the test specimen causes the stud to move away from the reference angles. This displacement is measured by the voltage output of two linear displacement measuring instruments that are attached to the stud and remain in contact with the reference angles throughout the tensile loading. The present invention obviates previous problems in obtaining specimen deformation measurements by monitoring the reference angles to the test specimen and the linear displacement measuring instruments to the stud.

NASA's Radio Frequency Bolt Monitor: A Lifetime of Spinoffs

NASA Technical Reports Server (NTRS)

2005-01-01

This story begins in the 1970s, when Dr. Joseph Heyman, a young scientist at NASA s Langley Research Center, was asked to support the investigation of a wind tunnel accident at a sister center. Although the work was outside of his physics background, it sparked a research focus that guided his lengthy NASA career and would earn him a slew of accolades, including NASA s highest award medals for Exceptional Leadership, Exceptional Achievement, and Exceptional Service; the coveted Silver Snoopy Astronaut Award for Space Shuttle Return to Flight; and the Arthur Fleming Award for being one of the Top Ten Federal Scientists in Government Service. He won 30 additional NASA awards, including the Agency s Invention of the Year and the Agency s highest award for technology transfer, and was the only person to ever win 4 R&D 100 Awards. Back in 1973, though, Heyman was a young civil servant with a background in physics who was asked to sit on an accident review panel. The panel met at Ames Research Center, in Moffet Field, California, and after considerable investigation, concluded that a high-pressure pebble heater used for heating gas had failed, due to improperly tightened bolts in a 1,000-pound gate valve control section. The accident showered the facility with incendiary ceramic spheres and nearly a ton of metal, but, luckily, caused no injuries. Heyman returned to Langley and began work on a solution. He developed an ultrasonic device that would measure bolt elongation, as opposed to torque, the factor typically measured in testing bolt preload or tension. Torque measurement can lead to load errors, with miscalculations as high as 80 percent that can be passed over during installation. Bolt stretch, however, is nearly always accurate to 1 percent or better. Within 1 month, he had an acoustic resonance solution that accurately determined bolt elongation. He assumed his work on this project had ended, but it was actually the start of nearly 15 years of work perfecting, improving, inventing, and modifying the "bolt monitor", all the while, filing numerous patents, presenting papers, and holding demonstrations as the technology matured. Industry engineers challenged Heyman s inventiveness, and reminded the physicist that most bolts are not perfect resonators, and that early devices required that the bolt have reasonably flat and parallel faces. The U.S. Geological Survey asked NASA for help in determining the load in mine roof bolts, which are 8- to 10-feet-long and rough cut. To solve that problem, Heyman modified the original device to operate at a lower frequency and to generate propagation modes that could be used to "lock" the instrument on a particular mode. Further work in this vein led to the development of the Pulsed Phase Locked Loop (P2L2) that worked on the mine bolts. The next set of problems involved high-strength bolts with head markings. For this solution, Heyman invented a modified P2L2 that tracked a specific phase point in the measurement wave. This class of instrumentation, well suited to measuring small changes in acoustic velocity, won the NASA "Invention of the Year" award in 1982. Other scientists and engineers have continued the evolution of this technology both inside NASA and outside of the Agency. Within NASA, the technology has been improved for medical applications, with a particular focus on intercranial pressure (ICP) monitoring.

A Novel RFID-Based Sensing Method for Low-Cost Bolt Loosening Monitoring

PubMed Central

Wu, Jian; Cui, Xingmei; Xu, Yunpeng

2016-01-01

In coal mines, bolt loosening in the cage guide is affected by the harsh environmental factors and cage hoist vibration, leading to significant threats to work safety. It is crucial, to this effect, to successfully detect the status of multipoint bolts of guide structures. This paper proposes a system to monitor bolt status in harsh environments established based on the RFID technique. A proof-of-concept model was demonstrated consisting of a bolt gearing system, passive UHF RFID tags, a reader, and monitoring software. A tinfoil metal film is fixed on the retaining plate and an RFID tag bonded to a large gear, with the bolt to be detected fixed in the center of a smaller gear. The radio-frequency signal cannot be received by the reader if the tag is completely obscured by the tinfoil, and if the bolt is loose, the tag’s antenna is exposed when the gear revolves. A radio-frequency signal that carries corresponding bolt’s information is transmitted by the RFID tag to the RFID reader due to coil coupling, identifying loose bolt location and reporting them in the software. Confirmatory test results revealed that the system indeed successfully detects bolt loosening and comparative test results (based on a reed switch multipoint bolt loosening monitor system) provided valuable information regarding the strengths and weaknesses of the proposed system. PMID:26828498

Solid Rocket Booster Hydraulic Pump Port Cap Joint Load Testing

NASA Technical Reports Server (NTRS)

Gamwell, W. R.; Murphy, N. C.

2004-01-01

The solid rocket booster uses hydraulic pumps fabricated from cast C355 aluminum alloy, with 17-4 PH stainless steel pump port caps. Corrosion-resistant steel, MS51830 CA204L self-locking screw thread inserts are installed into C355 pump housings, with A286 stainless steel fasteners installed into the insert to secure the pump port cap to the housing. In the past, pump port cap fasteners were installed to a torque of 33 Nm (300 in-lb). However, the structural analyses used a significantly higher nut factor than indicated during tests conducted by Boeing Space Systems. When the torque values were reassessed using Boeing's nut factor, the fastener preload had a factor of safety of less than 1, with potential for overloading the joint. This paper describes how behavior was determined for a preloaded joint with a steel bolt threaded into steel inserts in aluminum parts. Finite element models were compared with test results. For all initial bolt preloads, bolt loads increased as external applied loads increased. For higher initial bolt preloads, less load was transferred into the bolt, due to external applied loading. Lower torque limits were established for pump port cap fasteners and additional limits were placed on insert axial deformation under operating conditions after seating the insert with an initial preload.

Thermal conductance measurements of bolted copper joints for SuperCDMS

DOE PAGES

Schmitt, R. L.; Tatkowski, G.; Ruschman, M.; ...

2015-04-28

Joint thermal conductance testing has been undertaken for bolted copper to copper connections from 60 mK to 26 K. This testing was performed to validate an initial design basis for the SuperCDMS experiment, where a dilution refrigerator will be coupled to a cryostat via multiple bolted connections. Copper used during testing was either gold plated or passivated with citric acid to prevent surface oxidation. Finally, the results we obtained are well fit by a power law regression of joint thermal conductance to temperature and match well with data collected during a literature review.

Locking design affects the jamming of screws in locking plates.

PubMed

Sandriesser, Sabrina; Rupp, Markus; Greinwald, Markus; Heiss, Christian; Augat, Peter; Alt, Volker

2018-06-01

The seizing of locking screws is a frequently encountered clinical problem during implant removal of locking compression plates (LCP) after completion of fracture healing. The aim of this study was to investigate the effect of two different locking mechanisms on the seizing of locking screws. Specifically, the removal torques before and after cyclic dynamic loading were assessed for screws inserted at the manufacturer-recommended torque or at an increased insertion torque. The seizing of 3.5-mm angular stable screws was assessed as a function of insertion torque for two different locking mechanisms (Thread & Conus and Thread Only). Locking screws (n=10 for each configuration) were inserted either according to the manufacturer-recommended torque or at an increased torque of 150% to simulate an over-insertion of the screw. Half of the screws were removed directly after insertion and the remaining half was removed after a dynamic load protocol of 100,000 cycles. The removal torques of locking screws exceeded the insertion torques for all tested conditions confirming the adequacy of the test setup in mimicking screw seizing in locked plating. Screw seizing was more pronounced for Thread Only design (+37%) compared to Thread & Conus design (+14%; P<0.0001). Cyclic loading of the locking construct consistently resulted in an increased seizing of the locking screws (P<0.0001). Clinical observations from patients treated with the Thread & Conus locking design confirm the biomechanical findings of reduction in seizing effect by using a Thread & Conus design. In conclusion, both over-tightening and cyclic loading are potential causes for screw seizing in locking plate implants. Both effects were found to be less pronounced in the Thread & Conus design as compared to the traditional Thread Only design. © 2018 Elsevier Ltd. All rights reserved.

Seismic Stability of St. Stephen Hydropower Plant, South Carolina

DTIC Science & Technology

2006-11-01

looking from the fish-lift side ....................................... 9 Figure 1-9. Upstream T- beam connection : shim plates welded to embedded wall (an...Figure 1-10. Downstream T- beam connection : T- beam bearing plate rests on Neoprene pad, bolt through plate with slotted holes (an ideal roller condition...37 Figure 4-1. Beam - column model of the erection bay

Corrosion Behavior of Sacrificial Coatings on Grade 10.9 Fasteners for Multimetal Armor Applications

DTIC Science & Technology

2013-08-01

hexavalent chromium , immersion, magniplate, trivalent chromium (TCP), bolts nonchromate, hexavalent chrome, grade 10.9 fasteners, bolt-on armor...for Testing and Materials (ASTM) B633 (4) electroplated zinc with hexavalent chromium conversion coating 2. Trivalent Chromium Process (TCP): ASTM...B633 (4) electroplated zinc with trivalent chromium conversion coating 3. AlumiPlate: Process details, entire surface electroplated with aluminum (Al

Comparison between locked intramedullary nailing and anatomical locking plating in the treatment of displaced clavicular midshaft fractures.

PubMed

Zehir, Sinan; Çalbıyık, Murat; Şahin, Ercan; İpek, Deniz

2016-01-01

The aim of this study was to compare the results of expandable flexible locked intramedullary nailing and anatomical locking plating in clavicular midshaft fractures. Thirty-three patients (21 male, 12 female) who had displaced fractures and at least 2-cm shortening fixed with expandable flexible locked intramedullary nailing and 38 patients (24 male, 14 female) who underwent anatomical locking plating were recruited. Duration of surgery, incision size, duration of hospital stay, union time, and early and late complications were compared between the groups. Functional results were compared with Constant scoring system. Mean duration of surgery was 32.4±9.1 minutes (range: 20-42 minutes) in the nailing group and 54.1±11.9 minutes (range: 42-70 minutes) in the plating group. The incision was 4.1±0.9 cm (range: 3-5 cm) in the nailing group and 9.5±1.7 cm (range: 7-12 cm) in the plating group. Mean union time was 14.8 weeks (range: 10-24 weeks) in the nailing group and 21.3 weeks (range: 12-33 weeks) in the plating group. Mean duration of hospital stay was 3.6±1.1 days (range: 2-4 days) in the plating group, whereas it was 2.3±0.8 days (range: 1-3 days) in the nailing group. In the plating group, an average of 2.7-mm (range: 0-7 mm) shortening was determined in the clavicles that underwent surgery as compared to the intact clavicles, whereas shortening was 2.3 mm (range: 0-6 mm) in the nailing group. Expandable flexible locked intramedullary nailing can provide more successful outcomes than plating in displaced clavicular midshaft fractures, due to advantages such as shorter union time, lower complication rate, and better cosmetic outcomes.

Locking, mass flux and topographic response at convergent plate boundaries - the Chilean case

NASA Astrophysics Data System (ADS)

Oncken, Onno

2016-04-01

On the long term, convergent plate boundaries have been shown to be controlled by either accretion/underplating or by subduction erosion. Vertical surface motion is coupled to convergence rate - typically with an uplift rate of the coastal area ranging from 0 to +50% of convergence rate in accretive systems, and -20 to +30% in erosive systems. Vertical kinematics, however, are not necessarily linked to horizontal strain mode, i.e. upper plate shortening or extension, in a simple way. This range of kinematic behaviors - as well as their acceleration where forearcs collide with oceanic ridges/plateau - is well expressed along the Chilean plate margin. Towards the short end of the time scale, deformation appears to exhibit a close correlation with the frictional properties and geodetic locking at the plate interface. Corroborating analogue experiments of strain accumulation during multiple earthquake cycles, forearc deformation and uplift focus above the downdip and updip end of seismic coupling and slip and are each related to a particular stage of the seismic cycle, but with opposite trends for both domains. Similarly, barriers separating locked domains along strike appear to accumulate most upper plate faulting interseismically. Hence, locking patters are reflected in topography. From the long-term memory contained in the forearc topography the relief of the Chilean forearc seems to reflect long term stability of the observed heterogeneity of locking at the plate interface. This has fundamental implications for spatial and temporal distribution of seismic hazard. Finally, the nature of locking at the plate interface controlling the above kinematic behavior appears to be strongly controlled by the degree of fluid overpressuring at the plate interface suggesting that the hydraulic system at the interface takes a key role for the forearc response.

Effect of screw position on single cycle to failure in bending and torsion of a locking plate-rod construct in a synthetic feline femoral gap model.

PubMed

Niederhäuser, Simone K; Tepic, Slobodan; Weber, Urs T

2015-05-01

To evaluate the effect of screw position on strength and stiffness of a combination locking plate-rod construct in a synthetic feline femoral gap model. 30 synthetic long-bone models derived from beechwood and balsa wood. 3 constructs (2 locking plate-rod constructs and 1 locking plate construct; 10 specimens/construct) were tested in a diaphyseal bridge plating configuration by use of 4-point bending and torsion. Variables included screw position (near the fracture gap and far from the fracture gap) and application of an intramedullary pin. Constructs were tested to failure in each loading mode to determine strength and stiffness. Failure was defined as plastic deformation of the plate or breakage of the bone model or plate. Strength, yield angle, and stiffness were compared by use of a Wilcoxon test. Placement of screws near the fracture gap did not increase bending or torsional stiffness in the locking plate-rod constructs, assuming the plate was placed on the tension side of the bone. Addition of an intramedullary pin resulted in a significant increase in bending strength of the construct. Screw positioning did not have a significant effect on any torsion variables. Results of this study suggested that, in the investigated plate-rod construct, screw insertion adjacent to the fracture lacked mechanical advantages over screw insertion at the plate ends. For surgeons attempting to minimize soft tissue dissection, the decision to make additional incisions for screw placement should be considered with even more caution.

Locking of the Chile subduction zone controlled by fluid pressure before the 2010 earthquake

NASA Astrophysics Data System (ADS)

Moreno, Marcos; Haberland, Christian; Oncken, Onno; Rietbrock, Andreas; Angiboust, Samuel; Heidbach, Oliver

2014-04-01

Constraints on the potential size and recurrence time of strong subduction-zone earthquakes come from the degree of locking between the down-going and overriding plates, in the period between large earthquakes. In many cases, this interseismic locking degree correlates with slip during large earthquakes or is attributed to variations in fluid content at the plate interface. Here we use geodetic and seismological data to explore the links between pore-fluid pressure and locking patterns at the subduction interface ruptured during the magnitude 8.8 Chile earthquake in 2010. High-resolution three-dimensional seismic tomography reveals variations in the ratio of seismic P- to S-wave velocities (Vp/Vs) along the length of the subduction-zone interface. High Vp/Vs domains, interpreted as zones of elevated pore-fluid pressure, correlate spatially with parts of the plate interface that are poorly locked and slip aseismically. In contrast, low Vp/Vs domains, interpreted as zones of lower pore-fluid pressure, correlate with locked parts of the plate interface, where unstable slip and earthquakes occur. Variations in pore-fluid pressure are caused by the subduction and dehydration of a hydrothermally altered oceanic fracture zone. We conclude that variations in pore-fluid pressure at the plate interface control the degree of interseismic locking and therefore the slip distribution of large earthquake ruptures.

Methodology for Determining Limit Torques for Threaded Fasteners

NASA Technical Reports Server (NTRS)

Hissam, Andy

2011-01-01

In aerospace design, where minimizing weight is always a priority, achieving the full capacity from fasteners is essential. To do so, the initial bolt preload must be maximized. The benefits of high preload are well documented and include improved fatigue resistance, a stiffer joint, and resistance to loosening. But many factors like elastic interactions and embedment tend to lower the initial preload placed on the bolt. These factors provide additional motivation to maximize the initial preload. But, to maximize bolt preload, you must determine what torque to apply. Determining this torque is greatly complicated by the large preload scatter generally seen with torque control. This paper presents a detailed methodology for generating limit torques for threaded fasteners. This methodology accounts for the large scatter in preload found with torque control, and therefore, addresses the statistical nature of the problem. It also addresses prevailing torque, a feature common in aerospace fasteners. Although prevailing torque provides a desired locking feature, it can also increase preload scatter. In addition, it can limit the amount of preload that can be generated due to the torsion it creates in the bolt. This paper discusses the complications of prevailing torque and how best to handle it. A wide range of torque-tension bolt testing was conducted in support of this research. The results from this research will benefit the design engineer as well as analyst involved in the design of bolted joints, leading to better, more optimized structural designs.

Biomechanical Assessment of Locked Plating for the Fixation of Patella Fractures.

PubMed

Wurm, Simone; Augat, Peter; Bühren, Volker

2015-09-01

To analyze the mechanical stability of locked plating in comparison with tension-band wiring for the fixation of fractures of the patella. Biomechanical tests were performed on artificial foam patella specimens comparing an angular stable plate and monocortical screws with tension-band wiring. Tests were performed under combined tension and bending until failure simulating physiological loading of the tibia during walking. Tension-band wiring failed at 66% of the failure load of plating (1052 N, P = 0.002) and had 5 times larger fracture gap displacements (P = 0.002). Based on the biomechanical advantages, locked plating of the patella may constitute a reasonable alternative in the treatment of patella fractures.

49 CFR 571.209 - Standard No. 209; Seat belt assemblies.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., plates, or washers, need not have such hardware, but shall have 7/16-20 UNF-2A or 1/2-13 UNC-2A... and other parts from becoming disengaged from the vehicle while in service. Reinforcing plates or... projected area. The distance between any edge of the plate and the edge of the bolt hole shall be at least...

49 CFR 571.209 - Standard No. 209; Seat belt assemblies.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., plates, or washers, need not have such hardware, but shall have 7/16-20 UNF-2A or 1/2-13 UNC-2A... and other parts from becoming disengaged from the vehicle while in service. Reinforcing plates or... projected area. The distance between any edge of the plate and the edge of the bolt hole shall be at least...

49 CFR 571.209 - Standard No. 209; Seat belt assemblies.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., plates, or washers, need not have such hardware, but shall have 7/16-20 UNF-2A or 1/2-13 UNC-2A... and other parts from becoming disengaged from the vehicle while in service. Reinforcing plates or... projected area. The distance between any edge of the plate and the edge of the bolt hole shall be at least...

49 CFR 571.209 - Standard No. 209; Seat belt assemblies.

Code of Federal Regulations, 2011 CFR

2011-10-01

... anchorage nuts, plates, or washers, need not have such hardware, but shall have 7/16-20 UNF-2A or 1/2-13UNC... plates or washers furnished for universal floor, installations shall be of steel, free from burrs and... 2580 mm2 in projected area. The distance between any edge of the plate and the edge of the bolt hole...

Semi-rigid screws provide an auxiliary option to plate working length to control interfragmentary movement in locking plate fixation at the distal femur.

PubMed

Heyland, Mark; Duda, Georg N; Haas, Norbert P; Trepczynski, Adam; Döbele, Stefan; Höntzsch, Dankward; Schaser, Klaus-Dieter; Märdian, Sven

2015-10-01

Extent and orientation of interfragmentary movement (IFM) are crucially affecting course and quality of fracture healing. The effect of different configurations for implant fixation on successful fracture healing remain unclear. We hypothesize that screw type and configuration of locking plate fixation profoundly influences stiffness and IFM for a given load in a distal femur fracture model. Simple analytical models are presented to elucidate the influence of fixation configuration on construct stiffness. Models were refined with a consistent single-patient-data-set to create finite-element femur models. Locking plate fixation of a distal femoral 10mm-osteotomy (comminution model) was fitted with rigid locking screws (rLS) or semi-rigid locking screws (sLS). Systematic variations of screw placements in the proximal fragment were tested. IFM was quantitatively assessed and compared for different screw placements and screw types. Different screw allocations significantly affect IFM in a locking plate construct. LS placement of the first screw proximal to the fracture (plate working length, PWL) has a significant effect on axial IFM (p < 0.001). Replacing rLS with sLS caused an increase (p < 0.001) of IFM under the plate (cis-cortex) between +8.4% and +28.1% for the tested configurations but remained constant medially (<1.1%, trans-cortex). Resultant shear movements markedly increased at fracture level (p < 0.001) to the extent that plate working length increased. The ratio of shear/axial IFM was found to enhance for longer PWL. sLS versus rLS lead to significantly smaller ratios of shear/axial IFM at the cis-cortex for PWL of ≥ 62 mm (p ≤ 0.003). Mechanical frame conditions can be significantly influenced by type and placement of the screws in locking plate osteosynthesis of the distal femur. By varying plate working length stiffness and IFM are modulated. Moderate axial and concomitantly low shear IFM could not be achieved through changes in screw placement alone. In the present transverse osteotomy model, ratio of shear/axial IFM with simultaneous moderate axial IFM is optimized by the use of appropriate plate working length of about 42-62 mm. Fixation with sLS demonstrated significantly more axial IFM underneath the plate and may further contribute to compensation of asymmetric straining. Copyright © 2015 Elsevier Ltd. All rights reserved.

29 CFR 1917.49 - Spouts, chutes, hoppers, bins, and associated equipment.

Code of Federal Regulations, 2013 CFR

2013-07-01

... turned off, locked out and tagged. (3) The employee entering the bin wears a lifeline and safety harness... equipment to be used. The inspection shall include at least the eye bolts, wires, and sheaves. (2) Power... adjustments are made to a power shovel, wire, or associated equipment, the power supply to the shovel shall be...

29 CFR 1917.49 - Spouts, chutes, hoppers, bins, and associated equipment.

Code of Federal Regulations, 2012 CFR

2012-07-01

... turned off, locked out and tagged. (3) The employee entering the bin wears a lifeline and safety harness... equipment to be used. The inspection shall include at least the eye bolts, wires, and sheaves. (2) Power... adjustments are made to a power shovel, wire, or associated equipment, the power supply to the shovel shall be...

29 CFR 1917.49 - Spouts, chutes, hoppers, bins, and associated equipment.

Code of Federal Regulations, 2014 CFR

2014-07-01

... turned off, locked out and tagged. (3) The employee entering the bin wears a lifeline and safety harness... equipment to be used. The inspection shall include at least the eye bolts, wires, and sheaves. (2) Power... adjustments are made to a power shovel, wire, or associated equipment, the power supply to the shovel shall be...

Close the Gate, Lock the Windows, Bolt the Doors: Securing Library Computers. Online Treasures

ERIC Educational Resources Information Center

Balas, Janet

2005-01-01

This article, written by a systems librarian at the Monroeville Public Library, discusses a major issue affecting all computer users, security. It indicates that while, staying up-to-date on the latest security issues has become essential for all computer users, it's more critical for network managers who are responsible for securing computer…

The effect of load obliquity on the strength of locking and nonlocking constructs in synthetic osteoporotic bone.

PubMed

Tensmeyer, Daniel F; Gustafson, Peter A; Jastifer, James R; Patel, Bipin; Chess, Joseph L

2015-11-01

The biomechanical performance of internal fracture fixation depends on several factors. One measure of performance is the strength of the construct. The objective of this biomechanical study was to identify the effect of load obliquity on the strength of locking and nonlocking plate and screw constructs. For this study, plates and screws were fixed to synthetic osteoporotic bone that had a 1 mm thick synthetic cortical shell. An 8-hole, 3.5 mm thick hybrid plate was fixed with either two 3.5 mm major diameter locking screws or two 4.0 mm major diameter cancellous screws. Forces were applied at 0, 45, and 90 degrees to the plate normal. Eight specimens were loaded to failure for each group. When loads were applied normal to the plate, the nonlocking construct failed initially at higher loads (123.2 ± 13.2 N) than the locking construct (108.7 ± 7.6 N, P = 0.020). For oblique loads, the locking construct failed at higher mean loads but the difference of means was not statistically significant (167.7 ± 14.9 N compared to 154.2 ± 9.4 N, P = 0.052). For loads parallel to the plate, the locking construct was much stronger than the nonlocking construct (1591 ± 227 N compared to 913 ± 237 N, P < 0.001). Stiffness and Energy outcomes are also compared. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

Congruency of scapula locking plates: implications for implant design.

PubMed

Park, Andrew Y; DiStefano, James G; Nguyen, Thuc-Quyen; Buckley, Jenni M; Montgomery, William H; Grimsrud, Chris D

2012-04-01

We conducted a study to evaluate the congruency of fit of current scapular plate designs. Three-dimensional image-processing and -analysis software, and computed tomography scans of 12 cadaveric scapulae were used to generate 3 measurements: mean distance from plate to bone, maximum distance, and percentage of plate surface within 2 mm of bone. These measurements were used to quantify congruency. The scapular spine plate had the most congruent fit in all 3 measured variables. The lateral border and glenoid plates performed statistically as well as the scapular spine plate in at least 1 of the measured variables. The medial border plate had the least optimal measurements in all 3 variables. With locking-plate technology used in a wide variety of anatomical locations, the locking scapula plate system can allow for a fixed-angle construct in this region. Our study results showed that the scapular spine, glenoid, and lateral border plates are adequate in terms of congruency. However, design improvements may be necessary for the medial border plate. In addition, we describe a novel method for quantifying hardware congruency, a method that can be applied to any anatomical location.

Biomechanics of far cortical locking.

PubMed

Bottlang, Michael; Feist, Florian

2011-02-01

The development of far cortical locking (FCL) was motivated by a conundrum: locked plating constructs provide inherently rigid stabilization, yet they should facilitate biologic fixation and secondary bone healing that relies on flexible fixation to stimulate callus formation. Recent studies have confirmed that the high stiffness of standard locked plating constructs can suppress interfragmentary motion to a level that is insufficient to reliably promote secondary fracture healing by callus formation. Furthermore, rigid locking screws cause an uneven stress distribution that may lead to stress fracture at the end screw and stress shielding under the plate. This review summarizes four key features of FCL constructs that have been shown to enhance fixation and healing of fractures: flexible fixation, load distribution, progressive stiffening, and parallel interfragmentary motion. Specifically, flexible fixation provided by FCL reduces the stiffness of a locked plating construct by 80% to 88% to actively promote callus proliferation similar to an external fixator. Load is evenly distributed between FCL screws to mitigate stress risers at the end screw. Progressive stiffening occurs by near cortex support of FCL screws and provides additional support under elevated loading. Finally, parallel interfragmentary motion by the S-shaped flexion of FCL screws promotes symmetric callus formation. In combination, these features of FCL constructs have been shown to induce more callus and to yield significantly stronger and more consistent healing compared with standard locked plating constructs. As such, FCL constructs function as true internal fixators by replicating the biomechanical behavior and biologic healing response of external fixators.

[Current status of surgical technique for unreamed nailing of tibial shaft fractures with the UTN (unreamed tibia nail)].

PubMed

Krettek, C; Schandelmaier, P; Rudolf, J; Tscherne, H

1994-11-01

Nailing technique has changed in recent years in some important aspects which are not limited to the omitted reaming procedure. These changes concern patient positioning, reduction technique, the use of temporary stabilizers such as the 'Pinless', and determination of implant length and diameter. Approach and exposure techniques have been modified to new, less invasive procedures, in order to fulfill technical, functional and aesthetic requirements. Techniques and tricks have been developed for avoidance of fragment diastasis and axial and torsional malalignment. Finally, simple algorithms are described for the management of large bone defects, bilateral tibia shaft or ipsilateral femoral shaft fractures, number and location of locking bolts, the 'when and how' of patient mobilization and load bearing, and primary and secondary dynamization. These algorithms, techniques and procedures were developed in a series of 152 tibia shafts, which were stabilized with the AO unreamed tibia nail (UTN) in a prospective study between March 1989 and June 1994. Of these, 75 cases with a mean follow-up of 19.4 +/- 6.3 (range 11-37) months after trauma were reviewed. Fractures were classified according to Müller (1990): 14 type A, 37 type B and 24 type C. Closed soft tissue damage was categorized according to our classification: C0/1, n = 5; C2, n = 12; C3, n = 9 (Tscherne 1982). Among 49 open fractures 8 were OI, 18 OII, 10 OIIIA and 13 OIIIB (Gustilo 1976). The main minor intraoperative complication was drill bit breakage (n = 10), most frequently at the proximal locking holes. The main postoperative complication was breakage of locking bolts (n = 16), mainly between weeks 6 and 20. Minor secondary reinterventions were, in most cases, secondary dynamization under local anaesthesia. Major reintervention were: soft tissue reconstructions (n = 5), isolated cancellous bone graft (n = 6), and change of treatment (n = 12). There were nine changes to a reamed nail, two changes, in very proximal fractures, to plate osteosyntheses. There were three deep infections. Mean time to union was 23.9 weeks (range 10-48 weeks, n = 73); in two cases non-union was observed. The overall result was judged with the Karlström-Olerud score, which was applicable in 66 of 75 cases; excellent, n = 2; good, n = 22; satisfactory, n = 24; fair, n = 9; poor, n = 9. In the remaining nine cases no scoring was attempted because of severe injuries around the knee or ankle.

External Coulomb-Friction Damping For Hydrostatic Bearings

NASA Technical Reports Server (NTRS)

Buckmann, Paul S.

1992-01-01

External friction device damps vibrations of shaft and hydrostatic ring bearing in which it turns. Does not rely on wear-prone facing surfaces. Hydrostatic bearing ring clamped in radially flexing support by side plates clamped against radial surfaces by spring-loaded bolts. Plates provide friction against radial motions of shaft.

Intraoral technique for locking reconstruction plate fixation using an implant handpiece with adapted drills.

PubMed

Haas, Orion Luiz; Scolari, Neimar; Meirelles, Lucas da Silva; Becker, Otávio Emmel; Melo, Marcelo Fernandes Santos; Viegas, Vinícius Nery; de Oliveira, Rogério Belle

2016-09-01

Locking reconstruction plates are used in the treatment of jaw trauma and diseases if there is a need for surgical resection and to prevent pathologic fracture after tumor excision. Fixation is typically performed using an extraoral approach. This article describes a technique for the intraoral fixation of locking reconstruction plates that uses prototyping to model the plate before the procedure as well as an implant handpiece with adapted drills for bone drilling and the insertion of screws into relatively inaccessible areas. Intraoral fixation not only prevents nerve damage and facial scarring but also minimizes the plate's risk of extraoral exposure and reduces surgical morbidity. © 2016 Wiley Periodicals, Inc. Head Neck 38: 1436-1439, 2016. © 2016 Wiley Periodicals, Inc.

Volar fixed-angle plating of extra-articular distal radius fractures--a biomechanical analysis comparing threaded screws and smooth pegs.

PubMed

Weninger, Patrick; Dall'Ara, Enrico; Leixnering, Martin; Pezzei, Christoph; Hertz, Harald; Drobetz, Herwig; Redl, Heinz; Zysset, Philippe

2010-11-01

Distal radius fractures represent the most common fractures in adult individuals. Volar fixed-angle plating has become a popular modality for treating unstable distal radius fractures. Most of the plates allow insertion of either threaded locking screws or smooth locking pegs. To date, no biomechanical studies compare locking screws and pegs under axial and torsional loading. Ten Sawbones radii were used to simulate an AO/OTA A3 fracture. Volar fixed-angle plates (Aptus Radius 2.5, Medartis, Switzerland) with threaded locking screws (n = 5) or smooth locking pegs (n = 5) were used to fix the distal metaphyseal fragment. Each specimen was tested under axial compression and under torsional load with a servohydraulic testing machine. Qualitative parameters were recorded as well as axial and torsional stiffness, torsion strength, energy absorbed during monotonic loading and energy absorbed in one cycle. Axial stiffness was comparable between both groups (p = 0.818). If smooth pegs were used, a 17% reduction of torsional stiffness (p = 0.017) and a 12% reduction of minimum torque (p = 0.012) were recorded. A 12% reduction of energy absorbed (p = 0.013) during monotonic loading and unloading was recorded if smooth pegs were used. A 34% reduction of energy absorbed in one cycle (p < 0.007) was recorded if threaded screws were used. Sliding of the pegs out of the distal radius metaphyses of the synthetic bones was recorded at a mean torque of 3.80 Nm ± 0.19 Nm. No sliding was recorded if threaded screws were used. According to the results of this study using Sawbones, volar fixed-angle plates with threaded locking screws alone are mechanically superior to volar fixed-angle plates with smooth locking pegs alone under torsional loading.

Polyaxial Screws in Locked Plating of Tibial Pilon Fractures.

PubMed

Yenna, Zachary C; Bhadra, Arup K; Ojike, Nwakile I; Burden, Robert L; Voor, Michael J; Roberts, Craig S

2015-08-01

This study examined the axial and torsional stiffness of polyaxial locked plating techniques compared with fixed-angle locked plating techniques in a distal tibia pilon fracture model. The effect of using a polyaxial screw to cross the fracture site was examined to determine its ability to control relative fracture site motion. A laboratory experiment was performed to investigate the biomechanical stiffness of distal tibia fracture models repaired with 3.5-mm anterior polyaxial distal tibial plates and locking screws. Sawbones Fourth Generation Composite Tibia models (Pacific Research Laboratories, Inc, Vashon, Washington) were used to model an Orthopaedic Trauma Association 43-A1.3 distal tibia pilon fracture. The polyaxial plates were inserted with 2 central locking screws at a position perpendicular to the cortical surface of the tibia and tested for load as a function of axial displacement and torque as a function of angular displacement. The 2 screws were withdrawn and inserted at an angle 15° from perpendicular, allowing them to span the fracture and insert into the opposing fracture surface. Each tibia was tested again for axial and torsional stiffness. In medial and posterior loading, no statistically significant difference was found between tibiae plated with the polyaxial plate and the central screws placed in the neutral position compared with the central screws placed at a 15° position. In torsional loading, a statistically significant difference was noted, showing greater stiffness in tibiae plated with the polyaxial plate and the central screws placed at a 15° position compared with tibiae plated with the central screws placed at a 0° (or perpendicular) position. This study showed that variable angle constructs show similar stiffness properties between perpendicular and 15° angle insertions in axial loading. The 15° angle construct shows greater stiffness in torsional loading. Copyright 2015, SLACK Incorporated.

Advanced Concepts for Composite Structure Joints and Attachment Fittings. Volume I. Design and Evaluation.

DTIC Science & Technology

1981-11-01

interlaminar tension). The analysis is also influenced by other factors such as bolt location, washer/bolt size, fastener pattern, laminate thickness, corner...to reduce the cost of tooling were also studied. These include: * Pultrusion dies for under $5, 000 * Stable, accurate, low-cost chopped-fiber phenolic ...fittings were state-of- the-art methods developed for laminated composite plates, shells, beams, and columns as used in analyses of discontinuities, edge

Comparative study of single lateral locked plating versus double plating in type C bicondylar tibial plateau fractures.

PubMed

Neogi, Devdatta Suhas; Trikha, Vivek; Mishra, Kaushal Kant; Bandekar, Shivanand M; Yadav, Chandra Shekhar

2015-01-01

Bicondylar tibial plateau fractures are complex injuries and treatment is challenging. Ideal method is still controversial with risk of unsatisfactory results if not treated properly. Many different techniques of internal and external fixation are used. This study compares the clinical results in single locked plating versus dual plating (DP) using two incision approaches. Our hypothesis was that DP leads to less collapse and change in alignment at final followup compared with single plating. 61 cases of Type C tibial plateau fractures operated between January 2007 and June 2011 were included in this prospective study. All cases were operated either by single lateral locked plate by anterolateral approach or double plating through double incision. All cases were followed for a minimum of 24 months radiologically and clinically. The statistical analysis was performed using software SPSS 10.0 to analyze the data. Twenty nine patients in a single lateral locked plate and 32 patients in a double plating group were followed for minimum 2 years. All fractures healed, however there was a significant incidence of malalignment in the single lateral plating group. Though there was a significant increase in soft tissue issues with the double plating group; however, there was only 3.12% incidence of deep infection. There was no significant difference in Hospital for special surgery score at 2 years followup. Double plating through two incisions resulted in a better limb alignment and joint reduction with an acceptable soft tissue complication rate.

Biomechanical in vitro - stability testing on human specimens of a locking plate system against conventional screw fixation of a proximal first metatarsal lateral displacement osteotomy.

PubMed

Arnold, Heino; Stukenborg-Colsman, Christina; Hurschler, Christof; Seehaus, Frank; Bobrowitsch, Evgenij; Waizy, Hazibullah

2012-01-01

The aim of this study was to examine resistance to angulation and displacement of the internal fixation of a proximal first metatarsal lateral displacement osteotomy, using a locking plate system compared with a conventional crossed screw fixation. Seven anatomical human specimens were tested. Each specimen was tested with a locking screw plate as well as a crossed cancellous srew fixation. The statistical analysis was performed by the Friedman test. The level of significance was p = 0.05. We found larger stability about all three axes of movement analyzed for the PLATE than the crossed screws osteosynthesis (CSO). The Friedman test showed statistical significance at a level of p = 0.05 for all groups and both translational and rotational movements. The results of our study confirm that the fixation of the lateral proximal first metatarsal displacement osteotomy with a locking plate fixation is a technically simple procedure of superior stability.

Biomechanical In Vitro - Stability Testing on Human Specimens of a Locking Plate System Against Conventional Screw Fixation of a Proximal First Metatarsal Lateral Displacement Osteotomy

PubMed Central

Arnold, Heino; Stukenborg-Colsman, Christina; Hurschler, Christof; Seehaus, Frank; Bobrowitsch, Evgenij; Waizy, Hazibullah

2012-01-01

Introduction: The aim of this study was to examine resistance to angulation and displacement of the internal fixation of a proximal first metatarsal lateral displacement osteotomy, using a locking plate system compared with a conventional crossed screw fixation. Materials and Methodology: Seven anatomical human specimens were tested. Each specimen was tested with a locking screw plate as well as a crossed cancellous srew fixation. The statistical analysis was performed by the Friedman test. The level of significance was p = 0.05. Results: We found larger stability about all three axes of movement analyzed for the PLATE than the crossed screws osteosynthesis (CSO). The Friedman test showed statistical significance at a level of p = 0.05 for all groups and both translational and rotational movements. Conclusion: The results of our study confirm that the fixation of the lateral proximal first metatarsal displacement osteotomy with a locking plate fixation is a technically simple procedure of superior stability. PMID:22675409

76 FR 61343 - Certain Helical Spring Lock Washers From Taiwan and the People's Republic of China: Final Results...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-04

... bearing surface. The scope does not include internal or external tooth washers, nor does it include spring... are lock washers of carbon steel, of carbon alloy steel, or of stainless steel, heat-treated or non-heat-treated, plated or non-plated, with ends that are off-line. Lock washers are designed to: (1...

75 FR 29720 - Certain Helical Spring Lock Washers From the People's Republic of China: Final Results of...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-27

...) provide a hardened bearing surface. The scope does not include internal or external tooth washers, nor... helical spring lock washers of carbon steel, of carbon alloy steel, or of stainless steel, heat- treated or non-heat-treated, plated or non-plated, with ends that are off-line. Helical spring lock washers...

Periarticular locking plate vs intramedullary nail for tibiotalocalcaneal arthrodesis: a biomechanical investigation.

PubMed

Ohlson, Blake L; Shatby, Meena W; Parks, Brent G; White, Kacey L; Schon, Lew C

2011-02-01

Augmented retrograde intramedullary (IM) nail fixation was compared with augmented periarticular locking- plate fixation for tibiotalocalcaneal arthrodesis. Specimens in 10 matched pairs were randomly assigned to a fixation construct and loaded cyclically in dorsiflexion. The groups did not differ in initial or final stiffness, load to failure, or construct deformation. No correlation was found between bone mineral density and construct deformation for either group. A humeral locking plate may be a viable alternative to an IM nail for tibiotalocalcaneal fixation in cases not amenable to IM nailing.

Development of Live-working Robot for Power Transmission Lines

NASA Astrophysics Data System (ADS)

Yan, Yu; Liu, Xiaqing; Ren, Chengxian; Li, Jinliang; Li, Hui

2017-07-01

Dream-I, the first reconfigurable live-working robot for power transmission lines successfully developed in China, has the functions of autonomous walking on lines and accurately positioning. This paper firstly described operation task and object of the robot; then designed a general platform, an insulator replacement end and a drainage plate bolt fastening end of the robot, presented a control system of the robot, and performed simulation analysis on operation plan of the robot; and finally completed electrical field withstand voltage tests in a high voltage hall as well as online test and trial on actual lines. Experimental results show that by replacing ends of manipulators, the robot can fulfill operation tasks of live replacement of suspension insulators and live drainage plate bolt fastening.

Percutaneous locking plates for fractures of the distal tibia: our experience and a review of the literature.

PubMed

Ahmad, Mudussar Abrar; Sivaraman, Alagappan; Zia, Ahmed; Rai, Amarjit; Patel, Amratlal D

2012-02-01

Distal tibial metaphyseal fractures pose many complexities. This study assessed the outcomes of distal tibial fractures treated with medial locking plates. Eighteen patients were selected based on the fracture pattern and classified using the AO classification and stabilized with an AO medial tibial locking plate. Time to fracture union, complications, and outcomes were assessed with the American Orthopedic Foot and Ankle Society Ankle score at 12 months. Sixteen of the 18 patients achieved fracture union, with 1 patient lost to follow-up. Twelve fractures united within 24 weeks, with an average union time of 23.1 weeks. Three delayed unions, two at 28 weeks and one at 56 weeks. The average time to union was 32 weeks in the smokers and 15.3 weeks in the nonsmokers. Five of the 18 patients (27%) developed complications. One superficial wound infection, and one chronic wound infection, resulting in nonunion at 56 weeks, requiring revision. Two patients required plate removal, one after sustaining an open fracture at the proximal end of the plate 6 months after surgery (postfracture union)and the other for painful hardware. One patient had implant failure of three proximal diaphyseal locking screws at the screwhead/neck junction, but successful fracture union. The average American Orthopedic Foot and Ankle Society ankle score was 88.8 overall, and 92.1 in fractures that united within 24 weeks. Distal tibial locking plates have high fracture union rates, minimum soft tissue complications, and good functional outcomes. The literature shows similar fracture union and complication rates in locking and nonlocking plates. Copyright © 2012 by Lippincott Williams & Wilkins

Dynamic locked plating for fixation of distal femur fractures using near- cortical over-drilling: Preliminary results of a prospective observational study.

PubMed

Galal, Sherif

2017-01-01

Nonunion after locked plating of distal femur fractures is not uncommon. Authors wanted to assess if "Dynamic" locked plating using near-cortex over-Drilling technique would provide a mechanical environment the promotes callus formation, thereby avoiding non-union encountered when applying locked plates with the conventional method. This study was conducted at an academic Level 1 Trauma Center. This is a prospective study conducted from November 2015 to November 2016. Follow-up was 10 months on average (ranging from 8 to 12 months). The study included 20 patients with 20 fractures (13 males, 7 females). The average patients' age was 41.2 years (18-64 years). According to the Müller AO classification of distal femur fractures (33A-C) there were 15 cases with extra-articular fractures (AO 33A), 5 patients with intra-articular fractures (AO 33C). Dynamic Locked plating using near-cortical over-drilling technique was done for all patients. Two blinded observers assessed callus score on 6-week radiographs using a 4-point ordinal scale. A 2-tailed t -test. Two-way mixed intra-class correlation testing was performed to determine reliability of the callus measurements by the 2 observers. All patients achieved union, time to union was 13.4 weeks on average (range form 8-24 weeks). Delayed union was observed in 2 patients. The average callus score for fractures was 1.8 (SD 0.6). All fractures united in alignment except 1 fracture which united in valgus malalignment, the deformity was appreciated in the postoperative radiographs. No wound related complications, no loss of reduction, no catastrophic implant failure or screw breakage were detected. Dynamic locked plating using near-cortex over-drilling is a simple technique that uses standard locked plates that promotes callus formation when used for fixing distal femur fractures.

Combined In-Plane and Through-the-Thickness Analysis for Failure Prediction of Bolted Composite Joints

NASA Technical Reports Server (NTRS)

Kradinov, V.; Madenci, E.; Ambur, D. R.

2004-01-01

Although two-dimensional methods provide accurate predictions of contact stresses and bolt load distribution in bolted composite joints with multiple bolts, they fail to capture the effect of thickness on the strength prediction. Typically, the plies close to the interface of laminates are expected to be the most highly loaded, due to bolt deformation, and they are usually the first to fail. This study presents an analysis method to account for the variation of stresses in the thickness direction by augmenting a two-dimensional analysis with a one-dimensional through the thickness analysis. The two-dimensional in-plane solution method based on the combined complex potential and variational formulation satisfies the equilibrium equations exactly, and satisfies the boundary conditions and constraints by minimizing the total potential. Under general loading conditions, this method addresses multiple bolt configurations without requiring symmetry conditions while accounting for the contact phenomenon and the interaction among the bolts explicitly. The through-the-thickness analysis is based on the model utilizing a beam on an elastic foundation. The bolt, represented as a short beam while accounting for bending and shear deformations, rests on springs, where the spring coefficients represent the resistance of the composite laminate to bolt deformation. The combined in-plane and through-the-thickness analysis produces the bolt/hole displacement in the thickness direction, as well as the stress state in each ply. The initial ply failure predicted by applying the average stress criterion is followed by a simple progressive failure. Application of the model is demonstrated by considering single- and double-lap joints of metal plates bolted to composite laminates.

Design of New Muzzle for 80mm Diamter Single-Stage Gas Gun

NASA Astrophysics Data System (ADS)

Russell, R. T.; Starks, K. S.; Grote, D. L., II; Vandersall, K. S.; Zhou, M.; Thadhani, N. N.

1999-06-01

In this paper, we describe the design of a new muzzle for the Georgia Institute of Technology's 80mm diameter single-stage gas gun. The muzzle is designed to accommodate both normal and inclined impact experiments. Modular target-holding assemblies are mounted on a hardened tool steel annular plate 3 inches in thickness and 15 inches in diameter. This plate is threaded on to the gun barrel and locked into place by an anti-backlash assembly to prevent loss of alignment. The target mount for normal impact experiments consists of two 4.5 inch diameter semi-cylindrical ring sections with surfaces lapped perpendicular to the major bore axis. The inclined target mount includes a pair of concentric cylinder sections with an inner diameter of 8 inches. Tilt adjustment is achieved around two mutually perpendicular and intersecting axis of rotation, as in a gimbals assembly. Coarse alignment allows for angles between -10 and +30 degrees. Fine alignment is achieved using 3/8 inch machine screws with 40 threads per inch. This mechanism yields a precision of 0.025 inches per revolution, the same precision found in a micrometer. The linear distance between the adjustment mechanisms and the axes of rotation geometrically enhances fine alignment. Velocity measurement assemblies using shear pins, time of arrival pins, and laser/photo-diode circuits are designed as bolt-on modules.

Fixation of a split fracture of the lateral tibial plateau with a locking screw plate instead of cannulated screws would allow early weight bearing: a computational exploration.

PubMed

Carrera, Ion; Gelber, Pablo Eduardo; Chary, Gaetan; González-Ballester, Miguel A; Monllau, Juan Carlos; Noailly, Jerome

2016-10-01

To assess, with finite element (FE) calculations, whether immediate weight bearing would be possible after surgical stabilization either with cannulated screws or with a locking plate in a split fracture of the lateral tibial plateau (LTP). A split fracture of the LTP was recreated in a FE model of a human tibia. A three-dimensional FE model geometry of a human femur-tibia system was obtained from the VAKHUM project database, and was built from CT images from a subject with normal bone morphologies and normal alignment. The mesh of the tibia was reconverted into a geometry of NURBS surfaces. A split fracture of the lateral tibial plateau was reproduced by using geometrical data from patient radiographs. A locking screw plate (LP) and a cannulated screw (CS) systems were modelled to virtually reduce the fracture and 80 kg static body-weight was simulated. While the simulated body-weight led to clinically acceptable interfragmentary motion, possible traumatic bone shear stresses were predicted nearby the cannulated screws. With a maximum estimation of about 1.7 MPa maximum bone shear stresses, the Polyax system might ensure more reasonable safety margins. Split fractures of the LTP fixed either with locking screw plate or cannulated screws showed no clinically relevant IFM in a FE model. The locking screw plate showed higher mechanical stability than cannulated screw fixation. The locking screw plate might also allow full or at least partial weight bearing under static posture at time zero.

Locking plate fixation provides superior fixation of humerus split type greater tuberosity fractures than tension bands and double row suture bridges.

PubMed

Gaudelli, Cinzia; Ménard, Jérémie; Mutch, Jennifer; Laflamme, G-Yves; Petit, Yvan; Rouleau, Dominique M

2014-11-01

This paper aims to determine the strongest fixation method for split type greater tuberosity fractures of the proximal humerus by testing and comparing three fixation methods: a tension band with No. 2 wire suture, a double-row suture bridge with suture anchors, and a manually contoured calcaneal locking plate. Each method was tested on eight porcine humeri. A osteotomy of the greater tuberosity was performed 50° to the humeral shaft and then fixed according to one of three methods. The humeri were then placed in a testing apparatus and tension was applied along the supraspinatus tendon using a thermoelectric cooling clamp. The load required to produce 3mm and 5mm of displacement, as well as complete failure, was recorded using an axial load cell. The average load required to produce 3mm and 5mm of displacement was 658N and 1112N for the locking plate, 199N and 247N for the double row, and 75N and 105N for the tension band. The difference between the three groups was significant (P<0.01). The average load to failure of the locking plate (810N) was significantly stronger than double row (456N) and tension band (279N) (P<0.05). The stiffness of the locking plate (404N/mm) was significantly greater than double row (71N/mm) and tension band (33N/mm) (P<0.01). Locking plate fixation provides the strongest and stiffest biomechanical fixation for split type greater tuberosity fractures. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biomechanical comparison of locking plate and crossing metallic and absorbable screws fixations for intra-articular calcaneal fractures.

PubMed

Ni, Ming; Wong, Duo Wai-Chi; Mei, Jiong; Niu, Wenxin; Zhang, Ming

2016-09-01

The locking plate and percutaneous crossing metallic screws and crossing absorbable screws have been used clinically to treat intra-articular calcaneal fractures, but little is known about the biomechanical differences between them. This study compared the biomechanical stability of calcaneal fractures fixed using a locking plate and crossing screws. Three-dimensional finite-element models of intact and fractured calcanei were developed based on the CT images of a cadaveric sample. Surgeries were simulated on models of Sanders type III calcaneal fractures to produce accurate postoperative models fixed by the three implants. A vertical force was applied to the superior surface of the subtalar joint to simulate the stance phase of a walking gait. This model was validated by an in vitro experiment using the same calcaneal sample. The intact calcaneus showed greater stiffness than the fixation models. Of the three fixations, the locking plate produced the greatest stiffness and the highest von Mises stress peak. The micromotion of the fracture fixated with the locking plate was similar to that of the fracture fixated with the metallic screws but smaller than that fixated with the absorbable screws. Fixation with both plate and crossing screws can be used to treat intra-articular calcaneal fractures. In general, fixation with crossing metallic screws is preferable because it provides sufficient stability with less stress shielding.

Better Axial Stiffness of a Bicortical Screw Construct Compared to a Cable Construct for Comminuted Vancouver B1 Proximal Femoral Fractures.

PubMed

Griffiths, Jamie T; Taheri, Arash; Day, Robert E; Yates, Piers J

2015-12-01

The aim of this study was to biomechanically evaluate the Locking attachment plate (LAP) construct in comparison to a Cable plate construct, for the fixation of periprosthetic femoral fractures after cemented total hip arthroplasty. Each construct incorporated a locking compression plate with bi-cortical locking screws for distal fixation. In the Cable construct, 2 cables and 2 uni-cortical locking screws were used for proximal fixation. In the LAP construct, the cables were replaced by a LAP with 4 bi-cortical locking screws. The LAP construct was significantly stiffer than the cable construct under axial load with a bone gap (P=0.01). The LAP construct offers better axial stiffness compared to the cable construct in the fixation of comminuted Vancouver B1 proximal femoral fractures. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

Analysis of Bolted and Bonded Composite

DTIC Science & Technology

1992-09-01

pp. 1067-1079. 2-73. Askins, D. R. and D. R. Byrge, "Evaluation of 350°F Curing Adhesive Systems on Phosphoricn Acid Anodized Aluminum Substrates...Acceptable Aluminum Not compatible Cadmium Not compatible Chrom. plate Adequate with A286, PHI 3-8MO INCO 600 (Cobalt alloys) Good Low alloy steel Not... aluminum . Their tensile moduli are 30, 16 and 10 msi, respectively. The range for tensile strengths of steel and titanium bolts is approximately 220 to

Comparative study of single lateral locked plating versus double plating in type C bicondylar tibial plateau fractures

PubMed Central

Neogi, Devdatta Suhas; Trikha, Vivek; Mishra, Kaushal Kant; Bandekar, Shivanand M.; Yadav, Chandra Shekhar

2015-01-01

Background: Bicondylar tibial plateau fractures are complex injuries and treatment is challenging. Ideal method is still controversial with risk of unsatisfactory results if not treated properly. Many different techniques of internal and external fixation are used. This study compares the clinical results in single locked plating versus dual plating (DP) using two incision approaches. Our hypothesis was that DP leads to less collapse and change in alignment at final followup compared with single plating. Materials and Methods: 61 cases of Type C tibial plateau fractures operated between January 2007 and June 2011 were included in this prospective study. All cases were operated either by single lateral locked plate by anterolateral approach or double plating through double incision. All cases were followed for a minimum of 24 months radiologically and clinically. The statistical analysis was performed using software SPSS 10.0 to analyze the data. Results: Twenty nine patients in a single lateral locked plate and 32 patients in a double plating group were followed for minimum 2 years. All fractures healed, however there was a significant incidence of malalignment in the single lateral plating group. Though there was a significant increase in soft tissue issues with the double plating group; however, there was only 3.12% incidence of deep infection. There was no significant difference in Hospital for special surgery score at 2 years followup. Conclusion: Double plating through two incisions resulted in a better limb alignment and joint reduction with an acceptable soft tissue complication rate. PMID:26015609

Femoral fracture repair using a locking plate technique in an adult captive polar bear (Ursus maritimus).

PubMed

Zimmerman, Dawn M; Dew, Terry; Douglass, Michael; Perez, Edward

2010-02-01

To report successful femoral fracture repair in a polar bear. Case report. Female polar bear (Ursus maritimus) 5 years and approximately 250 kg. A closed, complete, comminuted fracture of the distal midshaft femur was successfully reduced and stabilized using a compression plating technique with 2 specialized human femur plates offering axial, rotational, and bending support, and allowing the bone to share loads with the implant. Postoperative radiographs were obtained at 11.5 weeks, 11 months, and 24 months. Bone healing characterized by marked periosteal reaction was evident at 11 months with extensive remodeling evident at 24 months. No complications were noted. Distal mid shaft femoral fracture was reduced, stabilized, and healed in an adult polar bear with a locking plate technique using 2 plates. Previously, femoral fractures in polar bears were considered irreparable. Use of 2 plates applied with a locking plate technique can result in successful fracture repair despite large body weight and inability to restrict postoperative activity.

Biomechanics of Far Cortical Locking

PubMed Central

Bottlang, Michael; Feist, Florian

2011-01-01

The development of FCL was motivated by a conundrum: locked plating constructs provide inherently rigid stabilization, yet they should facilitate biological fixation and secondary bone healing that relies on flexible fixation to stimulate callus formation. Recent studies have confirmed that the high stiffness of standard locked plating constructs can suppress interfragmentary motion to a level that is insufficient to reliably promote secondary fracture healing by callus formation. Furthermore, rigid locking screws cause an uneven stress distribution that may lead to stress fracture at the end screw and stress shielding under the plate. This review summarizes four key features of FCL constructs that have shown to enhance fixation and fracture healing: Flexible fixation, load distribution, progressive stiffening, and parallel interfragmentary motion. Specifically, flexible fixation provided by FCL reduces the stiffness of a locked plating construct by 80–88% to actively promote callus proliferation similar to an external fixator. Load distribution is evenly shared between FCL screws to mitigate stress risers at the end screw. Progressive stiffening occurs by near cortex support of FCL screws and provides additional support under elevated loading. Finally, parallel interfragmentary motion by s-shaped flexion of FCL screws has shown to induce symmetric callus formation. In combination, these features of FCL constructs have shown to induce more callus and to yield significantly stronger and more consistent healing compared to standard locked plating constructs. As such, FCL constructs function as true internal fixators by replicating the biomechanical behavior and biological healing response of external fixators. PMID:21248556

Clamp-mount device

NASA Technical Reports Server (NTRS)

Clark, K. H. (Inventor)

1983-01-01

A clamp-mount device is disclosed for mounting equipment to an associated I-beam and the like structural member of the type having oppositely extending flanges wherein the device comprises a base and a pair of oppositely facing clamping members carried diagonally on the base clamping flanges therebetween and having flange receiving openings facing one another. Lock means are carried diagonally by the base opposite the clamping members locking the flanges in the clamping members. A resilient hub is carried centrally of the base engaging and biasing a back side of the flanges maintaining tightly clamped and facilitating use on vertical as well as horizontal members. The base turns about the hub to receive the flanges within the clamping members. Equipment may be secured to the base by any suitable means such as bolts in openings. Slidable gate latches secure the hinged locks in an upright locking position. The resilient hub includes a recess opening formed in the base and a rubber-like pad carried in this opening being depressably and rotatably carried therein.

Method and apparatus for close packing of nuclear fuel assemblies

DOEpatents

Newman, Darrell F.

1993-01-01

The apparatus of the present invention is a plate of neutron absorbing material. The plate may have a releasable locking feature permitting the plate to be secured within a nuclear fuel assembly between nuclear fuel rods during storage or transportation then removed for further use or destruction. The method of the present invention has the step of placing a plate of neutron absorbing material between nuclear fuel rods within a nuclear fuel assembly, preferably between the two outermost columns of nuclear fuel rods. Additionally, the plate may be releasably locked in place.

Method and apparatus for close packing of nuclear fuel assemblies

DOEpatents

Newman, D.F.

1993-03-30

The apparatus of the present invention is a plate of neutron absorbing material. The plate may have a releasable locking feature permitting the plate to be secured within a nuclear fuel assembly between nuclear fuel rods during storage or transportation then removed for further use or destruction. The method of the present invention has the step of placing a plate of neutron absorbing material between nuclear fuel rods within a nuclear fuel assembly, preferably between the two outermost columns of nuclear fuel rods. Additionally, the plate may be releasably locked in place.

Distal radius fractures and the volar lunate facet fragment: Kirschner wire fixation in addition to volar-locked plating.

PubMed

Moore, Amy M; Dennison, David G

2014-06-01

The volar lunate facet fragment of a distal radius fracture may not be stabilized with volar-locked plating alone due to the small size and distal location of the fragment. Identification and stabilization of this small fragment is critical as unstable fixation may result in radiocarpal and radioulnar joint subluxation. The addition of spring wire fixation with volar plating can provide stable internal fixation of this critical fracture fragment. A retrospective review (2006-2011) identified nine patients with distal radius fractures with an associated volar lunate facet fragment that were treated with volar-locked plating and spring wire fixation of the volar lunate facet fragment. Radiographic indices, range of motion, grip strength, and postoperative Patient-related wrist evaluation (PRWE) scores were obtained to assess pain and function. All distal radius fractures healed, and the volar lunate facet fragment reduction was maintained. The mean follow-up was 54 weeks. Mean active range of motion was 46° wrist flexion, 51° wrist extension, 80° pronation, and 68° supination. The mean grip strength was 21 Kg, achieving 66 % of the uninjured limb. The average PRWE score was 17. No patient required removal of hardware or had evidence of tendon irritation. The addition of spring wire fixation to volar-locked plating provided stable fixation of the volar lunate facet fragment of distal radius fractures without complication. This technique addresses a limitation of volar-locked plating to control the small volar lunate facet fragment in distal radius fractures otherwise amenable to volar plating. A retrospective case series, Level IV.

Plate Versus Intramedullary Nail Fixation of Anterior Tibial Stress Fractures: A Biomechanical Study.

PubMed

Markolf, Keith L; Cheung, Edward; Joshi, Nirav B; Boguszewski, Daniel V; Petrigliano, Frank A; McAllister, David R

2016-06-01

Anterior midtibial stress fractures are an important clinical problem for patients engaged in high-intensity military activities or athletic training activities. When nonoperative treatment has failed, intramedullary (IM) nail and plate fixation are 2 surgical options used to arrest the progression of a fatigue fracture and allow bone healing. A plate will be more effective than an IM nail in preventing the opening of a simulated anterior midtibial stress fracture from tibial bending. Controlled laboratory study. Fresh-frozen human tibias were loaded by applying a pure bending moment in the sagittal plane. Thin transverse saw cuts, 50% and 75% of the depth of the anterior tibial cortex, were created at the midtibia to simulate a fatigue fracture. An extensometer spanning the defect was used to measure the fracture opening displacement (FOD) before and after the application of IM nail and plate fixation constructs. IM nails were tested without locking screws, with a proximal screw only, and with proximal and distal screws. Plates were tested with unlocked bicortical screws (standard compression plate) and locked bicortical screws; both plate constructs were tested with the plate edge placed 1 mm from the anterior tibial crest (anterior location) and 5 mm posterior to the crest. For the 75% saw cut depth, the mean FOD values for all IM nail constructs were 13% to 17% less than those for the saw cut alone; the use of locking screws had no significant effect on the FOD. The mean FOD values for all plate constructs were significantly less than those for all IM nail constructs. The mean FOD values for all plates were 28% to 46% less than those for the saw cut alone. Anterior plate placement significantly decreased mean FOD values for both compression and locked plate constructs, but the mean percentage reductions for locked and unlocked plates were not significantly different from each other for either plate placement. The percentage FOD reductions for all plate constructs and the unlocked IM nail were significantly less with a 50% saw cut depth. Plate fixation was superior to IM nail fixation in limiting the opening of a simulated midtibial stress fracture, and anterior-posterior placement of the plate was an important variable for this construct. Results from these tests can help guide the selection of fixation hardware for patients requiring surgical treatment for a midtibial stress fracture. © 2016 The Author(s).

Surgical Treatment of the Atrophic Mandibular Fractures by Locked Plates Systems: Our Experience and a Literature Review

PubMed Central

Novelli, Giorgio; Sconza, Cristiano; Ardito, Emanuela; Bozzetti, Alberto

2012-01-01

The management of atrophic mandibular fractures in edentulous patients represents an insidious issue for the maxillofacial surgeon due to the biological and biomechanical conditions that are unfavorable for fracture fixation and bone healing. The purpose of this study was to evaluate the results of the treatment of atrophic mandibular fractures and to compare the outcomes of different plating systems used for stabilization. We selected a study group of 16 patients with fractures of completely edentulous atrophic mandibles who were treated in our department between 2004 and 2010. All patients were surgically treated by open reduction and internal rigid fixation using 2.0-mm large-profile locking and 2.4-mm locking bone plates. All patients achieved a complete fracture healing and fast functional recovery of mandibular movements without intraoperative or postoperative surgical complications. The results of our study demonstrated the efficacy of this type of treatment in association with a low postoperative complication rate, a reduction in the recovery time, and the possibility to have an immediately functional rehabilitation. There were very similar results using each of the two bone plating methods considered: no case had hardware failure or nonunion of the fracture. The 2.0-mm large locking plate is thinner, exposes through the soft tissues less frequently, and is much easier to shape and adapt to the mandibular anatomy. However, the 2.4-mm locking plate system still represents the reference hardware in the condition of severe bone atrophy. PMID:23730420

Open-wedge high tibial osteotomy: incidence of lateral cortex fractures and influence of fixation device on osteotomy healing.

PubMed

Dexel, Julian; Fritzsche, Hagen; Beyer, Franziska; Harman, Melinda K; Lützner, Jörg

2017-03-01

Open-wedge high tibial osteotomy (HTO) is an established treatment for young and middle-aged patients with medial compartment knee osteoarthritis and varus malalignment. Although not intended, a lateral cortex fracture might occur during this procedure. Different fixation devices are available to repair such fractures. This study was performed to evaluate osteotomy healing after fixation with two different locking plates. Sixty-nine medial open-wedge HTO without bone grafting were followed until osteotomy healing. In patients with an intact lateral hinge, no problems were noted with either locking plate. A fracture of the lateral cortex occurred in 21 patients (30.4 %). In ten patients, the fracture was not recognized during surgery but was visible on the radiographs at the 6-week follow-up. Lateral cortex fracture resulted in non-union with the need for surgical treatment in three out of eight (37.5 %) patients using the newly introduced locking plate (Position HTO Maxi Plate), while this did not occur with a well-established locking plate (TomoFix) (0 out of 13, p = 0.023). With regard to other adverse events, no differences between both implants were observed. In cases of lateral cortex fracture, fixation with a smaller locking plate resulted in a relevant number of non-unions. Therefore, it is recommended that bone grafting, another fixation system, or an additional lateral fixation should be used in cases with lateral cortex fracture. III.

Percutaneous fixation with Kirschner wires versus volar locking plate fixation in adults with dorsally displaced fracture of distal radius: randomised controlled trial.

PubMed

Costa, Matthew L; Achten, Juul; Parsons, Nick R; Rangan, Amar; Griffin, Damian; Tubeuf, Sandy; Lamb, Sarah E

2014-08-05

To compare the clinical effectiveness of Kirschner wire fixation with locking plate fixation for patients with a dorsally displaced fracture of the distal radius. A multicentre two arm parallel group assessor blind randomised controlled trial with 1:1 treatment allocation. 18 trauma centres in the United Kingdom. 461 adults with a dorsally displaced fracture of the distal radius within 3 cm of the radiocarpal joint that required surgical fixation. Patients were excluded if the surgeon thought that the surface of the wrist joint was so badly displaced it required open reduction. Kirschner wire fixation: wires are passed through the skin over the dorsal aspect of the distal radius and into the bone to hold the fracture in the correct anatomical position. Locking plate fixation: a locking plate is applied through an incision over the volar (palm) aspect of the wrist and secured to the bone with fixed angle locking screws. validated patient rated wrist evaluation (PRWE). This rates wrist function in two (equally weighted) sections concerning the patient's experience of pain and disability to give a score out of 100. disabilities of arm, shoulder, and hand (DASH) score, the EuroQol (EQ-5D), and complications related to the surgery. The baseline characteristics of the two groups were well balanced, and over 90% of patients completed follow-up. The wrist function of both groups of patients improved by 12 months. There was no clinically relevant difference in the patient rated wrist score at three, six, or 12 months (difference in favour of the plate group was -1.3, 95% confidence interval -4.5 to 1.8; P=0.40). Nor was there a clinically relevant difference in health related quality of life or the number of complications in each group. Contrary to the existing literature, and against the rapidly increasing use of locking plate fixation, this trial found no difference in functional outcome in patients with dorsally displaced fractures of the distal radius treated with Kirschner wires or volar locking plates. Kirschner wire fixation, however, is cheaper and quicker to perform. Current Controlled Trials ISCRTN 31379280. UKCRN 8956. © Costa et al 2014.

Screw Versus Plate Fixation for Chevron Osteotomy: A Retrospective Study.

PubMed

Andrews, Boyd J; Fallat, Lawrence M; Kish, John P

2016-01-01

The chevron osteotomy is a popular procedure used for the correction of moderate hallux abducto valgus deformity. Fixation is typically accomplished with Kirschner wires or bone screws; however, in cystic or osteoporotic bone, these could be inadequate, resulting in displacement of the capital fragment. We propose using a locking plate and interfragmental screw for fixation of the chevron osteotomy that could reduce the healing time and decrease the incidence of displacement. We performed a retrospective cohort study for chevron osteotomies on 75 feet (73 patients). The control groups underwent fixation with 1 screw in 30 feet (40%) and 2 screws in 30 feet (40%). A total of 15 feet (20%) were included in the locking plate and interfragmental screw group. The patients were followed up until bone healing was achieved at a median of 7 (range 6 to 14) weeks. Our hypothesis was that those treated with the locking plate and interfragmental screw would have a faster healing time and fewer incidents of capital fragment displacement compared with the 1- or 2-screw groups. The corresponding mean intervals to healing for the 1-screw group was 7.71 ± 1.28 (range 6 to 10) weeks, for the 2-screw group was 7.27 ± 1.57 (range 6 to 14) weeks, and for the locking plate and interfragmental screw group was 7.01 ± 1.00 (range 6 to 9) weeks. One case of capital fragment displacement occurred in the single screw group and one in the 2-screw group. No displacement occurred in the locking plate and interfragmental screw group. Neither finding was statistically significant. However, we believe the locking plate and interfragmental screw could be a viable option in patients with osteoporotic and cystic bone changes for correction of hallux abducto valgus. Copyright © 2016 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Locked versus standard unlocked plating of the symphysis pubis in a Type-C pelvic injury: a cadaver biomechanical study.

PubMed

Moed, Berton R; O'Boynick, Christopher P; Bledsoe, J Gary

2014-04-01

The benefits of locked plating for pubic symphyseal disruption have not been established. The purpose of this biomechanical study was to determine whether locked plating offers any advantage over conventional unlocked plating of the pubic symphysis in the vertically unstable, Type-C pelvic injury. In each of eight embalmed cadaver pelvis specimens, sectioning of the pubic symphysis in conjunction with a unilateral release of the sacroiliac, sacrospinous, and sacrotuberous ligaments and pelvic floor was performed to simulate a vertically unstable Type-C (Orthopaedic Trauma Association 61-C1.2) pelvic injury. The disrupted SI joint was then reduced and fixed using two 6.5mm cannulated screws inserted into the S1 body. Using a six-hole 3.5mm plate specifically designed for the symphysis pubis having both locked and unlocked capability, four pelvises were fixed with locked screws and four pelvises were fixed with standard unlocked bicortical screws. Both groups were similar based on a dual-emission X-ray absorptiometry evaluation (P=0.69). Each pelvis was then mounted on a servohydraulic materials-testing apparatus using a bilateral stance model to mainly stress the symphyseal fixation and was cycled up to 1 million cycles or failure, whichever occurred first. Five specimens experienced failure at the jig mounting/S1 vertebral body interface, occurring between 360,000 and 715,000 cycles. Frank failure of the anterior or posterior instrumentation did not occur. However, end-trialing diastasis of the initial pubic symphysis reduction was found in all pelvises. There were no differences between the groups with respect to this loss of symphyseal reduction (P=0.69) or average cycles to failure (P=1.0). Pubic symphyseal locked plating does not appear to offer any advantage over standard unlocked plating for a Type-C (OTA 61-C1.2) pelvic ring injury. Copyright © 2013 Elsevier Ltd. All rights reserved.

One size does not fit all: distal radioulnar joint dysfunction after volar locking plate fixation.

PubMed

Jones, Christopher W; Lawson, Richard D

2014-02-01

Background Fractures of the distal radius are among the most common injuries treated by orthopedic surgeons worldwide. Failure to restore distal radius alignment can lead to fracture malunion and poor clinical outcomes, including distal radioulnar joint (DRUJ) instability and limitation of motion. Case Description We present a unique case of DRUJ dysfunction following volar plate fixation of bilateral distal radius fractures and analyze the biomechanical causes of this complication. As a result of a relatively excessive tilt of the precontoured locking plate (in comparison to the patient's particular anatomy), the fracture on one side was "over-reduced," disrupting the biomechanics of the DRUJ, causing a supination block. Clinical Relevance Volar locking plates are not a panacea to all distal radius fractures. Plate selection and fixation technique must include consideration of patient anatomy. Robust plates offer the advantage of providing rigid fixation but can be difficult to contour when reconstructing normal anatomy. Restoration of patient-specific anatomy is crucial to the management of distal radius fractures.

Design aspects and clinical performance of the thrust plate hip prosthesis.

PubMed

Jacob, H A C; Bereiter, H H; Buergi, M L

2007-01-01

The thrust plate hip prosthesis (TPP) was conceived to maintain the physiological stress distribution in the proximal femur so as to prevent bone atrophy in this region, often encountered after implantation of conventional stem-type prostheses. A thrust plate of TiAlNb is firmly fixed to the neck of the femur by means of a forged CoCrMo bolt introduced through the lateral cortex, just below the greater trochanter, and through the metaphysis. A boss that contains the bolt head rests on the lateral cortex. A proximal extension from the thrust plate terminates in the ball head of the hip joint. Bone remodelling causes the initial prestressing of the structure (primary stability) to decline, but full integration of the thrust plate with the underlying host bone affords secondary stability. A total of 102 TPPs were implanted in the Cantonal Hospital, Chur, Switzerland, from 1992 to 1999 in 84 patients. The TPP was selected particularly for patients of the younger age group (26-76). Through its ability to load the medial cortex of the proximal femur in a physiological manner, the cortical bone in this region is preserved. The mean Harris hip score is 97 points and the survival rate 98 per cent, 144 months post-operatively.

Treatment of proximal humerus fractures with locking plates: a systematic review.

PubMed

Thanasas, Christos; Kontakis, George; Angoules, Antonios; Limb, David; Giannoudis, Peter

2009-01-01

Locking plates with special configuration for the anatomic region of the proximal humerus have been introduced recently to address the difficulties of stabilizing proximal humeral fractures. The purpose of this study was to carry out a systematic review of the literature on the efficacy and early to medium term functional results of locking plates for stabilization of proximal humeral fractures. Using the PubMed database, a systematic review of the English and German literature was carried out in order to assess the efficacy and complications related to the use of these plates and the patients' functional outcome, using the key words "locking plates proximal humeral fractures," "angular stability plates proximal humeral fractures," "PHILOS plate," and "LPHP plate." Our criteria for eligibility were clinical studies with more than ten cases followed-up, adult patients, and adequate data provided at least in terms of implant related complications. Articles written in English and German language were included. Exclusion criteria were: studies dealing exclusively with 2-part fractures (since this category has a more favorable outcome); experimental studies; case reports; and, literature other than English or German. Each one of the articles was evaluated for quality of the study using the Structured Effectiveness Quality Evaluation Scale (SEQES). Twelve studies including 791 patients met the inclusion criteria. Patients in these studies continued to improve up to one year, achieving a mean Constant score of 74.3. The incidence of the reported complications was: avascular necrosis 7.9%, screw cut-out 11.6% and re-operation rate 13.7%. The high incidence of cut-out may be secondary to the rigidity of the implant in combination with medial inadequate support, in cases compromised by severe underlying osteoporotic bone. Definition of indications for the use of locking plates and attention on technical aspects of applying them would help optimization of the results. Systematic Review.

Fixation of osteoporotic fractures in the upper limb with a locking compression plate.

PubMed

Neuhaus, V; King, J D; Jupiter, J B

2012-01-01

Locking Compression Plate (LCP) has the advantageous feature that screws can be locked in the plate leaving an angular stable construct. There is no need to have contact between the plate and the bone to achieve stability resulting from friction of the plate-bone-construct. Therefore the plate does not need to be contoured exactly to the bone and the healing bone's periosteal blood supply is not affected. The LCP is used as a bridging plate to gain relative stability in multi-fragmentary, diaphyseal or metaphyseal fractures. Depending on the fracture, the combination hole can also allow the LCP to achieve absolute stability similar to conventional fixation techniques. Osteoporotic fractures have significant impact on morbidity and mortality. Proximal humeral and distal radius fractures are typical examples. These osteoporotic and often comminuted fractures are ideal settings/indications for LCP utilization in the upper extremity. However, the data quality is due to mostly small study populations not so powerful. Unquestionably there has been a clear and fashionable trend to choose operative treatment for these fractures, because the angular stability allows stable fixation and early functional mobilization.

8. BUILDING NO. 611. INTERIOR OF ARMOR PLATELINED TESTING CHAMBER. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. BUILDING NO. 611. INTERIOR OF ARMOR PLATE-LINED TESTING CHAMBER. 1/2' THICK ARMOR PLATING BOLTED TO WALLS, FLOOR AND CEILING. WALLS CONSTRUCTED OF 24' THICK REINFORCED CONCRETE. VENTS IN CEILING EXHAUST SMOKE FROM EXPLOSIONS. SMALLEST WHEELED VEHICLES HOLD DUDS. - Picatinny Arsenal, 600 Area, Test Areas District, State Route 15 near I-80, Dover, Morris County, NJ

Effectiveness of the surgical torque limiter: a model comparing drill- and hand-based screw insertion into locking plates.

PubMed

Ioannou, Christopher; Knight, Matthew; Daniele, Luca; Flueckiger, Lee; Tan, Ezekiel S L

2016-10-17

The objective of this study is to analyse the effectiveness of the surgical torque limiter during operative use. The study also investigates the potential differences in torque between hand and drill-based screw insertion into locking plates using a standardised torque limiter. Torque for both hand and power screw insertion was measured through a load cell, registering 6.66 points per second. This was performed in a controlled environment using synthetic bone, a locking plate and locking screws to simulate plate fixation. Screws were inserted by hand and by drill with torque values measured. The surgical torque limiter (1.5 Nm) was effective as the highest recorded reading in the study was 1.409 Nm. Comparatively, there is a statistically significant difference between screw insertion methods. Torque produced for manually driven screw insertion into locking plates was 1.289 Nm (95 % CI 1.269-1.308) with drill-powered screw insertion at 0.740 Nm (95 % CI 0.723-0.757). The surgical torque limiter proved to be effective as per product specifications. Screws inserted under power produce significantly less torque when compared to manual insertion by hand. This is likely related to the mechanism of the torque limiter when being used at higher speeds for which it was designed. We conclude that screws may be inserted using power to the plate with the addition of a torque limiter. It is recommended that all screws inserted by drill be hand tightened to achieve adequate torque values.

An impedance-based approach for detection and quantification of damage in cracked plates and loose bolts in bridge structures

NASA Astrophysics Data System (ADS)

Rabiei, Masoud; Sheldon, Jeremy; Palmer, Carl

2012-04-01

The applicability of Electro-Mechanical Impedance (EMI) approach to damage detection, localization and quantification in a mobile bridge structure is investigated in this paper. The developments in this paper focus on assessing the health of Armored Vehicle Launched Bridges (AVLBs). Specifically, two key failure mechanisms of the AVLB to be monitored were fatigue crack growth and damaged (loose) rivets (bolts) were identified. It was shown through experiment that bolt damage (defined here as different torque levels applied to bolts) can be detected, quantified and located using a network of lead zirconate titanate (PZT) transducers distributed on the structure. It was also shown that cracks of various sizes can be detected and quantified using the EMI approach. The experiments were performed on smaller laboratory specimens as well as full size bridge-like components that were built as part of this research. The effects of various parameters such as transducer type and size on the performance of the proposed health assessment approach were also investigated.

SE Capstone Project: Building Systems Engineering Education and Workforce Capacity

DTIC Science & Technology

2012-04-01

This project developed a system to improve fuel efficiency by means of regenerative braking . The team designed a simple system that allows "bolt-on...air traffic control, social networking, credit/debit cards, and anti-lock brakes are only a few functions enabled by complex systems of systems . We...Building Systems Engineering Education and Workforce Capacity SE Capstone Project APRIL 2012 Report Documentation Page Form ApprovedOMB No. 0704

Post-Service Examination of PWR Baffle Bolts, Part I. Examination and Test Plan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leonard, Keith J.; Sokolov, Mikhail A.; Gussev, Maxim N.

2015-04-30

In support of extended service and current operations of the US nuclear reactor plants, the Oak Ridge National Laboratory (ORNL), through the Department of Energy (DOE), Light Water Reactor Sustainability (LWRS) Program, is coordinating with Ginna Nuclear Power Plant, The Westinghouse Electric Company, LLC, and ATI Consulting, the selective procurement of baffle bolts that were withdrawn from service in 2011 and currently stored on site at Ginna. The goal of this program is to perform detailed microstructural and mechanical property characterization of baffle former bolts following in-service exposures. This report outlines the selection criteria of the bolts and the techniquesmore » to be used in this study. The bolts available are the original alloy 347 steel fasteners used in holding the baffle plates to the baffle former structures within the lower portion of the pressurized water reactor vessel. Of the eleven possible bolts made available for this work, none were identified to have specific damage. The bolts, however, did show varying levels of breakaway torque required in their removal. The bolts available for this study varied in peak fluence (highest dose within the head of the bolt) between 9.9 and 27.8x10 21 n/cm 2 (E>1MeV). As no evidence for crack initiation was determined for the available bolts from preliminary visual examination, two bolts with the higher fluence values were selected for further post-irradiation examination. The two bolts showed different breakaway torque levels necessary in their removal. The information from these bolts will be integral to the LWRS program initiatives in evaluating end of life microstructure and properties. Furthermore, valuable data will be obtained that can be incorporated into model predictions of long-term irradiation behavior and compared to results obtained in high flux experimental reactor conditions. The two bolts selected for the ORNL study will be shipped to Westinghouse with bolts of interest to their collaborative efforts with the Electric Power Research Institute. Westinghouse will section the ORNL bolts into samples specified in this report and return them to ORNL. Samples will include bend bars for fracture toughness and crack propagation studies along with thin sections from which specimens for bend testing, subscale tensile and microstructural analysis can be obtained. Additional material from the high stress concentration region at the transition between the bolt head and shank will also be preserved to allow for further investigation of possible crack initiation sites.« less

Shear-strain energy rate distribution caused by the interplate locking along the Nankai Trough, southwest Japan: An integration analysis using stress tensor inversion and slip deficit inversion

NASA Astrophysics Data System (ADS)

Saito, T.; Noda, A.; Yoshida, K.; Tanaka, S.

2017-12-01

In the Nankai Trough, southwest Japan, the Philippine Sea Plate descends beneath the Eurasian plate. The locking, or the slip deficit, on the plate interface causes stress fluctuation in the inland area. The interplate locking does not always result in stress accumulation but also causes stress release. The stress increase/decrease is not determined only from the stress fluctuation but also depends on the background stress, in particular, its orientation. This study proposes a method to estimate the shear-strain energy increase/decrease distribution caused by the interplate locking. We at first investigated the background stress field in and around the Nankai Trough. The spatial distribution of the principal stress orientations and the stress ratio were estimated by analysis of 130,000 focal mechanisms of small earthquakes (e.g., Yoshida et al. 2015 Tectonophysics). For example, in an area called Chugoku region, the maximum and minimum compression axes were E-W and N-S directions, respectively. We also estimated the slip-deficit rate at the plate interface by analyzing GNSS data and calculated the stress fluctuation due to the deficit (e.g., Noda et al. 2013 GJI). The interplate locking causes the maximum compression in the direction of plate convergence. This is significantly different from the orientations of the background stress characterized by the E-W compressional strike-slip stress regime.. By combining the results of the background stress and the stress fluctuation, we made a map indicating the shear-strain energy change due to the interplate locking. In the Chugoku region, the shear-strain energy decreases due to the interplate locking. This is because the N-S compressional stress caused by the interplate locking compensates the N-S extensional stress in the background. The shear-strain energy increases in some parts of the analyzed areas. By statistically comparing the shear strain energy rate with the seismicity in the inland area, we found that the seismicity tends to be high where the interplate locking increases the shear-strain energy. Our results suggest that the stress fluctuation due to the interplate locking is not dominant in the background stress but surely contributes to the inland seismicity in southwest Japan.

Nuclear fuel element nut retainer cup. [PWR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walton, L.A.

1977-07-19

A typical embodiment has an end fitting for a nuclear reactor fuel element that is joined to the control rod guide tubes by means of a nut plate assembly. The nut plate assembly has an array of nuts, each engaging the respective threaded end of the control rod guide tubes. The nuts, moreover, are retained on the plate during handling and before fuel element assembly by means of hollow cylindrical locking cups that are brazed to the plate and loosely circumscribe the individual enclosed nuts. After the nuts are threaded onto the respective guide tube ends, the locking cups aremore » partially deformed to prevent one or more of the nuts from working loose during reactor operation. The locking cups also prevent loose or broken end fitting parts from becoming entrained in the reactor coolant.« less

Portable appliance security apparatus

NASA Technical Reports Server (NTRS)

Kerley, J. J. (Inventor)

1981-01-01

An apparatus for securing a small computer, or other portable appliance, against theft is described. It is comprised of a case having an open back through which the computer is installed or removed. Guide members in the form of slots are formed in a rear portion of opposite walls of the case for receiving a back plate to cover the opening and thereby secure the computer within the case. An opening formed in the top wall of the case exposes the keyboard and display of the computer. The back plate is locked in the closed position by a key-operated plug type lock. The lock is attached to one end of a hold down cable, the opposite end thereof being secured to a desk top or other stationary object. Thus, the lock simultaneously secures the back plate to the case and retains the case to the stationary object.

Sealed Plant-Growth Chamber For Clinostat

NASA Technical Reports Server (NTRS)

Brown, Christopher S.; Dreschel, Thomas W.

1993-01-01

Laboratory chamber for growing plants used to measure photosynthesis and respiration in simulated microgravity. Holds plant specimens while rotated on clinostat, see article, "Clinostat Delivers Power To Plant-Growth Cabinets" (KSC-11537). Provides way of comparing gas-exchange rates of plants rotated horizontally on clinostat with those of stationary or vertically rotated plants. Gas extracted for analysis without stopping clinostat. Chamber includes potlike base and cylindrical cover, both made of transparent acrylic pipe. Gasket forms seal between cover and bottom plate of base. Cover bolted to pot baseplate, which in turn bolted to clinostat.

Project Cheesebox: a Journey into History. Volume 1

DTIC Science & Technology

1974-12-01

china and drapes . 89 In addition, the builders were also to provide "masts, spars, sails and rigging of sufficient dimensions to drive the vessel...plate iron 3/8 innh thick with a 4 inch angle iron rivetted at the top extending all round the vessel. A plate iron armour 5 feet deep, 6 inches...thick is firmly bolted to the outside of the wooden bulwark extending all round the upper vessel. This armour is composed of six thicknesses of plate

Nondestructive Evaluation (NDE) Capabilities Data Book (3rd Edition)

DTIC Science & Technology

1997-11-01

include: 4340 Steel Flat Plate Panels Bolt Holes in i85 Scvcnth Stage Compressor Disks Visual Inspection of Fatigue Cracks in Inconel 718 and HaynEs 188...safety engineer * The maintenance engineer * Thc manufacturing / production process engineer • The liaison (rework and repair) engineer a ’[ lhc life...TC03: Through crnck from an offset hole in a plate TC04: Through crack from hole in a lug TC05: Through crack from hole in plate with a row of holcs

Methods of Measuring Stress Relaxation in Composite Tape Springs

DTIC Science & Technology

2015-03-26

plate in order to spread the load evenly and prevent excess torque . The plate also allows for force on the tape spring to be applied to the entire...aluminum squares that can be tightened to the base. The test fixture is secured to the marble base. The tape springs are folded in three locations with...top plate is pressed down by tightening the bolt on each nut. The tightening is complete when the tape spring just begins to create an M shape and

Second generation locked plating for complex proximal humerus fractures in very elderly patients.

PubMed

Gavaskar, Ashok S; Karthik B, Bhupesh; Tummala, Naveen C; Srinivasan, Parthasarathy; Gopalan, Hitesh

2016-11-01

Humeral head sacrificing procedures are more favored in elderly patients with complex proximal humerus fractures because of high incidence of failures and complications with osteosynthesis. The purpose of this study is to assess the outcome of second generation locked plating techniques in 3 and 4 part fractures in active elderly patients >70years with an emphasis on function and complications. 29 patients with displaced 3 and 4 part proximal humerus fractures were treated using the principles of second-generation proximal humerus locked plating. Fixed angle locked plating (PHILOS) using the anterolateral deltoid spilt approach augmented with traction cuff sutures was performed. Minimum of 7 locking head screws including 2 calcar screws were used. In cases with a comminuted medial calcar, an endosteal fibular strut was used. Subchondral metaphyseal bone voids were filled with injectable calcium phosphate cement. Radiological outcome (union, head - shaft angle, tuberosity reduction), functional outcome assessment (Constant and ASES scores) and complications (loss of reduction, nonunion and osteonecrosis) were assessed. The fracture united in 24 of the 26 patients available for follow up at a mean of 27 months (12-40 months). 3 patients developed complications that required arthroplasty (fixation failure in 2 patients and osteonecrosis in 1 patient). Follow up age adjusted Constant (63.1±11.9) and ASES scores (62.58±7.5) showed the extent of functional improvement post surgery. Patients with fractures having a non-comminuted medial calcar and valgus displacement of the humeral head had better functional scores and fewer complications. Osteosynthesis with second generation locked plating techniques provide satisfactory outcome in very elderly patients with complex proximal humerus fractures with minimal complications. Copyright © 2016 Elsevier Ltd. All rights reserved.

On the Possibility of Interseismic Creep of the Cascadia Megathrust

NASA Astrophysics Data System (ADS)

Wang, Y.; Wang, K.; He, J.

2012-12-01

Without any instrumental records of large megathrust earthquakes, our knowledge of the seismic potential of the Cascadia subduction zone depends critically on our understanding of the present state of interseismic fault locking. The traditional view of a fully and uniformly locked Cascadia megathrust, consistent with the extremely low modern interplate seismicity, is now challenged for two reasons. First, recent quantitative analyses of high-quality microfossil data indicate that fault slip in the great Cascadia earthquake of 1700 was heterogeneous, with high-slip areas separated by low-slip areas. This leads to the question whether the low-slip areas should exhibit interseismic creeping after the earthquake and even at present. Second, the most recent inversion of GPS measurements to infer simultaneously megathrust locking, permanent upper plate deformation, and block motion features large creeping (i.e., partial locking) segments along the margin. For example, in northern Cascadia offshore of Vancouver Island, the creep rate is reported to be about 40% of the plate convergence rate of ~50 mm/yr used in this inversion. Here we re-examine the locking state of the northern Cascadia megathrust by exploring the following issues. (1) The geodetically observed contemporary margin-normal shortening has a relatively low velocity gradient but extends quite far inland. In an elastic model, the near-field low strain rate can be explained by partial locking, and the broad pattern is explained by permanent shortening, e.g., across the Canadian Coast Mountains. We investigate whether a viscoelastic model can explain the geodetic strains with a fully locked megathrust without permanent upper plate shortening. (2) The new global plate motion model MORVEL predicts a lower convergence rate of only ~40 mm/yr at northern Cascadia. We investigate its implications to the interpretation of the geodetic observations. (3) Globally, afterslip following a great earthquake is generally observed to have a short duration. We investigate whether the contemporary Cascadia deformation field could still be under the influence of the 1700 event, especially that of the post-seismic behaviour of its low-slip areas. (4) We investigate to what extent land-based GPS observations can resolve partial locking vs. full locking of the offshore seismogenic zone. We develop a 3-D viscoelastic model with a fully locked plate interface but with the locking width varying along strike and test whether this model can explain GPS observations as well as does the partially locked elastic model. We also develop an alternative model with multiple slow slip events of spatiotemporally varying source regions, in order to investigate whether their integrated effect could be identified as partial locking by land-based GPS. Our work at Cascadia may also help understand the interseismic creep reported for other subduction zones.

[Development of polyaxial locking plate screw system of sacroiliac joint].

PubMed

Fan, Weijie; Xie, Xuesong; Zhou, Shuping; Zhang, Yonghu

2014-09-01

To develop an instrument for sacroiliac joint fixation with less injury and less complications. Firstly, 18 adult pelvic specimens (8 males and 10 females) were used to measure the anatomical data related to the locking plates and locking screws on the sacrum and ilium, and the polyaxial locking plate screw system of the sacroiliac joint was designed according to the anatomic data. This system was made of medical titanium alloy. Then 4 adult male plevic specimens were harvested and the experiment was divided into 3 groups: group A (normal pelvic), group B (the dislocated sacroiliac joint fixed with sacroiliac screws), and group C (the dislocated sacroiliac joint fixed with polyaxial locking plate screw system). The vertical displacement of sacroiliac joint under the condition of 0-700 N vertical load and the horizontal displacement on angle under the condition of 0-12 N·m torsional load were compared among the 3 groups by using the biological material test system. Finally, the simulated application test was performed on 1 adult male cadaveric specimen to observe soft tissue injury and the position of the locking plate and screw by X-ray films. According to the anatomic data of the sacrum and ilium, the polyaxial locking plate screw system of the sacroiliac joint was designed. The biomechanical results showed that the vertical displacement of the sacroiliac joint under the condition of 0-700 N vertical load in group A was significantly bigger than that in group B and group C (P < 0.05), but there was no significant difference between group B and group C (P > 0.05). The horizontal displacement on angle under the condition of 0-12 N·m torsional load in group A was significantly less than that in group B and group C (P < 0.05). The horizontal displacement on angle under the condition of 0-6 N·m torsional load in group B was bigger than that in group C, and the horizontal displacement on angle under the condition of 6-12 N·m torsional load in group B was less than that in group C, but there was no significant difference between group B and group C (P > 0.05). The test of simulating application showed that the specimen suffered less soft tissue injury, and this instrument could be implanted precisely and safely. The polyaxial locking plate screw system of the sacroiliac joint has the advantages of smaller volume and less injury; polyaxial fixation enables flexible adjustment screw direction. The simulated application test shows satisfactory fixing effect.

Three-dimensional finite element analysis of occipitocervical fixation using an anterior occiput-to-axis locking plate system: a pilot study.

PubMed

Cai, Xianhua; Yu, Yang; Liu, Zhichao; Zhang, Meichao; Huang, Weibing

2014-08-01

Although there are many techniques for occipitocervical fixation, there have been no reports regarding occipitocervical fixation via the use of an anterior anatomical locking plate system. The biomechanics of this new system were analyzed by a three-dimensional finite element to provide a theoretical basis for clinical application. This was a modeling study. We studied a 27-year-old healthy male volunteer in whom cervical disease was excluded via X-ray examination. The states of stress and strain of these two internal fixation devices were analyzed. A three-dimensional finite element model of normal occiput-C2 was established based on the anatomical data from a Chinese population. An unstable model of occipital-cervical region was established by subtracting several unit structures from the normal model. An anterior occiput-to-axis locking titanium plate system was then applied and an anterior occiput-to-axis screw fixation was performed on the unstable model. Limitation of motion was performed on the surface of the fixed model, and physiological loads were imposed on the surface of the skull base. Under various loads from different directions, the peak values of displacement of the anterior occiput-to-axis locking titanium plate system decreased 15.5%, 12.5%, 14.4%, and 23.7%, respectively, under the loads of flexion, extension, lateral bending, and axial rotation. Compared with the anterior occiput-to-axis screw fixation, the peak values of stress of the anterior occiput-to-axis locking titanium plate system also decreased 3.9%, 2.9%, 9.7%, and 7.2%, respectively, under the loads of flexion, extension, lateral bending, and axial rotation. The anterior occiput-to-axis locking titanium plate system proved superior to the anterior occiput-to-axis screw system both in the stress distribution and fixation stability based on finite element analysis. It provides a new clinical option for anterior occipitocervical fixation. Copyright © 2014 Elsevier Inc. All rights reserved.

Percutaneous fixation with Kirschner wires versus volar locking plate fixation in adults with dorsally displaced fracture of distal radius: randomised controlled trial

PubMed Central

Achten, Juul; Parsons, Nick R; Rangan, Amar; Griffin, Damian; Tubeuf, Sandy; Lamb, Sarah E

2014-01-01

Objectives To compare the clinical effectiveness of Kirschner wire fixation with locking plate fixation for patients with a dorsally displaced fracture of the distal radius. Design A multicentre two arm parallel group assessor blind randomised controlled trial with 1:1 treatment allocation. Setting 18 trauma centres in the United Kingdom. Participants 461 adults with a dorsally displaced fracture of the distal radius within 3 cm of the radiocarpal joint that required surgical fixation. Patients were excluded if the surgeon thought that the surface of the wrist joint was so badly displaced it required open reduction. Interventions Kirschner wire fixation: wires are passed through the skin over the dorsal aspect of the distal radius and into the bone to hold the fracture in the correct anatomical position. Locking plate fixation: a locking plate is applied through an incision over the volar (palm) aspect of the wrist and secured to the bone with fixed angle locking screws. Main outcome measures Primary outcome measure: validated patient rated wrist evaluation (PRWE). This rates wrist function in two (equally weighted) sections concerning the patient’s experience of pain and disability to give a score out of 100. Secondary outcomes: disabilities of arm, shoulder, and hand (DASH) score, the EuroQol (EQ-5D), and complications related to the surgery. Results The baseline characteristics of the two groups were well balanced, and over 90% of patients completed follow-up. The wrist function of both groups of patients improved by 12 months. There was no clinically relevant difference in the patient rated wrist score at three, six, or 12 months (difference in favour of the plate group was −1.3, 95% confidence interval −4.5 to 1.8; P=0.40). Nor was there a clinically relevant difference in health related quality of life or the number of complications in each group. Conclusions Contrary to the existing literature, and against the rapidly increasing use of locking plate fixation, this trial found no difference in functional outcome in patients with dorsally displaced fractures of the distal radius treated with Kirschner wires or volar locking plates. Kirschner wire fixation, however, is cheaper and quicker to perform. Trial registration Current Controlled Trials ISCRTN 31379280. UKCRN 8956. PMID:25096595

Style of Plate Spreading Derived from the 2008-2014 Velocity Field Across the Northern Volcanic Zone of Iceland

NASA Astrophysics Data System (ADS)

Drouin, V.; Sigmundsson, F.; Hreinsdottir, S.; Ofeigsson, B.; Sturkell, E.; Einarsson, P.

2015-12-01

The Northern Volcanic Zone (NVZ) of Iceland is a subaerial part of the divergent boundary between the North-American and Eurasian Plates. At this latitude, the full spreading between the plates is accommodated by the NVZ. We derived the plate boundary velocity field from GPS campaign and continuous measurements between 2008 and 2014, a time period free of any magma intrusion. Average velocities were estimated in the ITRF08 reference frame. The overall extension is consistent with 18 mm/yr in the 104°N direction spreading, in accordance with the MORVEL2010 plate motion model. We find that a 40km-wide band along the plate boundary accommodates about 75% of the full plate velocities. Within this zone, the average strain rate is approximately 0.35 μstrain/yr. The deformation field and the strain rate are, however, much affected by other sources of deformations in the NVZ. These include magmatic sources at the most active volcanic centers, glacial rebound near the ice-caps and geothermal power-plant water extraction. Magmatic sources include a shallow magma chamber deflation under Askja caldera, as well as under Þeistareykir and eventual deep magma inflation north of Krafla volcano. Vatnajökull ice cap melting causes large uplift and outward displacements in the southern part of the NVZ. The two geothermal power-plants near Krafla are inducing local deflations. Our GPS velocities show a 35° change in the direction of the plate boundary axis north of Askja volcano that we infer to be linked to the geometric arrangement of volcanic systems within the NVZ.We use a simple arctangent model to describe the plate spreading to provide constraints on the location and the locking depth of the spreading axis. For that purpose we divided the area in short overlapping segments having the same amount of GPS points along the plate spreading direction and inverted for the location of the center of the spreading axis and locking depth. With this simple model we can account for most of the plate spreading related deformation in the NVZ. It appears that the locking depth is not uniform all along the length of the plate boundary, with a deeper locking depth in the low activity volcanic systems and a shallower locking depth in the more active volcanic systems of Krafla and Askja.

75 FR 74001 - Foreign-Trade Zone 72-Indianapolis, IN, Application for Subzone, GEA Bloomington Production...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-30

... fittings, rubber gaskets, screws, bolts, hinges, brackets, metal plates, compressors, filters, taps, valves... exported. On its domestic sales, GEA Bloomington would be able to choose the duty rates during customs...

29 CFR 1919.27 - Unit proof tests-winches, derricks and gear accessory thereto.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., goosenecks, eye plates, eye bolts, or other attachments), shall be tested with a proof load which shall..., a qualified technical office of an accredited gear certification agency, with the recognition that...

Biomechanical investigation of an alternative concept to angular stable plating using conventional fixation hardware.

PubMed

Windolf, Markus; Klos, Kajetan; Wähnert, Dirk; van der Pol, Bas; Radtke, Roman; Schwieger, Karsten; Jakob, Roland P

2010-05-21

Angle-stable locking plates have improved the surgical management of fractures. However, locking implants are costly and removal can be difficult. The aim of this in vitro study was to evaluate the biomechanical performance of a newly proposed crossed-screw concept ("Fence") utilizing conventional (non-locked) implants in comparison to conventional LC-DCP (limited contact dynamic compression plate) and LCP (locking compression plate) stabilization, in a human cadaveric diaphyseal gap model. In eight pairs of human cadaveric femora, one femur per pair was randomly assigned to receive a Fence construct with either elevated or non-elevated plate, while the contralateral femur received either an LCP or LC-DCP instrumentation. Fracture gap motion and fatigue performance under cyclic loading was evaluated successively in axial compression and in torsion. Results were statistically compared in a pairwise setting. The elevated Fence constructs allowed significantly higher gap motion compared to the LCP instrumentations (axial compression: p

Gradual unlocking of plate boundary controlled initiation of the 2014 Iquique earthquake.

PubMed

Schurr, Bernd; Asch, Günter; Hainzl, Sebastian; Bedford, Jonathan; Hoechner, Andreas; Palo, Mauro; Wang, Rongjiang; Moreno, Marcos; Bartsch, Mitja; Zhang, Yong; Oncken, Onno; Tilmann, Frederik; Dahm, Torsten; Victor, Pia; Barrientos, Sergio; Vilotte, Jean-Pierre

2014-08-21

On 1 April 2014, Northern Chile was struck by a magnitude 8.1 earthquake following a protracted series of foreshocks. The Integrated Plate Boundary Observatory Chile monitored the entire sequence of events, providing unprecedented resolution of the build-up to the main event and its rupture evolution. Here we show that the Iquique earthquake broke a central fraction of the so-called northern Chile seismic gap, the last major segment of the South American plate boundary that had not ruptured in the past century. Since July 2013 three seismic clusters, each lasting a few weeks, hit this part of the plate boundary with earthquakes of increasing peak magnitudes. Starting with the second cluster, geodetic observations show surface displacements that can be associated with slip on the plate interface. These seismic clusters and their slip transients occupied a part of the plate interface that was transitional between a fully locked and a creeping portion. Leading up to this earthquake, the b value of the foreshocks gradually decreased during the years before the earthquake, reversing its trend a few days before the Iquique earthquake. The mainshock finally nucleated at the northern end of the foreshock area, which skirted a locked patch, and ruptured mainly downdip towards higher locking. Peak slip was attained immediately downdip of the foreshock region and at the margin of the locked patch. We conclude that gradual weakening of the central part of the seismic gap accentuated by the foreshock activity in a zone of intermediate seismic coupling was instrumental in causing final failure, distinguishing the Iquique earthquake from most great earthquakes. Finally, only one-third of the gap was broken and the remaining locked segments now pose a significant, increased seismic hazard with the potential to host an earthquake with a magnitude of >8.5.

Biomechanical in vitro assessment of screw augmentation in locked plating of proximal humerus fractures.

PubMed

Röderer, Götz; Scola, Alexander; Schmölz, Werner; Gebhard, Florian; Windolf, Markus; Hofmann-Fliri, Ladina

2013-10-01

Proximal humerus fracture fixation can be difficult because of osteoporosis making it difficult to achieve stable implant anchorage in the weak bone stock even when using locking plates. This may cause implant failure requiring revision surgery. Cement augmentation has, in principle, been shown to improve stability. The aim of this study was to investigate whether augmentation of particular screws of a locking plate aimed at a region of low bone quality is effective in improving stability in a proximal humerus fracture model. Twelve paired human humerus specimens were included. Quantitative computed tomography was performed to determine bone mineral density (BMD). Local bone quality in the direction of the six proximal screws of a standard locking plate (PHILOS, Synthes) was assessed using mechanical means (DensiProbe™). A three-part fracture model with a metaphyseal defect was simulated and fixed with the plate. Within each pair of humeri the two screws aimed at the region of the lowest bone quality according to the DensiProbe™ were augmented in a randomised manner. For augmentation, 0.5 ml of bone cement was injected in a screw with multiple outlets at its tip under fluoroscopic control. A cyclic varus-bending test with increasing upper load magnitude was performed until failure of the screw-bone fixation. The augmented group withstood significantly more load cycles. The correlation of BMD with load cycles until failure and BMD with paired difference in load cycles to failure showed that augmentation could compensate for a low BMD. The results demonstrate that augmentation of screws in locked plating in a proximal humerus fracture model is effective in improving primary stability in a cyclic varus-bending test. The augmentation of two particular screws aimed at a region of low bone quality within the humeral head was almost as effective as four screws with twice the amount of bone cement. Screw augmentation combined with a knowledge of the local bone quality could be more effective in enhancing the primary stability of a proximal humerus locking plate because the effect of augmentation can be exploited more effectively limiting it to the degree required. Copyright © 2013 Elsevier Ltd. All rights reserved.

Rapid prototyping to design a customized locking plate for pancarpal arthrodesis in a giant breed dog.

PubMed

Petazzoni, M; Nicetto, T

2014-01-01

This report describes the treatment of traumatic carpal hyperextension in a giant breed dog by pancarpal arthrodesis using a custom-made Fixin locking plate, created with the aid of a three-dimensional plastic model of the bones of the antebrachium produced by rapid prototyping technology. A three-year-old 104 kg male Mastiff dog was admitted for treatment of carpal hyperextension injury. After diagnosis of carpal instability, surgery was recommended. Computed tomography images were used to create a life-size three-dimensional plastic model of the forelimb. The model was used as the basis for constructing a customized 12-hole Fixin locking plate. The plate was used to attain successful pancarpal arthrodesis in the animal. Radiographic examination after 74 and 140 days revealed signs of osseous union of the arthrodesis. Further clinical and radiographic follow-up examination three years later did not reveal any changes in implant position or complications.

Magnetically Operated Holding Plate And Ball-Lock Pin

NASA Technical Reports Server (NTRS)

Monford, Leo G., Jr.

1992-01-01

Magnetically operated holding plate and ball-locking-pin mechanism part of object attached to, or detached from second object. Mechanism includes tubular housing inserted in hole in second object. Plunger moves inside tube forcing balls to protrude from sides. Balls prevent tube from sliding out of second object. Simpler, less expensive than motorized latches; suitable for robotics applications.

Lightweight structural design of a bolted case joint for the space shuttle solid rocket motor

NASA Technical Reports Server (NTRS)

Dorsey, John T.; Stein, Peter A.; Bush, Harold G.

1988-01-01

The structural design of a bolted joint with a static face seal which can be used to join Space Shuttle Solid Rocket Motor (SRM) case segments is given. Results from numerous finite element parametric studies indicate that the bolted joint meets the design requirement of preventing joint opening at the O-ring locations during SRM pressurization. A final design recommended for further development has the following parameters: 180 one-in.-diam. studs, stud centerline offset of 0.5 in radially inward from the shell wall center line, flange thickness of 0.75 in, bearing plate thickness of 0.25 in, studs prestressed to 70 percent of ultimate load, and the intermediate alcove. The design has a mass penalty of 1096 lbm, which is 164 lbm greater than the currently proposed capture tang redesign.

Designing of Timber Bolt Connection Subjected To Double Unequal Shears

NASA Astrophysics Data System (ADS)

Musilek, Josef; Plachy, Jan

2017-10-01

The paper deals with load-carrying capacity of bolted connections subjected to unequal double shear with thin plates as outer members and inner timber member. This type of connection is usually widespread and in building support structures made of wood is commonly used. This may occur for example in skeletal structures which contain structural elements based on wood, but also for smaller wooden buildings. Specifically, this type of connection can be found in ceiling structures in the joint joists and beams. If one joist greater margin than the second, bringing the load on the side of the joists of a larger span greater loads than on the side with a smaller span joist. Structure engineer, who is designing such a connection, must use for the design of the connection design procedures and formulas from which he or she calculates the design resistance in order to carry out further assessment of the reliability of the connection in the ultimate limit state. The load-carrying capacity of this connections type can be calculated at present according to Johansen’s equations, which are also contained in present European standard for the design timber structures -Eurocode 5. These Johansen’s equations assume that the loads which act on the outer plates are equal. For this reason, the structure engineer is often forced to use formulas intended for the timber bolt connection subjected to double equal shear and he or she must find ways how to use them although the formulas are not suitable. This paper deals with the case, when the loads acting on the outer plates are unequal.

12. VIEW OF TYPICAL CELL LOCKING MECHANISM, BUILDING 220 CELL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. VIEW OF TYPICAL CELL LOCKING MECHANISM, BUILDING 220 CELL BLOCK 'A'. THE FACE PLATE OF THE CELL LOCK IS SHOWN REMOVED, EXPOSING THE ELECTROMAGNETIC LOCKING MECHANISM COMPRISING OF 2 MICROSWITCHES FOR LOCK POSITION INDICATION (FRONT LEFT CENTER AND REAR RIGHT CENTER OF PANEL); KEY SLOT MECHANICAL LOCK; LOCK SPRING (UPPER RIGHT OF PANEL); ELECTRIC SOLENOID (BOTTOM RIGHT CORNER OF PANEL); AND MISCELLANEOUS MECHANICAL LINKAGES. - U.S. Naval Base, Pearl Harbor, Brig, Neville Way near Ninth Street at Marine Barracks, Pearl City, Honolulu County, HI

Classification and treatment of periprosthetic supracondylar femur fractures.

PubMed

Ricci, William

2013-02-01

Locked plating and retrograde nailing are two accepted methods for treatment of periprosthetic distal femur fractures. Each has relative benefits and potential pitfalls. Appropriate patient selection and knowledge of the specific femoral component geometry are required to optimally choose between these two methods. Locked plating may be applied to most periprosthetic distal femur fractures. The fracture pattern, simple or comminuted, will dictate the specific plating technique, compression plating or bridge plating. Nailing requires an open intercondylar box and a distal fragment of enough size to allow interlocking. With proper patient selection and proper techniques, good results can be obtained with either method. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

78 FR 28190 - Foreign-Trade Zone (FTZ) 134-Chattanooga, Tennessee; Notification of Proposed Production Activity...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-14

... domestic sales, Komatsu would be able to choose the duty rates during customs entry procedures that apply... abroad include: cleaning agents; glues; adhesives; adhesive plates; O-rings; rubber bolts/rods; hoses...

Biomechanical analysis of two fixation methods for proximal chevron osteotomy of the first metatarsal.

PubMed

Schuh, Reinhard; Hofstaetter, Jochen Gerhard; Benca, Emir; Willegger, Madeleine; von Skrbensky, Gobert; Zandieh, Shahin; Wanivenhaus, Axel; Holinka, Johannes; Windhager, Reinhard

2014-05-01

The proximal chevron osteotomy provides high correctional power. However, relatively high rates of dorsiflexion malunion of up to 17 % are reported for this procedure. This leads to insufficient weight bearing of the first ray and therefore to metatarsalgia. Recent biomechanical and clinical studies pointed out the importance of rigid fixation of proximal metatarsal osteotomies. Therefore, the aim of the present study was to compare biomechanical properties of fixation of proximal chevron osteotomies with variable locking plate and cancellous screw respectively. Ten matched pairs of human fresh frozen cadaveric first metatarsals underwent proximal chevron osteotomy with either variable locking plate or cancellous screw fixation after obtaining bone mineral density. Biomechanical testing included repetitive plantar to dorsal loading from 0 to 31 N with the 858 Mini Bionix(®) (MTS(®) Systems Corporation, Eden Prairie, MN, USA). Dorsal angulation of the distal fragment was recorded. The variable locking plate construct reveals statistically superior results in terms of bending stiffness and dorsal angulation compared to the cancellous screw construct. There was a statistically significant correlation between bone mineral density and maximum tolerated load until construct failure occurred for the screw construct (r = 0.640, p = 0.406). The results of the present study indicate that variable locking plate fixation shows superior biomechanical results to cancellous screw fixation for proximal chevron osteotomy. Additionally, screw construct failure was related to levels of low bone mineral density. Based on the results of the present study we recommend variable locking plate fixation for proximal chevron osteotomy, especially in osteoporotic bone.

Four-corner fusion: comparison of patient satisfaction and functional outcome of conventional K-wire technique vs. a new locking plate.

PubMed

Hernekamp, J F; Reinecke, A; Neubrech, F; Bickert, B; Kneser, U; Kremer, T

2016-04-01

Four-corner fusion is a standard procedure for advanced carpal collapse. Several operative techniques and numerous implants for osseous fixation have been described. Recently, a specially designed locking plate (Aptus©, Medartis, Basel, Switzerland) was introduced. The purpose of this study was to compare functional results after osseous fixation using K-wires (standard of care, SOC) with four-corner fusion and locking plate fixation. 21 patients who underwent four-corner fusion in our institution between 2008 and 2013 were included in a retrospective analysis. In 11 patients, osseous fixation was performed using locking plates whereas ten patients underwent bone fixation with conventional K-wires. Outcome parameters were functional outcome, osseous consolidation, patient satisfaction (DASH- and Krimmer Score), pain and perioperative morbidity and the time until patients returned to daily work. Patients were divided in two groups and paired t-tests were performed for statistical analysis. No implant related complications were observed. Osseous consolidation was achieved in all cases. Differences between groups were not significant regarding active range of motion (AROM), pain and function. Overall patient satisfaction was acceptable in all cases; differences in the DASH questionnaire and the Krimmer questionnaire were not significant. One patient of the plate group required conversion to total wrist arthrodesis without implant-related complications. Both techniques for four-corner fusion have similar healing rates. Using the more expensive locking implant avoids a second operation for K-wire removal, but no statistical differences were detected in functional outcome as well as in patient satisfaction when compared to SOC.

Simulation of tectonic evolution of the Kanto basin of Japan since 1 Ma due to subduction of the Pacific and Philippine sea plates and collision of the Izu-Bonin arc

NASA Astrophysics Data System (ADS)

Hashima, Akinori; Sato, Toshinori; Sato, Hiroshi; Asao, Kazumi; Furuya, Hiroshi; Yamamoto, Shuji; Kameo, Koji; Miyauchi, Takahiro; Ito, Tanio; Tsumura, Noriko; Kaneda, Heitaro

2015-04-01

The Kanto basin, the largest lowland in Japan, developed by flexure as a result of (1) the subduction of the Philippine Sea (PHS) and the Pacific (PAC) plates and (2) the collision of the Izu-Bonin arc with the Japanese island arc. Geomorphological, geological, and thermochronological data on long-term vertical movements over the last 1 My suggest that subsidence initially affected the entire Kanto basin after which the area of subsidence gradually narrowed until, finally, the basin began to experience uplift. In this study, we modelled the tectonic evolution of the Kanto basin following the method of Matsu'ura and Sato (1989) for a kinematic subduction model with dislocations, in order to quantitatively assess the effects of PHS and PAC subduction. We include the steady slip-rate deficit (permanent locking rate at the plate interface) in our model to account for collision process. We explore how the arc-arc collision process has been affected by a westerly shift in the PHS plate motion vector with respect to the Eurasian plate, thought to have occurred between 1.0-0.5 Ma, using long-term vertical deformation data to constrain extent of the locked zone on the plate interface. We evaluated the change in vertical deformation rate for two scenarios: (1) a synchronous shift in the orientation of the locked zone as PHS plate motion shifts and (2) a delayed shift in the orientation of the locked zone following a change in plate motion. Observed changes in the subsidence/uplift pattern are better explained by scenario (2), suggesting that recent (<1 My) deformation in the Kanto basin shows a lag in crustal response to the shift in plate motion. We also calculated recent stress accumulation rates and found a good match with observed earthquake mechanisms, which shows that intraplate earthquakes serve to release stress accumulated through long-term plate interactions.

Simulation of tectonic evolution of the Kanto Basin of Japan since 1 Ma due to subduction of the Pacific and Philippine Sea plates and the collision of the Izu-Bonin arc

NASA Astrophysics Data System (ADS)

Hashima, Akinori; Sato, Toshinori; Sato, Hiroshi; Asao, Kazumi; Furuya, Hiroshi; Yamamoto, Shuji; Kameo, Koji; Miyauchi, Takahiro; Ito, Tanio; Tsumura, Noriko; Kaneda, Heitaro

2016-06-01

The Kanto Basin, the largest lowland in Japan, developed by flexure as a result of (1) the subduction of the Philippine Sea (PHS) and the Pacific (PAC) plates and (2) the repeated collision of the Izu-Bonin arc fragments with the Japanese island arc. Geomorphological, geological, and thermochronological data on vertical movements over the last 1 My suggest that subsidence initially affected the entire basin after which the area of subsidence gradually narrowed until, finally, the basin began to experience uplift. In this study, we modeled the tectonic evolution of the Kanto Basin following the method of Matsu'ura and Sato (1989) for a kinematic subduction model with dislocations, in order to quantitatively assess the effects of PHS and PAC subduction. We include the steady slip-rate deficit (permanent locking rate at the plate interface) in our model to account for collision process. We explore how the latest collision of the Izu Peninsula block has been affected by a westerly shift in the PHS plate motion vector with respect to the Eurasian plate, thought to have occurred between 1.0-0.5 Ma, using long-term vertical deformation data to constrain extent of the locked zone on the plate interface. We evaluated the change in vertical deformation rate for two scenarios: (1) a synchronous shift in the orientation of the locked zone as PHS plate motion shifts and (2) a delayed shift in the orientation of the locked zone following the shift in plate motion. Observed changes in the uplift/subsidence pattern are better explained by scenario (2), suggesting that recent (< 1 My) deformation in the Kanto Basin shows a lag in crustal response to the plate motion shift. We also calculated stress accumulation rates and found a good match with observed earthquake mechanisms, which shows that intraplate earthquakes serve to release stress accumulated through long-term plate interactions.

Inverted distal clavicle anatomic locking plate for displaced medial clavicle fracture.

PubMed

Wang, Yong; Jiang, Jiannong; Dou, Bin; Zhang, Panjun

2015-09-01

Fractures of the medial clavicle are rare injuries. Recently, open reduction and internal fixation has been recommended for displaced medial clavicle fractures in order to prevent non-union and dysfunction. Because of the rarity of this injury, the optimal fixation device has not yet been established. In this report, we describe a case of a 40-year-old male patient who sustained a significantly displaced medial clavicle fracture treated by open reduction and internal fixation using an inverted distal clavicle anatomic locking plate. At the 12 months follow-up, the patient recovered well, had returned to pre-injury job, and was quite satisfied with the outcome. Internal fixation of medial clavicle fracture using an inverted distal clavicle anatomic locking plate of the ipsilateral side appears to be a good treatment option.

Cooling/grounding mount for hybrid circuits

NASA Technical Reports Server (NTRS)

Bagstad, B.; Estrada, R.; Mandel, H.

1981-01-01

Extremely short input and output connections, adequate grounding, and efficient heat removal for hybrid integrated circuits are possible with mounting. Rectangular clamp holds hybrid on printed-circuit board, in contact with heat-conductive ground plate. Clamp is attached to ground plane by bolts.

20. Detail of 8" square solid wood column at fruit ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

20. Detail of 8" square solid wood column at fruit and vegetable storage room; note ledger plates bolted to top of column - Fort Hood, World War II Temporary Buildings, Cold Storage Building, Seventeenth Street, Killeen, Bell County, TX

Treatment of linear mandibular fractures using a single 2.0-mm AO locking reconstruction plate: is a second plate necessary?

PubMed

Scolozzi, Paolo; Martinez, Alvaro; Jaques, Bertrand

2009-12-01

To prospectively evaluate the use of a single Arbeitsgemeinschaft für Osteosynthesefragen (AO) 2.0-mm locking reconstruction plate for linear noncomminuted mandibular fractures without the use of a second plate. We analyzed the clinical and radiologic data of 45 patients with 74 fractures (21 single fractures, 22 double fractures, and 2 triple fractures). Fracture locations were the symphysis (n = 35, 47.3%), body (n = 15, 20.3%), and angle (n = 24, 32.4%). We recorded the mechanism of injury, time between admission to the hospital and surgery, gender and age, temporary maxillomandibular fixation and its duration, and the surgical approach. Postsurgical complications that were recorded as minor did not require surgical intervention, whereas major complications required further surgical intervention. All patients had satisfactory fracture reduction and a successful treatment outcome without major complications. Ten patients (22.2%) developed minor complications. The present study has demonstrated that treating linear noncomminuted mandibular fractures with a single AO 2.0-mm locking reconstruction plates is associated with no major complications and sound bone healing in all patients.

Volar locking plate (VLP) versus non-locking plate (NLP) in the treatment of die-punch fractures of the distal radius, an observational study.

PubMed

Zhang, Xiong; Hu, Chunhe; Yu, Kunlun; Bai, Jiangbo; Tian, Dehu; Xu, Yi; Zhang, Bing

2016-10-01

This study aims to evaluate whether volar locking plate was superior over non-locking plate in the treatment of die-punch fractures of the distal radius. A total of 57 patients with closed die-punch fractures of the distal radius were included and analyzed. Of them, 32 were treated by non-locking plate (NLP) and the remaining 25 were treated by volar locking plate (VLP). Preoperative radiographs, computer tomographs and three-dimensional reconstruction, radiographs taken at immediate postoperation and at last follow-up were extracted and evaluated. Patients' electronic medical records were inquired and related demographic and medical data were documented. The documented contents were volar tilt, radial inclination, ulnar variance, grip strength, Disabilities of the Arm, Shoulder, and Hand (DASH) and visual analog scale (VAS) scores and complications. VLP group demonstrated a significantly reduced radial subsidence of 1.5 mm (0.7 versus 2.2 mm), during the interval of bony union (P < 0.001), compared to NLP group. Larger proportion of patients (88% versus 62.5%) in VLP group gained acceptable joint congruity (step-off <2 mm) at the final follow-up (P = 0.037). No significant differences were observed between the groups in the measurements of volar tilt, radial inclination, DASH, VAS and grip strength recovery at the last follow-up. There was a trend of fewer overall complications (5/25 versus 10/32) and major complications that required surgery interventions (1/25 versus 4/32) in VLP than NLP groups, although the difference did not approach to significance (P = 0.339, 0.372). VLP leaded to significantly better results of reduction maintainance and the final joint congruity than NLP, while reducing overall and major complications. However, the results should be treated in the context of limitations and the clinical significance of the difference required further studies to investigate. Copyright © 2016 IJS Publishing Group Ltd. Published by Elsevier Ltd. All rights reserved.

Silicon force sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galambos, Paul C.; Crenshaw, Thomas B.; Nishida, Erik E.

The various technologies presented herein relate to a sensor for measurement of high forces and/or high load shock rate(s), whereby the sensor utilizes silicon as the sensing element. A plate of Si can have a thinned region formed therein on which can be formed a number of traces operating as a Wheatstone bridge. The brittle Si can be incorporated into a layered structure comprising ductile and/or compliant materials. The sensor can have a washer-like configuration which can be incorporated into a nut and bolt configuration, whereby tightening of the nut and bolt can facilitate application of a compressive preload uponmore » the sensor. Upon application of an impact load on the bolt, the compressive load on the sensor can be reduced (e.g., moves towards zero-load), however the magnitude of the preload can be such that the load on the sensor does not translate to tensile stress being applied to the sensor.« less

Structural design of an in-line bolted joint for the space shuttle solid rocket motor case segments

NASA Technical Reports Server (NTRS)

Dorsey, John T.; Stein, Peter A.; Bush, Harold G.

1987-01-01

Results of a structural design study of an in-line bolted joint concept which can be used to assemble Space Shuttle Solid Rocket Motor (SRM) case segments are presented. Numerous parametric studies are performed to characterize the in-line bolted joint behavior as major design variables are altered, with the primary objective always being to keep the inside of the joint (where the O-rings are located) closed during the SRM firing. The resulting design has 180 1-inch studs, an eccentricity of -0.5 inch, a flange thickness of 3/4 inch, a bearing plate thickness of 1/4 inch, and the studs are subjected to a preload which is 70% of ultimate. The mass penalty per case segment joint for the in-line design is 346 lbm more than the weight penalty for the proposed capture tang fix.

Additive fiber-cerclages in proximal humeral fractures stabilized by locking plates

PubMed Central

Hurschler, Christof; Rech, Louise; Vosshenrich, Rolf; Lill, Helmut

2009-01-01

Background and purpose The effect of additive fiber-cerclages in proximal humeral fractures stabilized by locking plates on fracture stabilization and rotator cuff function is unclear. Here it was assessed in a human cadaver study. Methods 24 paired human shoulder specimens were harvested from median 77-year-old (range 66–85) female donors. An unstable 3-part fracture model with an intact rotator cuff was developed. 1 specimen of each pair received an additive fiber-cerclage of the rotator cuff after plate fixation, and the other one received a plate fixation without an additive fiber-cerclage. Force-controlled hydraulic cylinders were used to simulate physiological rotator cuff tension, while a robot-assisted shoulder simulator performed 4 relevant cases of load: (1) axial loading at 0°, (2) glenohumeral abduction at 60°, (3) internal rotation at 0° abduction, and (4) external rotation at 0° abduction, and imitated hanging arm weight during loading without affecting joint kinematics. A 3-dimensional real-time interfragmentary motion analysis was done in fracture gaps between the greater tuberosity and the head, as well as subcapital. The capacity of the rotator cuff to strain was analyzed with an optical system. Results Interfragmentary motion was similar between the groups with and without fiber-cerclages, in both fracture gaps and in any of the cases of load. Cerclages did not impair the capacity of the rotator cuff to strain. Interpretation Provided that unstable 3-part fractures are reduced and stabilized anatomically by a locking plate, additive fiber-cerclages do not reduce interfragmentary motion. Additive fiber-cerclages may be necessary in locking plate osteosyntheses of multiple-fractured greater tuberosities or lesser tuberosity fractures that cannot be fixed sufficiently by the plate. PMID:19562564

46 CFR 50.25-1 - General.

Code of Federal Regulations, 2010 CFR

2010-10-01

... subchapter. (b) Plate, bar stock, pipe, tube, pipe joining fittings (tees, elbows, reducers, etc.), bolting... or the cognizant Officer in Charge, Marine Inspection. (e) Components designed for hydraulic service... tested hydraulic components is granted by the Marine Safety Center or the cognizant Officer in Charge...

12. DETAIL OF CONNECTION BETWEEN SOUTHEAST END POST AND TOP ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. DETAIL OF CONNECTION BETWEEN SOUTHEAST END POST AND TOP CHORD, SHOWING BOLT, RIVETED PLATES, AND EYE BAR; VIEW FROM WEST. - Mitchell's Mill Bridge, Spanning Winter's Run on Carrs Mill Road, west of Bel Air, Bel Air, Harford County, MD

Spline screw payload fastening system

NASA Technical Reports Server (NTRS)

Vranish, John M. (Inventor)

1993-01-01

A system for coupling an orbital replacement unit (ORU) to a space station structure via the actions of a robot and/or astronaut is described. This system provides mechanical and electrical connections both between the ORU and the space station structure and between the ORU and the ORU and the robot/astronaut hand tool. Alignment and timing features ensure safe, sure handling and precision coupling. This includes a first female type spline connector selectively located on the space station structure, a male type spline connector positioned on the orbital replacement unit so as to mate with and connect to the first female type spline connector, and a second female type spline connector located on the orbital replacement unit. A compliant drive rod interconnects the second female type spline connector and the male type spline connector. A robotic special end effector is used for mating with and driving the second female type spline connector. Also included are alignment tabs exteriorally located on the orbital replacement unit for berthing with the space station structure. The first and second female type spline connectors each include a threaded bolt member having a captured nut member located thereon which can translate up and down the bolt but are constrained from rotation thereabout, the nut member having a mounting surface with at least one first type electrical connector located on the mounting surface for translating with the nut member. At least one complementary second type electrical connector on the orbital replacement unit mates with at least one first type electrical connector on the mounting surface of the nut member. When the driver on the robotic end effector mates with the second female type spline connector and rotates, the male type spline connector and the first female type spline connector lock together, the driver and the second female type spline connector lock together, and the nut members translate up the threaded bolt members carrying the first type electrical connector up to the complementary second type connector for interconnection therewith.

Detailed finite element analysis and preliminary study of the effects of friction and fastener pre-tension on the mechanical behavior of fastened built-up members

NASA Astrophysics Data System (ADS)

Bonachera Martin, Francisco Javier

The characterization of fatigue resistance is one of the main concerns in structural engineering, a concern that is particularly important in the evaluation of existing bridge members designed or erected before the development of fatigue design provisions. The ability of a structural member to develop alternate load paths after the failure of a component is known as member-level or internal redundancy. In fastened built-up members, these alternate load paths are affected by the combination of fastener pre-tension and friction between the structural member components in contact. In this study, a finite element methodology to model and analyze riveted and bolted built-up members was developed in ABAQUS and validated with experimental results. This methodology was used to created finite element models of three fastened plates subjected to tension, in which the middle plate had failed, in order to investigate the fundamental effects of combined fastener pre-tension and friction on their mechanical behavior. Detailed finite element models of riveted and bolted built-up flexural members were created and analyze to understand the effect of fastener pre-tension in member-level redundancy and resistance to fatigue and fracture. The obtained results showed that bolted members are able to re-distribute a larger portion of the load away from the failing component into the rest of the member than riveted members, and that this transfer of load also took place over a smaller length. Superior pre-tension of bolts, in comparison to rivets, results in larger frictional forces that develop at the contact interfaces between components and constitute additional alternate load paths that increase member-level redundancy which increase the fatigue and fracture resistance of the structural member during the failure of one of its components. Although fatigue and fracture potential may be mitigated by compressive stresses developing around the fastener hole due to fastener pre-tension, it was also observed, that at the surface of the fastener hole and at the contact interface with another plate, tensional stresses could develop; however, further computational and experimental work should be performed to verify this claim.

CFD Simulations of the IHF Arc-Jet Flow: Compression-Pad Separation Bolt Wedge Tests

NASA Technical Reports Server (NTRS)

Gokcen, Tahir; Skokova, Kristina A.

2017-01-01

This paper reports computational analyses in support of two wedge tests in a high enthalpy arc-jet facility at NASA Ames Research Center. These tests were conducted using two different wedge models, each placed in a free jet downstream of a corresponding different conical nozzle in the Ames 60-MW Interaction Heating Facility. Each panel test article included a metallic separation bolt imbedded in Orion compression-pad and heatshield materials, resulting in a circular protuberance over a flat plate. The protuberances produce complex model flowfields, containing shock-shock and shock-boundary layer interactions, and multiple augmented heating regions on the test plate. As part of the test calibration runs, surface pressure and heat flux measurements on water-cooled calibration plates integrated with the wedge models were also obtained. Surface heating distributions on the test articles as well as arc-jet test environment parameters for each test configuration are obtained through computational fluid dynamics simulations, consistent with the facility and calibration measurements. The present analysis comprises simulations of the non-equilibrium flow field in the facility nozzle, test box, and flow field over test articles, and comparisons with the measured calibration data.

CFD Simulations of the IHF Arc-Jet Flow: Compression-Pad/Separation Bolt Wedge Tests

NASA Technical Reports Server (NTRS)

Goekcen, Tahir; Skokova, Kristina A.

2017-01-01

This paper reports computational analyses in support of two wedge tests in a high enthalpy arc-jet facility at NASA Ames Research Center. These tests were conducted using two different wedge models, each placed in a free jet downstream of a corresponding different conical nozzle in the Ames 60-MW Interaction Heating Facility. Each panel test article included a metallic separation bolt imbedded in Orion compression-pad and heatshield materials, resulting in a circular protuberance over a flat plate. The protuberances produce complex model flowfields, containing shock-shock and shock-boundary layer interactions, and multiple augmented heating regions on the test plate. As part of the test calibration runs, surface pressure and heat flux measurements on water-cooled calibration plates integrated with the wedge models were also obtained. Surface heating distributions on the test articles as well as arc-jet test environment parameters for each test configuration are obtained through computational fluid dynamics simulations, consistent with the facility and calibration measurements. The present analysis comprises simulations of the nonequilibrium flowfield in the facility nozzle, test box, and flowfield over test articles, and comparisons with the measured calibration data.

Biomechanical analysis of fixation of middle third fractures of the clavicle.

PubMed

Drosdowech, Darren S; Manwell, Stuart E E; Ferreira, Louis M; Goel, Danny P; Faber, Kenneth J; Johnson, James A

2011-01-01

This biomechanical study compares four different techniques of fixation of middle third clavicular fractures. Twenty fresh-frozen clavicles were randomized into four groups. Each group used a different fixation device (3.5 Synthes reconstruction plate, 3.5 Synthes limited contact dynamic compression plate, 3.5 Synthes locking compression plate, and 4.5 DePuy Rockwood clavicular pin). All constructs were mechanically tested in bending and torque modes both with and without a simulated inferior cortical defect. Bending load to failure was also conducted. The four groups were compared using an analysis of variance test. The plate constructs were stiffer than the pin during both pure bending and torque loads with or without an inferior cortical defect. Bending load to failure with an inferior cortical defect revealed that the reconstruction plate was weaker compared with the other three groups. The limited contact and locking plates were stiffer than the reconstruction plate but demonstrated statistical significance only with the cortical defect. As hypothesized, the 3.5 limited contact dynamic compression plate and 3.5 locking compression plate demonstrated the greatest resistance to bending and torque loads, especially in the presence of simulated comminution of a middle third clavicular fracture. The reconstruction plate demonstrated lower stiffness and strength values compared with the other plates, especially with a cortical defect, whereas the pin showed poor resistance to bending and torque loads in all modes of testing. This information may help surgeons to choose the most appropriate method of fixation when treating fractures of the middle third of the clavicle.

Radiographic Outcomes of Volar Locked Plating for Distal Radius Fractures

PubMed Central

Mignemi, Megan E.; Byram, Ian R.; Wolfe, Carmen C.; Fan, Kang-Hsien; Koehler, Elizabeth A.; Block, John J.; Jordanov, Martin I.; Watson, Jeffry T.; Weikert, Douglas R.; Lee, Donald H.

2013-01-01

Purpose To assess the ability of volar locked plating to achieve and maintain normal radiographic parameters for articular stepoff, volar tilt, radial inclination, ulnar variance, and radial height in distal radius fractures. Methods We performed a retrospective review of 185 distal radius fractures that underwent volar locked plating with a single plate design over a 5-year period. We reviewed radiographs and recorded measurements for volar tilt, radial inclination, ulnar variance, radial height, and articular stepoff. We used logistic regression to determine the association between return to radiographic standard norms and fracture type. Results At the first and final postoperative follow-up visits, we observed articular congruence less than 2 mm in 92% of fractures at both times. Normal volar tilt (11°) was restored in 46% at the first follow-up and 48% at the final one. Radial inclination (22°) was achieved in 44% at the first follow-up and 43% at the final one, and ulnar variance (01 ± 2 mm) was achieved in 53% at the first follow-up and 53% at the final one. In addition, radial height (14 ± 1mm) was restored in 14% at the first follow-up and 12% at the final one. More complex, intra-articular fractures (AO class B and C and Frykman types 3, 4, 7, and 8) were less likely to be restored to normal radiographic parameters. However, because of the small sample size for some fracture types, it was difficult to discover significant associations between fracture type and radiographic outcome. Conclusions Volar locked plating for distal radius fractures achieved articular stepoff less than 2 mm in most fractures but only restored and maintained normal radiographic measurements for volar tilt, radial inclination, and ulnar variance in 50% of fractures. The ability of volar locked plating to restore and maintain ulnar variance and volar tilt decreased with more complex intra-articular fracture types. PMID:23218558

Tangential Bicortical Locked Fixation Improves Stability in Vancouver B1 Periprosthetic Femur Fractures: A Biomechanical Study.

PubMed

Lewis, Gregory S; Caroom, Cyrus T; Wee, Hwabok; Jurgensmeier, Darin; Rothermel, Shane D; Bramer, Michelle A; Reid, John Spence

2015-10-01

The biomechanical difficulty in fixation of a Vancouver B1 periprosthetic fracture is purchase of the proximal femoral segment in the presence of the hip stem. Several newer technologies provide the ability to place bicortical locking screws tangential to the hip stem with much longer lengths of screw purchase compared with unicortical screws. This biomechanical study compares the stability of 2 of these newer constructs to previous methods. Thirty composite synthetic femurs were prepared with cemented hip stems. The distal femur segment was osteotomized, and plates were fixed proximally with either (1) cerclage cables, (2) locked unicortical screws, (3) a composite of locked screws and cables, or tangentially directed bicortical locking screws using either (4) a stainless steel locking compression plate system with a Locking Attachment Plate (Synthes) or (5) a titanium alloy Non-Contact Bridging system (Zimmer). Specimens were tested to failure in either axial or torsional quasistatic loading modes (n = 3) after 20 moderate load preconditioning cycles. Stiffness, maximum force, and failure mechanism were determined. Bicortical constructs resisted higher (by an average of at least 27%) maximum forces than the other 3 constructs in torsional loading (P < 0.05). Cables constructs exhibited lower maximum force than all other constructs, in both axial and torsional loading. The bicortical titanium construct was stiffer than the bicortical stainless steel construct in axial loading. Proximal fixation stability is likely improved with the use of bicortical locking screws as compared with traditional unicortical screws and cable techniques. In this study with a limited sample size, we found the addition of cerclage cables to unicortical screws may not offer much improvement in biomechanical stability of unstable B1 fractures.

Three-dimensional flat shell-to-shell coupling: numerical challenges

NASA Astrophysics Data System (ADS)

Guo, Kuo; Haikal, Ghadir

2017-11-01

The node-to-surface formulation is widely used in contact simulations with finite elements because it is relatively easy to implement using different types of element discretizations. This approach, however, has a number of well-known drawbacks, including locking due to over-constraint when this formulation is used as a twopass method. Most studies on the node-to-surface contact formulation, however, have been conducted using solid elements and little has been done to investigate the effectiveness of this approach for beam or shell elements. In this paper we show that locking can also be observed with the node-to-surface contact formulation when applied to plate and flat shell elements even with a singlepass implementation with distinct master/slave designations, which is the standard solution to locking with solid elements. In our study, we use the quadrilateral four node flat shell element for thin (Kirchhoff-Love) plate and thick (Reissner-Mindlin) plate theory, both in their standard forms and with improved formulations such as the linked interpolation [1] and the Discrete Kirchhoff [2] elements for thick and thin plates, respectively. The Lagrange multiplier method is used to enforce the node-to-surface constraints for all elements. The results show clear locking when compared to those obtained using a conforming mesh configuration.

Fasteners and fastening techniques: A compilation

NASA Technical Reports Server (NTRS)

1972-01-01

Technology on fasteners and fastening devices is presented, as part of NASA's TU program to provide technical information on devices, methods, and techniques resulting from aerospace research. The material is divided into two sections which include: (1) data concerning a selected group of fasteners and concept for fasteners such as locking devices, couplings, and connect and release mechanisms; and (2) discussions on a number of fastening techniques such as those for mounting panel lamps, clamping flange bolts, stretching fasteners, and transferring fuel from a tanker to another vehicle.

Full title: Biomechanical comparison between stainless steel, titanium and carbon-fiber reinforced polyetheretherketone volar locking plates for distal radius fractures.

PubMed

Mugnai, Raffaele; Tarallo, Luigi; Capra, Francesco; Catani, Fabio

2018-05-25

As the popularity of volar locked plate fixation for distal radius fractures has increased, so have the number and variety of implants, including variations in plate design, the size and angle of the screws, the locking screw mechanism, and the material of the plates. carbon-fiber reinforced polyetheretherketone (CFR-PEEK) plate features similar biomechanical properties to metallic plates, representing, therefore, an optimal alternative for the treatment of distal radius fractures. three different materials-composed plates were evaluated: stainless steel volar lateral column (Zimmer); titanium DVR (Hand Innovations); CFR-PEEK DiPHOS-RM (Lima Corporate). Six plates for each type were implanted in sawbones and an extra-articular rectangular osteotomy was created. Three plates for each material were tested for load to failure and bending stiffness in axial compression. Moreover, 3 constructs for each plate were evaluated after dynamically loading for 6000 cycles of fatigue. the mean bending stiffness pre-fatigue was significantly higher for the stainless steel plate. The titanium plate yielded the higher load to failure both pre and post fatigue. After cyclic loading, the bending stiffness increased by a mean of 24% for the stainless steel plate; 33% for the titanium; and 17% for the CFR-PEEK plate. The mean load to failure post-fatigue increased by a mean of 10% for the stainless steel and 14% for CFR-PEEK plates, whereas it decreased (-16%) for the titanium plate. Statistical analysis between groups reported significant values (p <.001) for all comparisons except for Hand Innovations vs. Zimmer bending stiffness post fatigue (p = .197). the significant higher load to failure of the titanium plate, makes it indicated for patients with higher functional requirements or at higher risk of trauma in the post-operative period. The CFR-PEEK plate showed material-specific disadvantages, represented by little tolerance to plastic deformation, and lower load to failure. N/A. Copyright © 2018. Published by Elsevier Masson SAS.

CFD Simulations of the IHF Arc-Jet Flow: Compression-Pad/Separation Bolt Wedge Tests

NASA Technical Reports Server (NTRS)

Gokcen, Tahir; Skokova, Kristina A.

2017-01-01

This paper reports computational analyses in support of two wedge tests in a high enthalpy arc-jet facility at NASA Ames Research Center. These tests were conducted using two different wedge models, each placed in a free jet downstream of a corresponding different conical nozzle in the Ames 60-MW Interaction Heating Facility. Panel test articles included a metallic separation bolt imbedded in the compression-pad and heat shield materials, resulting in a circular protuberance over a flat plate. As part of the test calibration runs, surface pressure and heat flux measurements on water-cooled calibration plates integrated with the wedge models were also obtained. Surface heating distributions on the test articles as well as arc-jet test environment parameters for each test configuration are obtained through computational fluid dynamics simulations, consistent with the facility and calibration measurements. The present analysis comprises simulations of the non-equilibrium flow field in the facility nozzle, test box, and flow field over test articles, and comparisons with the measured calibration data.

Behaviour and Analysis of Mechanically Fastened Joints in Composite Structures

DTIC Science & Technology

1988-03-01

Safety Factors for Use When Designing bolted Joints In GRP," Composites , April 1979, pp. M376. 93. Dastln, S., "Joining and Machining Techniques... MACHINE SPACER LOCKmm STEEL PLATE FASTENER 203 mm OR DOWEL FiN EXTENSOMETER EXTENSOMETER TGAUGE LENGTH ATTACHMENT COMPOSITE - PLATE 31 mm p NOTE: NOT TO...No.427 Behaviour and Analysis of Mechanically Fastened Joints in Composite Structures DTIC CXVTflUTION STATEME~r £ELECTE Approved fm Vubhc sIlam l JUL

Power consumption and lumber yields for reduced-kerf circular saws cutting hardwoods

Treesearch

Donald G. Cuppett

1982-01-01

Two 50-inch diameter headsaws were used for sawing (a) hardwood cants into boards, and (b) hardwood bolts into pallet parts. One saw had a 9x10 gage plate with 114-inch kerf teeth, and the other had a 7x8 gage plate with 9/32-inch kerf teeth. Power consumption for the two saws was determined with a watt-hour meter, measuring power used for paired cuts in 6-inch thick...

Experimental Investigation on Strengthening of Bolted Connections in Transmission/Communication Towers

NASA Astrophysics Data System (ADS)

Balagopal, R.; Prasad Rao, N.; Rokade, R. P.; Umesha, P. K.

2018-06-01

Due to increase in demand for power supply and increase in bandwidth for communication industry, the existing transmission line (TL) and communication towers needs to be strengthened. The strengthening of existing tower is economical rather than installation of new towers due to constraints in acquisition of land. The size of conductors have to be increased or additional number of antenna needs to be installed in existing TL/communication tower respectively. The compression and tension capacity of members in the existing towers have to be increased to sustain the additional loads due to wind and self-weight of these components. The tension capacity enhancement of existing angle sections in live line condition without power shut-down is a challenging task. In the present study, the use of Glass Fiber Reinforced Plastic (GFRP) plate/angle sections is explored to strengthen existing bolted connections in TL/communication towers. Experimental investigation conducted at component level on strengthening of existing two types of single cover steel butt joint, one made of steel plate and another joint made of steel angle sections respectively. First series of experiment conducted on strengthening the connection using GFRP plate/cleat angle sections. The second series of strengthening experiment is conducted using steel plate/angle sections to replace GFRP sections. The load sharing behaviour of strengthened GFRP and steel section is compared and suitable recommendations are given.

Experimental Investigation on Strengthening of Bolted Connections in Transmission/Communication Towers

NASA Astrophysics Data System (ADS)

Balagopal, R.; Prasad Rao, N.; Rokade, R. P.; Umesha, P. K.

2018-02-01

Due to increase in demand for power supply and increase in bandwidth for communication industry, the existing transmission line (TL) and communication towers needs to be strengthened. The strengthening of existing tower is economical rather than installation of new towers due to constraints in acquisition of land. The size of conductors have to be increased or additional number of antenna needs to be installed in existing TL/communication tower respectively. The compression and tension capacity of members in the existing towers have to be increased to sustain the additional loads due to wind and self-weight of these components. The tension capacity enhancement of existing angle sections in live line condition without power shut-down is a challenging task. In the present study, the use of Glass Fiber Reinforced Plastic (GFRP) plate/angle sections is explored to strengthen existing bolted connections in TL/communication towers. Experimental investigation conducted at component level on strengthening of existing two types of single cover steel butt joint, one made of steel plate and another joint made of steel angle sections respectively. First series of experiment conducted on strengthening the connection using GFRP plate/cleat angle sections. The second series of strengthening experiment is conducted using steel plate/angle sections to replace GFRP sections. The load sharing behaviour of strengthened GFRP and steel section is compared and suitable recommendations are given.

Fragment-Specific Fixation Versus Volar Locking Plates in Primarily Nonreducible or Secondarily Redisplaced Distal Radius Fractures: A Randomized Controlled Study.

PubMed

Landgren, Marcus; Abramo, Antonio; Geijer, Mats; Kopylov, Philippe; Tägil, Magnus

2017-03-01

To compare the patient-reported, clinical, and radiographic outcome of 2 methods of internal fixation in distal radius fractures. Fifty patients, mean age 56 years (range, 21-69 years) with primarily nonreducible or secondarily redisplaced distal radius fractures were randomized to open reduction internal fixation using volar locking plates (n = 25) or fragment-specific fixation (n = 25). The patients were assessed on grip strength, range of motion, patient-reported outcome (Quick Disabilities of the Arm, Shoulder, and Hand), pain (visual analog scale), health-related quality of life (Short Form-12 [SF-12]), and radiographic evaluation. Grip strength at 12 months was the primary outcome measure. At 12 months, no difference was found in grip strength, which was 90% of the uninjured side in the volar plate group and 87% in the fragment-specific fixation group. No differences were found in range of motion and the median Quick Disabilities of the Arm, Shoulder, and Hand score was 5 in both groups. The overall complication rate was significant, 21% in the volar locking plate group, compared with 52% in the fragment-specific group. In treatment of primarily nonreducible or secondarily redisplaced distal radius fractures, volar locking plates and fragment-specific fixation both achieve good and similar patient-reported outcomes, although more complications were recorded in the fragment-specific group. Therapeutic II. Copyright © 2017 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Interprosthetic femoral fractures treated with locking plate.

PubMed

Ebraheim, Nabil; Carroll, Trevor; Moral, Muhammad Z; Lea, Justin; Hirschfeld, Adam; Liu, Jiayong

2014-10-01

Interprosthetic fractures are challenging to manage. Although treatment of femoral fractures around a single implant has been described, there is little literature for treatment of interprosthetic femoral fractures. This study analyses the management and outcomes of 15 patients with interprosthetic femoral fractures treated with locking plates. A retrospective chart review was conducted of 17 patients with interprosthetic femur fracture treated with locking plates from 2002 to 2013. Patient demographics and comorbidities were collected. Preoperatively, patients were classified with the Vancouver or Su classification system. Intraoperative use of bone graft and/or cerclage cables was also examined. Clinical and radiographic outcomes were evaluated for union, time to full weight bearing, return to preinjury level of activity, and pain assessed with visual analog scale (VAS). There were 15 patients with interprosthetic fractures meeting criteria for this study. Average patient age was 80.53 (range, 61-92) years. Bone grafting was used in 23.5% (four of 17) and cerclage cables in 29.4% (five of 17). Patients achieved complete union and return to full weight bearing an average of 4.02 (range, two to six) months later. Average VAS pain score was 1.00 (range, zero to six). All patients returned to their preoperative ambulatory status. Locking plates could achieve satisfactory results for interprosthetic fractures. Considering an individual's fracture type, bone quality and protheses to determine the appropriate plate length and optional use of cerclage and/or bone graft was essential. In this limited sample size, interprosthetic fractures occurred at similar rates at the supracondylar region and diaphysis.

Biomechanical Property of a Newly Designed Assembly Locking Compression Plate: Three-Dimensional Finite Element Analysis

PubMed Central

Liu, Da

2017-01-01

In this study, we developed and validated a refined three-dimensional finite element model of middle femoral comminuted fracture to compare the biomechanical stability after two kinds of plate fixation: a newly designed assembly locking compression plate (NALCP) and a locking compression plate (LCP). CT data of a male volunteer was converted to middle femoral comminuted fracture finite element analysis model. The fracture was fixated by NALCP and LCP. Stress distributions were observed. Under slow walking load and torsion load, the stress distribution tendency of the two plates was roughly uniform. The anterolateral femur was the tension stress area, and the bone block shifted toward the anterolateral femur. Maximum stress was found on the lateral border of the number 5 countersink of the plate. Under a slow walking load, the NALCP maximum stress was 2.160e+03 MPa and the LCP was 8.561e+02 MPa. Under torsion load, the NALCP maximum stress was 2.260e+03 MPa and the LCP was 6.813e+02 MPa. Based on those results of finite element analysis, the NALCP can provide adequate mechanical stability for comminuted fractures, which would help fixate the bone block and promote bone healing. PMID:29065654

Newly designed anterolateral and posterolateral locking anatomic plates for lateral tibial plateau fractures: a finite element study.

PubMed

Chen, Pengbo; Lu, Hua; Shen, Hao; Wang, Wei; Ni, Binbin; Chen, Jishizhan

2017-02-23

Lateral column tibial plateau fracture fixation with a locking screw plate has higher mechanical stability than other fixation methods. The objectives of the present study were to introduce two newly designed locking anatomic plates for lateral tibial plateau fracture and to demonstrate their characteristics of the fixation complexes under the axial loads. Three different 3D finite element models of the lateral tibial plateau fracture with the bone plates were created. Various axial forces (100, 500, 1000, and 1500 N) were applied to simulate the axial compressive load on an adult knee during daily life. The equivalent maps of displacement and stress were output, and relative displacement was calculated along the fracture lines. The displacement and stresses in the fixation complexes increased with the axial force. The equivalent displacement or stress map of each fixation under different axial forces showed similar distributing characteristics. The motion characteristics of the three models differed, and the max-shear stress of trabecula increased with the axial load. These two novel plates could fix lateral tibial plateau fractures involving anterolateral and posterolateral fragments. Motions after open reduction and stable internal fixation should be advised to decrease the risk of trabecular microfracture. The relative displacement of the posterolateral fragments is different when using anterolateral plate and posterolateral plate, which should be considered in choosing the implants for different posterolateral plateau fractures.

Biomechanical analysis of plate systems for proximal humerus fractures: a systematic literature review.

PubMed

Jabran, Ali; Peach, Chris; Ren, Lei

2018-04-27

Proximal humerus fractures are the third most common in the human body but their management remains controversial. Open reduction and internal fixation with plates is one of the leading modes of operative treatment for these fractures. The development of technologies and techniques for these plates, during the recent decades, promise a bright future for their clinical use. A comprehensive review of in vitro biomechanical studies is needed for the comparison of plates' mechanical performance and the testing methodologies. This will not only guide clinicians with plate selection but also with the design of future in vitro biomechanical studies. This review was aimed to systematically categorise and review the in vitro biomechanical studies of these plates based on their protocols and discuss their results. The technologies and techniques investigated in these studies were categorised and compared to reach a census where possible. Web of Science and Scopus database search yielded 62 studies. Out of these, 51 performed axial loading, torsion, bending and/or combined bending and axial loading while 11 simulated complex glenohumeral movements by using tendons. Loading conditions and set-up, failure criteria and performance parameters, as well as results for each study, were reviewed. Only two studies tested four-part fracture model while the rest investigated two- and three-part fractures. In ten studies, synthetic humeri were tested instead of cadaveric ones. In addition to load-displacement data, three-dimensional motion analysis systems, digital image correlation and acoustic emission testing have been used for measurement. Overall, PHILOS was the most tested plate and locking plates demonstrated better mechanical performance than non-locking ones. Conflicting results have been published for their comparison with non-locking blade plates and polyaxial locking screws. Augmentation with cement [calcium phosphate or poly(methyl methacrylate)] or allografts (fibular and femoral head) was found to improve bone-plate constructs' mechanical performance. Controversy still lies over the use of rigid and semi-rigid implants and the insertion of inferomedial screws for calcar region support. This review will guide the design of in vitro and in silico biomechanical tests and also supplement the study of clinical literature.

Biomechanical comparison of orthogonal versus parallel double plating systems in intraarticular distal humerus fractures.

PubMed

Atalar, Ata C; Tunalı, Onur; Erşen, Ali; Kapıcıoğlu, Mehmet; Sağlam, Yavuz; Demirhan, Mehmet S

2017-01-01

In intraarticular distal humerus fractures, internal fixation with double plates is the gold standard treatment. However the optimal plate configuration is not clear in the literature. The aim of this study was to compare the biomechanical stability of the parallel and the orthogonal anatomical locking plating systems in intraarticular distal humerus fractures in artificial humerus models. Intraarticular distal humerus fracture (AO13-C2) with 5 mm metaphyseal defect was created in sixteen artificial humeral models. Models were fixed with either orthogonal or parallel plating systems with locking screws (Acumed elbow plating systems). Both systems were tested for their stiffness with loads in axial compression, varus, valgus, anterior and posterior bending. Then plastic deformation after cyclic loading in posterior bending and load to failure in posterior bending were tested. The failure mechanisms of all the samples were observed. Stiffness values in every direction were not significantly different among the orthogonal and the parallel plating groups. There was no statistical difference between the two groups in plastic deformation values (0.31 mm-0.29 mm) and load to failure tests in posterior bending (372.4 N-379.7 N). In the orthogonal plating system most of the failures occurred due to the proximal shaft fracture, whereas in the parallel plating system failure occurred due to the shift of the most distal screw in proximal fragment. Our study showed that both plating systems had similar biomechanical stabilities when anatomic plates with distal locking screws were used in intraarticular distal humerus fractures in artificial humerus models. Copyright © 2016 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

13. Emplacement no. 2, overhead view of counterweight well, showing ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. Emplacement no. 2, overhead view of counterweight well, showing channel for gun motor cable and bolt plates upon which base ring of gun carriage was mounted - Fort Wadsworth Battery Romeyn B. Ayers, South side of Ayers Road, Staten Island, Rosebank, Richmond County, NY

Experimental and numerical investigation into the influence of loading conditions in biomechanical testing of locking plate fracture fixation devices

PubMed Central

MacLeod, A.; Simpson, A. H. R. W.

2018-01-01

Objectives Secondary fracture healing is strongly influenced by the stiffness of the bone-fixator system. Biomechanical tests are extensively used to investigate stiffness and strength of fixation devices. The stiffness values reported in the literature for locked plating, however, vary by three orders of magnitude. The aim of this study was to examine the influence that the method of restraint and load application has on the stiffness produced, the strain distribution within the bone, and the stresses in the implant for locking plate constructs. Methods Synthetic composite bones were used to evaluate experimentally the influence of four different methods of loading and restraining specimens, all used in recent previous studies. Two plate types and three screw arrangements were also evaluated for each loading scenario. Computational models were also developed and validated using the experimental tests. Results The method of loading was found to affect the gap stiffness strongly (by up to six times) but also the magnitude of the plate stress and the location and magnitude of strains at the bone-screw interface. Conclusions This study demonstrates that the method of loading is responsible for much of the difference in reported stiffness values in the literature. It also shows that previous contradictory findings, such as the influence of working length and very large differences in failure loads, can be readily explained by the choice of loading condition. Cite this article: A. MacLeod, A. H. R. W. Simpson, P. Pankaj. Experimental and numerical investigation into the influence of loading conditions in biomechanical testing of locking plate fracture fixation devices. Bone Joint Res 2018;7:111–120. DOI: 10.1302/2046-3758.71.BJR-2017-0074.R2. PMID:29363522

Implant material and design alter construct stiffness in distal femur locking plate fixation: a pilot study.

PubMed

Schmidt, Ulf; Penzkofer, Rainer; Bachmaier, Samuel; Augat, Peter

2013-09-01

Construct stiffness affects healing of bones fixed with locking plates. However, variable construct stiffness reported in the literature may be attributable to differing test configurations and direct comparisons may clarify these differences. We therefore asked whether different distal femur locking plate systems and constructs will lead to different (1) axial and rotational stiffness and (2) fatigue under cyclic loading. We investigated four plate systems for distal femur fixation (AxSOS, LCP, PERI-LOC, POLYAX) of differing designs and materials using bone substitutes in a distal femur fracture model (OTA/AO 33-A3). We created six constructs of each of the four plating systems. Stiffness under static and cyclic loading and fatigue under cyclic loading were measured. Mean construct stiffness under axial loading was highest for AxSOS (100.8 N/mm) followed by PERI-LOC (80.8 N/mm) and LCP (62.6 N/mm). POLYAX construct stiffness testing showed the lowest stiffness (51.7 N/mm) with 50% stiffness of AxSOS construct testing. Mean construct stiffness under torsional loading was similar in the group of AxSOS and PERI-LOC (3.40 Nm/degree versus 3.15 Nm/degree) and in the group of LCP and POLYAX (2.63 Nm/degree versus 2.56 Nm/degree). The fourth load level of > 75,000 cycles was reached by three of six AxSOS, three of six POLYAX, and two of six PERI-LOC constructs. All others including all LCP constructs failed earlier. Implant design and material of new-generation distal femur locking plate systems leads to a wide range of differences in construct stiffness. Assuming construct stiffness affects fracture healing, these data may influence surgical decision-making in choosing an implant system.

Outcome of Repair of Distal Radial and Ulnar Fractures in Dogs Weighing 4 kg or Less Using a 1.5-mm Locking Adaption Plate or 2.0-mm Limited Contact Dynamic Compression Plate.

PubMed

Nelson, Thomas A; Strom, Adam

2017-11-01

Objectives  Retrospective evaluation of repairing distal radial and ulnar fractures in small breed dogs with the Synthes 1.5-mm locking Adaption plate system and compare results in a similar group of patients repaired with the Synthes 2.0-mm limited contact-dynamic compression plate (LC-DCP). Methods  Electronic medical records from one specialty referral centre were reviewed from March 21, 2010, to October 9, 2015, for patients weighing less than or equal to 4 kg that had a distal one-third radial and ulnar fracture repaired with a Synthes 1.5-mm locking adaption plate or Synthes 2.0-mm LC-DCP. Further inclusion criteria included application of the plate to the cranial surface of the radius via open reduction and internal fixation. Results  Six 1.5-mm Adaption plates and 7 2.0-mm LC-DCPs were used to repair 13 distal radial and ulnar fractures in 12 dogs. There were three major complications in the 1.5-mm adaption plate group (one plate fracture, one screw pull-out and one fracture through a distal screw hole) and one major complication in the 2.0-mm LC-DCP group due to a re-fracture. All patients without a complication had good or excellent functional outcome. Clinical Significance  The authors recommend that the 1.5-mm Adaption plate be used only when a 2.0-mm LC-DCP would not allow for a minimum of two screws in the distal segment and at the discretion of the surgeon. Schattauer GmbH Stuttgart.

Limiting Impact Force Due to Yielding and Buckling of the Plates and Internal Structural Frame at the Bow of a Barge during Its Head-on Impact with a Bullnose or Cellular Structure

DTIC Science & Technology

2009-08-01

Locks and Dam. ERDC/ITL TR-09-3 16 The proposed flexible approach walls at Lock and Dams 22 and 25 consist of precast concrete beams supported...Figures 2.3 and 2.5. The rounded hull plate connecting the front and side hull plates (in blue) is shown in brown in Figures 2.2 and 2.3. Figure 2.4...approach angle column in Table 3.1 is of no consequence for these analyses. Table 3.1. Three design load condition categories, frequency of loadings

Quick-Change Anode for Plating

NASA Technical Reports Server (NTRS)

Beasley, J. L.

1987-01-01

Proposed fastener for attaching electroplating anode improves quality of plating and increases productivity. Notches in twist-lock fastener mates with projections on end of anode bar. Fastener made of titanium for compatibility with copper-plating solution. Also constructed in snap-on, snap-off configuration.

Locked plating of comminuted distal femur fractures: does unlocked screw placement affect stability and failure?

PubMed

Cui, Shari; Bledsoe, J G; Israel, Heidi; Watson, J T; Cannada, Lisa K

2014-02-01

Locked plates provide greater stiffness, possibly at the expense of fracture healing. The purpose of this study is to evaluate construct stiffness of distal femur plates as a function of unlocked screw position in cadaveric distal femur fractures. Osteoporotic cadaveric femurs were used. Four diaphyseal bridge plate constructs were created using 13-hole distal femur locking plates, all with identical condylar fixation. Constructs included all locked (AL), all unlocked (AUL), proximal unlocked (PUL), and distally unlocked (DUL) groups. Constructs underwent cyclic axial loading with increasing force per interval. Data were gathered on axial stiffness, torsional stiffness, maximum torque required for 5-degree external rotation, and axial force to failure. Twenty-one specimens were divided into AL, AUL, PUL, and DUL groups. Axial stiffness was not significantly different between the constructs. AL and PUL demonstrated greater torsional stiffness, maximum torque, and force to failure than AUL and AL showed greater final torsional stiffness and failure force than DUL (P < 0.05). AL and PUL had similar axial, torsion, and failure measures, as did AUL and DUL constructs. All but 2 specimens fractured before medial gap closure during failure tests. Drop-offs on load-displacement curves confirmed all failures. Only the screw nearest the gap had significant effect on torsional and failure stiffness but not axial stiffness. Construct mechanics depended on the type of screw placed in this position. This screw nearest the fracture dictates working length stiffness when the working length itself is constant and in turn determines overall construct stiffness in osteoporotic bone.

Silicon force sensor and method of using the same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galambos, Paul C.; Crenshaw, Thomas B.; Nishida, Erik E.

The various technologies presented herein relate to a sensor for measurement of high forces and/or high load shock rate(s), whereby the sensor utilizes silicon as the sensing element. A plate of Si can have a thinned region formed therein on which can be formed a number of traces operating as a Wheatstone bridge. The brittle Si can be incorporated into a layered structure comprising ductile and/or compliant materials. The sensor can have a washer-like configuration which can be incorporated into a nut and bolt configuration, whereby tightening of the nut and bolt can facilitate application of a compressive preload uponmore » the sensor. Upon application of an impact load on the bolt, the compressive load on the sensor can be reduced (e.g., moves towards zero-load), however the magnitude of the preload can be such that the load on the sensor does not translate to tensile stress being applied to the sensor.« less

Feasibility of fatigue crack detection and tracking with a multi-sensor in-situ monitoring system

NASA Astrophysics Data System (ADS)

Zhao, Xiaoliang; Qi, Kevin; Qian, Tao; Mei, Gang

2014-02-01

Fatigue crack is a common problem for steel bridges. A cost effective and reliable method for detecting and verifying growth of a crack is desired. In this work, feasibilities of fatigue crack monitoring with acoustic emission sensors and strain gauges were studied on an A36 steel compact-tension coupon under cyclic tensile loading. By examining the ultrasonic signal time-of-arrival and frequency spectrum, acoustic emissions from a crack growth can be distinguished from other structural borne noises such as those from the interaction of loading bolts with the bolt holes on the plate. Strain sensor and clip gauge sensor data were also correlated well with the growth of the crack.

Cement technique for reducing post-operative bursitis after trochanteric fixation.

PubMed

Derman, Peter B; Horneff, John G; Kamath, Atul F; Garino, Jonathan

2013-02-01

Post-operative trochanteric bursitis is a known complication secondary to the surgical approach in total hip arthroplasty. This phenomenon may be partially attributable to repetitive microtrauma generated when soft tissues rub against implanted hardware. Significant rates of post-operative trochanteric bursitis have been observed following procedures in which a trochanteric fixation device, such as a bolt-washer mechanism or a cable-grip/claw system, is used to secure the trochanteric fragment after trochanteric osteotomy. We present a simple technique for use with a bolt-washer system or grip plate in which trochanteric components are covered in bone wax followed by a layer of cement to decrease friction and to diminish the risk of post-operative bursitis.

Intramedullary nail fixation versus locking plate fixation for adults with a fracture of the distal tibia: the UK FixDT RCT.

PubMed

Costa, Matthew L; Achten, Juul; Hennings, Susie; Boota, Nafisa; Griffin, James; Petrou, Stavros; Maredza, Mandy; Dritsaki, Melina; Wood, Thomas; Masters, James; Pallister, Ian; Lamb, Sarah E; Parsons, Nick R

2018-05-01

The best treatment for fractures of the distal tibia remains controversial. Most of these fractures require surgical fixation, but the outcomes are unpredictable and complications are common. To assess disability, quality of life, complications and resource use in patients treated with intramedullary (IM) nail fixation versus locking plate fixation in the 12 months following a fracture of the distal tibia. This was a multicentre randomised trial. The trial was conducted in 28 UK acute trauma centres from April 2013 to final follow-up in February 2017. In total, 321 adult patients were recruited. Participants were excluded if they had open fractures, fractures involving the ankle joint, contraindication to nailing or inability to complete questionnaires. IM nail fixation ( n  = 161), in which a metal rod is inserted into the hollow centre of the tibia, versus locking plate fixation ( n  = 160), in which a plate is attached to the surface of the tibia with fixed-angle screws. The primary outcome measure was the Disability Rating Index (DRI) score, which ranges from 0 points (no disability) to 100 points (complete disability), at 6 months with a minimum clinically important difference of 8 points. The DRI score was also collected at 3 and 12 months. The secondary outcomes were the Olerud-Molander Ankle Score (OMAS), quality of life as measured using EuroQol-5 Dimensions (EQ-5D), complications such as infection, and further surgery. Resource use was collected to inform the health economic evaluation. Participants had a mean age of 45 years (standard deviation 16.2 years), were predominantly male (61%, 197/321) and had experienced traumatic injury after a fall (69%, 223/321). There was no statistically significant difference in DRI score at 6 months [IM nail fixation group, mean 29.8 points, 95% confidence interval (CI) 26.1 to 33.7 points; locking plate group, mean 33.8 points, 95% CI 29.7 to 37.9 points; adjusted difference, 4.0 points, 95% CI -1.0 to 9.0 points; p  = 0.11]. There was a statistically significant difference in DRI score at 3 months in favour of IM nail fixation (IM nail fixation group, mean 44.2 points, 95% CI 40.8 to 47.6 points; locking plate group, mean 52.6 points, 95% CI 49.3 to 55.9 points; adjusted difference 8.8 points, 95% CI 4.3 to 13.2 points; p  < 0.001), but not at 12 months (IM nail fixation group, mean 23.1 points, 95% CI 18.9 to 27.2 points; locking plate group, 24.0 points, 95% CI 19.7 to 28.3 points; adjusted difference 1.9 points, 95% CI -3.2 to 6.9 points; p  = 0.47). Secondary outcomes showed the same pattern, including a statistically significant difference in mean OMAS and EQ-5D scores at 3 and 6 months in favour of IM nail fixation. There were no statistically significant differences in complications, including the number of postoperative infections (13% in the locking plate group and 9% in the IM nail fixation group). Further surgery was more common in the locking plate group (12% in locking plate group and 8% in IM nail fixation group at 12 months). The economic evaluation showed that IM nail fixation provided a slightly higher quality of life in the 12 months after injury and at lower cost and, therefore, it was cost-effective compared with locking plate fixation. The probability of cost-effectiveness for IM nail fixation exceeded 90%, regardless of the value of the cost-effectiveness threshold. As wound dressings after surgery are clearly visible, it was not possible to blind the patients to their treatment allocation. This evidence does not apply to intra-articular (pilon) fractures of the distal tibia. Among adults with an acute fracture of the distal tibia who were randomised to IM nail fixation or locking plate fixation, there were similar disability ratings at 6 months. However, recovery across all outcomes was faster in the IM nail fixation group and costs were lower. The potential benefit of IM nail fixation in several other fractures requires investigation. Research is also required into the role of adjuvant treatment and different rehabilitation strategies to accelerate recovery following a fracture of the tibia and other long-bone fractures in the lower limb. The patients in this trial will remain in longer-term follow-up. Current Controlled Trials ISRCTN99771224 and UKCRN 13761. This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment ; Vol. 22, No. 25. See the NIHR Journals Library website for further project information.

Spatial Variation of Slip Behavior Beneath the Alaska Peninsula Along Alaska-Aleutian Subduction Zone

NASA Astrophysics Data System (ADS)

Li, Shanshan; Freymueller, Jeffrey T.

2018-04-01

We resurveyed preexisting campaign Global Positioning System (GPS) sites and estimated a highly precise GPS velocity field for the Alaska Peninsula. We use the TDEFNODE software to model the slip deficit distribution using the new GPS velocities. We find systematic misfits to the vertical velocities from the optimal model that fits the horizontal velocities well, which cannot be explained by altering the slip distribution, so we use only the horizontal velocities in the study. Locations of three boundaries that mark significant along-strike change in the locking distribution are identified. The Kodiak segment is strongly locked, the Semidi segment is intermediate, the Shumagin segment is weakly locked, and the Sanak segment is dominantly creeping. We suggest that a change in preexisting plate fabric orientation on the downgoing plate has an important control on the along-strike variation in the megathrust locking distribution and subduction seismicity.

A comparison of parallel and diverging screw angles in the stability of locked plate constructs.

PubMed

Wähnert, D; Windolf, M; Brianza, S; Rothstock, S; Radtke, R; Brighenti, V; Schwieger, K

2011-09-01

We investigated the static and cyclical strength of parallel and angulated locking plate screws using rigid polyurethane foam (0.32 g/cm(3)) and bovine cancellous bone blocks. Custom-made stainless steel plates with two conically threaded screw holes with different angulations (parallel, 10° and 20° divergent) and 5 mm self-tapping locking screws underwent pull-out and cyclical pull and bending tests. The bovine cancellous blocks were only subjected to static pull-out testing. We also performed finite element analysis for the static pull-out test of the parallel and 20° configurations. In both the foam model and the bovine cancellous bone we found the significantly highest pull-out force for the parallel constructs. In the finite element analysis there was a 47% more damage in the 20° divergent constructs than in the parallel configuration. Under cyclical loading, the mean number of cycles to failure was significantly higher for the parallel group, followed by the 10° and 20° divergent configurations. In our laboratory setting we clearly showed the biomechanical disadvantage of a diverging locking screw angle under static and cyclical loading.

Internal fixation of complex fractures of the tarsal navicular with locking plates. A report of 10 cases.

PubMed

Cronier, P; Frin, J-M; Steiger, V; Bigorre, N; Talha, A

2013-06-01

Tarsal navicular fractures are rare and treatment of comminuted fractures is especially difficult. Since 2007, the authors have had access to 3D reconstruction from CT scan images and specific locking plates, and they decided to evaluate whether these elements improved management of these severe cases. Between 2007 and 2011, 10 comminuted tarsal navicular fractures were treated in a prospective study. All of the fractures were evaluated by 3D reconstruction from CT scan images, with suppression of the posterior tarsal bones. The surgical approach was chosen according to the type of lesion. Reduction was achieved with a mini-distractor when necessary, and stabilized by AO locking plate fixation (Synthes™). Patient follow-up included a clinical and radiological evaluation (Maryland Foot score, AOFAS score). Eight patients underwent postoperative CT scan. All patients were followed up after a mean 20.5 months. Union was obtained in all patients and arthrodesis was not necessary in any of them. The mean Maryland Foot score was 92.8/100, and the AOFAS score 90.6/100. One patient with an associated comminuted calcaneal fracture had minimal sequella from a compartment syndrome of the foot. The authors did not find any series in the literature that reported evaluating tarsal navicular fractures by 3D reconstruction from CT scan images. The images obtained after suppression of the posterior tarsal bones systematically showed a lateral plantar fragment attached to the plantar calcaneonavicular ligament, which is essential for stability, and which helped determine the reduction technique. Locking plate fixation of these fractures has never been reported. Comminuted fractures of the tarsal navicular were successfully treated with specific imaging techniques in particular 3D reconstructions of CT scan images to choose the surgical approach and the reduction technique. Locking plate fixation of the navicular seems to be a satisfactory solution for the treatment of these particularly difficult fractures. Level IV. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

[Effectiveness of mini locking plate combined with Kirschner wire in treatment of comminuted Jones fracture].

PubMed

Yan, Rongliang; Qu, Jiafu; Cao, Lihai; Liu, Hongda; Chen, Jianghua; Gao, Yan; Peng, Yi

2018-05-01

To summarize the effectiveness of mini locking plate combined with Kirschner wire in treatment of comminuted Jones fracture. Between January 2011 and October 2016, 25 cases with comminuted Jones fracture were treated with mini locking plate combined with Kirschner wire. There were 9 males and 16 females with an average age of 31.4 years (range, 16-66 years). The fractures located on the left side in 11 cases and on the right side in 14 cases. The causes of injury included spraining in 21 cases, falling down in 3 cases, and bruise in 1 case. The bone fragment of all cases was more than 3 pieces. The fracture line was mostly Y-shape or T-shape. Twelve of them were combined with other fractures. The time from injury to operation was 1-9 days (mean, 5 days). The mini locking plate and Kirschner wire were removed at 9-12 months postoperatively. At 12 months postoperatively, the pain was evaluated by the visual analogue scale (VAS) score, and the function by the American Orthopaedic Foot & Ankle Society (AOFAS) score. All incisions healed by first intention. All cases were followed up 12-36 months with an average of 21.7 months. Fracture union was observed in all patients without complications such as nonunion, delayed union, and malunion. The fracture union time was 8-12 weeks (mean, 9.4 weeks). At 12 months postoperatively, the VAS score was 1.15±0.87; the AOFAS score was 89.45±6.24, and the results were excellent in 14 cases, good in 9 cases, fair in 1 case, and poor in 1 case, with an excellent and good rate of 92%. The procedure of mini locking plate combined with Kirschner wire for comminuted Jones fracture has such advantages as convenient operation, more rigid fixation, high rate of fracture healing, and good functional recovery in foot.

Quick connect fastener

NASA Technical Reports Server (NTRS)

Weddendorf, Bruce (Inventor)

1994-01-01

A quick connect fastener and method of use is presented wherein the quick connect fastener is suitable for replacing available bolts and screws, the quick connect fastener being capable of installation by simply pushing a threaded portion of the connector into a member receptacle hole, the inventive apparatus being comprised of an externally threaded fastener having a threaded portion slidably mounted upon a stud or bolt shaft, wherein the externally threaded fastener portion is expandable by a preloaded spring member. The fastener, upon contact with the member receptacle hole, has the capacity of presenting cylindrical threads of a reduced diameter for insertion purposes and once inserted into the receiving threads of the receptacle member hole, are expandable for engagement of the receptacle hole threads forming a quick connect of the fastener and the member to be fastened, the quick connect fastener can be further secured by rotation after insertion, even to the point of locking engagement, the quick connect fastener being disengagable only by reverse rotation of the mated thread engagement.

The Search for the Ideal Fixation of Palatal Fractures: Innovative Experience with a Mini-Locking Plate

PubMed Central

Pollock, Richard A.

2008-01-01

Fractures of the palate have defied conventional management, such that malrotation and disinclination of the palatal shelves occur in a significant number of patients after repair. The fractured palatal shelves of eight patients were first prealigned. To do so, one or more 205-mm ratchet clamps and two intermaxillary fixation (IMF) posts were used. Rigid fixation was then achieved by applying a 2.0-mm mini-locking titanium plate (across the palatal vault) and by applying an adaptation miniplate across the fracture line as it exited the anterior surface of the maxilla. Screws were passed directly through the mucoperiosteum, to engage the palatal shelves and to lock the locking plate into position. Lacerations in the mucoperiosteum were neither used to aid fixation nor used as portals for dissection; incisions and mucoperiosteal flaps in the palatal vault were avoided. Adjuncts, such as intraoral splints, have not been used in cases to date, and early mobilization was allowed. Reconstitution of the craniomaxillofacial buttresses was added in patients with more extensive maxillary injury. The palatal appliance and screws remained rigidly in position in the roof of the mouth, much like an external fixator, until their removal 8 to 12 weeks after the repair. No patient suffered erosion of the mucoperiosteum or other major morbidity, other than a transient fistula of the soft palate. The palatoalveolar segments remained in proper realignment and inclination, and pretraumatic occlusal patterns and the width and depth of the lower face appear to have been restored with one exception. The latter suffered a subtle posterolateral open bite that was corrected orthodontically. Prealignment of fractured palatal shelves with one or more large ratchet clamps and two IMF posts provides several points of forced reduction of the palatal shelves, along the dental arch. In addition, stabilization with mini-locking plate(s) in the palatal vault and an adaptation plate across the fracture line, as it exits the maxilla, appear to have merit, based on this preliminary report (n = 8). Outcomes seen on computed tomography and clinical examination during this 3-year experience have been favorable. PMID:22110785

Two fault tolerant toggle-hook release

NASA Technical Reports Server (NTRS)

Graves, Thomas Joseph (Inventor); Brown, Christopher William (Inventor)

1991-01-01

A coupling device is disclosed which is mechanically two fault tolerant for release. The device comprises a fastener plate and fastener body, each of which is attachable to a different one of a pair of structures to be joined. The fastener plate and body are coupled by an elongate toggle mounted at one end in a socket on the fastener plate for universal pivotal movement thereon. The other end of the toggle is received in an opening in the fastener body and adapted for limited pivotal movement therein. The toggle is adapted to be restrained by three latch hooks arranged in symmetrical equiangular spacing about the axis of the toggle, each hook being mounted on the fastener body for pivotal movement between an unlatching non-contact position with respect to the toggle and a latching position in engagement with a latching surface of the toggle. The device includes releasable lock means for locking each latch hook in its latching position whereby the toggle couples the fastener plate to the fastener body and means for releasing the lock means to unlock each said latch hook from the latch position whereby the unlocking of at least one of the latch hooks from its latching position results in the decoupling of the fastener plate from the fastener body.

Proximal tibial fractures: early experience using polyaxial locking-plate technology.

PubMed

Nikolaou, Vassilios S; Tan, Hiang Boon; Haidukewych, George; Kanakaris, Nikolaos; Giannoudis, Peter V

2011-08-01

Between 2004 and 2009, 60 patients with proximal tibial fractures were included in this prospective study. All fractures were treated with the polyaxial locked-plate fixation system (DePuy, Warsaw, IN, USA). Clinical and radiographic data, including fracture pattern, changes in alignment, local and systemic complications, hardware failure and fracture union were analysed. The mean follow-up was 14 (12-36) months. According to the Orthopaedic Trauma Association (OTA) classification, there were five 41-A, 28 41-B and 27 41-C fractures. Fractures were treated percutaneously in 30% of cases. Double-plating was used in 11 cases. All but three fractures progressed to union at a mean of 3.2 (2.5-5) months. There was no evidence of varus collapse as a result of polyaxial screw failure. No plate fractured, and no screw cut out was noted. There was one case of lateral joint collapse (>10°) in a patient with open bicondylar plateau fracture. The mean Knee Society Score at the time of final follow-up was 91 points, and the mean functional score was 89 points. The polyaxial locking-plate system provided stable fixation of extra-articular and intra-articular proximal tibial fractures and good functional outcomes with a low complication rate.

Scapulothoracic dissociation with acromioclavicular separation: a case report of a novel fixation method.

PubMed

Merk, Bradley R; Minihane, Keith P; Shah, Nirav A

2008-09-01

We present a case of 39-year-old female with a scapulothoracic dissociation and acromioclavicular (AC) separation and who had fixation of the AC joint with a locking plate, coracoclavicular screw, and transarticular AC screw. The coracoclavicular and AC relationships were maintained during postoperative rehabilitation and after hardware removal. Use of a locking plate can lead to good functional outcome without the complications associated with the use of pin and wire constructs or without violating the subacromial space.

Hole size, location optimization in a plate and cylindrical shell for minimum stress points interfacing ANSYS and MATLAB

NASA Astrophysics Data System (ADS)

Thangavel, Soundararaj

Discontinuities in Structures are inevitable. One such discontinuity in a plate and cylindrical shell is presence of a hole / holes. In Plates they are used for mounting bolts where as in Cylinder / Pressure Vessel, they provide provision for mounting Nozzles / Instruments. Location of these holes plays a primary role in minimizing the stress acting with out any external reinforcement. In this Thesis work, Location Parameters are optimized for the presence of one or more holes in a plate and cylindrical shell interfacing ANSYS and MATLAB with boundary constraints based on the geometry. Contour plots are generated for understanding stress distribution and analytical solutions are also discussed for some of the classical problems.

Mechanical stress in plates for bridging reconstruction mandibular defects and purposes of double plate reinforcement.

PubMed

Hoefert, Sebastian; Taier, Roberto

2018-05-01

To evaluate the biomechanical performance of a commercially available bridging plate (2.4) as well as screws and bone simulating the reconstruction of hemimandibular defects and to indicate alternatives of reinforcement to prevent plate fractures either by strength or fatigue. Two common hemimandibular defects are investigated using computed finite element analysis (FEA) approach. Simplified and refined computational models are developed for the geometry of the screw. Conditions of non-locking and locking plate-screw interfaces are considered. Static loads of 120 N are applied. Von Mises stresses and fatigue are calculated. As reinforcement, a second complete or partial plate is placed onto the original plate. Results demonstrate that reconstruction plates are often subjected to excessive stress that may lead to fracture either by strength or by fatigue. An attached complete or partial second plate is able to reduce stress in the plate, in screws and bone so that stress remains below the allowable limit of the materials. A simplified technique of attaching a whole or sectioned second plate onto the original plate can reduce the stress calculated and may reduce the frequency of plate fractures for the patient's comfort, security and financial savings. Copyright © 2018 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Joining strength performances of metal skin and CFRP core laminate structures realized by compression-curing process, with supporting experiments

NASA Astrophysics Data System (ADS)

Quagliato, Luca; Jang, Changsoon; Kim, Naksoo

2018-05-01

In the recent years, the trend of lightening vehicles and structures of every kind has become an ever-growing issue, both for university and industrial researchers. As demonstrated in previous authors' works, laminate structures made of metal skin (MS) and carbon fiber reinforced polymer (CFRP) core show high specific bending strength properties while granting considerable weight reduction but, so far, no investigations have been carried out on the hole sensitivity and joinability of these hybrid structures. In the present research work, the hole size sensitivity of MS-CFRP structure has been studied by means of uniaxial tensile test on 160mm (length), 25mm (width), 2.0mm (average thickness) specimens bored with Ø06mm, Ø9mm, and Ø12mm holes. The specimen thickness is composed of two metal skins of 0.4mm thickness each, 8×0.2mm CFRP stacked layers and two thin epoxy-based adhesive layers. The specimens have been manufactured by means of a compression-curing process in which the different materials are stacked and, thanks to die pressure and temperature, the curing process is completed in a relatively short time (15˜20 minutes). The specimens have been tested by means of simple tension test showing that, for the MS-CFRP material, the smaller the hole the smaller the maximum bearable load. Moreover, specimens with the same hole sizes have been bolted together with class 12 resistance bolts and tested by means of tensile test, allowing to determine the maximum transferable load between the two MS-CFRP plates. Aiming to prove the improvement in the specific transferable load, experiments on only-steel specimens with the same weight of the MS-CFRP ones and joined with the same method and bolts have been carried out, allowing to conclude that, for the 9mm hole bolted plates, the proposed material has a specific maximum transferable 27% higher than that of the steel composing their skins.

Acoustic emissions (AE) monitoring of large-scale composite bridge components

NASA Astrophysics Data System (ADS)

Velazquez, E.; Klein, D. J.; Robinson, M. J.; Kosmatka, J. B.

2008-03-01

Acoustic Emissions (AE) has been successfully used with composite structures to both locate and give a measure of damage accumulation. The current experimental study uses AE to monitor large-scale composite modular bridge components. The components consist of a carbon/epoxy beam structure as well as a composite to metallic bonded/bolted joint. The bonded joints consist of double lap aluminum splice plates bonded and bolted to carbon/epoxy laminates representing the tension rail of a beam. The AE system is used to monitor the bridge component during failure loading to assess the failure progression and using time of arrival to give insight into the origins of the failures. Also, a feature in the AE data called Cumulative Acoustic Emission counts (CAE) is used to give an estimate of the severity and rate of damage accumulation. For the bolted/bonded joints, the AE data is used to interpret the source and location of damage that induced failure in the joint. These results are used to investigate the use of bolts in conjunction with the bonded joint. A description of each of the components (beam and joint) is given with AE results. A summary of lessons learned for AE testing of large composite structures as well as insight into failure progression and location is presented.

Clinical application of locked plating system in children. An orthopaedic view

PubMed Central

Zafra-Jimenez, Jose Alberto; Rodriguez Martin, Juan

2010-01-01

In recent years, the locked plating system has gained favour in the treatment of certain fractures in adults; however, there is not much information regarding its use in children. We think there could be some advantages and applications such as: an alternative to external fixation, the bridge plating technique, unicortical screws, removal of hardware, metadiaphyseal fractures, periarticular fractures, poor quality bone, and allograft fixation. However, there are some disadvantages to keep in mind and the final decision for using it should be based on the osteosynthesis method principle the surgeon would like to apply. In this review article we discuss the up-to-date possible clinical applications and issues of this system. PMID:20162415

Management of distal femoral periprosthetic fractures by distal femoral locking plate: A retrospective study.

PubMed Central

Thukral, Rajiv; Marya, SKS; Singh, Chandeep

2015-01-01

Background: Management of periprosthetic supracondylar femoral fractures is difficult. Osteoporosis, comminution and bone loss, compromise stability with delayed mobility and poor functional outcomes. Open reduction and internal fixation (ORIF) with anatomic distal femoral (DF) locking plate permits early mobilization. However, this usually necessitates bone grafting (BG). Biological fixation using minimally invasive techniques minimizes periosteal stripping and morbidity. Materials and Methods: 31 patients with comminuted periprosthetic DF fractures were reviewed retrospectively from October 2006 to September 2012. All patients underwent fixation using a DF locking compression plate (Synthes). 17 patients underwent ORIF with primary BG, whereas 14 were treated by closed reduction (CR) and internal fixation using biological minimally invasive techniques. Clinical and radiological followup were recorded for an average 36 months. Results: Mean time to union for the entire group was 5.6 months (range 3-9 months). Patients of ORIF group took longer (Mean 6.4 months, range 4.5-9 months) than the CR group (mean 4.6 months, range 3-7 months). Three patients of ORIF and one in CR group had poor results. Mean knee society scores were higher for CR group at 6 months, but nearly identical at 12 months, with similar eventual range of motion. Discussion: Locked plating of comminuted periprosthetic DF fractures permits stable rigid fixation and early mobilization. Fixation using minimally invasive biological techniques minimizes morbidity and may obviate the need for primary BG. PMID:26015610

UK DRAFFT - A randomised controlled trial of percutaneous fixation with kirschner wires versus volar locking-plate fixation in the treatment of adult patients with a dorsally displaced fracture of the distal radius

PubMed Central

2011-01-01

Background Fractures of the distal radius are extremely common injuries in adults. However, the optimal management remains controversial. In general, fractures of the distal radius are treated non-operatively if the bone fragments can be held in anatomical alignment by a plaster cast or orthotic. However, if this is not possible, then operative fixation is required. There are several operative options but the two most common in the UK, are Kirschner-wire fixation (K-wires) and volar plate fixation using fixed-angle screws (locking-plates). The primary aim of this trial is to determine if there is a difference in the Patient-Reported Wrist Evaluation one year following K-wire fixation versus locking-plate fixation for adult patients with a dorsally-displaced fracture of the distal radius. Methods/design All adult patients with an acute, dorsally-displaced fracture of the distal radius, requiring operative fixation are potentially eligible to take part in this study. A total of 390 consenting patients will be randomly allocated to either K-wire fixation or locking-plate fixation. The surgery will be performed in trauma units across the UK using the preferred technique of the treating surgeon. Data regarding wrist function, quality of life, complications and costs will be collected at six weeks and three, six and twelve months following the injury. The primary outcome measure will be wrist function with a parallel economic analysis. Discussion This pragmatic, multi-centre trial is due to deliver results in December 2013. Trial registration Current Controlled Trials ISRCTN31379280 UKCRN portfolio ID 8956 PMID:21914196

High-Precision Coupling Mechanism Operable By Robots

NASA Technical Reports Server (NTRS)

Voellmer, George

1992-01-01

Coupling mechanism has features making it easily operable by hand and suitable for operation by robots: tolerates some initial misalignment, imposes precise final alignment, and protects itself against overtightening. Typically used to mount equipment module on structure. Mechanism includes kinematic mounts, which tolerate small initial misalignment and enforce precise final alignment as two assemblies brought together. Clamping force applied to kinematic mounts via two flexible plates. Bolt and nut tightened on flexible plates to impose spring clamping load. Repeatability of interface tested and found to be better than forty-millionths of inch.

Stress analysis of the space telescope focal plane structure joint

NASA Technical Reports Server (NTRS)

Foster, W. A., Jr.; Shoemaker, W. L.

1985-01-01

Two major efforts were begun concerning the Space Telescope focal plane structure joint. The 3-D solid finite element modeling of the bipod flexure plate was carried out. Conceptual models were developed for the load transfer through the three major bolts to the flexure plate. The flexure plate drawings were reconstructed using DADAM for the purpose of developing a file from which the coordinates of any point on the flexure plate could be determined and also to locate the attachment points of the various components which connect with the flexure plate. For modeling convenience the CADAM drawing of the flexure plate has been divided into several regions which will be subdivided into finite elements using MSGMESH, which is a finite element mesh generator available with MSC/NASTRAN. In addition to the CADAM work on the flexure plate, an effort was also begun to develop computer aided drawings of the peripheral beam which will be used to assist in modeling the connection between it and the flexure plate.

Biomechanical principles and mechanobiologic aspects of flexible and locked plating.

PubMed

Claes, Lutz

2011-02-01

The goal of minimally invasive surgery in extramedullary internal fixation has led to the development of flexible plates, bridging plates, and locked internal fixators. The change from conventional compression plates to these new implants, however, resulted in different biomechanics of fixation and different mechanobiologic processes for fracture healing. The aim of a flexible fixation is the stimulation of fracture healing by callus formation. Fracture healing follows mechanobiologic rules based mainly on interfragmentary strain, which is dependent on the stability of the fixation construct and the type of fracture. Knowledge of the mechanobiologic processes and the factors influencing the stability of fracture fixation are necessary for the surgeon to choose the correct technique for fracture fixation. Problems in the selection of the correct technique and limitations with the available implants as well as possible future developments are discussed.

A biomechanical comparison of four different fixation methods for midshaft clavicle fractures.

PubMed

Chen, Yang; Yang, Yang; Ma, Xinlong; Xu, Weiguo; Ma, Jianxiong; Zhu, Shaowen; Ma, Baoyi; Xing, Dan

2016-01-01

Clavicle fractures may occur in all age groups, and 70%-80% of clavicle fractures occur in the midshaft. Many methods for treating midshaft clavicular fractures have been reported and remain controversial. To provide some guidance for clinical treatment, 30 artificial polymethyl methacrylate models of the clavicle were sewn obliquely at the midshaft to simulate the most common type of clavicular fractures, and the fracture models were divided into five groups randomly and were fixed as follows: the reconstruction plates were placed at the superior position of the fracture model (R-S group), the reconstruction plates were placed at the anteroinferior position of the fracture model (R-AI group), the locking plates were placed at the superior position (L-S group), the locking plates were placed at the anteroinferior position (L-AI group); and the control models were unfixed (control group). The strain gauges were attached to the bone surface near the fracture fragments, and then, the biomechanical properties of the specimens were measured using the compression test, torsion test and three-point bending test. The results showed that plate fixation can provide a stable construct to help with fracture healing and is the preferred method in the treatment of clavicle fractures. The locking plate provides the best biomechanical stability when placed at the anteroinferior position, and this surgical method can reduce the operation time and postoperative complications; thus, it would be a better choice in clinical practice. © IMechE 2015.

Distal radius osteotomy with volar locking plates based on computer simulation.

PubMed

Miyake, Junichi; Murase, Tsuyoshi; Moritomo, Hisao; Sugamoto, Kazuomi; Yoshikawa, Hideki

2011-06-01

Corrective osteotomy using dorsal plates and structural bone graft usually has been used for treating symptomatic distal radius malunions. However, the procedure is technically demanding and requires an extensive dorsal approach. Residual deformity is a relatively frequent complication of this technique. We evaluated the clinical applicability of a three-dimensional osteotomy using computer-aided design and manufacturing techniques with volar locking plates for distal radius malunions. Ten patients with metaphyseal radius malunions were treated. Corrective osteotomy was simulated with the help of three-dimensional bone surface models created using CT data. We simulated the most appropriate screw holes in the deformed radius using computer-aided design data of a locking plate. During surgery, using a custom-made surgical template, we predrilled the screw holes as simulated. After osteotomy, plate fixation using predrilled screw holes enabled automatic reduction of the distal radial fragment. Autogenous iliac cancellous bone was grafted after plate fixation. The median volar tilt, radial inclination, and ulnar variance improved from -20°, 13°, and 6 mm, respectively, before surgery to 12°, 24°, and 1 mm, respectively, after surgery. The median wrist flexion improved from 33° before surgery to 60° after surgery. The median wrist extension was 70° before surgery and 65° after surgery. All patients experienced wrist pain before surgery, which disappeared or decreased after surgery. Surgeons can operate precisely and easily using this advanced technique. It is a new treatment option for malunion of distal radius fractures.

Outcomes and complications of fractures of distal radius (AO type B and C): volar plating versus nonoperative treatment.

PubMed

Sharma, Himanshu; Khare, Ghanshyam Narayan; Singh, Saurabh; Ramaswamy, Arun Govindraj; Kumaraswamy, Vinay; Singh, Ashutosh Kumar

2014-07-01

Management of AO type B and C fractures of the distal radius is controversial. This study compares outcomes and complications of AO type B and C fractures of the distal radius treated with volar locked plating and nonoperative methods. Sixty-four patients with fractures of the distal radius (AO type B and C) were included in this study, according to inclusion criteria, and were allocated to the volar plating group or nonoperative group by alternate randomization: 32 patients with odd numbers went into the nonoperative group and the other 32 with even numbers went into the volar plating group. Patients in the nonoperative group were managed with closed reduction of the fracture and plaster cast application under an image intensifier. Those in the volar plating group were managed by open reduction and fixation with a volar locked plate. Preoperative and postoperative serial clinico-radiological follow-up was done. The range of movement, grip strength, functional outcome scores and radiological parameters were compared. Student's t-test was used for statistical analysis with significance at p < 0.05. Range of movement and functional scores were significantly (p < 0.001) better in the volar plating group, but the difference in ulnar variance and radial and ulnar deviation was insignificant as compared to the nonoperative group. At 24 months follow-up, the nonoperative group had significantly more cases with malunion, articular incongruity and osteoarthritis. In cases of AO type B or C fractures of the distal radius, volar locked plating provides anatomical stable fixation and early mobilization with better clinico-radiological outcome as compared to conservative treatment.

Fatigue Failure in Extra-Articular Proximal Tibia Fractures: Locking Intramedullary Nail Versus Double Locking Plates-A Biomechanical Study.

PubMed

Kandemir, Utku; Herfat, Safa; Herzog, Mary; Viscogliosi, Paul; Pekmezci, Murat

2017-02-01

The goal of this study is to compare the fatigue strength of a locking intramedullary nail (LN) construct with a double locking plate (DLP) construct in comminuted proximal extra-articular tibia fractures. Eight pairs of fresh frozen cadaveric tibias with low bone mineral density [age: 80 ± 7 (SD) years, T-score: -2.3 ± 1.2] were used. One tibia from each pair was fixed with LN, whereas the contralateral side was fixed with DLP for complex extra-articular multifragmentary metaphyseal fractures (simulating OTA 41-A3.3). Specimens were cyclically loaded under compression simulating single-leg stance by staircase method out to 260,000 cycles. Every 2500 cycles, localized gap displacements were measured with a 3D motion tracking system, and x-ray images of the proximal tibia were acquired. To allow for mechanical settling, initial metrics were calculated at 2500 cycles. The 2 groups were compared regarding initial construct stiffness, initial medial and lateral gap displacements, stiffness at 30,000 cycles, medial and lateral gap displacements at 30,000 cycles, failure load, number of cycles to failure, and failure mode. Failure metrics were reported for initial and catastrophic failures. DLP constructs exhibited higher initial stiffness and stiffness at 30,000 cycles compared with LN constructs (P < 0.03). There were no significant differences between groups for loads at failure or cycles to failure. For the fixation of extra-articular proximal tibia fractures, a LN provides a similar fatigue performance to double locked plates. The locked nail could be safely used for fixation of proximal tibia fractures with the advantage of limited extramedullary soft tissue damage.

Multi-operational tuneable Q-switched mode-locking Er fibre laser

NASA Astrophysics Data System (ADS)

Qamar, F. Z.

2018-01-01

A wavelength-spacing tuneable, Q-switched mode-locking (QML) erbium-doped fibre laser based on non-linear polarization rotation controlled by four waveplates and a cube polarizer is proposed. A mode-locked pulse train using two quarter-wave plates and a half-wave plate (HWP) is obtained first, and then an extra HWP is inserted into the cavity to produce different operation regimes. The evolutions of temporal and spectral dynamics with different orientation angles of the extra HWP are investigated. A fully modulated stable QML pulse train is observed experimentally. This is, to the author’s best knowledge, the first experimental work reporting QML operation without adding an extra saturable absorber inside the laser cavity. Multi-wavelength pulse laser operation, multi-pulse train continuous-wave mode-locking operation and pulse-splitting operations are also reported at certain HWP angles. The observed operational dynamics are interpreted as a mutual interaction of dispersion, non-linear effect and insertion loss. This work provides a new mechanism for fabricating cheap tuneable multi-wavelength lasers with QML pulses.

Riveting in metal airplane construction. Part IV : strength of riveted joints in duralumin (concluded)

NASA Technical Reports Server (NTRS)

Pleines, Wilhelm

1930-01-01

Tests were made to determine the crushing strength of a riveted joint, in order to define the difference in crushing stregth between a strictly bolted joint and a riveted joint. The object was to tabulate the crushing strength by failure on various plate thicknesses for a one-rivet double-shear riveted joint.

13. DETAIL OF CONNECTION BETWEEN TOP CHORD AND POST IN ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. DETAIL OF CONNECTION BETWEEN TOP CHORD AND POST IN WEST TRUSS, SHOWING CHANNELS AND REINFORCED CAST-IRON LACING, I-BEAMS FASTENED TOGETHER WITH RIVETTED PLATES, AND ASSEMBLY OF DIAGONAL EYE BEAM AND BOLT; VIEW FROM EAST SIDE. - Mitchell's Mill Bridge, Spanning Winter's Run on Carrs Mill Road, west of Bel Air, Bel Air, Harford County, MD

Tube support

DOEpatents

Mullinax, Jerry L.

1988-01-01

A tube support for supporting horizontal tubes from an inclined vertical support tube passing between the horizontal tubes. A support button is welded to the vertical support tube. Two clamping bars or plates, the lower edges of one bearing on the support button, are removably bolted to the inclined vertical tube. The clamping bars provide upper and lower surface support for the horizontal tubes.

A prospective, randomised trial comparing closed intramedullary nailing with percutaneous plating in the treatment of distal metaphyseal fractures of the tibia.

PubMed

Guo, J J; Tang, N; Yang, H L; Tang, T S

2010-07-01

We compared the outcome of closed intramedullary nailing with minimally invasive plate osteosynthesis using a percutaneous locked compression plate in patients with a distal metaphyseal fracture in a prospective study. A total of 85 patients were randomised to operative stabilisation either by a closed intramedullary nail (44) or by minimally invasive osteosynthesis with a compression plate (41). Pre-operative variables included the patients' age and the side and pattern of the fracture. Peri-operative variables were the operating time and the radiation time. Postoperative variables were wound problems, the time to union of the fracture, the functional American Orthopaedic Foot and Ankle surgery score and removal of hardware. We found no significant difference in the pre-operative variables or in the time to union in the two groups. However, the mean radiation time and operating time were significantly longer in the locked compression plate group (3.0 vs 2.12 minutes, p < 0.001, and 97.9 vs 81.2 minutes, p < 0.001, respectively).After one year, all the fractures had united. Patients who had intramedullary nailing had a higher mean pain score (40 = no pain, 0 = severe pain), [corrected] but better function, alignment and total American Orthopaedic Foot and Ankle surgery scores, although the differences were not statistically significant (p = 0.234, p = 0.157, p = 0.897, p = 0.177 respectively). Three (6.8%) patients in the intramedullary nailing group and six (14.6%) in the locked compression plate group showed delayed wound healing, and 37 (84.1%) in the former group and 38 (92.7%) in the latter group expressed a wish to have the implant removed. We conclude that both closed intramedullary nailing and a percutaneous locked compression plate can be used safely to treat Orthopaedic Trauma Association type-43A distal metaphyseal fractures of the tibia. However, closed intramedullary nailing has the advantage of a shorter operating and radiation time and easier removal of the implant. We therefore prefer closed intramedullary nailing for patients with these fractures.

[Advanced bone graft combined with locking compression plate for the treatment of middle and distal tibia nonunion].

PubMed

Zhao, Xue; Wang, Pan-feng; Zhang, Yun-tong; Zhang, Chun-cai; Xu, Shuo-gui; Zhang, Xin

2014-12-01

To explore methods of treating middle and distal tibia nonunion with the treatment of advanced bone graft combined with locking compression plate. From January 2011 to December 2012, 12 patients with middle and distal tibia nonunion were treated with advanced bone graft combined with locking compression plate. Among patients, there were 8 males and 4 females aged from 20 to 69 with an average of 47 years old. The time from first injuries to bone nonunion was from 9 months to 5 years, avergaed 19 months. Four cases were treated with external fixation, 6 cases were treated with plate fixation, 2 cases of 12 patients occurred broken of plate and nail. Eleven patients were non-infective bone nonunion and 1 patient was infective bone nonunion. Preoperative X-ray and CT showed all patients had sequestration and formation of ossified bone with different degrees. Operative time, blood loss, wound healing were observed, fracture healing time was evaluated by postoperative X-ray. Johner-Wruhs scoring standards was used to evaluate ankle joint function after operation at 10 months. Operative time ranged from 90 to 185 min with an average of (125.00±20.15) min; blood loss ranged from 225 to 750 ml with an average of (415.00±120.00) ml. All patients were followed up from 10 months to 2.5 years with an average of 1.5 years. Postoperative X-ray showed bone union was formed around fracture after operation at 4 months in all patients, 3 cases obtained bone healing within 6 months after operation, 9 cases obtained from 8 to 12 months. No infection, injury of nerve and vessles, and broken of plate and nail were ocurred. According to Johner-Wruhs scoring at 10 months after operation, 10 cases obtained excellent results, 1 good and 1 moderate. Advanced bone graft combined with locking compression plate, which can build fracture multi-point supporting based on full compression of bone nonunion to get effective fixation, is an effective method in treating middle and distal tibia nonunion.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Unneberg, L.

The main features of the 16 core grids (top guides) designed by ABB ATOM AB are briefly described and the evolution of the design is discussed. One important characteristic of the first nine grids is the existence of bolts securing guide bars to the core grid plates. These bolts are made of precipitation hardened or solution annealed stainless steel. During operation, bolts in all none grids have cracked. The failure analyses indicate that intergranular stress corrosion cracking (IGSCC), possibly accelerated by crevice conditions and/or irradiation, was the cause of failure. Fast neutron fluences approaching or exceeding the levels considered asmore » critical for irradiation assisted stress corrosion cracking (IASCC) will be reached in a few cases only. Temporary measures were taken immediately after the discovery of the cracking. For five of the nine reactors affected, it was decided to replace the complete grids. Two of these replacements have been successfully carried out to date. IASCC as a potential future problem is discussed and it is pointed out that, during their life times, the ABB ATOM core grids will be exposed to sufficiently high fast neutron fluences to cause some concern.« less

[Outcomes of minimally invasive plate osteosynthesis (MIPO) with volar locking plates in distal radius fractures: A review].

PubMed

Liverneaux, P; Ichihara, S; Facca, S; Hidalgo Diaz, J J

2016-12-01

Minimally invasive plate osteosynthesis (MIPO) has been used in recent years to treat fractures of the distal radius with volar locking plates. Its advantages are the preservation of the pronator quadratus and good esthetics. The MIPO technique was described originally with two incisions: one distal transverse or longitudinal incision and one proximal longitudinal incision. The trend is now to use a single longitudinal incision less than 20mm long. Functional and radiological outcomes are comparable to those of conventional techniques. The MIPO technique is indicated for extra-articular and intra-articular fractures. Arthroscopy may be used concurrently in the latter case. When the distal radius fracture is associated with a proximal shaft fracture, a double incision is needed to introduce a longer plate. The relative contraindications of the MIPO technique are comminuted intra-articular fractures in osteoporotic elderly patients. If reduction is problematic, a larger incision can easily be made. Copyright © 2016 SFCM. Published by Elsevier Masson SAS. All rights reserved.

Operative treatment of 2-part surgical neck fractures of the proximal humerus (AO 11-A3) in the elderly: Cement augmented locking plate Philos™ vs. proximal humerus nail MultiLoc®.

PubMed

Helfen, Tobias; Siebenbürger, Georg; Mayer, Marcel; Böcker, Wolfgang; Ockert, Ben; Haasters, Florian

2016-10-28

Proximal humeral fractures are with an incidence of 4-5 % the third most common fractures in the elderly. In 20 % of humeral fractures there is an indication for surgical treatment according to the modified Neer-Criteria. A secondary varus dislocation of the head fragment and cutting-out are the most common complications of angle stable locking plates in AO11-A3 fractures of the elderly. One possibility to increase the stability of the screw-bone-interface is the cement augmentation of the screw tips. A second is the use of a multiplanar angle stablentramedullary nail that might provide better biomechanical properties after fixation of 2-part-fractures. A comparison of these two treatment options augmented locking plate versus multiplanar angle stable locking nail in 2-part surgical neck fractures of the proximal humerus has not been carried out up to now. Forty patients (female/male, ≥60 years or female postmenopausal) with a 2-part-fracture of the proximal humerus (AO type 11-A3) will be randomized to either to augmented plate fixation group (PhilosAugment) or to multiplanar intramedullary nail group (MultiLoc). Outcome parameters are Disabilities of the Shoulder, Arm and Hand-Score (DASH) Constant Score (CS), American Shoulder and Elbow Score (ASES), Oxford Shoulder Score (OSS), Range of motion (ROM) and Short Form 36 (SF-36) after 3 weeks, 6 weeks, 3 months, 6 months, 12 and 24 months. Because of the lack of clinical studies that compare cement augmented locking plates with multiplanar humeral nail systems after 2-part surgical neck fractures of the proximal humerus, the decision of surgical method currently depends only on surgeons preference. Because only a randomized clinical trial (RCT) can sufficiently answer the question if one treatment option provides advantages compared to the other method we are planning to perform a RCT. Clinical Trial ( NCT02609906 ), November 18, 2015, registered retrospectively.

Multidirectional volar fixed-angle plating using cancellous locking screws for distal radius fractures--evaluation of three screw configurations in an extra-articular fracture model.

PubMed

Weninger, Patrick; Dall'Ara, Enrico; Drobetz, Herwig; Nemec, Wolfgang; Figl, Markus; Redl, Heinz; Hertz, Harald; Zysset, Philippe

2011-01-01

Volar fixed-angle plating is a popular treatment for unstable distal radius fractures. Despite the availability of plating systems for treating distal radius fractures, little is known about the mechanical properties of multidirectional fixed-angle plates. The aim of this study was to compare the primary fixation stability of three possible screw configurations in a distal extra-articular fracture model using a multidirectional fixed-angle plate with metaphyseal cancellous screws distally. Eighteen Sawbones radii (Sawbones, Sweden, model# 1027) were used to simulate an extra-articular distal radius fracture according to AO/OTA 23 A3. Plates were fixed to the shaft with one non-locking screw in the oval hole and two locking screws as recommended by the manufacturer. Three groups (n = 6) were defined by screw configuration in the distal metaphyseal fragment: Group 1: distal row of screws only; Group 2: 2 rows of screws, parallel insertion; Group 3: 2 rows of screws, proximal screws inserted with 30° of inclination. Specimens underwent mechanical testing under axial compression within the elastic range and load controlled between 20 N and 200 N at a rate of 40 N/s. Axial stiffness and type of construct failure were recorded. There was no difference regarding axial stiffness between the three groups. In every specimen, failure of the Sawbone-implant-construct occurred as plastic bending of the volar titanium plate when the dorsal wedge was closed. Considering the limitations of the study, the recommendation to use two rows of screws or to place screws in the proximal metaphyseal row with inclination cannot be supported by our mechanical data.

[Treatment of complex scapular body fractures by locking reconstructive plates].

PubMed

Zhang, Jun-wei; Hou, Jin-yong; Yang, Mao-qing

2011-03-01

To investigate the method and effect of treatment of complex scapular body fractures by locking reconstructive plate through modified posterior approach. From August 2005 to November 2009, 27 patients with complex scapula body fractures were treated by locking reconstruction bone plate fixation,including 19 males and 8 females with an average age of 36 years old ranging from 16 to 64 years. The time after injury was 0.5 hours to 11 days (averaged 3 days). Of all the patients, 9 cases were associated with ipsilateral clavicle fracture, 2 cases were associated with acromioclavicular joint dislocation,16 cases were associated with multiple rib fractures, 1 case were associated with humeral shaft fractures, 5 cases were associated with pleural effusion, atelectasis, lung contusion etc. After operating,shoulder functional recovery were followed up. Twenty-four patients were followed up from 2 to 35 months with an average of 19 months. According to Hardegger shoulder function,the results were excellent in 15 cases, good in 7 cases, general in 2 cases. This method had the advantage of less trauma and clear exposure, firm and reliable fixation, and early activities.

External fixation using locking plate in distal tibial fracture: a finite element analysis.

PubMed

Zhang, Jingwei; Ebraheim, Nabil; Li, Ming; He, Xianfeng; Schwind, Joshua; Liu, Jiayong; Zhu, Limei

2015-08-01

External fixation of tibial fractures using a locking plate has been reported with favorable results in some selected patients. However, the stability of external plate fixation in this fracture pattern has not been previously demonstrated. We investigated the stability of external plate fixation with different plate-bone distances. In this study, the computational processing model of external fixation of a distal tibial metaphyseal fracture utilizing the contralateral femoral less invasive stabilization system plate was analyzed. The plate was placed on the anteromedial aspect of tibia with different plate-bone distances: 1, 10, 20, and 30 mm. Under axial load, the stiffness of construct in all groups was higher than intact tibia. Under axial load with an internal rotational force, the stiffness of construct with 1 and 10 mm plate-bone distances was similar to that of an intact tibia and the stiffness of the construct with 20 and 30 mm distances was lower than that of an intact tibia. Under axial load with an external rotational force, the stiffness of the construct in all groups was lower than that of an intact tibia. The maximum plate stresses were concentrated at the two most distal screws and were highest in the construct with the 10 mm plate-bone distance, and least in the construct with a 1 mm plate-bone distance. To guarantee a stable external plate fixation in distal tibial fracture, the plate-bone distance should be less than 30 mm.

Biomechanical evaluation of a new MatrixMandible plating system on cadaver mandibles.

PubMed

Gateno, Jaime; Cookston, Christopher; Hsu, Sam Sheng-Pin; Stal, Drew N; Durrani, Salim K; Gold, Jonathan; Ismaily, Sabir; Alexander, Jerry W; Noble, Philip C; Xia, James J

2013-11-01

Current mandibular plating systems contain a wide range of plates and screws needed for the treatment of mandibular reconstruction and mandibular fractures. The authors' hypothesis was that a single diameter screw could be used in all applications in a plating system. Therefore, the purpose of this study was to test if the 2.0-mm locking screws could replace the 2.4-mm screws to stabilize a 2.5-mm-thick reconstruction plate in the treatment of mandibular discontinuity. Thirty-six fresh human cadaveric mandibles were used: 18 were plated using 2.0-mm locking screws (experimental) and the other 18 were plated using 2.4-mm locking screws (control). Each group was further divided into 3 subgroups based on the site of loading application: the ipsilateral (right) second premolar region, the central incisal region, and the contralateral (left) first molar region. The same ipsilateral (right) mandibular angular discontinuity was created by the same surgeon. The mandible was mounted on a material testing machine. The micromotions between the 2 segments, permanent and elastic displacements, were recorded after incremental ramping loads. The magnitude of screw back-out and the separation between plate and bone were recorded using a laser scanner (resolution, 0.12 mm) before and after the loading applications. The data were processed. Descriptive analyses and a general linear model for repeated measures analysis of variance were performed. There was no statistically significant difference in permanent displacement (mean, 1.16 and 0.82 mm, respectively) between the 2.0-mm and 2.4-mm screw groups. There also was no statistically significant difference in elastic displacement between the 2 groups (mean, 1.48 and 1.21 mm, respectively). Finally, there were no statistically significant differences in screw back-out or separation between plate and bone between the 2 groups. All means for screw back-out and separation between screw and bone for each group were judged within the error of the laser scanning system (<0.12 mm). One may anticipate that the mechanical functions of the 2.0-mm locking screws are not different from those of the 2.4-mm screws when a 2.5-mm-thick reconstruction plate is used to reconstruct mandibular angular discontinuity. However, further biomechanical studies (ie, fatigue of screws) are warranted before a randomized clinical trial can be conducted to definitively prove that the 2.4-mm screws can be replaced by 2.0-mm screws. Copyright © 2013 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Intramedullary Stabilization of Periprosthetic Fractures of the Femur Taking Special Account of Bone Defects.

PubMed

Eingartner, Christoph; Volkmann, Rüdiger; Ochs, Uwe; Egetemeyr, Daniel; Weise, Kuno

2007-10-01

Healing of the periprosthetic fracture and area of defective bone by the bone healing mechanisms of intramedullary stabilization. Reconstruction of the correct length, axial alignment, and rotation of the fractured femoral shaft by anchoring a revision stem in the intact femoral diaphysis. Periprosthetic femoral shaft fracture in the region of the prosthetic stem combined with preexistent loosening and/or defect in the periprosthetic bone bed (Vancouver classification type B2 and B3). General contraindications, local infection. Lateral transmuscular approach to the femoral shaft. Longitudinal osteotomy of the proximal femur taking the geometry of the fracture into account. Opening of an anterior "bone shell". Removal of the loose prosthetic stem and cement. Debridement. Preparation of the femoral diaphysis and insertion of a distally anchored revision stem. Distal locking. Repositioning of the "bone shell", reduction of the fracture, and retention with cerclage wires. Bed rest for approximately 1 week, mobilization with 20 kg partial weight bearing for 12 weeks, gradual increase in weight bearing with radiologic checks on progress, removal of the distal locking bolts after 12-24 months at the earliest. 21 patients (13 women, eight men) aged between 43 and 86 years (mean age: 71.2 years) with periprosthetic fracture of the femur, additional loosening of the stem in eight cases (Vancouver B2) and additional bone loss in 13 cases (Vancouver B3). Postoperative complications: two fractures following another fall (repeat operations: one replacement, one plate), four revisions due to subsidence of the stem (three replacements involving change to a standard stem with healed proximal femur, one replacement with another interlocked revision stem). Bone healing occurred for all fractures after a mean 5.6 months (3-11 months). Follow- up examination after a mean 4.5 years: all patients were able to walk, average Harris Score 70.5 points (29- 95 points).

Intramedullary stabilization of periprosthetic fractures of the femur taking special account of bone defects.

PubMed

Eingartner, Christoph; Volkmann, Rüdiger; Ochs, Uwe; Egetemeyr, Daniel; Weise, Kuno

2006-10-01

Healing of the periprosthetic fracture and area of defective bone by the bone healing mechanisms of intramedullary stabilization. Reconstruction of the correct length, axial alignment, and rotation of the fractured femoral shaft by anchoring a revision stem in the intact femoral diaphysis. Periprosthetic femoral shaft fracture in the region of the prosthetic stem combined with preexistent loosening and/or defect in the periprosthetic bone bed (Vancouver classification type B2 and B3). General contraindications, local infection. Lateral transmuscular approach to the femoral shaft. Longitudinal osteotomy of the proximal femur taking the geometry of the fracture into account. Opening of an anterior "bone shell". Removal of the loose prosthetic stem and cement. Debridement. Preparation of the femoral diaphysis and insertion of a distally anchored revision stem. Distal locking. Repositioning of the "bone shell", reduction of the fracture, and retention with cerclage wires. Bed rest for approximately 1 week, mobilization with 20 kg partial weight bearing for 12 weeks, gradual increase in weight bearing with radiologic checks on progress, removal of the distal locking bolts after 12-24 months at the earliest. 21 patients (13 women, eight men) aged between 43 and 86 years (mean age: 71.2 years) with periprosthetic fracture of the femur, additional loosening of the stem in eight cases (Vancouver B2) and additional bone loss in 13 cases (Vancouver B3). Postoperative complications: two fractures following another fall (repeat operations: one replacement, one plate), four revisions due to subsidence of the stem (three replacements involving change to a standard stem with healed proximal femur, one replacement with another interlocked revision stem). Bone healing occurred for all fractures after a mean 5.6 months (3-11 months). Follow-up examination after a mean 4.5 years: all patients were able to walk, average Harris Score 70.5 points (29-95 points).

Fractures of the distal tibia treated with polyaxial locking plating.

PubMed

Gao, Hong; Zhang, Chang-Qing; Luo, Cong-Feng; Zhou, Zu-Bin; Zeng, Bing-Fang

2009-03-01

We evaluated the healing rate, complications, and functional outcomes in 32 adult patients with very short metaphyseal fragments in fractures of the distal tibia treated with a polyaxial locking system. The average distance from the distal extent of the fracture to the tibial plafond was 11 mm. All fractures healed and the average time to union was 14 weeks. Six patients (19%) reported occasional local disturbance over the medial malleolus. There were two cases of postoperative superficial infections and evidence of delayed wound healing. Using the American Orthopaedic Foot and Ankle Society ankle score, the average functional score was 87.3 points (of 100 total possible points). Our results show the polyaxial locking plates, which offer more fixation versatility, may be a reasonable treatment option for distal tibia fractures with very short metaphyseal segments.

Design and Fabrication of Quadrupole Ion Mass Spectrometer for Upper Atmosphere.

DTIC Science & Technology

1981-09-30

34 diameter con-flat flange were T.I.G. welded to the end of each of three bowls. All bowls were then electro- polished, cleaned and sent out to have...plated surface was .0001" to .0002" thick. After gold plating, the hemispheres were mated and T.I.G. welded to form a sphere with a con-flat flange at...Valve Rotatable Conflat to fit k" Swage Lock Weld Adaptors. 5 2 3/4" Conflat Flanges machined to fit Swage Lock unions. 12 10-24 x 2 " Brass Screws necket

High current capacity electrical connector

DOEpatents

Bettis, Edward S.; Watts, Harry L.

1976-01-13

An electrical connector is provided for coupling high current capacity electrical conductors such as copper busses or the like. The connector is arranged in a "sandwiched" configuration in which a conductor plate contacts the busses along major surfaces thereof clamped between two stainless steel backing plates. The conductor plate is provided with a plurality of contact buttons affixed therein in a spaced array such that the caps of the buttons extend above the conductor plate surface to contact the busses. When clamping bolts provided through openings in the sandwiched arrangement are tightened, Belleville springs provided under the rim of each button cap are compressed and resiliently force the caps into contact with the busses' contacting surfaces to maintain a predetermined electrical contact area provided by the button cap tops. The contact area does not change with changing thermal or mechanical stresses applied to the coupled conductors.

Method of recertifying a loaded bearing member

NASA Technical Reports Server (NTRS)

Allison, Sidney G. (Inventor)

1992-01-01

A method is described of recertifying a loaded bearing member using ultrasound testing to compensate for different equipment configurations and temperature conditions. The standard frequency F1 of a reference block is determined via an ultrasonic tone burst generated by a first pulsed phased locked loop (P2L2) equipment configuration. Once a lock point number S is determined for F1, the reference frequency F1a of the reference block is determined at this lock point number via a second P2L2 equipment configuration to permit an equipment offset compensation factor Fo1=((F1-F1a)/F1)(1000000) to be determined. Next, a reference frequency F2 of the unloaded bearing member is determined using a second P2L2 equipment configuration and is then compensated for equipment offset errors via the relationship F2+F2(Fo1)/1000000. A lock point number b is also determined for F2. A resonant frequency F3 is determined for the reference block using a third P2L2 equipment configuration to determine a second offset compensation factor F02=((F1-F3)/F1) 1000000. Next the resonant frequency F4 of the loaded bearing member is measured at lock point number b via the third P2L2 equipment configuration and the bolt load determined by the relationship (-1000000)CI(((F2-F4)/F2)-Fo2), wherein CI is a factor correlating measured frequency shift to the applied load. Temperature compensation is also performed at each point in the process.

Tool for Coupling a Torque Wrench to a Round Cable Connector

NASA Technical Reports Server (NTRS)

Hacker, Scott C.; Dean, Richard J.; Burge, Scott W.

2006-01-01

A tool makes it possible to couple a torque wrench to an externally knurled, internally threaded, round cable connector. The purpose served by the tool is to facilitate the tightening of multiple such connectors (or the repeated tightening of the same connector) to repeatable torques. The design of a prior cable-connector/ torque-wrench coupling tool provided for application of the torque-wrench jaws to a location laterally offset from the axis of rotation of the cable connector, making it necessary to correct the torque reading for the offset. Unlike the design of the prior tool, the design of the present tool provides for application of the torque-wrench jaws to a location on the axis of rotation, obviating correction of the torque reading for offset. The present tool (see figure) consists of a split collet containing a slot that provides clearance for inserting and bending the cable, a collet-locking sleeve, a collet-locking nut, and a torque-wrench adaptor that is press-fit onto the collet. Once the collet is positioned on the cable connector, the collet-locking nut is turned to force the collet-locking sleeve over the collet, compressing the collet through engagement of tapered surfaces on the outside of the collet and the inside of the locking sleeve. Because the collet is split and therefore somewhat flexible, this compression forces the collet inward to grip the connector securely. The torque wrench is then applied to the torque-wrench adaptor in the usual manner for torquing a nut or a bolt.

Automatic locking orthotic knee device

NASA Technical Reports Server (NTRS)

Weddendorf, Bruce C. (Inventor)

1993-01-01

An articulated tang in clevis joint for incorporation in newly manufactured conventional strap-on orthotic knee devices or for replacing such joints in conventional strap-on orthotic knee devices is discussed. The instant tang in clevis joint allows the user the freedom to extend and bend the knee normally when no load (weight) is applied to the knee and to automatically lock the knee when the user transfers weight to the knee, thus preventing a damaged knee from bending uncontrollably when weight is applied to the knee. The tang in clevis joint of the present invention includes first and second clevis plates, a tang assembly and a spacer plate secured between the clevis plates. Each clevis plate includes a bevelled serrated upper section. A bevelled shoe is secured to the tank in close proximity to the bevelled serrated upper section of the clevis plates. A coiled spring mounted within an oblong bore of the tang normally urges the shoes secured to the tang out of engagement with the serrated upper section of each clevic plate to allow rotation of the tang relative to the clevis plate. When weight is applied to the joint, the load compresses the coiled spring, the serrations on each clevis plate dig into the bevelled shoes secured to the tang to prevent relative movement between the tang and clevis plates. A shoulder is provided on the tang and the spacer plate to prevent overextension of the joint.

Stress analysis method for clearance-fit joints with bearing-bypass loads

NASA Technical Reports Server (NTRS)

Naik, R. A.; Crews, J. H., Jr.

1989-01-01

Within a multi-fastener joint, fastener holes may be subjected to the combined effects of bearing loads and loads that bypass the hole to be reacted elsewhere in the joint. The analysis of a joint subjected to search combined bearing and bypass loads is complicated by the usual clearance between the hole and the fastener. A simple analysis method for such clearance-fit joints subjected to bearing-bypass loading has been developed in the present study. It uses an inverse formulation with a linear elastic finite-element analysis. Conditions along the bolt-hole contact arc are specified by displacement constraint equations. The present method is simple to apply and can be implemented with most general purpose finite-element programs since it does not use complicated iterative-incremental procedures. The method was used to study the effects of bearing-bypass loading on bolt-hole contact angles and local stresses. In this study, a rigid, frictionless bolt was used with a plate having the properties of a quasi-isotropic graphite/epoxy laminate. Results showed that the contact angle as well as the peak stresses around the hole and their locations were strongly influenced by the ratio of bearing and bypass loads. For single contact, tension and compression bearing-bypass loading had opposite effects on the contact angle. For some compressive bearing-bypass loads, the hole tended to close on the fastener leading to dual contact. It was shown that dual contact reduces the stress concentration at the fastener and would, therefore, increase joint strength in compression. The results illustrate the general importance of accounting for bolt-hole clearance and contact to accurately compute local bolt-hole stresses for combined bearings and bypass loading.

Accuracy of specimen-specific nonlinear finite element analysis for evaluation of radial diaphysis strength in cadaver material.

PubMed

Matsuura, Yusuke; Kuniyoshi, Kazuki; Suzuki, Takane; Ogawa, Yasufumi; Sukegawa, Koji; Rokkaku, Tomoyuki; Thoreson, Andrew Ryan; An, Kai-Nan; Takahashi, Kazuhisa

2015-01-01

The feasibility of a user-specific finite element model for predicting the in situ strength of the radius after implantation of bone plates for open fracture reduction was established. The effect of metal artifact in CT imaging was characterized. The results were verified against biomechanical test data. Fourteen cadaveric radii were divided into two groups: (1) intact radii for evaluating the accuracy of radial diaphysis strength predictions with finite element analysis and (2) radii with a locking plate affixed for evaluating metal artifact. All bones were imaged with CT. In the plated group, radii were first imaged with the plates affixed (for simulating digital plate removal). They were then subsequently imaged with the locking plates and screws removed (actual plate removal). Fracture strength of the radius diaphysis under axial compression was predicted with a three-dimensional, specimen-specific, nonlinear finite element analysis for both the intact and plated bones (bones with and without the plate captured in the scan). Specimens were then loaded to failure using a universal testing machine to verify the actual fracture load. In the intact group, the physical and predicted fracture loads were strongly correlated. For radii with plates affixed, the physical and predicted (simulated plate removal and actual plate removal) fracture loads were strongly correlated. This study demonstrates that our specimen-specific finite element analysis can accurately predict the strength of the radial diaphysis. The metal artifact from CT imaging was shown to produce an overestimate of strength.

CAD-CAM plates versus conventional fixation plates for primary mandibular reconstruction: A biomechanical in vitro analysis.

PubMed

Rendenbach, Carsten; Sellenschloh, Kay; Gerbig, Lucca; Morlock, Michael M; Beck-Broichsitter, Benedicta; Smeets, Ralf; Heiland, Max; Huber, Gerd; Hanken, Henning

2017-11-01

CAD/CAM reconstruction plates have become a viable option for mandible reconstruction. The aim of this study was to determine whether CAD/CAM plates provide higher fatigue strength compared with conventional fixation systems. 1.0 mm miniplates, 2.0 mm conventional locking plates (DePuy Synthes, Umkirch, Germany), and 2.0 mm CAD/CAM plates (Materialise, Leuven, Belgium/DePuy Synthes) were used to reconstruct a polyurethane mandible model (Synbone, Malans, CH) with cortical and cancellous bone equivalents. Mastication was simulated via cyclic dynamic testing using a universal testing machine (MTS, Bionix, Eden Prairie, MN, USA) until material failure reached a rate of 1 Hz with increasing loads on the left side. No significant difference was found between the groups until a load of 300 N. At higher loads, vertical displacement differed increasingly, with a poorer performance of miniplates (p = 0.04). Plate breakage occurred in miniplates and conventional locking plates. Screw breakage was recorded as the primary failure mechanism in CAD/CAM plates. Stiffness was significantly higher with the CAD/CAM plates (p = 0.04). CAD/CAM plates and reconstruction plates provide higher fatigue strength than miniplates, and stiffness is highest in CAD/CAM systems. All tested fixation methods seem sufficiently stable for mandible reconstruction. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Deformation and stress change associated with plate interaction at subduction zones: a kinematic modelling

NASA Astrophysics Data System (ADS)

Zhao, Shaorong; Takemoto, Shuzo

2000-08-01

The interseismic deformation associated with plate coupling at a subduction zone is commonly simulated by the steady-slip model in which a reverse dip-slip is imposed on the down-dip extension of the locked plate interface, or by the backslip model in which a normal slip is imposed on the locked plate interface. It is found that these two models, although totally different in principle, produce similar patterns for the vertical deformation at a subduction zone. This suggests that it is almost impossible to distinguish between these two models by analysing only the interseismic vertical deformation observed at a subduction zone. The steady-slip model cannot correctly predict the horizontal deformation associated with plate coupling at a subduction zone, a fact that is proved by both the numerical modelling in this study and the GPS (Global Positioning System) observations near the Nankai trough, southwest Japan. It is therefore inadequate to simulate the effect of the plate coupling at a subduction zone by the steady-slip model. It is also revealed that the unphysical assumption inherent in the backslip model of imposing a normal slip on the locked plate interface makes it impossible to predict correctly the horizontal motion of the subducted plate and the stress change within the overthrust zone associated with the plate coupling during interseismic stages. If the analysis made in this work is proved to be correct, some of the previous studies on interpreting the interseismic deformation observed at several subduction zones based on these two models might need substantial revision. On the basis of the investigations on plate interaction at subduction zones made using the finite element method and the kinematic/mechanical conditions of the plate coupling implied by the present plate tectonics, a synthesized model is proposed to simulate the kinematic effect of the plate interaction during interseismic stages. A numerical analysis shows that the proposed model, designed to simulate the motion of a subducted slab, can correctly produce the deformation and the main pattern of stress concentration associated with plate coupling at a subduction zone. The validity of the synthesized model is examined and partially verified by analysing the horizontal deformation observed by GPS near the Nankai trough, southwest Japan.

Time-Varying Upper-Plate Deformation during the Megathrust Subduction Earthquake Cycle

NASA Astrophysics Data System (ADS)

Furlong, Kevin P.; Govers, Rob; Herman, Matthew

2015-04-01

Over the past several decades of the WEGENER era, our abilities to observe and image the deformational behavior of the upper plate in megathrust subduction zones has dramatically improved. Several intriguing inferences can be made from these observations including apparent lateral variations in locking along subduction zones, which differs from interseismic to coseismic periods; the significant magnitude of post-earthquake deformation (e.g. following the 20U14 Mw Iquique, Chile earthquake, observed on-land GPS post-EQ displacements are comparable to the co-seismic displacements); and incompatibilities between rates of slip deficit accumulation and resulting earthquake co-seismic slip (e.g. pre-Tohoku, inferred rates of slip deficit accumulation on the megathrust significantly exceed slip amounts for the ~ 1000 year recurrence.) Modeling capabilities have grown from fitting simple elastic accumulation/rebound curves to sparse data to having spatially dense continuous time series that allow us to infer details of plate boundary coupling, rheology-driven transient deformation, and partitioning among inter-earthquake and co-seismic displacements. In this research we utilize a 2D numerical modeling to explore the time-varying deformational behavior of subduction zones during the earthquake cycle with an emphasis on upper-plate and plate interface behavior. We have used a simplified model configuration to isolate fundamental processes associated with the earthquake cycle, rather than attempting to fit details of specific megathrust zones. Using a simple subduction geometry, but realistic rheologic layering we are evaluating the time-varying displacement and stress response through a multi-earthquake cycle history. We use a simple model configuration - an elastic subducting slab, an elastic upper plate (shallower than 40 km), and a visco-elastic upper plate (deeper than 40 km). This configuration leads to an upper plate that acts as a deforming elastic beam at inter-earthquake loading times and rates with a viscously relaxed regime at depths greater than 40 km. Analyses of our preliminary model results lead to the following: 1. Co-seismic stress transfer from the unloading elastic layer (shallow) into an elastically loading visco-elastic layer (deeper) - extends ~ 100 km inboard of locked zone. This stress transfer affects both coseismic and post-seismic surface displacements. 2. Post-seismic response of upper plate involves seaward motion for initial 10-20 years (~ 2 Maxwell times) after EQ. This occurs in spite of there being no slip on locked plate boundary - i.e. this is not plate boundary after-slip but rather is a consequence of stress relaxation in co-seismically loaded visco-elastic layer. However standard inversions of the surface displacement field would indicate significant after-slip along the locked plate interface. 3. By approximately 80 years (8 Maxwell times) system has returned to simple linear displacement pattern - the expected behavior for a shortening elastic beam. Prior to that time, the surface (observable) displacement pattern changes substantially over time and would result in an apparent temporal variation in coupling - from near-zero coupling to fully locked over ~ 80 years post-earthquake. These preliminary results indicate that care is needed in interpreting observed surface displacement fields from GPS, InSAR, etc. during the interseismic period. temporal variations in crustal deformation observed in regions such as the recent Tohoku, Maule, and Iquique megathrust events which are ascribed to fault plane after-slip may in fact reflect processes associated with re-equilibration of the visco-elastic subduction system.

Biomechanical Comparison Study of Three Fixation Methods for Proximal Chevron Osteotomy of the First Metatarsal in Hallux Valgus.

PubMed

Kim, Jin Su; Cho, Hun Ki; Young, Ki Won; Kim, Ji Soo; Lee, Kyung Tai

2017-12-01

Fixation of proximal chevron metatarsal osteotomy has been accomplished using K-wires traditionally and with a locking plate recently. However, both methods have many disadvantages. Hence, we developed an intramedullary fixation technique using headless cannulated screws and conducted a biomechanical study to evaluate the superiority of the technique to K-wire and locking plate fixations. Proximal chevron metatarsal osteotomy was performed on 30 synthetic metatarsal models using three fixation techniques. Specimens in group I were fixated with K-wires (1.6 mm × 2) and in group II with headless cannulated screws (3.0 mm × 2) distally through the intramedullary canal. Specimens in group III were fixated with a locking X-shaped plate (1.3-mm thick) and screws (2.5 mm × 4). Eight metatarsal specimens were selected from each group for walking fatigue test. Bending stiffness and dorsal angulation were measured by 1,000 repetitions of a cantilever bending protocol in a plantar to dorsal direction. The remaining two samples from each group were subjected to 5 mm per minute axial loading to assess the maximal loading tolerance. All samples in group I failed walking fatigue test while group II and group III tolerated the walking fatigue test. Group II showed greater resistance to bending force and smaller dorsal angulation than group III ( p = 0.001). On the axial loading test, group I and group II demonstrated superior maximum tolerance to group III (54.8 N vs. 47.2 N vs. 28.3 N). Authors have demonstrated proximal chevron metatarsal osteotomy with intramedullary screw fixation provides superior biomechanical stability to locking plate and K-wire fixations. The new technique using intramedullary screw fixation can offer robust fixation and may lead to better outcomes in surgical treatment of hallux valgus.

Biomechanical loading test on reconstructed mandibles with fibular, iliac crest or scapula graft: a comparative study.

PubMed

Grohmann, Isabella; Raith, Stefan; Mücke, Thomas; Stimmer, Herbert; Rohleder, Nils; Kesting, Marco R; Hölzle, Frank; Steiner, Timm

2015-10-01

Advantages and disadavantages of the three most commonly-used bone grafts for mandibular reconstruction are widely known, but biomechanical experimental studies are rare. We have done loading tests on cadaveric mandibles reconstructed with fibular, iliac crest, and scapular grafts using 3 different osteosynthesis systems to detect and compare their primary stability. Loading tests were done on mandibles with grafts from the fibula and iliac crest and published previously. A 4.5cm paramedian L-type defect was reconstructed with scapula using 2 monocortical non-locking plates, 2 monocortical locking plates, or a single bicortical locking plate/fracture gap in 18 human cadaveric mandibles. These were loaded on to the "Mandibulator" test bench and the movement of fragments in 3 dimensions was assessed and quantified by a PONTOS® optical measurement system. Comparison of the osteosynthesis groups showed that the miniplate was significantly superior to the 6-hole TriLock® plate for both fibular and iliac crest grafts. The fibular graft gave greater stability than the iliac crest and scapular grafts for all 3 osteosynthesis systems. All bony specimens offered sufficient resistance to mechanical stress within the recognised range of biting forces after mandibular reconstruction, independently of the choice of bone graft and osteosynthesis system used. Anatomical and surgical advantages need to be taken into account when choosing a graft. Stability can be maximised with a fibular graft, and further optimised by enlarging the binding area by using the "double barrel" method. Computer simulated experiments could segregate factors that biased results, such as morphological differences among cadavers. Copyright © 2015 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Hydraulic Evaluation of Culvert Valves at Eisenhower and Snell Locks, St. Lawrence Seaway

DTIC Science & Technology

2015-06-01

ER D C/ CH L TR -1 5- 7 Hydraulic Evaluation of Culvert Valves at Eisenhower and Snell Locks, St. Lawrence Seaway Co as ta l a nd H...client/default. ERDC/CHL TR-15-7 June 2015 Hydraulic Evaluation of Culvert Valves at Eisenhower and Snell Locks, St. Lawrence Seaway...filling valve well of the Snell Lock’s south-wall culvert . The new vertical-frame valve operated at a slower rate than the double-skin-plate valve

Crustal deformation in great California earthquake cycles

NASA Technical Reports Server (NTRS)

Li, Victor C.; Rice, James R.

1986-01-01

Periodic crustal deformation associated with repeated strike slip earthquakes is computed for the following model: A depth L (less than or similiar to H) extending downward from the Earth's surface at a transform boundary between uniform elastic lithospheric plates of thickness H is locked between earthquakes. It slips an amount consistent with remote plate velocity V sub pl after each lapse of earthquake cycle time T sub cy. Lower portions of the fault zone at the boundary slip continuously so as to maintain constant resistive shear stress. The plates are coupled at their base to a Maxwellian viscoelastic asthenosphere through which steady deep seated mantle motions, compatible with plate velocity, are transmitted to the surface plates. The coupling is described approximately through a generalized Elsasser model. It is argued that the model gives a more realistic physical description of tectonic loading, including the time dependence of deep slip and crustal stress build up throughout the earthquake cycle, than do simpler kinematic models in which loading is represented as imposed uniform dislocation slip on the fault below the locked zone.

Plans for a Northern Cascadia Subduction Zone Observatory

NASA Astrophysics Data System (ADS)

Heesemann, M.; Wang, K.; Davis, E.; Chadwell, C. D.; Nissen, E.; Moran, K.; Scherwath, M.

2017-12-01

To accurately assess earthquake and tsunami hazards posed by the Cascadia Subduction Zone, it is critically important to know which area of the plate interface is locked and whether or not part of the energy is being released aseismically by slow creep on the fault. Deeper locking that extends further to the coast produces stronger shaking in population centers. Shallow locking, on the other hand, leads to bigger tsunamis. We will report on and discuss plans for a new amphibious Northern Cascadia Subduction Zone Observatory (NCSZO) that will leverage the existing NEPTUNE cabled seafloor observatory, which is operated by Ocean Networks Canada (ONC), and the onshore network of geodetic stations, which is operated by Natural Resources Canada (NRCan). To create a NCSZO we plan to (1) add a network of seven GPS-Acoustic (GPS-A) sites offshore Vancouver Island, (2) establish a Deformation Front Observatory, and (3) improve the existing onshore geodetic network (see Figure below). The GPS-A stations will provide the undisturbed motion of the Juan de Fuca (JdF) Plate (1), deformation of the JdF plate (2), deformation of the overriding plate (3-7) and a cabled laboratory to study the potential for continuous GPS-A measurements (6). The Deformation Front Observatory will be used to study possible transient slip events using seafloor pressure and tilt instruments and fluid flux meters.

High-Repeatability, Robot Friendly, ORU Interface

NASA Technical Reports Server (NTRS)

Voellmer, George M. (Inventor)

1992-01-01

A robot-friendly coupling device for an Orbital Replacement Unit (ORU). The invention will provide a coupling that is detached and attached remotely by a robot. The design of the coupling must allow for slight misalignments, over torque protection, and precision placement. This is accomplished by using of a triangular interface having three components. A base plate assembly is located on an attachment surface, such as a satellite. The base plate assembly has a cup member, a slotted member, and a post member. The ORU that the robot attaches to the base plate assembly has an ORU plate assembly with two cone members and a post member which mate to the base plate assembly. As the two plates approach one another, one cone member of the ORU plate assembly only has to be placed accurately enough to fall into the cup member of the base plate assembly. The cup forces alignment until a second cone falls into a slotted member which provides final alignment. A single bolt is used to attach the two plates. Two deflecting plates are attached to the backs of the plates. When pressure is applied to the center of the deflecting plates, the force is distributed preventing the ORU & base plates from deflecting. This accounts for precision in the placement of the article.

Comparison of the Mechanical Characteristics of a Universal Small Biplane Plating Technique Without Compression Screw and Single Anatomic Plate With Compression Screw.

PubMed

Dayton, Paul; Ferguson, Joe; Hatch, Daniel; Santrock, Robert; Scanlan, Sean; Smith, Bret

2016-01-01

To better understand the mechanical characteristics of biplane locked plating in small bone fixation, the present study compared the stability under cyclic cantilever loading of a 2-plate locked biplane (BPP) construct without interfragmentary compression with that of a single-plate locked construct with an additional interfragmentary screw (SPS) using surrogate bone models simulating Lapidus arthrodesis. In static ultimate plantar bending, the BPP construct failed at significantly greater load than did the SPS construct (556.2 ± 37.1 N versus 241.6 ± 6.3 N, p = .007). For cyclic failure testing in plantar bending at a 180-N starting load, the BPP construct failed at a significantly greater number of cycles (158,322 ± 50,609 versus 13,718 ± 10,471 cycles) and failure load (242.5 ± 25.0 N versus 180.0 ± 0.0 N) than the SPS construct (p = .002). For cyclic failure testing in plantar bending at a 120-N starting load, the results were not significantly different between the BPP and SPS constructs for the number of cycles (207,646 ± 45,253 versus 159,334 ± 69,430) or failure load (205.0 ± 22.4 N versus 185.0 ± 33.5 N; p = .300). For cyclic testing with 90° offset loading (i.e., medial to lateral bending) at a 120-N starting load, all 5 BPP constructs (tension side) and 2 of the 5 SPS constructs reached 250,000 cycles without failure. Overall, the present study found the BPP construct to have superior or equivalent stability in multiplanar orientations of force application in both static and fatigue testing. Thus, the concept of biplane locked plating, using 2 low profile plates and unicortical screw insertion, shows promise in small bone fixation, because it provides consistent stability in multiplanar orientations, making it universally adaptable to many clinical situations. Copyright © 2016 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

The stress distribution in pin-loaded orthotropic plates

NASA Technical Reports Server (NTRS)

Klang, E. C.; Hyer, M. W.

1985-01-01

The performance of mechanically fastened composite joints was studied. Specially, a single-bolt connector was modeled as a pin-loaded, infinite plate. The model that was developed used two dimensional, complex variable, elasticity techniques combined with a boundary collocation procedure to produce solutions for the problem. Through iteration, the boundary conditions were satisfied and the stresses in the plate were calculated. Several graphite epoxy laminates were studied. In addition, parameters such as the pin modulus, coefficient of friction, and pin-plate clearance were varied. Conclusions drawn from this study indicate: (1) the material properties (i.e., laminate configuration) of the plate alter the stress state and, for highly orthotropic materials, the contact stress deviates greatly from the cosinusoidal distribution often assumed; (2) friction plays a major role in the distribution of stresses in the plate; (3) reversing the load direction also greatly effects the stress distribution in the plate; (4) clearance (or interference) fits change the contact angle and thus the location of the peak hoop stress; and (5) a rigid pin appears to be a good assumption for typical material systems.

Multichannel Nephelometer.

DTIC Science & Technology

1986-10-01

consists of two near-hemispheric shells bolted to a mounted plate housing the sampling system. Its walls are anodized black to decrease 13 surface...a distinct advantage when the test aerosol contains a significant quantity of liquid. Membrane filters tend to load and reduce throughout while...Table 6. As indicated, these filters can be estremely efficient. Should absolute retention be required, the AAO grade filter with a pore size of 0.3

SURGICAL TREATMENT OF DISTAL RADIUS FRACTURES WITH A VOLAR LOCKED PLATE: CORRELATION OF CLINICAL AND RADIOGRAPHIC RESULTS

PubMed Central

Xavier, Claudio Roberto Martins; Dal Molin, Danilo Canesin; dos Santos, Rafael Mota Marins; dos Santos, Roberto Della Torre; Neto, Julio Cezar Ferreira

2015-01-01

Objectives: To analyze and correlate the clinical and radiographic results from patients with distal radius fractures who underwent surgical treatment with a fixed-angle volar locked plate. Methods: Sixty-four patients with distal radius fractures were evaluated. They all underwent surgical treatment with a volar locked plate for the distal radius, with a minimum of six months of postoperative follow-up. They underwent a physical examination that measured range of motion and grip strength, answered the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire and underwent radiographic examination. Results: In the physical examination on the patients, all the range-of-motion measurements were reduced. Grip strength measured in kgf was on average 85.8% of the strength on the unaffected side. The mean DASH score was 15.99. A significant relationship was found between lower DASH scores and losses of extension and grip strength. On the radiographs, the mean values in relation to the unfractured side were 84.0% for radial inclination, 85.4% for radial length and 86.8% for volar deviation of the radius. Loss of radial length was correlated with losses of extension and grip strength. PMID:27027046

[Distal clavicle fracture].

PubMed

Seppel, G; Lenich, A; Imhoff, A B

2014-06-01

Reposition and fixation of unstable distal clavicle fractures with a low profile locking plate (Acumed, Hempshire, UK) in conjunction with a button/suture augmentation cerclage (DogBone/FibreTape, Arthrex, Naples, FL, USA). Unstable fractures of the distal clavicle (Jäger and Breitner IIA) in adults. Unstable fractures of the distal clavicle (Jäger and Breitner IV) in children. Distal clavicle fractures (Jäger and Breitner I, IIB or III) with marked dislocation, injury of nerves and vessels, or high functional demand. Patients in poor general condition. Fractures of the distal clavicle (Jäger and Breitner I, IIB or III) without marked dislocation or vertical instability. Local soft-tissue infection. Combination procedure: Initially the lateral part of the clavicle is exposed by a 4 cm skin incision. After reduction of the fracture, stabilization is performed with a low profile locking distal clavicle plate. Using a special guiding device, a transclavicular-transcoracoidal hole is drilled under arthroscopic view. Additional vertical stabilization is arthroscopically achieved by shuttling the DogBone/FibreTape cerclage from the lateral portal cranially through the clavicular plate. The two ends of the FibreTape cerclage are brought cranially via adjacent holes of the locking plate while the DogBone button is placed under the coracoid process. Thus, plate bridging is achieved. Finally reduction is performed and the cerclage is secured by surgical knotting. Use of an arm sling for 6 weeks. Due to the fact that the described technique is a relatively new procedure, long-term results are lacking. In the short term, patients postoperatively report high subjective satisfaction without persistent pain.

Process Sensitivity, Performance, and Direct Verification Testing of Adhesive Locking Features

NASA Technical Reports Server (NTRS)

Golden, Johnny L.; Leatherwood, Michael D.; Montoya, Michael D.; Kato, Ken A.; Akers, Ed

2012-01-01

Phase I: The use of adhesive locking features or liquid locking compounds (LLCs) (e.g., Loctite) as a means of providing a secondary locking feature has been used on NASA programs since the Apollo program. In many cases Loctite was used as a last resort when (a) self-locking fasteners were no longer functioning per their respective drawing specification, (b) access was limited for removal & replacement, or (c) replacement could not be accomplished without severe impact to schedule. Long-term use of Loctite became inevitable in cases where removal and replacement of worn hardware was not cost effective and Loctite was assumed to be fully cured and working. The NASA Engineering & Safety Center (NESC) and United Space Alliance (USA) recognized the need for more extensive testing of Loctite grades to better understand their capabilities and limitations as a secondary locking feature. These tests, identified as Phase I, were designed to identify processing sensitivities, to determine proper cure time, the correct primer to use on aerospace nutplate, insert and bolt materials such as A286 and MP35N, and the minimum amount of Loctite that is required to achieve optimum breakaway torque values. The .1900-32 was the fastener size tested, due to wide usage in the aerospace industry. Three different grades of Loctite were tested. Results indicate that, with proper controls, adhesive locking features can be successfully used in the repair of locking features and should be considered for design. Phase II: Threaded fastening systems used in aerospace programs typically have a requirement for a redundant locking feature. The primary locking method is the fastener preload and the traditional redundant locking feature is a self-locking mechanical device that may include deformed threads, non-metallic inserts, split beam features, or other methods that impede movement between threaded members. The self-locking resistance of traditional locking features can be directly verified during assembly by measuring the dynamic prevailing torque. Adhesive locking features or LLCs are another method of providing redundant locking, but a direct verification method has not been used in aerospace applications to verify proper installation when using LLCs because of concern for damage to the adhesive bond. The reliability of LLCs has also been questioned due to failures observed during testing with coupons for process verification, although the coupon failures have often been attributed to a lack of proper procedures. It is highly desirable to have a direct method of verifying the LLC cure or bond integrity. The purpose of the Phase II test program was to determine if the torque applied during direct verification of an adhesive locking feature degrades that locking feature. This report documents the test program used to investigate the viability of such a direct verification method. Results of the Phase II testing were positive, and additional investigation of direct verification of adhesive locking features is merited.

The Use of Mesh Plates for Difficult Fractures of the Patella.

PubMed

Volgas, David; Dreger, Tina K

2017-03-01

Patella fractures present some of the more complicated fracture patterns in orthopaedic trauma care. This is partially due to the small size of the fragments but also the articular nature of each fragment. Fixation methods such as cerclage wiring, excision of smaller fragments, and screw fixation of larger fragments all have their own challenges. Our study examined our Level I trauma center's experience with variable angle locked 2.7 mm titanium plates for treatment of comminuted patella fractures or treatment of patellar nonunion. After Institutional Review Board approval, we used billing records to identify 105 patients who had undergone operative management of a displaced patella fracture between January 2011 and December 2015. We reviewed the radiographs of these patients to identify which patients underwent treatment with a mesh plate. We found 16 patients (6 males and 10 females) who had undergone fixation with a mesh plate; mean age was 47 years. Nine patients underwent primary open reduction internal fixation (ORIF) and seven underwent mesh plate fixation for failed ORIF of a patella fracture. The mean visual analog pain score was 2.75 (range, 0-9). The mean range of motion was 1 degree of extension (range, 0-10 degrees) to 110 degrees of flexion (range, 45-135 degrees). All fractures healed. Five patients required hardware removal for pain. This review illustrates the effectiveness of the locking mesh plate in two challenging clinical scenarios: that of patellar nonunion and comminuted fractures that preclude standard fixation methods. Although multiple options exist for patellar fracture fixation, the titanium mesh locking plate can be an effective option for retaining the patella in the setting of comminution. Further comparative studies should be undertaken to determine which method of treatment may be superior in the treatment of these fractures. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Plate rotations, fault slip rates, fault locking, and distributed deformation in northern Central America from 1999-2017 GPS observations

NASA Astrophysics Data System (ADS)

Ellis, A. P.; DeMets, C.; Briole, P.; Cosenza, B.; Flores, O.; Guzman-Speziale, M.; Hernandez, D.; Kostoglodov, V.; La Femina, P. C.; Lord, N. E.; Lasserre, C.; Lyon-Caen, H.; McCaffrey, R.; Molina, E.; Rodriguez, M.; Staller, A.; Rogers, R.

2017-12-01

We describe plate rotations, fault slip rates, and fault locking estimated from a new 100-station GPS velocity field at the western end of the Caribbean plate, where the Motagua-Polochic fault zone, Middle America trench, and Central America volcanic arc faults converge. In northern Central America, fifty-one upper-plate earthquakes caused approximately 40,000 fatalities since 1900. The proximity of main population centers to these destructive earthquakes and the resulting loss of human life provide strong motivation for studying the present-day tectonics of Central America. Plate rotations, fault slip rates, and deformation are quantified via a two-stage inversion of daily GPS position time series using TDEFNODE modeling software. In the first stage, transient deformation associated with three M>7 earthquakes in 2009 and 2012 is estimated and removed from the GPS position time series. In Stage 2, linear velocities determined from the corrected GPS time series are inverted to estimate deformation within the western Caribbean plate, slip rates along the Motagua-Polochic faults and faults in the Central America volcanic arc, and the gradient of extension in the Honduras-Guatemala wedge. Major outcomes of the second inversion include the following: (1) Confirmation that slip rates on the Motagua fault decrease from 17-18 mm/yr at its eastern end to 0-5 mm/yr at its western end, in accord with previous results. (2) A transition from moderate subduction zone locking offshore from southern Mexico and parts of southern Guatemala to weak or zero coupling offshore from El Salvador and parts of Nicaragua along the Middle America trench. (3) Evidence for significant east-west extension in southern Guatemala between the Motagua fault and volcanic arc. Our study also shows evidence for creep on the eastern Motagua fault that diminishes westward along the North America-Caribbean plate boundary.

Operative treatment of intra-articular calcaneal fractures with calcaneal plates and its complications

PubMed Central

Rak, Vaclav; Ira, Daniel; Masek, Michal

2009-01-01

Background: In a retrospective study we analysed intra-articular calcaneal fracture treatment by comparing results and complications related to fracture stabilization with nonlocking calcaneal plates and locking compression plates. Materials and Methods: We performed 76 osteosynthesis (67 patients) of intra-articular calcaneal fractures using the standard extended lateral approach from February 2004 to October 2007. Forty-two operations using nonlocking calcaneal plates (group A) were performed during the first three years, and 34 calcaneal fractures were stabilized using locking compression plates (group B) in 2007. In the Sanders type IV fractures, reconstruction of the calcaneal shape was attempted. Depending on the type of late complication, we performed subtalar arthroscopy in six cases, arthroscopically assisted subtalar distraction bone block arthrodesis in six cases, and plate removal with lateral-wall decompression in five cases. The patients were evaluated by the AOFAS Ankle-Hindfoot Scale. Results: Wound healing complications were 7/42 (17%) in group A and 1/34 (3%) in group B. No patient had deep osseous infection or foot rebound compartment syndrome. Preoperative size of Böhler's angle correlated with postoperative clinical results in both groups. There were no late complications necessitating corrective procedure or arthroscopy until December 2008 in Group B. All late complications ccurred in Group A. The overall results according to the AOFAS Ankle Hindfoot Scale were good or excellent in 23/42 (55%) in group A and in 30/34 (85%) in group B. Conclusion: Open reduction and internal fixation of intra-articular calcaneal fractures has become a standard surgical method. Fewer complications and better results related to treatment with locking compression plates confirmed in comparison to nonlocking ones were noted for all Sanders types of intra-articular calcaneal fractures. Age and Sanders type IV fractures are not considered to be the contraindications to surgery. PMID:19838350

[EFFECTIVENESS OF SHARP TEETH HOOK PLATE FOR TREATMENT OF OLECRANON FRACTURES].

PubMed

Yin, Qudong; Gu, Sanjun; Liu, Jun; Wu, Yongwei; Lu, Yao; Ma, Yunhong; Sheng, Youyin

2016-09-08

To investigate the effectiveness of sharp teeth hook plate by cutting for the treatment of olecranon fractures by comparison with Kirschner wire tension belt and locking plate. Between January 2011 and April 2015, 32 cases of olecranon fractures were treated. Fracture was fixed with sharp teeth hook plate by cutting in 12 cases (trial group) and with Kirschner wire tension belt or locking plate in 20 cases (control group). There was no significant difference in gender, age, side and type of fracture, and time from injury to operation between 2 groups ( P >0.05). The healing time of fractures and complications were recorded. At 1 year after operation, the subjective function results were evaluated according to Disability of Arm, Shoulder, and Hand (DASH) score, and objective function results by Mayo Elbow Score (MEPS); visual analogue scale (VAS) was used for elbow joint pain, and range of motion of flexion and extension of elbow joint was measured. All incisions healed by first intention, with no vascular and nerve injuries. All patients were followed up 12-36 months with an average of 18 months. All fractures healed, and there was no significant difference in the healing time between 2 groups ( P >0.05). Loosening of Kirschner wire occurred in 2 cases of control group, but no loosening of internal fixation was observed in trial group after operation. There was no significant difference in the incidence of complications between 2 groups ( P >0.05). The DASH, MEPS, VAS score, and range of motion of flexion in trial group were superior to those in control group, showing significant differences ( P <0.05) at 1 year after operation. There was no significant difference in range of motion of extension between 2 groups ( P >0.05). Sharp teeth hook plate for treatment of olecranon fractures overcomes the shortcomings that Kirschner wire tension is easy to slide and locking plate has a compression effect on triceps tendon, so it has good effectiveness.

Automated Setup Assembly Mechanisms for the Intelligent Machining Workstation

DTIC Science & Technology

1990-11-01

Autoimated analysis systems such as [36,37] use the Finite Elements Method ( FEM ) to evaluate or synthesize the structures of fixtures and workpiece...the angular orientation is not altered, and vice versa. This decoupling is accomplished by elastomers that are quite stiff in compression while being...Larger pins (#14), along with elastomers (#15), and the bolt and washer assembly (#6), provide compliance between top and bottom plate (#2), and by

Tangential Bicortical Locked Fixation Improves Stability in Vancouver B1 Periprosthetic Femur Fractures: A Biomechanical Study

PubMed Central

Lewis, Gregory S.; Caroom, Cyrus T.; Wee, Hwabok; Jurgensmeier, Darin; Rothermel, Shane D.; Bramer, Michelle A.; Reid, J. Spence

2015-01-01

Objectives The biomechanical difficulty in fixation of a Vancouver B1 periprosthetic fracture is purchase of the proximal femoral segment in the presence of the hip stem. Several newer technologies provide the ability to place bicortical locking screws tangential to the hip stem with much longer lengths of screw purchase compared to unicortical screws. This biomechanical study compares the stability of two of these newer constructs to previous methods. Methods Thirty composite synthetic femurs were prepared with cemented hip stems. The distal femur segment was osteotomized, and plates were fixed proximally with either: (1) cerclage cables; (2) locked unicortical screws; (3) a composite of locked screws and cables; or tangentially directed bicortical locking screws using either (4) a stainless steel LCP system with a Locking Attachment Plate (Synthes), or (5) a titanium alloy NCB system (Zimmer). Specimens were tested to failure in either axial or torsional quasi-static loading modes (n = 3) after 20 moderate load pre-conditioning cycles. Stiffness, maximum force, and failure mechanism were determined. Results Bicortical constructs resisted higher (by an average of at least 27%) maximum forces than the other three constructs in torsional loading (p<0.05). Cables constructs exhibited lower maximum force than all other constructs, in both axial and torsional loading. The bicortical titanium construct was stiffer than the bicortical stainless steel construct in axial loading. Conclusions Proximal fixation stability is likely improved with the use of bicortical locking screws as compared to traditional unicortical screws and cable techniques. In this study with a limited sample size, we found the addition of cerclage cables to unicortical screws may not offer much improvement in biomechanical stability of unstable B1 fractures. PMID:26053467

[Arthrodesis of the shoulder. A new and soft-tissue-sparing technique with a deep locking plate in the supraspinatus fossa].

PubMed

Klonz, A; Habermeyer, P

2007-10-01

Arthrodesis of the glenohumeral joint is a difficult intervention that involves a relatively high probability of complications. A stable internal fixation and secure consolidation is required. The operation needs to achieve several conditions: thorough denudation of the cartilage and partial decortication of the subchondral bone; good congruence of the corresponding surfaces; compression of the gap by tension screws and lasting stability. For increased primary stability a neutralizing plate is generally used as well as a compression screw. Up to now, the plate has usually been applied starting from the scapular spine and extending across the acromial corner to the humeral shaft. A wide exposure is needed for this procedure; the plate is difficult to shape during the operation and often causes some discomfort because it protrudes at the acromial corner. We present an alternative position of the plate in the supraspinatus fossa, where we have sited a 4.5 mm LCP locking plate (Synthes). The implant is inserted under the acromion, does not cause any discomfort at the acromial corner, and is far easier to shape. When it is used in association with a transarticular compressive screw, the technique results in a very stable situation, which allows physiotherapy from the first day after surgery onward.

Installation Torque Tables for Noncritical Applications

NASA Technical Reports Server (NTRS)

Rivera-Rosario, Hazel T.; Powell, Joseph S.

2017-01-01

The objective of this project is to define torque values for bolts and screws when loading is not a concern. Fasteners require a certain torque to fulfill its function and prevent failure. NASA Glenn Research Center did not have a set of fastener torque tables for non-critical applications without loads, usually referring to hand-tight or wrench-tight torqueing. The project is based on two formulas, torque and pullout load. Torque values are calculated giving way to preliminary data tables. Testing is done to various bolts and metal plates, torqueing them until the point of failure. Around 640 torque tables were developed for UNC, UNF, and M fasteners. Different lengths of thread engagement were analyzed for the 5 most common materials used at GRC. The tables were put together in an Excel spreadsheet and then formatted into a Word document. The plan is to later convert this to an official technical publication or memorandum.

[Case-control study on minimally invasive percutaneous locking compression plate internal fixation for the treatment of type II and III pilon fractures].

PubMed

Zhang, Zhi-Da; Ye, Xiu-Yi; Shang, Li-Yong; Xu, Rong-Ming; Zhu, Yan-Zhao

2011-12-01

To explore the clinical efficacy of delayed open reduction and internal fixation with minimally invasive percutaneous locking compression plate for the treatment of type II and III Pilon fractures. From January 2007 to September 2009, 32 patients with type II and III Pilon fractures were treated with open reduction and anatomic plate fixation (AP group) and minimally invasive percutaneous locking compression plate osteosynthesis (LCP group). There were 11 males and 6 females in AP group, with an average age of (37.4 +/- 13.3) years (ranged, 19 to 55 years). And there were 10 males and 5 females in LCP group, with an average age of (34.6 +/- 11.3) years(ranged, 21 to 56 years). The operating time, fracture healing time, aligned angulation and ankle function were compared between the two groups. All the patients were followed up, and the during ranged from 12 to 25 months, with a mean of (15.0 +/- 1.7) months. The average operation time was (76.5 +/- 8.3) min for AP group and (58.3 +/- 3.4) min for LCP group; the average time of fracture healing was (20.5 +/- 0.4) weeks for AP group and (15.7 +/- 0.2) weeks for LCP group; the total angulation between anterior posterior film and lateral film was averaged (6.6 +/- 0.5) degrees for AP group and (3.6 +/- 0.2) degrees for LCP group. As to above index, the results of LCP group were better than those of AP group (P < 0.05). According to Kofoed criteria for ankle joint, the results of LCP group were better than those of AP group in ankle joint pain, wakling and ankle joint function (P < 0.05). The method of minimally invasive percutaneous locking compression plate internal fixation is effective in the treatment of Pilon fracture with less invasion, faster bone union, more stabilized fixation, quicker recovery of ankle function and fewer complications, which is more advantaged for type II and III Pilon fractures.

[BIOMECHANICAL COMPARATIVE STUDY ON FOUR INTERNAL FIXATIONS FOR ACETABULAR FRACTURES IN QUADRILATERAL AREA].

PubMed

Wang, Lei; Wu, Xiaobo; Qi, Wei; Wang, Yongbin; He, Quanjie; Xu, Fengsong; Liu, Hongyang

2015-10-01

To compare the biomechanical difference of 4 kinds of internal fixations for acetabular fracture in quadrilateral area. The transverse fracture models were created in 16 hemipelves specimens from 8 adult males, and were randomly divided into 4 groups according to different internal fixation methods (n = 4): infrapectineal buttress reconstruction plate (group A), infrapectineal buttress locking reconstruction plate (group B), reconstruction plate combined with trans-plate quadrilateral screws (group C), and anterior reconstruction plate-lag screw (group D). Then the horizontal displacement, longitudinal displacement of fractures, and axial stiffness were measured and counted to compare the stability after continuous vertical loading. Under the same loading, the horizontal and longitudinal displacements of groups A, B, C, and D were decreased gradually; when the loading reached 1 800 N, the longitudinal displacement of group A was more than 3.00 mm, indicating the failure criterion, while the axial stiffness increased gradually. Under 200 N loading, there was no significant difference (P > 0.05) in horizontal displacement, longitudinal displacement, and axial stiffness among 4 groups. When the loading reached 600-1 800 N, significant differences were found in horizontal displacement, longitudinal displacement, and axial stiffness among 4 groups (P < 0.05) except the horizontal displacement between groups C and D (P > 0.05). For acetabular fracture in the quadrilateral area, anterior reconstruction plate-lag screw for internal fixation has highest stability, followed by reconstruction plate combined with trans-plate quadrilateral screws, and they are better than infrapectineal buttress reconstruction plate and infrapectineal buttress locking reconstruction plate.

Surgical treatment of extra-articular or simple intra-articular distal tibial fractures: MIPO versus supercutaneous plating.

PubMed

He, Xianfeng; Zhang, Jingwei; Li, Ming; Yu, Yihui; Zhu, Limei

2014-10-01

Minimally invasive plate osteosynthesis (MIPO) has become a widely accepted technique to treat distal tibial fractures. Recently, the novel application of a locking plate used as an external fixator (supercutaneous plating) was introduced for the management of open fractures and infected nonunions and even as an adjunct in distraction osteogenesis, which is considered another less invasive method. The aim of this study was to compare the results of supercutaneous plating with closed reduction and minimally invasive plating in the treatment of distal tibial fractures. Forty-eight matched patients were divided according to age, sex, Injury Severity Score, and fracture pattern into the MIPO group and the supercutaneous plating group. Minimum follow-up was 12 months (mean, 18.5 months; range, 12-26 months). No patient had nonunion, hardware breakdown, or deep infection. Patients in the supercutaneous plating group had a significantly shorter mean operative time (65.6±13.2 vs 85.9±14.0 minutes; P=.000), hospital stay (7.5±2.0 vs 13.0±4.4 days; P=.000), and union time (15.2±2.4 vs 17.0±2.8 weeks; P=.000). In the MIPO group, 15 (62.5%) patients reported implant impingement or discomfort and there was 1 incidence of stripping of 15.6% at the time of locking screw removal, whereas in the supercutaneous plating group, no patient reported skin irritation, and removal of the supercutaneous plate was easily performed in clinic without anesthesia. Distal tibial fractures may be treated successfully with MIPO or supercutaneous plating. However, the supercutaneous plating technique may represent a superior surgical option because it offers advantages in terms of mean operative time, hospital stay, and union time; skin irritation; and implant removal. Copyright 2014, SLACK Incorporated.

The IODP NanTroSEIZE Transect: Accomplishments and Future Plans

NASA Astrophysics Data System (ADS)

Tobin, H. J.; Kinoshita, M.; Araki, E.; Byrne, T. B.; Kimura, G.; McNeill, L. C.; Moore, G. F.; Saffer, D. M.; Underwood, M.; Saito, S.

2009-12-01

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is a decade-long project to investigate the processes and properties that determine the nature of frictional locking, creep and other fault behavior governing seismogenic rupture and tsunamigenesis on a major plate boundary where great subduction earthquakes occur. The main goal of the science plan is to sample and instrument the key faults in several locations across the transition from those dominated by frictionally stable, aseismic processes vs. those hypothesized to be frictionally locked (seismogenic) faults of the megathrust system. The transect includes primary drill sites from the incoming plate, across the outer accretionary complex of the lower slope, to the Kumano forearc basin and underlying up-dip end of the likely locked plate interface. The scale of this project required a division into multiple stages of operations, spanning a number of years and IODP expeditions. From September 2007 through October 2009, the NanTroSEIZE science team has achieved many of its primary goals during 5 expeditions. Completed drill sites to date include penetrations ranging from ~200 m to ~1600 m below the sea floor that have documented the faults and wall rocks of both the frontal thrust and out-of-sequence splay faults in the accretionary system, the sedimentary section of the subducting plate, and the thick forearc basin sedimentary record and underlying older subduction complex in the hanging wall of the main plate interface. Major results include characterization of: the fault zone geology, strain localization, and physical properties shallower than ~ 1 km, the distribution of ambient (and paleo-) stress orientations across the transect, the absence of evidence for focused fluid channeling along the principal shallow fault systems, and the tectonic history of the subduction system. Extensive downhole measurements and a 2-ship VSP have further documented stress, pressure, rock strength, and elastic properties around the boreholes. The first temporary long-term monitoring instruments are now in place in one sealed borehole, recording pore pressure and temperature. The most ambitious aspect of the NanTroSEIZE project remains for the now-scheduled next stage: drilling to ~ 7000 m below the sea bed across the faults of the main plate boundary, then placing long-term monitoring instruments into both deep and shallow sealed borehole observatories - all to test hypotheses of locking, strain accumulation, and interseismic fault processes.

Conventional plate fixation method versus pre-operative virtual simulation and three-dimensional printing-assisted contoured plate fixation method in the treatment of anterior pelvic ring fracture.

PubMed

Hung, Chun-Chi; Li, Yuan-Ta; Chou, Yu-Ching; Chen, Jia-En; Wu, Chia-Chun; Shen, Hsain-Chung; Yeh, Tsu-Te

2018-05-03

Treating pelvic fractures remains a challenging task for orthopaedic surgeons. We aimed to evaluate the feasibility, accuracy, and effectiveness of three-dimensional (3D) printing technology and computer-assisted virtual surgery for pre-operative planning in anterior ring fractures of the pelvis. We hypothesized that using 3D printing models would reduce operation time and significantly improve the surgical outcomes of pelvic fracture repair. We retrospectively reviewed the records of 30 patients with pelvic fractures treated by anterior pelvic fixation with locking plates (14 patients, conventional locking plate fixation; 16 patients, pre-operative virtual simulation with 3D, printing-assisted, pre-contoured, locking plate fixation). We compared operative time, instrumentation time, blood loss, and post-surgical residual displacements, as evaluated on X-ray films, among groups. Statistical analyses evaluated significant differences between the groups for each of these variables. The patients treated with the virtual simulation and 3D printing-assisted technique had significantly shorter internal fixation times, shorter surgery duration, and less blood loss (- 57 minutes, - 70 minutes, and - 274 ml, respectively; P < 0.05) than patients in the conventional surgery group. However, the post-operative radiological result was similar between groups (P > 0.05). The complication rate was less in the 3D printing group (1/16 patients) than in the conventional surgery group (3/14 patients). The 3D simulation and printing technique is an effective and reliable method for treating anterior pelvic ring fractures. With precise pre-operative planning and accurate execution of the procedures, this time-saving approach can provide a more personalized treatment plan, allowing for a safer orthopaedic surgery.

Surgical treatment of comminuted mandibular fractures using a low-profile locking mandibular reconstruction plate system

PubMed Central

Kanno, Takahiro; Sukegawa, Shintaro; Nariai, Yoshiki; Tatsumi, Hiroto; Ishibashi, Hiroaki; Furuki, Yoshihiko; Sekine, Joji

2014-01-01

Objective: The treatment of comminuted mandibular fractures is challenging due to the severity of associated injuries and the need for a careful diagnosis with adequate treatment planning. Recently, open reduction and stable internal fixation (OR-IF) with a load-bearing reconstruction plate have been advocated for reliable clinical outcomes with minimal complications. This clinical prospective study evaluated OR-IF in the surgical management of comminuted mandibular fractures with a new low-profile, thin, mandibular locking reconstruction plate. Materials and Methods: We prospectively assessed OR-IF of comminuted mandibular fractures with a low-profile locking mandibular reconstruction plate in 12 patients (nine men, three women; mean age 32.2 [range 16-71] years) between April 2010 and December 2011. The clinical characteristics and associated clinical parameters of patients were evaluated over a minimum follow-up period of 12 months. Results: Traffic accidents caused 50% of the fractures, followed by falls (25%). Four patients (33.3%) had associated midfacial maxillofacial fractures, while five patients had other mandibular fractures. Seven patients (58.3%) needed emergency surgery, mostly for airway management. Anatomical reduction of the comminuted segments re-established the mandibular skeleton in stable occlusion with rigid IF via extraoral (33.3%), intraoral (50%), or combined (16.7%) approaches. Immediate functional recovery was achieved. Sound bone healing was confirmed in all patients, with no complications such as malocclusion, surgical site infection, or malunion with a mean follow-up of 16.3 (range 12-24) months. Conclusions: OR-IF using a low-profile reconstruction plate system is a reliable treatment for comminuted mandibular fractures, enabling immediate functional recovery with good clinical results. PMID:25593862

Locking plate fixation in distal metaphyseal tibial fractures: series of 79 patients.

PubMed

Gupta, Rakesh K; Rohilla, Rajesh Kumar; Sangwan, Kapil; Singh, Vijendra; Walia, Saurav

2010-12-01

Open reduction and internal fixation in distal tibial fractures jeopardises fracture fragment vascularity and often results in soft tissue complications. Minimally invasive osteosynthesis, if possible, offers the best possible option as it permits adequate fixation in a biological manner. Seventy-nine consecutive adult patients with distal tibial fractures, including one patient with a bilateral fracture of the distal tibia, treated with locking plates, were retrospectively reviewed. The 4.5-mm limited-contact locking compression plate (LC-LCP) was used in 33 fractures, the metaphyseal LCP in 27 fractures and the distal medial tibial LCP in the remaining 20 fractures. Fibula fixation was performed in the majority of comminuted fractures (n = 41) to maintain the second column of the ankle so as to achieve indirect reduction and to prevent collapse of the fracture. There were two cases of delayed wound breakdown in fractures fixed with the 4.5-mm LC-LCP. Five patients required primary bone grafting and three patients required secondary bone grafting. All cases of delayed union (n = 7) and nonunion (n = 3) were observed in cases where plates were used in bridge mode. Minimally invasive plate osteosynthesis (MIPO) with LCP was observed to be a reliable method of stabilisation for these fractures. Peri-operative docking of fracture ends may be a good option in severely impacted fractures with gap. The precontoured distal medial tibial LCP was observed to be a better tolerated implant in comparison to the 4.5-mm LC-LCP or metaphyseal LCP with respect to complications of soft tissues, bone healing and functional outcome, though its contour needs to be modified.

Space Shuttle Columbia Aging Wiring Failure Analysis

NASA Technical Reports Server (NTRS)

McDaniels, Steven J.

2005-01-01

A Space Shuttle Columbia main engine controller 14 AWG wire short circuited during the launch of STS-93. Post-flight examination divulged that the wire had electrically arced against the head of a nearby bolt. More extensive inspection revealed additional damage to the subject wire, and to other wires as well from the mid-body of Columbia. The shorted wire was to have been constructed from nickel-plated copper conductors surrounded by the polyimide insulation Kapton, top-coated with an aromatic polyimide resin. The wires were analyzed via scanning electron microscope (SEM), energy dispersive X-Ray spectroscopy (EDX), and electron spectroscopy for chemical analysis (ESCA); differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were performed on the polyimide. Exemplar testing under laboratory conditions was performed to replicate the mechanical damage characteristics evident on the failed wires. The exemplar testing included a step test, where, as the name implies, a person stepped on a simulated wire bundle that rested upon a bolt head. Likewise, a shear test that forced a bolt head and a torque tip against a wire was performed to attempt to damage the insulation and conductor. Additionally, a vibration test was performed to determine if a wire bundle would abrade when vibrated against the head of a bolt. Also, an abrasion test was undertaken to determine if the polyimide of the wire could be damaged by rubbing against convolex helical tubing. Finally, an impact test was performed to ascertain if the use of the tubing would protect the wire from the strike of a foreign object.

Biomechanical Comparison Study of Three Fixation Methods for Proximal Chevron Osteotomy of the First Metatarsal in Hallux Valgus

PubMed Central

Kim, Jin Su; Young, Ki Won; Kim, Ji Soo; Lee, Kyung Tai

2017-01-01

Background Fixation of proximal chevron metatarsal osteotomy has been accomplished using K-wires traditionally and with a locking plate recently. However, both methods have many disadvantages. Hence, we developed an intramedullary fixation technique using headless cannulated screws and conducted a biomechanical study to evaluate the superiority of the technique to K-wire and locking plate fixations. Methods Proximal chevron metatarsal osteotomy was performed on 30 synthetic metatarsal models using three fixation techniques. Specimens in group I were fixated with K-wires (1.6 mm × 2) and in group II with headless cannulated screws (3.0 mm × 2) distally through the intramedullary canal. Specimens in group III were fixated with a locking X-shaped plate (1.3-mm thick) and screws (2.5 mm × 4). Eight metatarsal specimens were selected from each group for walking fatigue test. Bending stiffness and dorsal angulation were measured by 1,000 repetitions of a cantilever bending protocol in a plantar to dorsal direction. The remaining two samples from each group were subjected to 5 mm per minute axial loading to assess the maximal loading tolerance. Results All samples in group I failed walking fatigue test while group II and group III tolerated the walking fatigue test. Group II showed greater resistance to bending force and smaller dorsal angulation than group III (p = 0.001). On the axial loading test, group I and group II demonstrated superior maximum tolerance to group III (54.8 N vs. 47.2 N vs. 28.3 N). Conclusions Authors have demonstrated proximal chevron metatarsal osteotomy with intramedullary screw fixation provides superior biomechanical stability to locking plate and K-wire fixations. The new technique using intramedullary screw fixation can offer robust fixation and may lead to better outcomes in surgical treatment of hallux valgus. PMID:29201305

Interactions between strike-slip earthquakes and the subduction interface near the Mendocino Triple Junction

NASA Astrophysics Data System (ADS)

Gong, Jianhua; McGuire, Jeffrey J.

2018-01-01

The interactions between the North American, Pacific, and Gorda plates at the Mendocino Triple Junction (MTJ) create one of the most seismically active regions in North America. The earthquakes rupture all three plate boundaries but also include considerable intraplate seismicity reflecting the strong internal deformation of the Gorda plate. Understanding the stress levels that drive these ruptures and estimating the locking state of the subduction interface are especially important topics for regional earthquake hazard assessment. However owing to the lack of offshore seismic and geodetic instruments, the rupture process of only a few large earthquakes near the MTJ have been studied in detail and the locking state of the subduction interface is not well constrained. In this paper, first, we use the second moments inversion method to study the rupture process of the January 28, 2015 Mw 5.7 earthquake on the Mendocino transform fault that was unusually well recorded by both onshore and offshore strong motion instruments. We estimate the rupture dimension to be approximately 6 km by 3 km corresponding to a stress drop of ∼4 MPa for a crack model. Next we investigate the frictional state of the subduction interface by simulating the afterslip that would be expected there as a result of the stress changes from the 2015 earthquake and a 2010 Mw 6.5 intraplate earthquake within the subducted Gorda plate. We simulate afterslip scenarios for a range of depths of the downdip end of the locked zone defined as the transition to velocity strengthening friction and calculate the corresponding surface deformation expected at onshore GPS monuments. We can rule out a very shallow downdip limit owing to the lack of a detectable signal at onshore GPS stations following the 2010 earthquake. Our simulations indicate that the locking depth on the slab surface is at least 14 km, which suggests that the next M8 earthquake rupture will likely reach the coastline and strong shaking should be expected there.

Assessment of Optimum Value for Dip Angle and Locking Rate Parameters in Makran Subduction Zone

NASA Astrophysics Data System (ADS)

Safari, A.; Abolghasem, A. M.; Abedini, N.; Mousavi, Z.

2017-09-01

Makran subduction zone is one of the convergent areas that have been studied by spatial geodesy. Makran zone is located in the South Eastern of Iran and South of Pakistan forming the part of Eurasian-Arabian plate's border where oceanic crust in the Arabian plate (or in Oman Sea) subducts under the Eurasian plate ( Farhoudi and Karig, 1977). Due to lack of historical and modern tools in the area, a sampling of sparse measurements of the permanent GPS stations and temporary stations (campaign) has been conducted in the past decade. Makran subduction zone from different perspectives has unusual behaviour: For example, the Eastern and Western parts of the region have very different seismicity and also dip angle of subducted plate is in about 2 to 8 degrees that this value due to the dip angle in other subduction zone is very low. In this study, we want to find the best possible value for parameters that differs Makran subduction zone from other subduction zones. Rigid block modelling method was used to determine these parameters. From the velocity vectors calculated from GPS observations in this area, block model is formed. These observations are obtained from GPS stations that a number of them are located in South Eastern Iran and South Western Pakistan and a station located in North Eastern Oman. According to previous studies in which the locking depth of Makran subduction zone is 38km (Frohling, 2016), in the preparation of this model, parameter value of at least 38 km is considered. With this function, the amount of 2 degree value is the best value for dip angle but for the locking rate there is not any specified amount. Because the proposed model is not sensitive to this parameter. So we can not expect big earthquakes in West of Makran or a low seismicity activity in there but the proposed model definitely shows the Makran subduction layer is locked.

Outcomes of Pin and Plaster Versus Locking Plate in Distal Radius Intraarticular Fractures

PubMed Central

Bahari-Kashani, Mahmoud; Taraz-Jamshidy, Mohammad Hosein; Rahimi, Hassan; Ashraf, Hami; Mirkazemy, Masoud; Fatehi, Amirreza; Asadian, Mariam; Rezazade, Jafar

2013-01-01

Background Distal radius fractures are among the most prevalent fractures predictive of probable occurrence of other osteoporotic fractures. They are treated via a variety of methods, but the best treatment has not been defined yet. Objectives This study was performed to compare the results of open reduction and internal fixation with locking plates versus the pin and plaster method. Materials and Methods In this prospective study, 114 patients aged 40 to 60 years with Fernandez type III fracture referring to Imam-Reza and Mehr hospitals of Mashhad from 2009 to 2011, were selected randomly; after obtaining informed consent, they were treated with pin and plaster fixation (n = 57) or internal fixation with the volar locking plate (n = 57). They were compared at the one year follow up. Demographic features and standard radiographic indices were recorded and MAYO, DASH and SF - 36 tests were performed. Data was analyzed by SPSS software version 13, with descriptive indices, Mann-Whitney and Chi-square tests. Results SF-36 test demonstrated a better general health (P < 0.001), mental health (P = 0.006), physical functioning (P < 0.001), social functioning (P < 0.001) and energy/fatigue (P < 0.001) in LCP group. However, pain (P = 0.647) was not significantly different between the groups. Physical limitation (P < 0.001) and emotional limitation (P < 0.001) were greater in the pin and plaster group. Also, in the LCP group mean MAYO score (P < 0.001) was more than pin and plaster group. Mean DASH score was not different between the groups (P = 0.218). The rate of acceptable results of radiographic indices (P < 0.001), grip strength (P < 0.001) and range of motion in supination-pronation (P < 0.001) in LCP method were better than the pin and plaster method. Conclusions In treatment of intra-articular distal radius fractures in middle-aged patients internal fixation with locking plates may be prefered to pin and plaster as the treatment of choice. PMID:24350132

Impact of double-tiered subchondral support procedure with a polyaxial locking plate on the stability of distal radius fractures using fresh cadaveric forearms: Biomechanical and radiographic analyses.

PubMed

Tsutsui, Sadaaki; Kawasaki, Keikichi; Yamakoshi, Ken-Ichi; Uchiyama, Eiichi; Aoki, Mitsuhiro; Inagaki, Katsunori

2016-09-01

The present study compared the changes in biomechanical and radiographic properties under cyclic axial loadings between the 'double-tiered subchondral support' (DSS) group (wherein two rows of screws were used) and the 'non-DSS' (NDSS) group (wherein only one row of distal screws was used) using cadaveric forearm models of radius fractures fixed with a polyaxial locking plate. Fifteen fresh cadaveric forearms were surgically operated to generate an Arbeitsgemeinschaft für Osteosynthesefragen (AO) type 23-C2 fracture model with the fixation of polyaxial volar locking plates. The model specimens were randomized into two groups: DSS (n = 7) and NDSS (n = 8). Both the groups received 4 locking screws in the most distal row, as is usually applied, whereas the DSS group received 2 additional screws in the second row inserted at an inclination of about 15° to support the dorsal aspect of the dorsal subchondral bone. Cyclic axial compression test was performed (3000 cycles; 0-250 N; 60 mm/min) to measure absolute rigidity and displacement, after 1, 1000, 2000 and 3000 cycles, and values were normalized relative to cycle 1. These absolute and normalized values were compared between those two groups. Radiographic images were taken before and after the cyclic loading to measure changes in volar tilt (ΔVT) and radial inclination (ΔRI). The DSS group maintained significantly higher rigidity and lower displacement values than the NDSS group during the entire loading period. Radiographic analysis indicated that the ΔVT values of the DSS group were lower than those of the NDSS group. In contrast, the fixation design did not influence the impact of loading on the ΔRI values. Biomechanical and radiographic analyses demonstrated that two rows of distal locking screws in the DSS procedure conferred higher stability than one row of distal locking screws. Copyright © 2016 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.

[Development and clinical application of a new type of anatomical locking plate for sternoclavicular joint fracture and dislocation].

PubMed

Sun, Yuanlin; Yang, Yunkang; Ge, Jianhua; Yang, Kun; Xiang, Feifan; Zhou, Ju; Liang, Jie

2018-03-01

To report a new type of anatomical locking plate for sternocalvicular joint, and investigate its effectiveness in treatment of sternoclavicular joint fracture and dislocation. A new type of anatomical locking plate for sternoclavicular joint was developed, which accorded with the anatomical features and biomechanical characteristics of Chinese sternoclavicular joint. By adopting the method of clinical randomized controlled study, 32 patients with the sternoclavicular joint fracture and dislocation who met the selection criteria between June 2008 and May 2015 were randomly divided into groups A and B ( n =16), and the patients were treated with new anatomic locking plate and distal radial T locking plate internal fixation, respectively. There was no significant difference between 2 groups in gender, age, injured side, body mass index, cause of injury, type of injury, the time from injury to operation, and preoperative Rockwood grading score ( P >0.05). The operation time, intraoperative blood loss, incision length, hospitalization time, and postoperative complications in 2 groups were recorded, and the effectiveness was evaluated by Rockwood grading score. The operations of 2 groups completed successfully. The operation time, intraoperative blood loss, and hospitalization time in group A were significantly less than those in group B ( P <0.05), but there was no significant difference in the incision length between 2 groups ( t =0.672, P =0.507). All the patients were followed up 18-30 months (mean, 24 months). In group A, there were 1 case of sternoclavicular joint pain and 2 cases of wound infection; in group B, there were 1 case of sternoclavicular joint pain, 1 case of internal fixation loosening, and 1 case of sternoclavicular joint re-dislocation; there was no significant difference in complication incidence between 2 groups ( P =1.000). The Rockwood grading scores at each time point after operation in 2 groups were significantly higher than those before operation. At 1 month after operation, the Rockwood grading score in group A was significantly higher than that in group B ( t= 2.270, P =0.031); but there was no significant difference in the Rockwood grading scores between the 2 groups at 6 months and at last follow-up ( P >0.05). At last follow-up, according to the Rockwood scoring standard, the results of group A were excellent in 13 cases, good in 2 cases, poor in 1 case, the excellent and good rate was 93.75%; the results of group B were excellent in 11 cases, good in 4 cases, poor in 1 case, and the excellent and good rate was 93.75%; there was no significant difference between 2 groups ( Z =-0.748， P =0.455). The new type of anatomic locking plate accords with the Chinese anatomical characteristics. It has the advantages of easy operative procedure, less surgical trauma, shorter operation time, less intraoperative blood loss, shorter hospitalization time, and it can achieve better results in the treatment of sternoclavicular joint fracture and dislocation.

VIEW SHOWING THE ENTRY THROUGH THE RETAINING WALL (FOREGROUND) TO ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW SHOWING THE ENTRY THROUGH THE RETAINING WALL (FOREGROUND) TO THE CONCRETE SLAB. NOTE THE 1¾" MOUNTING BOLTS FOR THE STEEL PLATE BASE OF THE 5" GUN, SET IN THE GUN BLOCK. STEEL REINFORCING RODS PROTRUDING FROM THE BROKEN TOPS OF THE RETAINING WALLS ARE ALSO VISIBLE. VIEW FACING EAST - U.S. Naval Base, Pearl Harbor, Ford Island 5-Inch Antiaircraft Battery, South Gun Emplacement, Ford Island, Pearl City, Honolulu County, HI

A Multidisciplinary Approach to Health Monitoring and Materials Damage Prognosis for Metallic Aerospace Systems

DTIC Science & Technology

2013-03-01

framework of orientation distribution functions and crack-induced texture o Quantify effects of temperature on damage behavior and damage monitoring...measurement model was obtained from hidden Markov modeling (HMM) of joint time-frequency (TF) features extracted from the PZT sensor signals using the...considered PZT sensor signals recorded from a bolted aluminum plate. About only 20% of the samples of a signal were first randomly selected as

Dimensional Analysis of Impulse Loading Resulting from Detonation of Shallow-Buried Charges

DTIC Science & Technology

2013-01-01

lines running along the floor, floor-bolted seats , ammunition storage racks, power-train lines, etc.). MMMS 9,3 368 Traditionally, the floor-rupture...The power of dimensional analysis is that the functional relations offered are generalized, i.e. the effect of geometrical, kinematic , ambient, loading... ejected vdet Explosive detonation velocity L/T A new quantity added which controls the time of sand-overburden bubble burst Charge/plate positioning

History of internal fixation with plates (part 2): new developments after World War II; compressing plates and locked plates.

PubMed

Hernigou, Philippe; Pariat, Jacques

2017-07-01

The first techniques of operative fracture with plates were developed in the 19th century. In fact, at the beginning these methods consisted of an open reduction of the fracture usually followed by a very unstable fixation. As a consequence, the fracture had to be opened with a real risk of (sometimes lethal) infection, and due to unstable fixation, protection with a cast was often necessary. During the period between World Wars I and II, plates for fracture fixation developed with great variety. It became increasingly recognised that, because a fracture of a long bone normally heals with minimal resorption at the bone ends, this may result in slight shortening and collapse, so a very rigid plate might prevent such collapse. However, as a consequence, delayed healing was observed unless the patient was lucky enough to have the plate break. One way of dealing with this was to use a slotted plate in which the screws could move axially, but the really important advance was recognition of the role of compression. After the first description of compression by Danis with a "coapteur", Bagby and Müller with the AO improved the technique of compression. The classic dynamic compression plates from the 1970s were the key to a very rigid fixation, leading to primary bone healing. Nevertheless, the use of strong plates resulted in delayed union and the osteoporosis, cancellous bone, comminution, and/or pathological bone resulted in some failures due to insufficient stability. Finally, new devices represented by locking plates increased the stability, contributing to the principles of a more biological osteosynthesis while giving enough stability to allow immediate full weight bearing in some patients.

Crustal Deformation Rates and Mountain Building In Southern Alaska

NASA Astrophysics Data System (ADS)

Sauber, J.; Pavlis, T.; King, R.

In southern Alaska the northwest directed subduction of the Pacific plate, vp=51mm/yr,isaccompaniedbyaccretionoftheYakutatterranetocontinentalAlaska (va, 33-44mm/yr). The convergence, va, has been accommodated within a deforming zone that becomes increasingly wider and topographically lower from east to west (width, 80 to 120 km; average topographic height, 2500 to 1100m, respectively, Meigs and Sauber, 2000). This systematic change is correlated with an increase in the length of the shallowly dipping segment of the downgoing plate, a divergence of ma- jor upper plate structures, and a decrease in the obliquity of the Pacific plate motion relative to interior Alaska. In the Yakataga and Yakutat segments of the Pacific-North American plate boundary zone of south central Alaska recent crustal shortening and strike-slip faulting occurs offshore in the Gulf of Alaska (1970, MW =6.7; 1987-1988, MS = 6.9, 7.6, 7.6) and onshore in the Chugach-St. Elias mountains (1979, MS = 7.2). Prior great earthquakes in the region occurred in 1899 (MW = 8.1, Yakataga; MW = 8.1, Yakutat Bay). We have used GPS observations made between 1993 and 2001 to estimate short-term deformation rates. For coastal sites the horizontal defor- mation rate and orientation range from 26 to 36 mm/yr at N30-43W and the vertical uplift rates range from 6 to 23 mm/yr. Further inland above the down-dip portion of the locked zone the rate decreases to 8-15 mm/yr and the orientation is N15-26W. Fi- nite element modeling was used to calculate deformation rates and stresses associated with a shallow locked zone ( 40 km) and with ice mass fluctuations. If the elastic strain accumulated on the locked plate interface since the two 1899 earthquakes was seismically released on a single fault, it would correspond to a M 8.0 earthquake.

Development of stiffer and ductile glulam portal frame

NASA Astrophysics Data System (ADS)

Komatsu, Kohei

2017-11-01

Portal frame structures, which are constituted of straight glulam beams and columns connected semi-rigidly by steel insert gusset plate with a lot of drift pins, were the first successful glulam structures widely used in Japan. In addition to this connection system, the author invented also a new type of jointing devise for glulam structures named as "Lagscrewbolt" which had a full threaded portion at inner part to grip wooden member as well as another thread part at the end of shank to connect with other member. The initial type of "Lagscrewbolt" was successfully applied to a various types of glulam buildings which could be rapidly built-up on construction site. Its strength performance, however, was rather brittle therefore the improvement of the ductility was a crucial research subject. In order to give a sufficient ductility on the "Lagscrewbolted joint system", so-called "Slotted Bolted Connection" concept was adopted for making use of large energy dissipation characteristics due to high-tension bolted steel connection with slotted bolt holes. Static & dynamic performance of glulam portal frame specimens was evaluated by static cyclic loading test as well as shaking table test. Current latest form of the jointing system can show very high ductility as well as stable hysteretic cyclic loops by inserting brass-shim between steel-to-steel friction interfaces

Strong Ground Motion Analysis and Afterslip Modeling of Earthquakes near Mendocino Triple Junction

NASA Astrophysics Data System (ADS)

Gong, J.; McGuire, J. J.

2017-12-01

The Mendocino Triple Junction (MTJ) is one of the most seismically active regions in North America in response to the ongoing motions between North America, Pacific and Gorda plates. Earthquakes near the MTJ come from multiple types of faults due to the interaction boundaries between the three plates and the strong internal deformation within them. Understanding the stress levels that drive the earthquake rupture on the various types of faults and estimating the locking state of the subduction interface are especially important for earthquake hazard assessment. However due to lack of direct offshore seismic and geodetic records, only a few earthquakes' rupture processes have been well studied and the locking state of the subducted slab is not well constrained. In this study we first use the second moment inversion method to study the rupture process of the January 28, 2015 Mw 5.7 strike slip earthquake on Mendocino transform fault using strong ground motion records from Cascadia Initiative community experiment as well as onshore seismic networks. We estimate the rupture dimension to be of 6 km by 3 km and a stress drop of 7 MPa on the transform fault. Next we investigate the frictional locking state on the subduction interface through afterslip simulation based on coseismic rupture models of this 2015 earthquake and a Mw 6.5 intraplate eathquake inside Gorda plate whose slip distribution is inverted using onshore geodetic network in previous study. Different depths for velocity strengthening frictional properties to start at the downdip of the locked zone are used to simulate afterslip scenarios and predict the corresponding surface deformation (GPS) movements onshore. Our simulations indicate that locking depth on the slab surface is at least 14 km, which confirms that the next M8 earthquake rupture will likely reach the coastline and strong shaking should be expected near the coast.

Behavior of Fiber Glass Bolts, Rock Bolts and Cable Bolts in Shear

NASA Astrophysics Data System (ADS)

Li, Xuwei; Aziz, Naj; Mirzaghorbanali, Ali; Nemcik, Jan

2016-07-01

This paper experimentally compares the shear behavior of fiber glass (FG) bolt, rock bolt (steel rebar bolt) and cable bolt for the bolt contribution to bolted concrete surface shear strength, and bolt failure mode. Two double shear apparatuses of different size were used for the study. The tensile strength, the shear strength and the deformation modulus of bolt control the shear behavior of a sheared bolted joint. Since the strength and deformation modulus of FG bolt, rock bolt and cable bolt obtained from uniaxial tensile tests are different, their shear behavior in reinforcing joints is accordingly different. Test results showed that the shear stiffness of FG bolted joints decreased gradually from the beginning to end, while the shear stiffness of joints reinforced by rock bolt and cable bolt decreased bi-linearly, which is clearly consistent with their tensile deformation modulus. The bolted joint shear stiffness was highly influenced by bolt pretension in the high stiffness stage for both rock bolt and cable bolt, but not in the low stiffness stage. The rock bolt contribution to joint shear strength standardised by the bolt tensile strength was the largest, followed by cable bolts, then FG bolts. Both the rock bolts and cable bolts tended to fail in tension, while FG bolts in shear due to their low shear strength and constant deformation modulus.

Knee arthrodesis using a short locked intramedullary nail. A new technique.

PubMed

Cheng, S L; Gross, A E

1995-01-01

This article reports on the use of a new intramedullary nail designed specifically for fixation of knee fusions. The nail is a short locked stainless steel nail that is inserted through a single anterior knee incision and uses an outrigger targeting rod to guide the insertion of the locking screws. The successful use of this technique is illustrated in two cases. The advantages of this nail compared with previously reported techniques of fixation for knee fusions are that the short locked nail avoids the second incision required for the insertion of long knee fusion nails, the bulkiness of the double plating technique in the relatively subcutaneous anterior knee area, and the difficulties inherent with the prolonged use of pins for external fixation.

High Reliability Robot Friendly ORU Interface

NASA Technical Reports Server (NTRS)

Voellmer, George M. (Inventor)

1991-01-01

Presented here is a robot friendly coupling device for an orbital replacement unit (ORU). The invention will provide a coupling that is detached and attached remotely by a robot. The design of the coupling must allow for slight misalignments, over-torque protection, and precision placement. This is accomplished by means of a triangular interface comprising three components. A base plate assembly is located on an attachment surface, such as a satellite. The base plate assembly has a cup member, a slotted member, and a post member. The ORU that the robot attaches to the base plate assembly has an ORU plate assembly with two cone members and a post member which mate to the base plate assembly. As the two plates approach one another, one cone member of the ORU plate assembly has to be placed accurately enough to fall into the cup member of the base plate assembly. The cup member forces alignment until a second cone falls into a slotted member which provides final alignment. A single bolt is used to attach the two plates. Two deflecting plates are attached to the backs of the plates. When pressure is applied to the center of the deflecting plates, the force is distributed preventing the ORU and base plates from deflecting. This accounts for precision in the placement of the article. The novelty is believed to reside in using deflecting plates in conjunction with kinematic mounts to provide distributed forces to the two members.

Utility of cement injection to stabilize split-depression tibial plateau fracture by minimally invasive methods: A finite element analysis.

PubMed

Belaid, D; Vendeuvre, T; Bouchoucha, A; Brémand, F; Brèque, C; Rigoard, P; Germaneau, A

2018-05-08

Treatment for fractures of the tibial plateau is in most cases carried out by stable fixation in order to allow early mobilization. Minimally invasive technologies such as tibioplasty or stabilization by locking plate, bone augmentation and cement filling (CF) have recently been used to treat this type of fracture. The aim of this paper was to determine the mechanical behavior of the tibial plateau by numerically modeling and by quantifying the mechanical effects on the tibia mechanical properties from injury healing. A personalized Finite Element (FE) model of the tibial plateau from a clinical case has been developed to analyze stress distribution in the tibial plateau stabilized by balloon osteoplasty and to determine the influence of the cement injected. Stress analysis was performed for different stages after surgery. Just after surgery, the maximum von Mises stresses obtained for the fractured tibia treated with and without CF were 134.9 MPa and 289.9 MPa respectively on the plate. Stress distribution showed an increase of values in the trabecular bone in the treated model with locking plate and CF and stress reduction in the cortical bone in the model treated with locking plate only. The computed results of stresses or displacements of the fractured models show that the cement filling of the tibial depression fracture may increase implant stability, and decrease the loss of depression reduction, while the presence of the cement in the healed model renders the load distribution uniform. Copyright © 2018 Elsevier Ltd. All rights reserved.

Using external and internal locking plates in a two-stage protocol for treatment of segmental tibial fractures.

PubMed

Ma, Ching-Hou; Tu, Yuan-Kun; Yeh, Jih-Hsi; Yang, Shih-Chieh; Wu, Chin-Hsien

2011-09-01

The tibial segmental fractures usually follow high-energy trauma and are often associated with many complications. We designed a two-stage protocol for these complex injuries. The aim of this study was to assess the outcome of tibial segmental fractures treated according to this protocol. A prospective series of 25 consecutive segmental tibial fractures were treated using a two-stage procedure. In the first stage, a low-profile locking plate was applied as an external fixator to temporarily immobilize the fractures after anatomic reduction had been achieved followed by soft-tissue reconstruction. The second stage involved definitive internal fixation with a locking plate using a minimally invasive percutaneous plate osteosynthesis technique. The median follow-up was 32 months (range, 20-44 months). All fractures achieved union. The median time for the proximal fracture union was 23 weeks (range, 12-30 weeks) and that for distal fracture union was 27 weeks (range, 12-46 weeks; p = 0.08). Functional results were excellent in 21 patients and good in 4 patients. There were three cases of delayed union of distal fracture. Valgus malunion >5 degrees occurred in two patients, and length discrepancy >1 cm was observed in two patients. Pin tract infection occurred in three patients. Use of the two-stage procedure for treatment of segmental tibial fractures is recommended. Surgeons can achieve good reduction with stable temporary fixation, soft-tissue reconstruction, ease of subsequent definitive fixation, and high union rates. Our patients obtained excellent knee and ankle joint motion, good functional outcomes, and a comfortable clinical course.

Lithospheric Structure and Isostasy of Central Andes: Implication for plate Coupling

NASA Astrophysics Data System (ADS)

Mahatsente, R.; Rutledge, S.

2017-12-01

A significant section of the Peru-Chile convergent zone is building up stresses. The interseismic coupling in northern and southern Peru is significantly high indicating, elastic energy accumulation since the 1746 and 1868 earthquakes of magnitude 8.6 and 8.8 , respectively. Similar seismic patterns have also been observed in Central Chile. The plate interface beneath Central Chile is highly coupled, and the narrow zones of low coupling separate seismic gaps. The reasons for the seismic gaps and plate coupling are yet unknown, but the configuration of the slab is thought to be the main factor. Here, we assessed the locking mechanism and isostatic state of the Central Andes based on gravity models of the crust and upper mantle structure. The density models are based on satellite gravity data and are constrained by velocity models and earthquake hypocenters. The gravity models indicate a high-density batholithic structure in the fore-arc, overlying the subducting Nazca plate. This high-density body pushes downward on the slab, causing the slab to lock with the overlying continental plate. The increased compressive stress closer to the trench, due to the increased contact area between the subducting and overriding plates, may have increased the plate coupling in the Central Andes. Thus, trench parallel crustal thickness and density variations along the Central Andes and buoyancy force on the subducting Nazca plate may control plate coupling and asperity generation. The western part of the Central Andes may be undercompensated. There is a residual topography of 800 m in the western part of the Central Andes that cannot be explained by the observed crustal thicknesses. Thus, part of the observed topography in the western part of the Central Andes may be dynamically supported by mantle wedge flow below the overriding plate.

Arthroscopic-assisted Locking Compression Plate clavicular hook fixation for unstable fractures of the lateral end of the clavicle: a prospective study

PubMed Central

Lee, Kwang Won; Kim, Kap Jung; Kim, Yong In; Kwon, Won Cho; Choy, Won Sik

2009-01-01

The aim of this prospective study was to assess the clinical outcomes of an unstable fracture of the lateral end of the clavicle treated with an arthroscopic-assisted locking compressive plate (LCP) clavicular hook plate. Twenty-three patients underwent arthroscopic assisted LCP clavicular hook plate fixation for these fractures. All patients achieved clinical and radiological union over a mean of 4.2 months (range, 3.4–5 months). Four patients (17%) showed some degree of acromial osteolysis. Three patients (13%) showed radiological signs of arthrosis of the acromioclavicular joint. In one patient, a second fracture (stress) was observed between the medial two screws of the plate without an additional injury. Five patients (22%) showed subacromial bursitis on dynamic ultrasonography. The mean Constant and Murley score was 91 points (range, 81–98). The average level of pain in the shoulder at rest and on abduction was 1 (range, 0–2) and 2.4 (range, 0–4), respectively. Based on our experience, arthroscopic-assisted LCP hook plate fixation for the treatment of unstable fractures of the lateral end of the clavicle is not without complications. However, it is an acceptable alternative method that is easy to apply with good results. Furthermore, it prevents rotator cuff impingement, allows early mobilisation and maintains the acromioclavicular joint biomechanics. PMID:19998033

Filling Open Screw Holes in the Area of Metaphyseal Comminution Does Not Affect Fatigue Life of the Synthes Variable Angle Distal Femoral Locking Plate in the AO/OTA 33-A3 Fracture Model.

PubMed

Grau, Luis; Collon, Kevin; Alhandi, Ali; Kaimrajh, David; Varon, Maria; Latta, Loren; Vilella, Fernando

2018-06-01

The aim of this study is to evaluate the biomechanical effect of filling locking variable angle (VA) screw holes at the area of metaphyseal fracture comminution in a Sawbones® (Sawbones USA, Vashon, Washington) model (AO/OTA 33A-3 fracture) using a Synthes VA locking compression plate (LCP) (Depuy Synthes, Warsaw, Indiana). Seven Sawbones® femur models had a Synthes VA-LCP placed as indicated by the manufacturers technique. A 4cm osteotomy was then created to simulate an AO/OTA 33-A3 femoral fracture pattern with metaphyseal comminution. The control group consisted of four constructs in which the open screw holes at the area of comminution were left unfilled; the experimental group consisted of three constructs in which the VA screw holes were filled with locking screws. One of the control constructs was statically loaded to failure at a rate of 5mm/min. A value equal to 75% of the ultimate load to failure was used as the loading force for fatigue testing of 250,000 cycles at 3Hz. Cycles to failure was recorded for each construct and averages were compared between groups. The average number of cycles to failure in the control and experimental groups were 37524±8187 and 43304±23835, respectively (p=0.72). No significant difference was observed with respect to cycles to failure or mechanism of failure between groups. In all constructs in both the control and experimental groups, plate failure reproducibly occurred with cracks through the variable angle holes in the area of bridged comminution. The Synthes VA-LCP in a simulated AO/OTA 33-A3 comminuted metaphyseal femoral fracture fails in a reproducible manner at the area of comminution through the "honeycomb" VA screw holes. Filling open VA screw holes at the site of comminution with locking screws does not increase fatigue life of the Synthes VA-LCP in a simulated AO/OTA 33-A3 distal femoral fracture. Further studies are necessary to determine whether use of this particular plate is contraindicated when bridging distal femoral fractures with metaphyseal comminution.

Dynamic locking screw improves fixation strength in osteoporotic bone: an in vitro study on an artificial bone model.

PubMed

Pohlemann, Tim; Gueorguiev, Boyko; Agarwal, Yash; Wahl, Dieter; Sprecher, Christoph; Schwieger, Karsten; Lenz, Mark

2015-04-01

The novel dynamic locking screw (DLS) was developed to improve bone healing with locked-plate osteosynthesis by equalising construct stiffness at both cortices. Due to a theoretical damping effect, this modulated stiffness could be beneficial for fracture fixation in osteoporotic bone. Therefore, the mechanical behaviour of the DLS at the screw-bone interface was investigated in an artificial osteoporotic bone model and compared with conventional locking screws (LHS). Osteoporotic surrogate bones were plated with either a DLS or a LHS construct consisting of two screws and cyclically axially loaded (8,500 cycles, amplitude 420 N, increase 2 mN/cycle). Construct stiffness, relative movement, axial screw migration, proximal (P) and distal (D) screw pullout force and loosening at the bone interface were determined and statistically evaluated. DLS constructs exhibited a higher screw pullout force of P 85 N [standard deviation (SD) 21] and D 93 N (SD 12) compared with LHS (P 62 N, SD 28, p = 0.1; D 57 N, SD 25, p < 0.01) and a significantly lower axial migration over cycles compared with LHS (p = 0.01). DLS constructs showed significantly lower axial construct stiffness (403 N/mm, SD 21, p < 0.01) and a significantly higher relative movement (1.1 mm, SD 0.05, p < 0.01) compared with LHS (529 N/mm, SD 27; 0.8 mm, SD 0.04). Based on the model data, the DLS principle might also improve in vivo plate fixation in osteoporotic bone, providing enhanced residual holding strength and reducing screw cutout. The influence of pin-sleeve abutment still needs to be investigated.

Analysis of a spaceborne mirror on a main plate with isostatic mounts

NASA Astrophysics Data System (ADS)

Chan, Chia-Yen; Lien, Chun-Chieh; Huang, Po-Hsuan; Chang, Shenq-Tsong; Huang, Ting-Ming

2014-09-01

The paper is aimed at obtaining the deformation results and optical aberration configurations of a spaceborne mirror made of ZERODUR® glass on a main plate with three isostatic mounts for a space Cassegrain telescope. On the rear side of the main plate four screws will be locked to fix the focal plane assembly. The locking modes for the four screws will be simulated as push and pull motions in the Z axis for simplification. The finite element analysis and Zernike polynomial fitting are applied to the whole integrated optomechanical analysis process. Under the analysis, three isostatic mounts are bonded to the neutral plane of the mirror. The deformation results and optical aberration configurations under six types of push and pull motions as well as self-weight loading have been obtained. In addition, the comparison between the results under push and pull motions with 0.01 mm and 0.1 mm displacements in Z axis will be attained.

Systemic Effects of Shock and Resuscitation Monitored by Visible Hyperspectral Imaging

DTIC Science & Technology

2003-01-01

organs. Its causes include hemorrhage, cardiac failure, sepsis, hypoglycemia , and burns; the pathophysiology of these various shock states is quite...different. Depending on the cause of shock, the skin is one organ that readily manifests its ef- fects. The importance of skin oxygenation is well known...attachment of a 7.5-cm-diameter plate to the bolt, was used to cause a blunt right chest injury. A tube thora- costomy was immediately performed. After a

Locking Compression Plate in Distal Femoral Intra-Articular Fractures: Our Experience

PubMed Central

Kiran Kumar, G. N.; Sharma, Gaurav; Farooque, Kamran; Sharma, Vijay; Ratan, Ratnav; Yadav, Sanjay; Lakhotia, Devendra

2014-01-01

Background. Intra-articular fractures of distal femur present a huge surgical challenge. The aim of this study is to evaluate functional outcome, fracture healing, and the complications of distal femoral intra-articular fractures using locking compression plates. Material and Methods. We reviewed 46 distal femoral fractures treated with distal femoral locking compression plates between 2009 to 2012. There were 36 men and 10 women with mean age of 35 years (range 20–72). More than half of the patients were of type C3 (AO classification) and had been caused by high energy trauma with associated injuries. Results. 2 patients were lost to follow-up. Of the remaining 44 patients, the mean follow-up period was 25 months (range 18–36). The mean time for radiological union was 12 weeks (range 10–18) except 2 patients which had gone for nonunion. At the latest follow up ROM >120° is noted in 32 patients, 90–120 in 10 patients, and 70–90 in 2 patients. 38 patients (86%) had good/excellent outcome. Conclusion. Use of standard lateral approach for simple intra-articular distal femoral fractures (C1) and transarticular/minimally invasive techniques for complex intra-articular fractures (C2/C3) results in improved exposure of the knee joint and better union rates with low incidence of bone grafting. PMID:27355064

Biomechanical Concepts for Fracture Fixation

PubMed Central

Bottlang, Michael; Schemitsch, Christine E.; Nauth, Aaron; Routt, Milton; Egol, Kenneth; Cook, Gillian E.; Schemitsch, Emil H.

2015-01-01

Application of the correct fixation construct is critical for fracture healing and long-term stability; however, it is a complex issue with numerous significant factors. This review describes a number of common fracture types, and evaluates their currently available fracture fixation constructs. In the setting of complex elbow instability, stable fixation or radial head replacement with an appropriately sized implant in conjunction with ligamentous repair is required to restore stability. For unstable sacral fractures, “standard” iliosacral screw fixation is not sufficient for fractures with vertical or multiplanar instabilities. Periprosthetic femur fractures, in particular Vancouver B1 fractures, have increased stability when using 90/90 fixation versus a single locking plate. Far Cortical Locking combines the concept of dynamization with locked plating in order to achieve superior healing of a distal femur fracture. Finally, there is no ideal construct for syndesmotic fracture stabilization; however, these fractures should be fixed using a device that allows for sufficient motion in the syndesmosis. In general, orthopaedic surgeons should select a fracture fixation construct that restores stability and promotes healing at the fracture site, while reducing the potential for fixation failure. PMID:26584263

Stress analysis and evaluation of a rectangular pressure vessel

NASA Astrophysics Data System (ADS)

Rezvani, M. A.; Ziada, H. H.; Shurrab, M. S.

1992-10-01

This study addresses structural analysis and evaluation of an abnormal rectangular pressure vessel, designed to house equipment for drilling and collecting samples from Hanford radioactive waste storage tanks. It had to be qualified according to ASME boiler and pressure vessel code, section 8; however, it had the cover plate bolted along the long face, a configuration not addressed by the code. Finite element method was used to calculate stresses resulting from internal pressure; these stresses were then used to evaluate and qualify the vessel. Fatigue is not a concern; thus, it can be built according to section 8, division 1 instead of division 2. Stress analysis was checked against the code. A stayed plate was added to stiffen the long side of the vessel.

Stability of radial head and neck fractures: a biomechanical study of six fixation constructs with consideration of three locking plates.

PubMed

Burkhart, Klaus Josef; Mueller, Lars P; Krezdorn, David; Appelmann, Philipp; Prommersberger, Karl J; Sternstein, Werner; Rommens, Pol M

2007-12-01

Open reduction and internal fixation of radial neck fractures can lead to secondary loss of reduction and nonunion due to insufficient stability. Nevertheless, there are only a few biomechanical studies about the stability achieved by different osteosynthesis constructs. Forty-eight formalin-fixed, human proximal radii were divided into 6 groups according to their bone density (measured by dual-energy x-ray absorptiometry). A 2.7-mm gap osteotomy was performed to simulate an unstable radial neck fracture, which was fixed with 3 nonlocking implants: a 2.4-mm T plate, a 2.4-mm blade plate, and 2.0-mm crossed screws, and 3 locking plates: a 2.0-mm LCP T plate, a 2.0-mm 6x2 grid plate, and a 2.0-mm radial head plate. Implants were tested under axial (N/mm) and torsional (Ncm/ degrees ) loads with a servohydraulic materials testing machine. The radial head plate was significantly stiffer than all other implants under axial as well as under torsional loads, with values of 36 N/mm and 13 Ncm/ degrees . The second-stiffest implant was the blade plate, with values of 20 N/mm and 6 Ncm/ degrees . The weakest implants were the 2.0-mm LCP, with values of 6 N/mm and 2 Ncm/ degrees , and the 2.0-mm crossed screws, with values of 18 N/mm and 2 Ncm/ degrees . The 2.4-mm T plate, with values of 14 N/mm and 4 Ncm/ degrees , and the 2.0-mm grid plate, with values of 8 N/mm and 4 Ncm/ degrees came to lie in the midfield. The 2.0-mm angle-stable plates-depending on their design-allow fixation with comparable or even higher stability than the bulky 2.4-mm nonlocking implants and 2.0-mm crossed screws.

[Comparison of effect between early and delayed in primary intramedullary nailing combined with locked plate fixation for the treatment of multi-segments tibial fractures of type].

PubMed

Gao, Wei-qiang; Hu, Jiang-hai; Gu, Zhu-chao; Zhang, Huai-xian; Min, Peng; Zhang, Lin-jun; Yu, Wen-wen; Wang, Guang-lin

2015-02-01

To compare the clinical results of early and delayed intramedullary nailing and locked plating for the treatment of multi-segments tibial fractures of type AO/ASIF-42C2. Between January 2010 and January 2013,45 patients with multi-segments closed tibial fractures of AO/ASIF-42C2 were treated by early primary intramedullary nailing and locked plating in 20 cases as early group and delayed in 25 cases as delayed group. In early group,20 cases included 13 males and 7 females with an average age of (37.9±14.3) years old ranging from 20 to 56 years;according to soft tissue injury Tscherne classification, 8 fractures were frade I,12 were grade II. In delayed group, 25 cases included 17 males and 8 females with an average age of (38.7±17.2) years old ranging from 24 to 55 years,4 fractures were grade I ,19 were grade II ,2 were grade III. The operative time, blood loss, hospital stay,fracture healing time and complications were recorded. At final follow-up, the Johner-Wruhs score were used to evaluate functional efficacy, and the posterior-anterior and lateral X-ray to evaluate fracture reduction and alignment. All the patients were followed up for (12.5±2.5) months in early group and (13.2±2.8) months in delayed group (P>0.05). No wounds infections were happened. At the last follow-up, the mean range of knee joint was 10°-0°-120°. According to Johner-Wruhs scoring,there were 15 cases in excellent,3 in good,fair in 2 in early group; 21 in excellent,2 in good,2 in fair. The average operative time,blood loss had no significant differences between two groups (P>0.05), but hospital stay in early group was significantly shorter than those in delayed group(P<0.05). Average fracture healing time of early group and delayed group were (5.3±2.6) months and (6.0±2.9) months, respectively (P>0.05). For multi-segments tibial fractures of type AO/ASIF-42C2 with preoperative minor soft tissue injuries lighter of Tscherne grade I or II, early primary intramedullary nailing and locked plating does not significantly increase the postoperative incidence of soft tissue complications for patients. The early and delayed primary intramedullary nailing and locked plating for treatment of AO/ASIF-42C2 proximal third tibial fractures can get similar curative effect.

The Maule, 2010, earthquake - geophysical and kinematic observations of the South American margin prior to the earthquake (Invited)

NASA Astrophysics Data System (ADS)

Oncken, O.; Haberland, C. A.; Moreno, M.; Melnick, D.; Tilmann, F.; Tipteq Research Groups

2010-12-01

Accumulation of deformation at convergent plate margins is recently identified to be highly discontinuous and transient in nature: silent slip events, non-volcanic tremors, afterslip, fault coupling and complex response patterns of the upper plate during a single event as well as across several seismic cycles have all been observed in various settings and combinations. Segments of convergent plate margins with high recurrence rates and at different stages of the rupture cycle like the Chilean margin offer an exceptional opportunity to study these features and their interaction resolving behaviour during the seismic cycle and over repeated cycles. A past (TIPTEQ) and several active international initiatives (Integrated Plate Boundary Observatory Chile; IPOC-network.org) address these goals with research groups from IPG Paris, Seismological Survey of Chile, Free University Berlin, Potsdam University, Hamburg University, IFM-GEOMAR Kiel, GFZ Potsdam, and Caltech (USA) employing an integrated plate boundary observatory and associated projects. Results from these studies allow us to define the preseismic state - with respect to the Maule eartghquake - of the margin system at the south Central Chilean convergent margin. Here, two major seismic events have occurred in adjoining segments (Valdivia 1960, Mw = 9.5; Maule 2010, Mw = 8.8) yielding observations from critical time windows of the seismic cycle in the same region. Seismic imaging and seismological data have allowed us to relocate major rupture hypocentres and to locate the geometry and properties of the seismogenic zone. The reflection seismic data exhibit well defined changes of reflectivity and Vp/Vs ratio along the plate interface that can be correlated with different parts of the coupling zone and its hanging wall as well as with changes during the seismic cycle. Observations suggest an important role of the hydraulic system, and of lateral variation of locking degree on subsequent rupture and aftershock distribution as evidenced by the recent Maule earthquake. Moreover, the latter coseismic rupture pattern was foreseeable from its pre-seismic locking pattern as derived by inversion of GPS observations during the previous decade. Neogene surface deformation at the Chilean coast related to these locking properties has been complex exhibiting tectonically uplifting areas along the coast driven by interseismically active reverse faulting. In addition, we observe coseismically subsiding domains along other parts of the coast - mostly above fully locked patches. Finally, we note that the characteristic peninsulas along the South American margin constitute stable rupture boundaries and appear to have done so for a protracted time as evidenced by their long-term uplift history since at least the Late Pliocene. This suggests barriers to rupture being related to anomalous properties of the plate interface affecting the mode of strain accumulation and plate interface rupture - like e.g. velocity strengthening in contrast to the weakening property of most of the remaining domains.

Finite Element Analysis of the Maximum Stress at the Joints of the Transmission Tower

NASA Astrophysics Data System (ADS)

Itam, Zarina; Beddu, Salmia; Liyana Mohd Kamal, Nur; Bamashmos, Khaled H.

2016-03-01

Transmission towers are tall structures, usually a steel lattice tower, used to support an overhead power line. Usually, transmission towers are analyzed as frame-truss systems and the members are assumed to be pin-connected without explicitly considering the effects of joints on the tower behavior. In this research, an engineering example of joint will be analyzed with the consideration of the joint detailing to investigate how it will affect the tower analysis. A static analysis using STAAD Pro was conducted to indicate the joint with the maximum stress. This joint will then be explicitly analyzed in ANSYS using the Finite Element Method. Three approaches were used in the software which are the simple plate model, bonded contact with no bolts, and beam element bolts. Results from the joint analysis show that stress values increased with joint details consideration. This proves that joints and connections play an important role in the distribution of stress within the transmission tower.

Energy loss and impact of various stunning devices used for the slaughtering of water buffaloes.

PubMed

Glardon, Matthieu; Schwenk, Barbara K; Riva, Fabiano; von Holzen, Adrian; Ross, Steffen G; Kneubuehl, Beat P; Stoffel, Michael H

2018-01-01

Stock management of the Swiss water buffalo livestock results in the slaughtering of about 350 animals per year. As the stunning of water buffaloes still is an unresolved issue, we investigated the terminal ballistics of currently used perforating stunning devices. Cartridge fired captive bolt devices, handguns and a bullet casing gun were tested in a shooting steep by firing on bisected heads, forehead plates and soap blocks. Energy loss of captive bolts confirmed their inadequacy when used for heavy water buffaloes, notably adult males. As for the free projectiles, ballistics revealed that beyond the impact energy, bullet deformation has a strong impact on the outcome. Light 9mm Luger or .38 Spl bullets as well as large deformable .44 Rem. Magnum bullets should be avoided in favor of heavier .357 Magnum deformation ammunition. These data have been translated into the development of a new stunning device for water buffaloes meeting both animal welfare and occupational safety requirements. Copyright © 2017 Elsevier Ltd. All rights reserved.

Seismic verification of nuclear plant equipment anchorage, Revision 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Czarnecki, R M

1991-06-01

Guidelines have been developed to evaluate the seismic adequacy of the anchorage of various classes of electrical and mechanical equipment in nuclear power plants covered by NRC Unresolved Safety Issue A-46. The guidelines consist of anchorage strength capacities as a function of key equipment and installation parameters. The strength criteria for expansion anchor bolts were developed by collecting and analyzing a large quantity of test data. The strength criteria for Cast-in-Place bolts and welds to embedded steel plates and channels were taken from existing nuclear-industry design guidelines. For anchorage used in low strength concrete and in concrete with cracks, appropriatemore » strength reduction factors were developed. Reduction factors for parameters such as edge distance, spacing and embedment depth are also included. Based on the anchorage capacity and equipment configuration, inspection checklists for field verification of anchorage adequacy were developed, and provisions for outliners that can be used to further investigate anchorages that cannot be verified in the field were prepared. The screening tables are based on an analysis of the anchorage forces developed by common equipment types and on strength criteria to quantify the holding power of anchor bolts and welds. A computer code EBAC was developed for the evaluation of the adequacy of the equipment anchorage. Guidelines to evaluate anchorage adequacy for vertical and horizontal tanks and horizontal heat exchangers were also developed.« less

Outcome of locking compression plates in humeral shaft nonunions

PubMed Central

Kumar, Malhar N; Ravindranath, V Pratap; Ravishankar, MR

2013-01-01

Background: Nonunion of diaphyseal fractures of the humerus are frequently seen in clinical practice (incidence of up to 15% in certain studies) and osteosynthesis using dynamic compression plates, intra medullary nails and Ilizarov fixators have been reported previously. Locking compression plates (LCP) are useful in the presence of disuse osteoporosis, segmental bone loss and cortical defects that preclude strong fixation. We report a prospective followup study of the outcome of the use of LCP for humeral nonunion following failed internal fixation in which implants other than LCP had been used. Materials and Methods: Twenty four patients with nonunion of humeral shaft fractures following failed internal fixation were included in the study. The mean followup period was 3.4 years (range: 2.4 to 5.7 years) and the minimum followup period was 2 years. Mean age of the patients was 41.04 years (range: 24 to 57 years). All 24 patients underwent osteosynthesis using LCP and autologous bone grafting (cortico-cancellous iliac crest graft combined with or without fibular strut graft). Main outcome measurements included radiographic assessment of fracture union and pre and postoperative functional evaluation using the modified Constant and Murley scoring system. Results: 23 out of 24 fractures united following osteosynthesis. Average time to union was 16 weeks (range: 10 to 28 weeks). Complications included delayed union (n = 2), transient radial nerve palsy (n = 2) and persistent nonunion (n = 1). Functional evaluation using the Constant and Murley score showed excellent results in 11, good in 10, fair in two and poor outcome in one patient. Conclusions: Locking compression plating and cancellous bone grafting is a reliable option for achieving union in humeral diaphyseal nonunion with failed previous internal fixation and results in good functional outcome in patients with higher physiological demands. PMID:23682176

Societal costs in displaced transverse olecranon fractures: using decision analysis tools to find the most cost-effective strategy between tension band wiring and locked plating.

PubMed

Francis, Tittu; Washington, Travis; Srivastava, Karan; Moutzouros, Vasilios; Makhni, Eric C; Hakeos, William

2017-11-01

Tension band wiring (TBW) and locked plating are common treatment options for Mayo IIA olecranon fractures. Clinical trials have shown excellent functional outcomes with both techniques. Although TBW implants are significantly less expensive than a locked olecranon plate, TBW often requires an additional operation for implant removal. To choose the most cost-effective treatment strategy, surgeons must understand how implant costs and return to the operating room influence the most cost-effective strategy. This cost-effective analysis study explored the optimal treatment strategies by using decision analysis tools. An expected-value decision tree was constructed to estimate costs based on the 2 implant choices. Values for critical variables, such as implant removal rate, were obtained from the literature. A Monte Carlo simulation consisting of 100,000 trials was used to incorporate variability in medical costs and implant removal rates. Sensitivity analysis and strategy tables were used to show how different variables influence the most cost-effective strategy. TBW was the most cost-effective strategy, with a cost savings of approximately $1300. TBW was also the dominant strategy by being the most cost-effective solution in 63% of the Monte Carlo trials. Sensitivity analysis identified implant costs for plate fixation and surgical costs for implant removal as the most sensitive parameters influencing the cost-effective strategy. Strategy tables showed the most cost-effective solution as 2 parameters vary simultaneously. TBW is the most cost-effective strategy in treating Mayo IIA olecranon fractures despite a higher rate of return to the operating room. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Camarada on middeck

NASA Image and Video Library

2005-08-04

S114-E-7003 (4 August 2005) --- Astronaut Charles J. Camarda, STS-114 mission specialist, performs a middeck evaluation of the mechanical "plug" option for Reinforced Carbon-Carbon (RCC) repair aboard the Space Shuttle Discovery. Camarda used special pre-designated tools to accomplish the procedure, along with round thin, flexible 7-inch-diamter carbon-silicon cover plates designed to flex up to 0.25 inch to conform to the wing leading edge RCC panels, a hardware attachment mechanism similar to a toggle bolt and sealant.

[Comparison of clinical effect on locking plate for proximal humeral fracture with or without application of inferomedial screws].

PubMed

Guo, Xiu-wu; Fan, Jian; Yuan, Feng

2016-06-01

To compare clinical outcomes of locking plate for proximal humeral fracture whether application of inferomedial screws. From January 2012 to July 2013, 46 patients with proximal humeral fracture underwent locking plates were retrospectively analyzed. There were 25 males and 21 females aged from 29 to 80 years old with an average of 55.1 years old. Among them, 25 patients were treated with inferomedial screws (support group), including 13 males and 12 females aged from 38 to 80 years old with an average of (55.8 ± 11.8) years old; 8 cases were part two fracture,10 cases were part three fracture and 7 cases were part four fracture according to Neer classification. Twenty-one patients were treated without inferomedial screws (non-support group), including 12 males and 9 females aged from 29 to 79 years old with an average of (54.2 ± 14.8)years old; 6 cases were part two fracture, 9 cases were part three fracture and 6 cases were part four fracture according to Neer classification. Operative time, fracture healing time and complications were observed and compared, Neer scoring of shoulder joint were used to evaluate clinical effect. All patients were followed up from 12 to 41 months with an average of 15.6 months. Operative time and fracture healing time in support group was (1.6 ± 0.4) h and (3.0 ± 0.6) months, and (1.5 ± 0.4) h and (3.1 ± 0.6) months in non-support group, while there was no statistical difference in operative time and fracture healing time between two groups. There was significant differences in Neer score between support group (89.7± 4.9) and non-support group (83.1 ± 7.1). No complication occurred in support group,while 4 cases occurred complications in non-support group. Locking plate with inferomedial screws for proximal humeral fracture has advantages of stable fixation, less complications, quick recovery of function and satisfied clinical effect.

Distal radius fracture fixation with a volar locking plate and endoscopic carpal tunnel release using a single 15mm approach: Feasibility study.

PubMed

Zemirline, A; Taleb, C; Naito, K; Vernet, P; Liverneaux, P; Lebailly, F

2018-05-17

Distal radius fractures (DRF) may trigger, reveal or decompensate acute carpal tunnel syndrome (CTS) in 0.5-21% of cases. Internal fixation and median nerve release must then be carried out urgently. Less invasive approaches have been described for both the median nerve release using an endoscopic device and for the DRF fixation using a volar locking plate. We assessed the feasibility of DRF fixation and median nerve release through a single, minimally-invasive 15mm approach on a series of 10 cases. We reviewed retrospectively 10 consecutive cases of DRF associated with symptomatic CTS in 8 women and 2 men, aged 57 years on average. CTS was diagnosed clinically. All patients were treated during outpatient surgery with a volar locking plate and endoscopic carpal tunnel release using a single 15mm minimally-invasive approach. In one case, arthroscopic scapholunate repair was also required. Six months after the procedure, all patients were reviewed with a clinical examination and a radiological evaluation. The average values for the clinical and radiological outcomes were as follows: pain on VAS 1.5/10; QuickDASH 14.3/100; flexion 90%; extension 90.6%; pronation 95.6%; supination 87.9%; grip strength 90.1%; 2PD test 5.2mm (4-8mm). Five complications occurred: two cases of temporary dysesthesia in the territory of the median nerve and one case of temporary hypoesthesia of the palmar branch of the median nerve, which had all completely recovered; two cases of complex regional pain syndrome type I, which were still active at 6 months. Despite its methodological weaknesses, our study is the only one to describe the technical feasibility of a single 15mm minimally-invasive approach for both internal fixation using a volar locking plate and endoscopic nerve release, with no serious complications. This technique should be added to the surgical toolbox of minimally-invasive procedures for the hand and wrist. Copyright © 2018 SFCM. Published by Elsevier Masson SAS. All rights reserved.

Strain measurements and the potential for a great subduction earthquake off the coast of washington.

PubMed

Savage, J C; Lisowski, M

1991-04-05

Geodetic measurements of deformation in northwestern Washington indicate that strain is accumulating at a rate close to that predicted by a model of the Cascadia subduction zone in which the plate interface underlying the continental slope and outer continental shelf is currently locked but the remainder of the interface slips continuously. Presumably this locked segment will eventually rupture in a great thrust earthquake with a down-dip extent greater than 100 kilometers.

A new discrete Kirchhoff-Mindlin element based on Mindlin-Reissner plate theory and assumed shear strain fields. I - An extended DKT element for thick-plate bending analysis. II - An extended DKQ element for thick-plate bending analysis

NASA Astrophysics Data System (ADS)

Katili, Irwan

1993-06-01

A new three-node nine-degree-of-freedom triangular plate bending element is proposed which is valid for the analysis of both thick and thin plates. The element, called the discrete Kirchhoff-Mindlin triangle (DKMT), has a proper rank, passes the patch test for thin and thick plates in an arbitrary mesh, and is free of shear locking. As an extension of the DKMT element, a four-node element with 3 degrees of freedom per node is developed. The element, referred to as DKMQ (discrete Kirchhoff-Mindlin quadrilateral) is found to provide good results for both thin and thick plates without any compatibility problems.

Fractographic analysis of 2.0-mm plates with a screw locking system in simulated fractures of the mandibular body.

PubMed

de Medeiros, Raquel Correia; Lauria de Moura, Andrezza; Rodrigues, Danillo Costa; Menezes Mendes, Marcelo Breno; Sawazaki, Renato; Fernandes Moreira, Roger William

2014-06-01

The purpose of the present study was to analyze the fractured plates from 2 brands of 2.0-mm locking fixation systems submitted to axial linear load testing. Four aluminum hemimandibles with linear sectioning to simulate a mandibular body fracture were used as a substrate and fixed with 2 fixation techniques from 2 national brands: Tóride and Traumec. The techniques were as follows: one 4-hole plate, with four 6-mm screws in the tension zone, and one 4-hole plate, with four 10-mm screws in the compression zone; and one 4-hole plate, with four 6-mm holes in the neutral zone. The hemimandibles were submitted to vertical linear load tests using an Instron 4411 mechanical test machine. The system was submitted to the test until complete failure had occurred. Next, a topographic analysis of the surface of the plates was performed using a stereomicroscope and an electronic scanning microscope. The samples were evaluated using different magnifications, and images were obtained. The surface of the fracture analyzed in scanning electron microscopy demonstrated a ductile-type fracture, usually found in the traction test bodies of ductile materials, such as titanium. No evidence of failure was observed in any fracture surface from a change in the structure or composition of the material. The plates were fractured by a ductile rupture mechanism, as expected, suggesting that the manufacturing of the national brand name plates used in the present study has been under adequate quality control, with no structural changes produced by the manufacturing process that could compromise their function. Copyright © 2014 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Treatment of segmental tibial fractures with supercutaneous plating.

PubMed

He, Xianfeng; Zhang, Jingwei; Li, Ming; Yu, Yihui; Zhu, Limei

2014-08-01

Segmental tibial fractures usually follow a high-energy trauma and are often associated with many complications. The purpose of this report is to describe the authors' results in the treatment of segmental tibial fractures with supercutaneous locking plates used as external fixators. Between January 2009 and March 2012, a total of 20 patients underwent external plating (supercutaneous plating) of the segmental tibial fractures using a less-invasive stabilization system locking plate (Synthes, Paoli, Pennsylvania). Six fractures were closed and 14 were open (6 grade IIIa, 2 grade IIIb, 4 grade II, and 2 grade I, according to the Gustilo classification). When imaging studies confirmed bone union, the plates and screws were removed in the outpatient clinic. Average time of follow-up was 23 months (range, 12-47 months). All fractures achieved union. Median time to union was 19 weeks (range, 12-40 weeks) for the proximal fractures and 22 weeks (range, 12-42 weeks) for the distal fractures. Functional results were excellent in 17 patients and good in 3. Delayed union of the fracture occurred in 2 patients. All patients' radiographs showed normal alignment. No rotational deformities and leg shortening were seen. No incidences of deep infection or implant failures occurred. Minor screw tract infection occurred in 2 patients. A new 1-stage protocol using supercutaneous plating as a definitive fixator for segmental tibial fractures is less invasive, has a lower cost, and has a shorter hospitalization time. Surgeons can achieve good reduction, soft tissue reconstruction, stable fixation, and high union rates using supercutaneous plating. The current patients obtained excellent knee and ankle joint motion and good functional outcomes and had a comfortable clinical course. Copyright 2014, SLACK Incorporated.

A femtosecond Yb-doped fiber laser with generalized vector vortex beams output (Conference Presentation)

NASA Astrophysics Data System (ADS)

Huo, Tiancheng; Qi, Li; Zhang, Buyun; Chen, Zhongping

2017-03-01

Light carries both spin and orbital angular momentum (OAM) and the superpositions of these two dynamical properties have found many applications. Many techniques exist to create such light sources but none allow their creation at the femtosecond fiber laser. Here we report on a novel mode-locked Ytterbium-doped fiber laser that generates femtosecond pulses with generalized vector vortex states. The controlled generation of such pulses such as azimuthally and radially polarized light with definite orbital angular momentum modes are demonstrated. A unidirectional ring cavity constructed with the Yb-doped fiber placed at the end of the fiber section to reduces unnecessary nonlinear effects is employed for self-starting operation. Pairs of diffraction gratings are used for compensating the normal group velocity dispersion of the fiber and other elements. Mode-locked operation is achieved based on nonlinear polarization evolution, which is mainly implemented with the single mode fiber, the bulk wave plates and the variable spiral plates (q-plate with topological charge q=0.5). The conversion from spin angular momentum to the OAM and reverse inside the laser cavity are realized by means of a quarter-wave plate and a q-plate so that the polarization control was mapped to OAM mode control. The fiber laser is diode pumped by a wavelength-division multiplexing coupler, which leads to excellent stability and portability.

Implications of loading/unloading a subduction zone with a heterogeneously coupled interface

NASA Astrophysics Data System (ADS)

Herman, M. W.; Furlong, K. P.; Govers, R. M. A.

2017-12-01

Numerical models of subduction zones with appropriate physical properties may help understand deformation throughout great earthquake cycles, as well as associated observations such as the distribution of smaller magnitude megathrust earthquakes and surface displacements. Of particular interest are displacements near the trench, where tsunamis are generated. The patterns of co-seismic strain release in great megathrust earthquakes depend on the frictional coupling of the plate interface prior to the event. Geodetic observations during the inter-seismic stage suggest that the plates are fully locked at asperities surrounded by zones of apparent partial coupling. We simulate the accumulation (and release) of elastic strain in the subduction system using a finite element model with a relatively simple geometry and material properties. We demonstrate that inter-seismic apparent partial coupling can be dominantly explained by a distribution of completely locked asperities and zero friction elsewhere. In these models, the interface up-dip of the locked zone (< 15 km depth) accumulates large slip deficit even if its coefficient of friction is zero, as might be inferred from the scarcity of megathrust earthquakes shallower than 15 km in global earthquake catalogs. In addition, the upper plate above a low-friction shallow megathrust accumulates large displacements with little internal strain, potentially leading to large co-seismic block displacements (low displacement gradients) of the near-trench seafloor like those observed following the 2011 Mw 9.0 Tohoku earthquake. This is also consistent with anomalously low co-seismic frictional heating of the shallow megathrust indicated by borehole heat flow measurements after the Tohoku event. Our models also yield insights into slip partitioning throughout multiple earthquake cycles. In smaller ruptures, fault slip is inhibited by nearby locked zones; in subsequent multi-segment ruptures, the rest of this slip deficit may be released, producing significantly larger slip than might be expected based on historical earthquake magnitudes. Finally, because low-friction areas around asperities accumulate some slip deficit but may not rupture co-seismically, these regions may be the primary locations of afterslip following the rupture of the locked patch.

Vortex shedding experiment with flat and curved bluff plates in water

NASA Technical Reports Server (NTRS)

Reed, D.; Nesman, T.; Howard, P.

1988-01-01

Vortex shedding experiments were conducted in a water flow facility in order to simulate the strong discrete 4000-Hz vibration detected in the Space Shuttle Main Engine (SSME) which is thought to be associated with the SSME LOX inlet tee splitter vanes on the Main Injector. For the case of a flat vane with a blunt trailing edge excited by flow induced vortex shedding, lock-in with the first bending mode of the plate was observed. A curved vane displayed similar behavior, with the lock-in being a more discrete higher amplitude response. Aluminum vanes were employed to decouple the first vane bending mode from the vortex shedding mode. The application of an asymmetric 30-deg trailing edge bevel to both the flat and curved vanes was found to greatly reduce the strength of the shed vortices.

Design and application of nickel-titanium olecranon memory connector in treatment of olecranon fractures: a prospective randomized controlled trial.

PubMed

Chen, Xiao; Liu, Peng; Zhu, Xiaofei; Cao, Liehu; Zhang, Chuncai; Su, Jiacan

2013-06-01

We carried out this study to test the efficacy of the olecranon memory connector (OMC) in olecranon fractures. We designed a prospective randomised controlled trial involving 40 cases of olecranon fractures. From May 2004 to December 2009, 40 patients with olecranon fractures were randomly assigned into two groups. Twenty patients were treated with OMC, while another 20 patients were fixed with locking plates in our hospital. The DASH score, MEP score, range of motion and radiographs were used to evaluate the postoperative elbow function and complications. For MEP score, OMC was better than the locking plate; for DASH score, complication rate, and range of elbow motion, the two methods presented no significant difference. The study showed that OMC could be an effective alternative to treat olecranon fractures.

Seismicity near a Highly-Coupled Patch in the Central Ecuador Subduction Zone

NASA Astrophysics Data System (ADS)

Regnier, M. M.; Segovia, M.; Font, Y.; Charvis, P.; Galve, A.; Jarrin, P.; Hello, Y.; Ruiz, M. C.; Pazmino, A.

2017-12-01

The temporary onshore-offshore seismic network deployed during the 2-years period of the OSISEC project provides an unprecedented, detailed and well-focused image of the seismicity for magnitudes as low as 2.0 in the Central Ecuadorian subduction zone. Facing the southern border of the Carnegie Ridge, a shallow and discrete highly-coupled patch is correlated to the subduction of a large oceanic relief. No large earthquake is known in this area that is experiencing recurrent seismic swarms and slow slip events. The shallow and locked subduction interface shows no evidence of background seismicity that instead occurred down dip of the coupled patch where it is possibly controlled by structural features of the overriding plate. We show a clear spatial correlation between the background microseismicity, the down dip extension of the locked patch at 20 km depth and the geology of the upper plate. The dip angle of the interplate contact zone, defined by a smooth interpolation through the hypocenters of thrust events, is consistent with a progressive increase from 6° to 25° from the trench to 20 km depth. Offshore, a seismic swarm, concomitant with a slow slip event rupturing the locked area, highlights the reactivation of secondary active faults that developed within the thickened crust of the subducting Carnegie Ridge, at the leading edge of a large oceanic seamount. No seismicity was detected near the plate interface suggesting that stress still accumulates at small and isolated asperities

Locking plate and fibular strut-graft augmentation in the reconstruction of unicameral bone cyst of proximal femur in the paediatric population.

PubMed

Jamshidi, Khodamorad; Mirkazemi, Masoud; Izanloo, Azra; Mirzaei, Alireza

2018-01-01

Several therapeutic strategies have been used for managing unicameral bone cyst (UBC) of the proximal femur. However, there is insufficient evidence to support one treatment over another, and the optimal treatment is controversial. This study aims at describing our experience with surgical reconstruction of paediatric UBCs of the proximal femur using a proximal locking plate and fibular strut allograft. In total, 14 consecutive paediatric patients with Dormans types IB (four cases) and IIB (10 cases) UBC were assessed. Mean patient age was 8.6 ± 2.3 years, and mean follow-up period was 41.7 ± 29.8 months. Six patients (42.8%) were referred with a pathologic fracture. Clinical/radiological outcome and complication rates were evaluated at the final follow-up session. No cysts were Capanna's class III (recurrence) or IV (no response). Complete healing (Capanna's class I) was seen in ten cysts, while four other cysts healed with residual radiolucent areas (Capanna's class II). Mean healing period was 14.1 ± 5.1 (9-24 months). One patient had superficial infection, one heterotopic ossification, and one mild coxa vara, and mean Musculoskeletal Tumor Society (MSTS) score was 99.5%. According to our results, locking plate and fibular strut graft in Dormans classification types IB and IIB results in a favorable outcome in managing UBC of the proximal femur in the paediatric population.

Complex angular and torsional deformities (distal femoral malunions). Preoperative planning using stereolithography and surgical correction with locking plate fixation in four dogs.

PubMed

DeTora, Michael D; Boudrieau, Randy J

2016-09-20

To describe the surgical technique of complex distal femoral deformity correction with the aid of stereolithography apparatus (SLA) biomodels, stabilized with locking plate fixation. Full-size replica epoxy bone biomodels of the affected femurs (4 dogs/ 5 limbs) were used as templates for surgical planning. A rehearsal procedure was performed on the biomodels aided by a guide wire technique and stabilized with locking plate fixation. Surgery performed in all dogs was guided by the rehearsal procedure. All pre-contoured implants were subsequently used in the definitive surgical procedure with minimal modification. All dogs had markedly improved, with near normal functional outcomes; all but one had a mild persistent lameness at the final in-hospital follow-up examination (mean: 54.4 weeks; range: 24-113 weeks after surgery). All femurs healed without complications (mean: 34 weeks, median: 12 weeks; range: 8-12 weeks for closing osteotomies, and 26-113 weeks for opening wedge osteotomies). Long-term follow-up examination (mean: 28.6 months; range: 5-42 months) revealed all but one owner to be highly satisfied with the outcome. Complications were observed in two dogs: prolonged tibiotarsal joint decreased flexion that resolved with physical therapy. In one of these dogs, iatrogenic transection of the long digital extensor tendon was repaired, and the other had a peroneal nerve neurapraxia. Stereolithography apparatus biomodels and rehearsal surgery simplified the definitive surgical corrections of complex femoral malunions and resulted in good functional outcomes.

Relationship between the Cascadia fore-arc mantle wedge, nonvolcanic tremor, and the downdip limit of seismogenic rupture

USGS Publications Warehouse

McCrory, Patricia A.; Hyndman, Roy D.; Blair, James Luke

2014-01-01

Great earthquakes anticipated on the Cascadia subduction fault can potentially rupture beyond the geodetically and thermally inferred locked zone to the depths of episodic tremor and slip (ETS) or to the even deeper fore-arc mantle corner (FMC). To evaluate these extreme rupture limits, we map the FMC from southern Vancouver Island to central Oregon by combining published seismic velocity structures with a model of the Juan de Fuca plate. These data indicate that the FMC is somewhat shallower beneath Vancouver Island (36–38 km) and Oregon (35–40 km) and deeper beneath Washington (41–43 km). The updip edge of tremor follows the same general pattern, overlying a slightly shallower Juan de Fuca plate beneath Vancouver Island and Oregon (∼30 km) and a deeper plate beneath Washington (∼35 km). Similar to the Nankai subduction zone, the best constrained FMC depths correlate with the center of the tremor band suggesting that ETS is controlled by conditions near the FMC rather than directly by temperature or pressure. Unlike Nankai, a gap as wide as 70 km exists between the downdip limit of the inferred locked zone and the FMC. This gap also encompasses a ∼50 km wide gap between the inferred locked zones and the updip limit of tremor. The separation of these features offers a natural laboratory for determining the key controls on downdip rupture limits.

A wide depth distribution of seismic tremors along the northern Cascadia margin.

PubMed

Kao, Honn; Shan, Shao-Ju; Dragert, Herb; Rogers, Garry; Cassidy, John F; Ramachandran, Kumar

2005-08-11

The Cascadia subduction zone is thought to be capable of generating major earthquakes with moment magnitude as large as M(w) = 9 at an interval of several hundred years. The seismogenic portion of the plate interface is mostly offshore and is currently locked, as inferred from geodetic data. However, episodic surface displacements-in the direction opposite to the long-term deformation motions caused by relative plate convergence across a locked interface-are observed about every 14 months with an unusual tremor-like seismic signature. Here we show that these tremors are distributed over a depth range exceeding 40 km within a limited horizontal band. Many occurred within or close to the strong seismic reflectors above the plate interface where local earthquakes are absent, suggesting that the seismogenic process for tremors is fluid-related. The observed depth range implies that tremors could be associated with the variation of stress field induced by a transient slip along the deeper portion of the Cascadia interface or, alternatively, that episodic slip is more diffuse than originally suggested.

Bitter-type toroidal field magnet for zephyr

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nathrath, N.; Keinath, W.; Kobusch, W.

1981-09-01

A feasibility study concerning stress computations, design and material technology of a Bitter-type magnet for the ZEPHYR project conducted in West Germany is reported. The big overall dimensions of the magnet (6.50 m diam 2.80 m high), access for diagnostics and neutral injection (16 ports), the possibility of remote handling of activated parts and high forces form the main requirements for design and material. A design with 16 identical modules (coils) was chosen, each coil consisting of 16 Bitter plates, plate housings and one diagnostic/neutral injection wedge. The structural parts are connected by bolts and form the bending stiff structuremore » of the magnet. The most critical area of the magnet is the inner wedge-shaped part of the coils (''throat area'') with extremely high tension, compression and shear stress values, to which temperature effects contribute heavily. Steel-copper compounds are found to be the best Bitter-plate materials. Copper-plating austenitic steel can be done galvanically or by explosive techniques. Cold-worked austenitic steels fulfil the requirements in the throat, in the flat-plate region milder steels can be used. Different plate concepts are being considered. Plasma-sprayed Al/sub 2/O/sub 3//TiO/sub 2/ and reinforced epoxy layers are provided as insulating materials in different magnet areas.« less

Adhesion properties in systems of laminated pigmented polymers, carbon-graphite fiber composite framework and titanium surfaces in implant suprastructures.

PubMed

Segerström, Susanna; Ruyter, I Eystein

2009-09-01

For long-term stability the adhering interfaces of an implant-retained supraconstruction of titanium/carbon-graphite fiber-reinforced (CGFR) polymer/opaquer layer/denture base polymer/denture teeth must function as a unity. The aim was to evaluate adhesion of CGFR polymer to a titanium surface or CGFR polymer to two different opaquer layers/with two denture base polymers. Titanium plates were surface-treated and silanized and combined with a bolt of CGFR polymer or denture base polymer (Probase Hot). Heat-polymerized plates of CGFR polymer (47 wt% fiber) based on poly(methyl methacrylate) and a copolymer matrix were treated with an opaquer (Sinfony or Ropak) before a denture base polymer bolt was attached (Probase Hot or Lucitone 199). All specimens were heat-polymerized, water saturated (200 days) and thermally cycled (5000 cycles, 5/55 degrees C) before shear bond testing. Silicatized titanium surfaces gave higher bond strength to CGFR polymer (16.2+/-2.34 and 18.6+/-1.32) MPa and cohesive fracture than a sandblasted surface (5.9+/-2.11) MPa where the fracture was adhesive. The opaquer Sinfony gave higher adhesion values and mainly cohesive fractures than the opaquer Ropak. Different surface treatments (roughened or polished) of the CGFR polymer had no effect on bond strength. The fracture surfaces of silicatized titanium/CGFR polymer/opaquer layer (Sinfony)/denture base polymers were mainly cohesive. A combination of these materials in an implant-retained supraconstruction is promising for in vivo evaluation.

Carrier-envelope phase control by a composite plate.

PubMed

Ell, Richard; Birge, Jonathan R; Araghchini, Mohammad; Kärtner, Franz X

2006-06-12

We demonstrate a new concept to vary the carrier-envelope phase of a mode-locked laser by a composite plate while keeping all other pulse parameters practically unaltered. The effect is verified externally in an interferometric autocorrelator, as well as inside the cavity of an octave-spanning femtosecond oscillator. The carrier-envelope frequency can be shifted by half the repetition rate with negligible impact on pulse spectrum and energy.

Patient-specific distal radius locking plate for fixation and accurate 3D positioning in corrective osteotomy.

PubMed

Dobbe, J G G; Vroemen, J C; Strackee, S D; Streekstra, G J

2014-11-01

Preoperative three-dimensional planning methods have been described extensively. However, transferring the virtual plan to the patient is often challenging. In this report, we describe the management of a severely malunited distal radius fracture using a patient-specific plate for accurate spatial positioning and fixation. Twenty months postoperatively the patient shows almost painless reconstruction and a nearly normal range of motion.

The outcome of unstable proximal femoral fracture treated with reverse LISS plates.

PubMed

Lin, Shih-Jie; Huang, Kuo-Chin; Chuang, Po-Yao; Lee, Chien-Yin; Huang, Tsan-Wen; Lee, Mel S; Hsu, Robert Wen-Wei

2016-10-01

The Russel-Taylor type 2B fractures compromised the trochanteric region and medial buttress of proximal femur. This fracture pattern limits the choice of implants and raises the risk of adverse outcomes. We aimed to (i) determine the outcome of Russel-Taylor type 2B fractures treated using reverse less invasive stabilization system plates (LISS-DF) and to (ii) learn what factors affected outcomes after osteosynthesis with reverse LISS plates. A retrospective study SETTING: The study was conducted at a Level III trauma center in Taiwan. Twenty-five consecutive patients presenting with a Russel-Taylor type 2B fracture were enrolled. All cases were treated with reverse LISS plates. A Modified Radiographic Union Scale for Femur (RUSF), Radiographic parameters, functional scores, and complications were assessed. Union occurred in 21 cases at an average of 18.8 weeks. The average immediate postoperative neck-shaft angle was 130° (range: 122-135°) compared with 139° (range: 135-141°, p=0.05) on the contralateral side. Two cases had complications of proximal screws cutting out and two cases had broken implants. Finally, all 4 cases required repeated surgeries (16%). Malunion occurred in 4 patients and early mechanical failure (proximal screws cut out) occurred in 2. There was a significant difference in the purchase index of the proximal screws between cases with redisplacement and those without (26.4mm and 98.6mm, p=0.01). The use of reverse LISS plate appeared to be an alternative procedure for the specific pattern in the present study. We recommend using this reverse locking plate to treat unstable proximal femoral fractures with meticulous techniques of placing plates. Adequate purchase of the proximal locking screws might decrease the risks of complications. Copyright © 2016 Elsevier Ltd. All rights reserved.

Audio-based bolt-loosening detection technique of bolt joint

NASA Astrophysics Data System (ADS)

Zhang, Yang; Zhao, Xuefeng; Su, Wensheng; Xue, Zhigang

2018-03-01

Bolt joint, as the commonest coupling structure, is widely used in electro-mechanical system. However, it is the weakest part of the whole system. The increase of preload tension force can raise the reliability and strength of the bolt joint. Therefore, the pretension force is one of the most important factors to ensure the stability of bolt joint. According to the way of generating pretension force, the pretension force can be monitored by bolt torque, degrees and elongation. The existing bolt-loosening monitoring methods all require expensive equipment, which greatly restricts the practicality of the bolt-loosening monitoring. In this paper, a new method of bolt-loosening detection technique based on audio is proposed. The sound that bolt is hit by a hammer is recorded on the Smartphone, and the collected audio signal is classified and identified by support vector machine algorithm. First, a verification test was designed and the results show that this new method can identify the damage of bolt looseness accurately. Second, a variety of bolt-loosening was identified. The results indicate that this method has a high accuracy in multiclass classification of the bolt looseness. This bolt-loosening detection technique based on audio not only can reduce the requirements of technical and professional experience, but also make bolt-loosening monitoring simpler and easier.

Linking the kinematics of the interplate and the offshore morphology along the Chilean subduction margin

NASA Astrophysics Data System (ADS)

Urrutia, Isabel; Moreno, Marcos; Oncken, Onno

2016-04-01

Morphological features at subduction zones are undoubtedly influenced by the complex interplay between the subducting slab and the overriding plate. Several studies suggest that the subduction dynamics is strongly dependent on the geometry and rheology of the margin (including gravity/density anomalies, viscous mantle flow and roughness of the slab, among others). However, it is not clear how the geomorphological variation of the forearc along strike can be used as a proxy for better understanding the mechanics on the interface and seismotectonic segmentation. Here we investigate the links between the kinematics of the plate interface and the morphology of the overriding plate along the Chilean margin by combining morphometrical and statistical analysis. We constructed swath profiles subtracting the averaged topography and performed gradient analysis to characterize variations of morphological features, and we compared these results with the locking degree distribution derived from the inversion of GPS data. On the coastal area the bathymetry and topography analysis shows a planar feature, gently dipping ocean-wards and backed by a cliff, which exhibits spatial variations in its width, height and extension along-strike. This morphology suggests a quiescence process or a "stable tectonic condition", at least since the late Quaternary (over multiple seismic cycles). The results indicate that this planar feature spatially correlates with the rupture size of recent great earthquakes and locking degree areas, suggesting that earthquake cycle deformation has an imprint on the offshore morphology, which can be used to study the transfer of stresses among adjacent seismotectonic segments and the periodicity and location of large earthquakes. In addition, the longevity of this correlation between topography, earthquake rupture and geodetic locking that likely integrates over a time window of several 103 to several 105 years indicates that the instrumentally inferred locking has a long term memory across multiple seismic cycles.

Outcome of distal end clavicle fractures treated with locking plates.

PubMed

Vaishya, Raju; Vijay, Vipul; Khanna, Vikram

2017-02-01

Fractures of the lateral end of the clavicle are relatively uncommon. These fractures are unstable due to the various deforming forces which act on the fragments as well as the small distal fracture fragment. At most times the deforming forces are not taken into consideration, and the fracture is not fixed securely. In this study, we assessed a fixation technique using the precontoured locking plates to find out whether it provided a stable fixation with good functional outcome. Totally, 32 patients with lateral end clavicle fracture (Neer's Type II) were included in the study. After the informed consent and preoperative investigations were obtained, open reduction and internal fixation was done using a 3.5 mm precontoured superior locking plate with lateral extension under general anesthesia. Postoperative X-rays were done on day 1 and every 6 weeks after operation, until radiological union was achieved. The postoperative pain was assessed using Visual Analogue Scale (VAS) on postoperative days 1, 2 and 10. Postoperatively arm pouch sling was given for 2 weeks followed by active mobilization. Patients were asked to do their daily routine work and avoid lifting heavy weights. The functional outcome was assessed at the end of 2nd and 6th months with the help of Disabilities of the Arm, Shoulder and Hand (DASH) scoring. There were no intraoperative complications in the procedure. The mean VAS score on postoperative day 1 was found to be 5 which decreased to 3 on day 2 and 0 on day 10. The mean DASH score was calculated as 11.63 at the end of postoperative month 2 and then 4.6 at the end of month 6. There was one case of malunion in whom the overhead abduction was restricted but was not painful and was managed conservatively. The precontoured locking plates with lateral extension may be a good method to fix the fractures of the lateral end clavicle, which provide a stable fixation with good functional outcome with very few instances of stiffness and decreased range of motion of the shoulder with the hook plates and failure of fixation in screw and K-wire fixations. It may well be the answer to the fixation questions of the lateral clavicle fractures, although larger comparative studies between the surgical treatment methods are required to confirm the same. Copyright © 2017 Daping Hospital and the Research Institute of Surgery of the Third Military Medical University. Production and hosting by Elsevier B.V. All rights reserved.

Research on Debonding Defects in Thermal Barrier Coatings Structure by Thermal-Wave Radar Imaging (TWRI)

NASA Astrophysics Data System (ADS)

Wang, Fei; Liu, Junyan; Mohummad, Oliullah; Wang, Yang

2018-06-01

In this paper, thermal-wave radar imaging (TWRI) is introduced to detect debonding defects in SiC-coated Ni-based superalloy plates. Linear frequency modulation signal (chirp) is used as the excitation signal which has a large time-bandwidth product. Artificial debonding defects in SiC coating are excited by the laser beam with the light intensity modulated by a chirp signal. Cross-correlation algorithm and chirp lock-in algorithm are introduced to extract the thermal-wave signal characteristic. The comparative experiment between TWRI reflection mode and transmission mode was carried out. Experiments are conducted to investigate the influence of laser power density, chirp period, and excitation frequency. Experimental results illustrate that chirp lock-in phase has a better detection capability than other characteristic parameters. TWRI can effectively detect simulated debonding defects of SiC-coated Ni-based superalloy plates.

Intramedullary nail fixation of non-traditional fractures: Clavicle, forearm, fibula.

PubMed

Dehghan, Niloofar; Schemitsch, Emil H

2017-06-01

Locked intramedullary fixation is a well-established technique for managing long-bone fractures. While intramedullary nail fixation of diaphyseal fractures in the femur, tibia, and humerus is well established, the same is not true for other fractures. Surgical fixations of clavicle, forearm and ankle are traditionally treated with plate and screw fixation. In some cases, fixation with an intramedullary device is possible, and may be advantageous. However, there is however a concern regarding a lack of rotational stability and fracture shortening. While new generation of locked intramedullary devices for fractures of clavicle, forearm and fibula are recently available, the outcomes are not as reliable as fixation with plates and screws. Further research in this area is warranted with high quality comparative studies, to investigate the outcomes and indication of these fractures treated with intramedullary nail devices compared to intramedullary nail fixation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reissner-Mindlin Legendre Spectral Finite Elements with Mixed Reduced Quadrature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brito, K. D.; Sprague, M. A.

2012-10-01

Legendre spectral finite elements (LSFEs) are examined through numerical experiments for static and dynamic Reissner-Mindlin plate bending and a mixed-quadrature scheme is proposed. LSFEs are high-order Lagrangian-interpolant finite elements with nodes located at the Gauss-Lobatto-Legendre quadrature points. Solutions on unstructured meshes are examined in terms of accuracy as a function of the number of model nodes and total operations. While nodal-quadrature LSFEs have been shown elsewhere to be free of shear locking on structured grids, locking is demonstrated here on unstructured grids. LSFEs with mixed quadrature are, however, locking free and are significantly more accurate than low-order finite-elements for amore » given model size or total computation time.« less

Pneumatic wall-locking geophone system

DOEpatents

Kuhlman, Harland L.; Cumerlato, Calvin L.; Tweeton, Daryl R.

1991-01-01

A seismic signal receiving system is provided for use in boreholes to receive seismic waves in carrying out geophysical investigations. The system includes three pairs of opposed plates, each of the pairs of plates including oppositely facing outer surfaces for engagement with opposite sides of a borehole. A seismic receiver is mounted on the inner surface of each of the plates for receiving seismic signals. A double-acting, fluid-operated actuator selectively causes relative movement of the plates of the pairs of plates away from each other to provide expansion thereof so as to enable the plates to engage the walls of a borehole and selectively causes relative movement of the plates of the pairs of plates toward each other to provide retraction thereof so as to enable the system to be removed from a borehole. The pairs of plates each comprise a relatively long plate and a relatively short plate. An expandable linkage interconnects the long plates at the distal ends thereof. The plates are mechanically biassed into the retracted state so that the plates return to this state in the event of a system failure.

Camarada and Thomas on middeck

NASA Image and Video Library

2005-08-07

S114-E-7001 (4 August 2005) --- Astronaut Andrew S. W. Thomas, STS-114 mission specialist, photographs a middeck evaluation of the mechanical "plug" option for Reinforced Carbon-Carbon (RCC) repair aboard the Space Shuttle Discovery. Astronaut Charles J. Camarda, mission specialist, uses special pre-designated tools to accomplish the procedure, along with round thin, flexible 7-inch-diamter carbon-silicon cover plates designed to flex up to 0.25 inch to conform to the wing leading edge RCC panels, a hardware attachment mechanism similar to a toggle bolt and sealant.

Thomas and Camarda on middeck

NASA Image and Video Library

2005-08-04

S114-E-7005 (4 August 2005) --- Astronaut Andrew S. W. Thomas, STS-114 mission specialist, photographs a middeck evaluation of the mechanical "plug" option for Reinforced Carbon-Carbon (RCC) repair aboard the Space Shuttle Discovery. Astronaut Charles J. Camarda, mission specialist, uses special pre-designated tools to accomplish the procedure, along with round thin, flexible 7-inch-diamter carbon-silicon cover plates designed to flex up to 0.25 inch to conform to the wing leading edge RCC panels, a hardware attachment mechanism similar to a toggle bolt and sealant.

Mold bolt and means for achieving close tolerances between bolts and bolt holes

NASA Technical Reports Server (NTRS)

Johnston, David L. (Inventor); Bryant, Phillip G. (Inventor)

1993-01-01

In the space shuttle, a cargo bay storage rack was required which was to be manufactured from a metal-plastic composite and bolted to a cargo structure. Following completion, utilization of the rack was disallowed due to tolerances, that is, the size differences between the outside bolt diameter and the inside hole diameter. In addition to the space shuttle problem there are other close tolerance requirements for bolts. Such environments often benefit from close tolerance bolting. Frequently such fabrication is not cost effective. Consequently there is a need for means of achieving close tolerances between bolts and bolt holes. Such means are provided. After compressing the elements together a strong rigid plastic, ceramic, or ceramic plastic fluid is forced into a channel extending through the bolt.

Z-2 Threaded Insert Design and Testing Abstract

NASA Technical Reports Server (NTRS)

Rhodes, RIchard; Graziosi, Dave; Jones, Bobby; Ferl, Jinny; Scarborough, Steve; Sweeney, Mitch

2016-01-01

The Z-2 Prototype Planetary Extravehicular Space Suit Assembly is a continuation of NASA's Z series of spacesuits. The Z-2 is another step in the NASA's technology development roadmap leading to human exploration of the Martian surface. To meet a more challenging set of requirements than previous suit systems standard design features, such as threaded inserts, have been re-analyzed and improved. NASA's Z-2 prototype space suit contains several components fabricated from an advanced hybrid composite laminate consisting of IM10 carbon fiber and fiber glass. One requirement NASA levied on the suit composites was the ability to have removable, replaceable helicoil inserts to which other suit components would be fastened. An approach utilizing bonded in inserts with helicoils inside of them was implemented. The design of the interface flanges of the composites allowed some of the inserts to be a "T" style insert that was installed through the entire thickness of the laminate. The flange portion of the insert provides a mechanical lock as a redundancy to the adhesive aiding in the pullout load that the insert can withstand. In some locations it was not possible to utilize at "T" style insert and a blind insert was used instead. These inserts rely completely on the bond strength of the adhesive to resist pullout. It was determined during the design of the suit that the inserts did not need to withstand loads induced from pressure cycling but instead tension induced from torqueing the screws to bolt on hardware which creates a much higher stress on them. Bolt tension is determined by dividing the torque on the screw by a k value multiplied by the thread diameter of the bolt. The k value is a factor that accounts for friction in the system. A common value used for k for a non-lubricated screw is 0.2. The k value can go down by as much as 0.1 if the screw is lubricated which means for the same torque, a much larger tension could be placed on the bolt and insert. This paper summarizes testing that was performed to determine a k value for helicoil inserts in the Z2 suit and how the insert design was modified to resist a higher pull out tension.

Functional outcome of displaced intra-articular calcaneal fractures: a comparison between open reduction/internal fixation and a minimally invasive approach featured an anatomical plate and compression bolts.

PubMed

Wu, Zhanpo; Su, Yanling; Chen, Wei; Zhang, Qi; Liu, Yueju; Li, Ming; Wang, Haili; Zhang, Yingze

2012-09-01

The purpose of this study is to assess the clinical results of a minimally invasive treatment featured the concept of internal compression, including an anatomic plate and multiple compression bolts compared with open reduction and internal fixation for displaced intra-articular calcaneal fractures (DIACFs). We retrospectively analyzed 329 patients (383 feet) who were identified from trauma inpatient database in our hospital for DIACFs from January 2004 to December 2009. Of them, 148 patients (170 feet) were treated with open reduction and internal fixation (OR group), which involved using a traditional L-shaped extended lateral approach, and fractures were fixed by plate and screws from January 2004 to December 2006; 181 patients (213 feet) were treated with a minimally invasive approach featured the concept of calcaneal internal compression (CIC group), which was achieved by an anatomic plate and multiple compression bolts through a small lateral incision from January 2007 to December 2009. Postoperative complications were recorded. During follow-up, pain and functional outcome were evaluated with the American Orthopaedic Foot and Ankle Society (AOFAS) scores and compared between the two groups. Subsequent subtalar arthrodesis and early implant removal were performed when indicated. Routine hardware removal was scheduled for all patients at 1-year follow-up. There were no significant differences in sex, age, and fracture classification (Sanders classification) between the two groups. Wound healing complications were 4 of 213 (1.88%) in CIC group and 20 of 170 (11.76%) in OR group. Subtalar arthrodesis had to be performed in one case in OR group. Four cases in CIC group and four cases in OR group had the hardware removed earlier due to complications. The average time after surgery to start weight-bearing exercise is 5.64 weeks in CIC group and 9.38 weeks in OR group (p < 0.001). The mean AOFAS score is higher in CIC group than in OR group, although the difference is not statistically significant (87.53 vs. 84.95; p = 0.191). The overall results according to the AOFAS scoring system were good or excellent in 185 of 213 (86.85%) in CIC group and 144 of 170 (84.71%) in OR group. The subjective portion of the AOFAS survey answered by patients showed statistically significant difference in activity limitation and walking surface score (7.31 vs. 7.02 and 3.72 vs. 3.42; p < 0.05) but not in pain and walking distance between the two groups (32.72 vs. 32.29 and 4.37 vs. 4.42; p > 0.05). The study results suggest that this minimally invasive approach featured the concept of the calcaneal internal compression can achieve functional outcome as good as, if not better than the open techniques. It is proved to be an effective alternative treatment for DIACFs. Therapeutic study, level IV.

Bolted Double-Lap Composite Joints Under Mechanical and Thermal Loading

NASA Technical Reports Server (NTRS)

Kradinov, V.; Barut, A.; Madenci, E.; Walker, Sandra P. (Technical Monitor)

2000-01-01

This study concerns the determination of the contact stresses and contact region around bolt holes and the bolt load distribution in single- and double-lap joints of composite laminates with arbitrarily located bolts under general mechanical loading conditions and uniform temperature change. The unknown contact stress distribution and contact region between the bolt and laminates and the interaction among the bolts require the bolt load distribution, as well as the contact stresses, to be as part of the solution. The present method is based on the complex potential theory and the variational formulation in order to account for bolt stiffness, bolt-hole clearance, and finite geometry of the composite laminates.

The Geodetic Signature of the Earthquake Cycle at Subduction Zones: Model Constraints on the Deep Processes

NASA Astrophysics Data System (ADS)

Govers, R.; Furlong, K. P.; van de Wiel, L.; Herman, M. W.; Broerse, T.

2018-03-01

Recent megathrust events in Tohoku (Japan), Maule (Chile), and Sumatra (Indonesia) were well recorded. Much has been learned about the dominant physical processes in megathrust zones: (partial) locking of the plate interface, detailed coseismic slip, relocking, afterslip, viscoelastic mantle relaxation, and interseismic loading. These and older observations show complex spatial and temporal patterns in crustal deformation and displacement, and significant differences among different margins. A key question is whether these differences reflect variations in the underlying processes, like differences in locking, or the margin geometry, or whether they are a consequence of the stage in the earthquake cycle of the margin. Quantitative models can connect these plate boundary processes to surficial and far-field observations. We use relatively simple, cyclic geodynamic models to isolate the first-order geodetic signature of the megathrust cycle. Coseismic and subsequent slip on the subduction interface is dynamically (and consistently) driven. A review of global preseismic, coseismic, and postseismic geodetic observations, and of their fit to the model predictions, indicates that similar physical processes are active at different margins. Most of the observed variability between the individual margins appears to be controlled by their different stages in the earthquake cycle. The modeling results also provide a possible explanation for observations of tensile faulting aftershocks and tensile cracking of the overriding plate, which are puzzling in the context of convergence/compression. From the inversion of our synthetic GNSS velocities we find that geodetic observations may incorrectly suggest weak locking of some margins, for example, the west Aleutian margin.

[A finite element analysis of petal-shaped poly-axial locking plate fixation in treatment of Y-shaped patellar fracture].

PubMed

Meng, Depeng; Ouyang, Yueping; Hou, Chunlin

2017-12-01

To establish the finite element model of Y-shaped patellar fracture fixed with titanium-alloy petal-shaped poly-axial locking plate and to implement the finite element mechanical analysis. The three-dimensional model was created by software Mimics 19.0, Rhino 5.0, and 3-Matic 11.0. The finite element analysis was implemented by ANSYS Workbench 16.0 to calculate the Von-Mises stress and displacement. Before calculated, the upper and lower poles of the patella were constrained. The 2.0, 3.5, and 4.4 MPa compressive stresses were applied to the 1/3 patellofemoral joint surface of the lower, middle, and upper part of the patella respectively, and to simulated the force upon patella when knee flexion of 20, 45, and 90°. The number of nodes and elements of the finite element model obtained was 456 839 and 245 449, respectively. The max value of Von-Mises stress of all the three conditions simulated was 151.48 MPa under condition simulating the knee flexion of 90°, which was lower than the yield strength value of the titanium-alloy and patella. The max total displacement value was 0.092 8 mm under condition simulating knee flexion of 45°, which was acceptable according to clinical criterion. The stress concentrated around the non-vertical fracture line and near the area where the screws were sparse. The titanium-alloy petal-shaped poly-axial locking plate have enough biomechanical stiffness to fix the Y-shaped patellar fracture, but the result need to be proved in future.

Mechanical testing of internal fixation devices: A theoretical and practical examination of current methods.

PubMed

Grant, Caroline A; Schuetz, Michael; Epari, Devakar

2015-11-26

Successful healing of long bone fractures is dependent on the mechanical environment created within the fracture, which in turn is dependent on the fixation strategy. Recent literature reports have suggested that locked plating devices are too stiff to reliably promote healing. However, in vitro testing of these devices has been inconsistent in both method of constraint and reported outcomes, making comparisons between studies and the assessment of construct stiffness problematic. Each of the methods previously used in the literature were assessed for their effect on the bending of the sample and concordant stiffness. The choice of outcome measures used in in vitro fracture studies was also assessed. Mechanical testing was conducted on seven hole locked plated constructs in each method for comparison. Based on the assessment of each method the use of spherical bearings, ball joints or similar is suggested at both ends of the sample. The use of near and far cortex movement was found to be more comprehensive and more accurate than traditional centrally calculated interfragmentary movement values; stiffness was found to be highly susceptible to the accuracy of deformation measurements and constraint method, and should only be used as a within study comparison method. The reported stiffness values of locked plate constructs from in vitro mechanical testing is highly susceptible to testing constraints and output measures, with many standard techniques overestimating the stiffness of the construct. This raises the need for further investigation into the actual mechanical behaviour within the fracture gap of these devices. Copyright © 2015 Elsevier Ltd. All rights reserved.

Equine ulnar fracture repair with locking compression plates can be associated with inadvertent penetration of the lateral cortex of the radius.

PubMed

Kuemmerle, Jan M; Kühn, Karolin; Bryner, Marco; Fürst, Anton E

2013-10-01

To evaluate if the use of locking head screws (LHS) in the distal holes of a locking compression plate (LCP) applied to the caudal aspect of the ulna to treat equine ulnar fractures is associated with a risk of injury to the lateral cortex of the radius. Controlled laboratory study. Cadaveric equine forelimbs (n = 8 pair). After transverse ulnar osteotomy, osteosynthesis was performed with a narrow 10-13 hole 4.5/5.0 LCP applied to the caudal aspect of each ulna. The distal 3 holes were filled with 4.5 mm cortex screws (CS) in 1 limb (group 1) and with 5.0 mm LHS contralaterally (group 2). CS were inserted in an angle deemed appropriate by the surgeon and LHS were inserted perpendicular to the plate. Implant position and injury to the lateral cortex of the radius were assessed by radiography, CT, and limb dissection. In group 1, injury of the lateral radius cortex did not occur. In group 2, 4 limbs and 6/24 LHS were associated with injury of the lateral radius cortex by penetration of a LHS. This difference was statistically significant. CS were inserted with a mean angle of 17.6° from the sagittal plane in a caudolateral-craniomedial direction. Use of LHS in the distal part of a LCP applied to the caudal aspect of the ulna is associated with a risk of inadvertent injury to the lateral cortex of the radius. © Copyright 2013 by The American College of Veterinary Surgeons.

Strength of plate coupling in the southern Ryukyu subduction zone

NASA Astrophysics Data System (ADS)

Doo, Wen-Bin; Lo, Chung-Liang; Wu, Wen-Nan; Lin, Jing-Yi; Hsu, Shu-Kun; Huang, Yin-Sheng; Wang, Hsueh-Fen

2018-01-01

Understanding the strength of a plate coupling is critical for assessing potential seismic and tsunamic hazards in subduction zones. The interaction between an overriding plate and the associated subducting plate can be used to evaluate the strength of plate coupling by examining the mantle lithospheric buoyancy. Here, we calculate the mantle lithosphere buoyancy across the northern portion of the southern Ryukyu subduction zone based on gravity modeling with the constraints from a newly derived P-wave seismic velocity model. The result indicates that the strength of the plate coupling in the study area is relatively strong, which is consistent with previous observations in the southernmost Ryukyu subduction zone. Because few large earthquakes (Mw > 7) have occurred in the southern Ryukyu subduction zone, a large amount of energy is locked and accumulated by plate coupling, that could be released in the near future.

Plate on plate osteosynthesis for the treatment of nonhealed periplate fractures.

PubMed

Arealis, Georgios; Nikolaou, Vassilios S; Lacon, Andrew; Ashwood, Neil; Hamlet, Mark

2014-01-01

Purpose. The purpose of this paper is to present our technique for the treatment of periplate fractures. Methods. From 2009 to 2012 we treated three patients. In all cases the existing plate was left and the new one placed over the existing. Locking screws were placed through both plates. The other screws in the new plate were used as best suited the fracture. Results. In all cases less than 6 months had passed between fractures. None of the original fractures had healed. Mean followup was 2 years. All fractures proceeded to union within 7 months. No complications were recorded. All the patients returned to their normal activities and were satisfied with the results of their treatment. Conclusion. Our plate on plate technique is effective for the treatment of periplate fractures. A solid fusion can be achieved at the new fracture site without disturbing the previous fixation.

A case study to quantify prediction bounds caused by model-form uncertainty of a portal frame

NASA Astrophysics Data System (ADS)

Van Buren, Kendra L.; Hall, Thomas M.; Gonzales, Lindsey M.; Hemez, François M.; Anton, Steven R.

2015-01-01

Numerical simulations, irrespective of the discipline or application, are often plagued by arbitrary numerical and modeling choices. Arbitrary choices can originate from kinematic assumptions, for example the use of 1D beam, 2D shell, or 3D continuum elements, mesh discretization choices, boundary condition models, and the representation of contact and friction in the simulation. This work takes a step toward understanding the effect of arbitrary choices and model-form assumptions on the accuracy of numerical predictions. The application is the simulation of the first four resonant frequencies of a one-story aluminum portal frame structure under free-free boundary conditions. The main challenge of the portal frame structure resides in modeling the joint connections, for which different modeling assumptions are available. To study this model-form uncertainty, and compare it to other types of uncertainty, two finite element models are developed using solid elements, and with differing representations of the beam-to-column and column-to-base plate connections: (i) contact stiffness coefficients or (ii) tied nodes. Test-analysis correlation is performed to compare the lower and upper bounds of numerical predictions obtained from parametric studies of the joint modeling strategies to the range of experimentally obtained natural frequencies. The approach proposed is, first, to characterize the experimental variability of the joints by varying the bolt torque, method of bolt tightening, and the sequence in which the bolts are tightened. The second step is to convert what is learned from these experimental studies to models that "envelope" the range of observed bolt behavior. We show that this approach, that combines small-scale experiments, sensitivity analysis studies, and bounding-case models, successfully produces lower and upper bounds of resonant frequency predictions that match those measured experimentally on the frame structure. (Approved for unlimited, public release, LA-UR-13-27561).

Measuring mine roof bolt strains

DOEpatents

Steblay, Bernard J.

1986-01-01

A mine roof bolt and a method of measuring the strain in mine roof bolts of this type are disclosed. According to the method, a flat portion on the head of the mine roof bolt is first machined. Next, a hole is drilled radially through the bolt at a predetermined distance from the bolt head. After installation of the mine roof bolt and loading, the strain of the mine roof bolt is measured by generating an ultrasonic pulse at the flat portion. The time of travel of the ultrasonic pulse reflected from the hole is measured. This time of travel is a function of the distance from the flat portion to the hole and increases as the bolt is loaded. Consequently, the time measurement is correlated to the strain in the bolt. Compensation for various factors affecting the travel time are also provided.

The service impact of failed locking plate fixation of distal tibial fractures: a service and financial evaluation at a major trauma centre.

PubMed

Kent, Michael; Mumith, Aadil; McEwan, Jo; Hancock, Nicholas

2015-12-01

The surgical treatment of distal tibial fractures is challenging and controversial. Recently, locking plate fixation has become popular, but the outcomes of this treatment are mixed with complication rates as high as 50 % in the published literature. There are no reports specifically relating to the financial and resource costs of failed treatment in the literature. Retrospective service analysis of patients who had undergone locking plate fixation of a distal third tibial fracture between 2008 and 2011 with at least 12 months follow-up. Rates of readmission, reoperation, bony union and infection were ascertained. The financial and resource (hospital stay and number of outpatient appointments) implications of failed treatment were calculated. Forty-two patients were identified. There were 31 type A fractures, one type B fracture and 10 type C fractures. Three injuries were open. Twenty patients were treated with minimally invasive percutaneous osteosynthesis (MIPO). The readmission and reoperation rates were 26 % (n = 11) and 19 % (n = 8), respectively. A total of 89 % of readmissions were due to infection. All patients had received appropriate antibiotic regimens. The average costs of successful and failed treatment were £ 5538 and £ 18,335, respectively. The average time to union was 24.5 weeks. The rate of non-union was 21 % (n = 9). The rate of infection was 28 % (n = 12), with all patients with open fracture incurring an infection. Tourniquet time had no effect on the incidence of complications. Smokers were more likely to incur a complication (p < 0.05), and non-union was lower in the MIPO group (p < 0.05). The length and total cost of inpatient care were significantly lower in the MIPO group (p < 0.05). MIPO patients were five times less likely to incur readmission or reoperation. Failed treatment was three times more expensive and four times longer than successful treatment. The study identified a large burden to the service following failure of locking plate treatment of these fractures, but the outcomes were similar to series published in the literature. Readmission rates were high following these injuries, and failed treatment was costly and had a significant impact on hospital resources. The implementation of major trauma networks and centralised subspecialised units should improve quality and value for money.

[APPLICATION OF BUTTERFLY SHAPED LOCKING COMPRESSION PLATE IN COMPLEX DISTAL RADIUS FRACTURES].

PubMed

Jiang, Zongyuan; Ma, Tao; Xia, Jiang; Hu, Caizhi; Xu, Lei

2014-06-01

To investigate the effectiveness of butterfly shaped locking compression plate for the treatment of complex distal radius fractures. Between June 2011 and January 2013, 20 cases of complex distal radius fractures were treated with butterfly shaped locking compression plate fixation. There were 11 males and 9 females with an average age of 54 years (range, 25-75 years). Injury was caused by falling in 10 cases, by traffic accident in 7 cases, and by falling from height in 3 cases. All of fractures were closed. According to AO classification system, there were 8 cases of type C1, 8 cases of type C2, and 4 cases of type C3. Of them, 9 cases had radial styloid process fracture, 4 cases had sigmoid notch fracture, and 7 cases had both radial styloid process fracture and sigmoid notch fracture. The mean interval between injury and operation was 5.2 days (range, 3-15 days). All incisions healed by first intention; no complications of infection and necrosis occurred. All cases were followed up 14 months on average (range, 10-22 months). All factures healed after 9.3 weeks on average (range, 6-11 weeks). No complications such as displacement of fracture, joint surface subsidence, shortening of the radius, and carpal tunnel syndrome were found during follow-up. At last follow-up, the mean palmar tilt angle was 10.2° (range, 7-15°), and the mean ulnar deviation angle was 21.8° (range, 17-24°). The mean range of motion of the wrist was 45.3° (range, 35-68°) in dorsal extension, 53.5° (range, 40-78°) in palmar flexion, 19.8° (range, 12-27°) in radial inclination, 26.6° (range, 18-31°) in ulnar inclination, 70.2° (range, 45-90°) in pronation, and 68.4° (range, 25-88°) in supination. According to the Dienst scoring system, the results were excellent in 8 cases, good in 10 cases, and fair in 2 cases, and the excellent and good rate was 90%. Treatment of complex distal radius fractures with butterfly shaped locking compression plate can reconstruct normal anatomic structures, especially for radial styloid process and sigmoid notch fractures, and it can get good functional recovery of the wrist and the distal radioulnar joint.

The Influence of Local Bone Density on the Outcome of One Hundred and Fifty Proximal Humeral Fractures Treated with a Locking Plate.

PubMed

Kralinger, Franz; Blauth, Michael; Goldhahn, Jörg; Käch, Kurt; Voigt, Christine; Platz, Andreas; Hanson, Beate

2014-06-18

There is biomechanical evidence that bone density predicts the mechanical failure of implants. The aim of this prospective study was to evaluate the influence of local bone mineral density on the rate of mechanical failure after locking plate fixation of proximal humeral fractures. We enrolled 150 patients who were from fifty to ninety years old with a closed, displaced proximal humeral fracture fixed with use of a locking plate from July 2007 to April 2010. There were 118 women and thirty-two men who had a mean age of sixty-nine years. Preoperative computed tomography (CT) scans were done to assess bone mineral density of the contralateral humerus, and dual x-ray absorptiometry of the distal end of the radius of the unaffected arm was conducted within the first six weeks postoperatively. At follow-up evaluations at six weeks, three months, and one year postoperatively, pain, shoulder mobility, strength, and multiple functional and quality-of-life outcome measures (Disabilities of the Arm, Shoulder and Hand [DASH] questionnaire; Shoulder Pain and Disability Index [SPADI]; Constant score; and EuroQuol-5D [EQ-5D]) were done and standard radiographs were made. We defined mechanical failure as all complications related to bone quality experienced within one year. After locking plate fixation, fifty-three (35%) of 150 patients had mechanical failure; loss of reduction and secondary screw loosening with perforation were common. CT assessments of local bone mineral density showed no difference between patients with and without mechanical failure (89.82 versus 91.51 mg/cm 3 , respectively; p = 0.670). One-year DASH, SPADI, and Constant scores were significantly better for patients without mechanical failure (p ≤ 0.05). We did not find evidence of an association between bone mineral density and the rate of mechanical failures, which may suggest that patients with normal bone mineral density are less prone to sustain a proximal humeral fracture. Future studies should target other discriminating factors between patients with and without mechanical failure. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence. Copyright © 2014 by The Journal of Bone and Joint Surgery, Incorporated.

Minimally invasive fixation of type B and C interprosthetic femoral fractures.

PubMed

Ehlinger, M; Czekaj, J; Adam, P; Brinkert, D; Ducrot, G; Bonnomet, F

2013-09-01

Interprosthetic femoral fractures are rare and raise unresolved treatment issues such as the length of the fixation material that best prevents secondary fractures. Awareness of the advantages of locked-plate fixation via a minimally invasive approach remains limited, despite the potential of this method for improving success rates. Femur-spanning (from the trochanters to the condyles) locked-plate fixation via a minimally invasive approach provides high healing rates with no secondary fractures. From January 2004 to May 2011, all eight patients seen for interprosthetic fractures were treated with minimally invasive locked-plate fixation. Mean time since hip arthroplasty was 47.5 months and mean time since knee arthroplasty was 72.6 months. There were 12 standard primary prostheses and four revision prostheses; 11 prostheses were cemented and a single prosthesis showed femoral loosening. Classification about the hip prostheses was Vancouver B in one patient and Vancouver C in seven patients; about the knee prosthesis, the fracture was SoFCOT B in three patients and SOFCOT C in five patients, and a single fracture was SoFCOT D. Minimally invasive locking-plate fixation was performed in all eight patients, with installation on a traction table in seven patients. Healing was obtained in all eight patients, after a mean of 14 weeks (range, 12-16 weeks). One patient had malalignment with more than 5° of varus. There were no general or infectious complications. One patient died, 32 months after surgery. The mean Parker-Palmer mobility score decreased from 6.2 pre-operatively to 2.5 at last follow-up. Early construct failure after 3 weeks in one patient required surgical revision. There was no change in implant fixation at last follow-up. No secondary fractures were recorded. In patients with type B or C interprosthetic fractures, femur-spanning fixation not only avoids complications related to altered bone stock and presence of prosthetic material, but also decreases the risk of secondary fractures by eliminating stress riser zones. The minimally invasive option enhances healing by preserving the fracture haematoma. Thus, healing was obtained consistently in our patients, with no secondary fractures, although the construct failed in one patient. Level IV. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Evaluation of Stress Corrosion Cracking Susceptibility Using Fracture Mechanics Techniques, Part 1. [environmental tests of aluminum alloys, stainless steels, and titanium alloys

NASA Technical Reports Server (NTRS)

Sprowls, D. O.; Shumaker, M. B.; Walsh, J. D.; Coursen, J. W.

1973-01-01

Stress corrosion cracking (SSC) tests were performed on 13 aluminum alloys, 13 precipitation hardening stainless steels, and two titanium 6Al-4V alloy forgings to compare fracture mechanics techniques with the conventional smooth specimen procedures. Commercially fabricated plate and rolled or forged bars 2 to 2.5-in. thick were tested. Exposures were conducted outdoors in a seacoast atmosphere and in an inland industrial atmosphere to relate the accelerated tests with service type environments. With the fracture mechanics technique tests were made chiefly on bolt loaded fatigue precracked compact tension specimens of the type used for plane-strain fracture toughness tests. Additional tests of the aluminum alloy were performed on ring loaded compact tension specimens and on bolt loaded double cantilever beams. For the smooth specimen procedure 0.125-in. dia. tensile specimens were loaded axially in constant deformation type frames. For both aluminum and steel alloys comparative SCC growth rates obtained from tests of precracked specimens provide an additional useful characterization of the SCC behavior of an alloy.

Effect of Different Connection Modes on Bolt Structural Properties of TC4 Alloy in Selective Laser Melting

NASA Astrophysics Data System (ADS)

Li, Xiaodan; Huang, Shuangjun; Xu, Liang; Hui, Li; Zhou, Song

2017-12-01

The bolt structural properties of selective laser melted (SLM) samples produced from TC4 powder metal has been investigated. Two different connection molds relative to single lap joint and bilateral lap joint as well as two different state of surface quality were considered. Samples and test procedures were designed in accordance with HB 5143 and HB 5287 standard. The results show that there is a strong influence of connection molds on the dynamic behavior of SLM produced TC4. The mechanical properties of bilateral lap joint are better than those of the single lap joint. Meanwhile the fatigue performance of the bilateral lap joint is much stronger than that of the single lap joint which it is a symmetrical structure of the two-shear test on both sides of the force evenly, while the single lap joint is a single shear sample of the uneven force. There are two kinds of fracture form most of which are broken in the first row of screw and a small part in the middle of the connecting plate.

Investigation of the use of uniaxial comb-shaped Galfenol patches for a guided wave-based magnetostrictive phased array sensor

NASA Astrophysics Data System (ADS)

Yoo, Byungseok; Pines, Darryll J.

2018-05-01

This paper investigates the use of uniaxial comb-shaped Fe-Ga alloy (Galfenol) patches in the development of a Magnetostrictive Phased Array Sensor (MPAS) for the Guided Wave (GW) damage inspection technique. The MPAS consists of six highly-textured Galfenol patches with a <100> preferred orientation and a Hexagonal Magnetic Circuit Device (HMCD). The Galfenol patches individually aligned to distinct azimuthal directions were permanently attached to a thin aluminum plate specimen. The detachable HMCD encloses a biasing magnet and six sensing coils with unique directional sensing preferences, equivalent to the specific orientation of the discrete Galfenol patches. The preliminary experimental tests validated that the GW sensing performance and directional sensitivity of the Galfenol-based sensor were significantly improved by the magnetic shape anisotropy effect on the fabrication of uniaxial comb fingers to a Galfenol disc patch. We employed a series of uniaxial comb-shaped Galfenol patches to form an MPAS with a hexagonal sensor configuration, uniformly arranged within a diameter of 1". The Galfenol MPAS was utilized to identify structural damage simulated by loosening joint bolts used to fasten the plate specimen to a frame structure. We compared the damage detection results of the MPAS with those of a PZT Phased Array Sensor (PPAS) collocated to the back surface of the plate. The directional filtering characteristic of the Galfenol MPAS led to acquiring less complicated GW signals than the PPAS using omnidirectional PZT discs. However, due to the detection limit of the standard hexagonal patterned array, the two array sensors apparently identified only the loosened bolts located along one of the preferred orientations of the array configuration. The use of the fixed number of the Galfenol patches for the MPAS construction constrained the capability of sensing point multiplication of the HMCD by altering its rotational orientation, resulting in such damage detection limitation of the MPAS.

Universal Assembly for Captive Bolts

NASA Technical Reports Server (NTRS)

Marke, M. L.; Hagopian, B.

1982-01-01

New method allows for virtually any bolt to be easily converted to "captive" bolt. Method eliminates need for separate design for each application. Cup-shaped washer that is flattened secures tap to bolt. Wire attached to tab holds bolt assembly captive. Flattening washer can also be done during installation of bolt. Wash, tab and spacer are all made of corrosion-resistant steel.

46 CFR 56.25-20 - Bolting.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., Blanks, Flange Facings, Gaskets, and Bolting § 56.25-20 Bolting. (a) General. (1) Bolts, studs, nuts, and....01-2). (2) Bolts and studs must extend completely through the nuts. (3) See § 58.30-15(c) of this... steel stud bolts must be threaded full length or, if desired, may have reduced shanks of a diameter not...

[Arthrodesis of the First Metatarsophalangeal Joint by Locking Plate].

PubMed

Kunovský, R; Pink, T; Jarošík, J

2017-01-01

PURPOSE OF THE STUDY The authors in their paper evaluate a group of patients who underwent arthrodesis of the first metatarsophalangeal joint using a locking plate. MATERIAL AND METHODS In the period 2010-2015, we performed surgery in 51 patients (56 forefeet), of which in 5 cases bilaterally and in 46 cases unilaterally, in 38 women and 13 men. The mean age was 57.8 years, the mean follow-up was 3.1 years. The indications for surgery were hallux rigidus in 23 patients, hallux valgus in 15 patients, hallux varus in 3 patients, and hallux erectus in 2 patients. In 4 patients the surgery was performed for valgus deformity associated with rheumatoid arthritis, 9 patients were indicated for a failure of the prior surgical intervention. In all 56 forefeet, the anatomic, low-profile titanium plate Variable Angle LCP 1st MTP Fusion Plate 2.4/2.7 was used. RESULTS According to Gainor s score the surgical outcomes were assessed as excellent in 46 patients who underwent surgery (90%), good in 4 patients (8%), fair in 1 patient (2%), and poor in 0 patient (0%). In 53 forefeet, the control radiographs showed solid bone union. In 2 patients and 3 forefeet, non-union of the arthrodesis occurred. In 2 forefeet, revision arthrodesis was performed, after which solid bone union followed. Malpositioned union was reported in 5 forefeet, of which in 4 cases into valgosity and in 1 case into dorsiflexion. DISCUSSION Numerous fixation materials can be used for arthrodesis of the first metatarsophalangeal joint. The use of the least stable Kirschner wires (cerclage) is being abandoned and substituted with a more stable fixation by screws, memory staples and locking plates. The achievement of excellent results requires proper positioning of the arthrodesis. Impingement syndrome between the big toe and the second toe can result in painful callosities formation, too large dorsiflexion can lead to a hallux hammertoe, with reduced big toe support function, to metatarsalgia. CONCLUSIONS The arthrodesis is indicated in patients with Grade III and IV hallux rigidus, with severe hallux valgus, hallux varus, and in patients in whom the previous surgeries failed. We tend to prefer stable arthrodesis. Fixation by anatomic LCP plate facilitates early rehabilitation, loading and early return to work and sports activities. Key words: arthrodesis, metatarsophalangeal joint, hallux rigidus, hallux valgus.

[Biphasic ceramic wedge and plate fixation with locked adjustable screws for open wedge tibial osteotomy].

PubMed

Lavallé, F; Pascal-Mousselard, H; Rouvillain, J L; Ribeyre, D; Delattre, O; Catonné, Y

2004-10-01

The aim of this radiological study was to evaluate the use of a biphasic ceramic wedge combined with plate fixation with locked adjustable screws for open wedge tibial osteotomy. Twenty-six consecutive patients (27 knees) underwent surgery between December 1999 and March 2002 to establish a normal lower-limb axis. The series included 6 women and 20 men, mean age 50 years (16 right knees and 11 left knees). Partial weight-bearing with crutches was allowed on day 1. A standard radiological assessment was performed on day 1, 90, and 360 (plain AP and lateral stance films of the knee). A pangonogram was performed before surgery and at day 360. Presence of a lateral metaphyseal space, development of peripheral cortical bridges, and osteointegration of the bone substitute-bone interface were evaluated used to assess bone healing. The medial tibial angle between the line tangent to the tibial plateau and the anatomic axis of the tibia (beta) was evaluated to assess preservation of postoperative correction. The HKA angle was determined. Three patients were lost to follow-up and 23 patients (24 knees) were retained for analysis. At last follow-up, presence of peripheral cortical bridges and complete filling of the lateral metaphyseal space demonstrated bone healing in all patients. Good quality osteointegration was achieved since 21 knees did not present an interface between the bone substitute and native bone (homogeneous transition zone). The beta angle was unchanged for 23 knees. A normal axis was observed in patients (16 knees) postoperatively. Use of a biphasic ceramic wedge in combination with plate fixation with locked adjustable screws is a reliable option for open wedge tibial osteotomy. The bone substitute fills the gap well. Tolerance and integration are optimal. Bone healing is achieved. Plate fixation with protected weight bearing appears to be a solid assembly, maintaining these corrections.

[Locked volar plating for complex distal radius fractures: maintaining radial length].

PubMed

Jeudy, J; Pernin, J; Cronier, P; Talha, A; Massin, P

2007-09-01

Maintaining radial length, likely to be the main challenge in the treatment of complex distal radius fractures, is necessary for complete grip-strength and pro-supination range recovery. In spite of frequent secondary displacements, bridging external-fixation has remained the reference method, either isolated or in association with additional percutaneous pins or volar plating. Also, there seems to be a relation between algodystrophy and the duration of traction applied on the radio-carpal joint. Fixed-angle volar plating offers the advantage of maintaining the reduction until fracture healing, without bridging the joint. In a prospective study, forty-three consecutive fractures of the distal radius with a positivated ulnar variance were treated with open reduction and fixed-angle volar plating. Results were assessed with special attention to the radial length and angulation obtained and maintained throughout treatment, based on repeated measurements of the ulnar variance and radial angulation in the first six months postoperatively. The correction of the ulnar variance was maintained until complete recovery, independently of initial metaphyseal comminution, and of the amount of radial length gained at reduction. Only 3 patients lost more than 1 mm of radial length after reduction. The posterior tilt of the distal radial epiphysis was incompletely reduced in 13 cases, whereas reduction was partially lost in 6 elderly osteoporotic female patients. There was 8 articular malunions, all of them less than 2 mm. Secondary displacements were found to be related to a deficient locking technique. Eight patients developed an algodystropy. The risk factors for algodystrophy were articular malunion, associated posterior pining, and associated lesions of the ipsilateral upper limb. Provided that the locking technique was correct, this type of fixation appeared efficient in maintaining the radial length in complex fractures of the distal radius. The main challenge remains the reduction of displaced articular fractures. Based on these results, it is not possible to conclude that this method is superior to external fixation.

Clinical, radiological and histological evaluation of biphasic calcium phosphate bioceramic wedges filling medial high tibial valgisation osteotomies.

PubMed

Rouvillain, J L; Lavallé, F; Pascal-Mousselard, H; Catonné, Y; Daculsi, G

2009-10-01

We report clinical, radiological and histological findings following high tibial valgisation osteotomy (HTVO) using micro-macroporous biphasic calcium phosphate wedges fixed with a plate and locking screws. From 1999 to 2002, 43 knees were operated on and studied prospectively. All underwent clinical and radiological follow-up at days 1, 90, and 365 to evaluate consolidation and bone substitute interfaces. Additionally, biopsies were taken for histology at least 1 year after implantation from 10 patients who requested plate removal. Radiologically, consolidation was observed in 98% of cases. At 1 year, correction was unchanged in 95% of cases. Histological analysis revealed considerable MBCP resorption and bone ingrowth, both into the pores and replacing the bioceramic material. Polarised light microscopy confirmed normal bony architecture with trabecular and/or dense lamellar bone growth at the expense of the wedge implants. X-ray and micro-CT scan revealed a well organised and mineralised structure in the newly-formed bone. This study shows that using MBCP wedges in combination with orientable locking screws and a plate is a simple, safe and fast surgical technique for HTVO. The is the first study to examine the results by histological analysis, which confirmed good outcomes.

Tectonics and Current Plate Motions of Northern Vancouver Island and the Adjacent Mainland

NASA Astrophysics Data System (ADS)

Jiang, Y.; Leonard, L. J.; Henton, J.; Hyndman, R. D.

2016-12-01

Northern Vancouver Island comprises a complex transition zone along the western margin of the North America plate, between the subducting Juan de Fuca plate to the south and the transcurrent Queen Charlotte Fault to the north off Haida Gwaii. The tectonic history and seismic potential for this region are unclear. Here we present current plate motions for northern Vancouver Island and the adjacent mainland, determined from continuous and campaign GPS measurements processed in a consistent manner. Immediately to the north of the mid-Vancouver Island Nootka Fault Zone, the northern limit of Juan de Fuca plate subduction, GPS velocity vectors show slower Explorer plate subduction than the Juan de Fuca Plate. Off northernmost Vancouver Island, the Winona Block is possibly converging at a slow rate that decreases northward to zero. We find a constant northward margin-parallel translation of up to 5 mm/year from northern Vancouver Island extending to Alaska. The southern limit of this translation coincides with areas of high heat flow that may reflect extension and the northern limit of episodic tremor and slip (ETS) on the Cascadia megathrust. The origin of the northward translation is poorly understood. We find a mainland coastal shear zone extends as far south as northern Vancouver Island where the offshore plate boundary is likely subduction. The pattern of the observed coastal shear cannot reflect interseismic locking on a major offshore transcurrent fault. The geodetically determined mainland coastal zone velocities decrease landward from 5 to 0 mm/yr across a region where no active faults have been identified and there is very little current seismicity. In Haida Gwaii, oblique convergence is apparent in the GPS data, consistent with partitioning between margin-parallel and margin-perpendicular strain. After removing the margin parallel translation from the data, we determine an average maximum locking depth of 15 km for the Queen Charlotte transcurrent fault, consistent with seismicity and seismic structure data.

A Review of Rock Bolt Monitoring Using Smart Sensors.

PubMed

Song, Gangbing; Li, Weijie; Wang, Bo; Ho, Siu Chun Michael

2017-04-05

Rock bolts have been widely used as rock reinforcing members in underground coal mine roadways and tunnels. Failures of rock bolts occur as a result of overloading, corrosion, seismic burst and bad grouting, leading to catastrophic economic and personnel losses. Monitoring the health condition of the rock bolts plays an important role in ensuring the safe operation of underground mines. This work presents a brief introduction on the types of rock bolts followed by a comprehensive review of rock bolt monitoring using smart sensors. Smart sensors that are used to assess rock bolt integrity are reviewed to provide a firm perception of the application of smart sensors for enhanced performance and reliability of rock bolts. The most widely used smart sensors for rock bolt monitoring are the piezoelectric sensors and the fiber optic sensors. The methodologies and principles of these smart sensors are reviewed from the point of view of rock bolt integrity monitoring. The applications of smart sensors in monitoring the critical status of rock bolts, such as the axial force, corrosion occurrence, grout quality and resin delamination, are highlighted. In addition, several prototypes or commercially available smart rock bolt devices are also introduced.

A Review of Rock Bolt Monitoring Using Smart Sensors

PubMed Central

Song, Gangbing; Li, Weijie; Wang, Bo; Ho, Siu Chun Michael

2017-01-01

Rock bolts have been widely used as rock reinforcing members in underground coal mine roadways and tunnels. Failures of rock bolts occur as a result of overloading, corrosion, seismic burst and bad grouting, leading to catastrophic economic and personnel losses. Monitoring the health condition of the rock bolts plays an important role in ensuring the safe operation of underground mines. This work presents a brief introduction on the types of rock bolts followed by a comprehensive review of rock bolt monitoring using smart sensors. Smart sensors that are used to assess rock bolt integrity are reviewed to provide a firm perception of the application of smart sensors for enhanced performance and reliability of rock bolts. The most widely used smart sensors for rock bolt monitoring are the piezoelectric sensors and the fiber optic sensors. The methodologies and principles of these smart sensors are reviewed from the point of view of rock bolt integrity monitoring. The applications of smart sensors in monitoring the critical status of rock bolts, such as the axial force, corrosion occurrence, grout quality and resin delamination, are highlighted. In addition, several prototypes or commercially available smart rock bolt devices are also introduced. PMID:28379167

Reinforcing the role of the conventional C-arm--a novel method for simplified distal interlocking.

PubMed

Windolf, Markus; Schroeder, Josh; Fliri, Ladina; Dicht, Benno; Liebergall, Meir; Richards, R Geoff

2012-01-25

The common practice for insertion of distal locking screws of intramedullary nails is a freehand technique under fluoroscopic control. The process is technically demanding, time-consuming and afflicted to considerable radiation exposure of the patient and the surgical personnel. A new concept is introduced utilizing information from within conventional radiographic images to help accurately guide the surgeon to place the interlocking bolt into the interlocking hole. The newly developed technique was compared to conventional freehand in an operating room (OR) like setting on human cadaveric lower legs in terms of operating time and radiation exposure. The proposed concept (guided freehand), generally based on the freehand gold standard, additionally guides the surgeon by means of visible landmarks projected into the C-arm image. A computer program plans the correct drilling trajectory by processing the lens-shaped hole projections of the interlocking holes from a single image. Holes can be drilled by visually aligning the drill to the planned trajectory. Besides a conventional C-arm, no additional tracking or navigation equipment is required.Ten fresh frozen human below-knee specimens were instrumented with an Expert Tibial Nail (Synthes GmbH, Switzerland). The implants were distally locked by performing the newly proposed technique as well as the conventional freehand technique on each specimen. An orthopedic resident surgeon inserted four distal screws per procedure. Operating time, number of images and radiation time were recorded and statistically compared between interlocking techniques using non-parametric tests. A 58% reduction in number of taken images per screw was found for the guided freehand technique (7.4 ± 3.4) (mean ± SD) compared to the freehand technique (17.6 ± 10.3) (p < 0.001). Total radiation time (all 4 screws) was 55% lower for the guided freehand technique compared to conventional freehand (p = 0.001). Operating time per screw (from first shot to screw tightened) was on average 22% reduced by guided freehand (p = 0.018). In an experimental setting, the newly developed guided freehand technique for distal interlocking has proven to markedly reduce radiation exposure when compared to the conventional freehand technique. The method utilizes established clinical workflows and does not require cost intensive add-on devices or extensive training. The underlying principle carries potential to assist implant positioning in numerous other applications within orthopedics and trauma from screw insertions to placement of plates, nails or prostheses.

Double plating of intra-articular multifragmentary C3-type distal femoral fractures through the anterior approach.

PubMed

Imam, Mohamed A; Torieh, Ahmed; Matthana, Ahmed

2018-01-01

In this prospective case series, we report a mean of 12-month follow-up of the utilization of a dual plating of distal femoral fractures. Our technique included a lateral distal femoral locked plate with a low-contact-locked medial plate and bone graft through an extended medial parapatellar anterior approach for the fixation of C3-type distal femoral fractures. Sixteen patients (11 males and 5 females) presented with supracondylar femoral fracture type C3, according to Müller long-bone classification system and its revision OA/OTA classification. These were treated using dual plating through extended anterior approach and bone grafting. Our outcomes included clinical and radiological outcomes. Secondary outcomes included postoperative complications. The mean time of complete radiological union in the studied population was 6.0 ± 3.5 months with a range of 3-14 months. We have not observed postoperative varus or valgus deformity in our cohort. The majority (68.75%) of the studied patients showed significant improvement in range of motion (90°-120°) during follow-up. Eleven out of sixteen patients (68.75%) had well-to-excellent functional outcome. Poor outcome was reported in only two patients (12.50%). Dual plating fixation using anterior approach for type C3 distal femoral fractures is an efficient method of management. It has several advantages such as precise exposure, easy manipulation, anatomical reduction and stable fixation. However, operative indications and instructions should be strictly followed. The surgical technique must be rigorous, and the biomechanical qualities of these implants must be understood to prevent the development of major complications.

Technical Errors May Affect Accuracy of Torque Limiter in Locking Plate Osteosynthesis.

PubMed

Savin, David D; Lee, Simon; Bohnenkamp, Frank C; Pastor, Andrew; Garapati, Rajeev; Goldberg, Benjamin A

2016-01-01

In locking plate osteosynthesis, proper surgical technique is crucial in reducing potential pitfalls, and use of a torque limiter makes it possible to control insertion torque. We conducted a study of the ways in which different techniques can alter the accuracy of torque limiters. We tested 22 torque limiters (1.5 Nm) for accuracy using hand and power tools under different rotational scenarios: hand power at low and high velocity and drill power at low and high velocity. We recorded the maximum torque reached after each torque-limiting event. Use of torque limiters under hand power at low velocity and high velocity resulted in significantly (P < .0001) different mean (SD) measurements: 1.49 (0.15) Nm and 3.73 (0.79) Nm. Use under drill power at controlled low velocity and at high velocity also resulted in significantly (P < .0001) different mean (SD) measurements: 1.47 (0.14) Nm and 5.37 (0.90) Nm. Maximum single measurement obtained was 9.0 Nm using drill power at high velocity. Locking screw insertion with improper technique may result in higher than expected torque and subsequent complications. For torque limiters, the most reliable technique involves hand power at slow velocity or drill power with careful control of insertion speed until 1 torque-limiting event occurs.

Behaviour of steel-concrete composite beams using bolts as shear connectors

NASA Astrophysics Data System (ADS)

Tran, Minh-Tung; Nguyen Van Do, Vuong; Nguyen, Tuan-Anh

2018-04-01

The paper presents an experimental program on the application of bolts as shear connectors for steel-composite beams. Four steel- concrete composite beams and a reference steel beam were made and tested. The aim of the testing program is to examine which forms of the steel bolts can be used effectively for steel-composite beams. The four types of the bolts include: Type 1 the bolt with the nut at the end; Type 2 the bolt bending at 900 hook; Type 3 the bolt without the nut at the end and Type 4 the bolt with the nut at the end but connected with the steel beam by hand welding in other to be connected with the steel beam by bolt connection as in the first three types. The test results showed that beside the traditional shear connectors like shear studs, angle type, channel type, bolts can be used effectively as the shear connectors in steel-composite beams and the application of bolts in Types 1 and 2 in the composite beams gave the better performance for the tested beam.

Seismotectonic segmentation along the Chilean megathrust (Invited)

NASA Astrophysics Data System (ADS)

Melnick, D.; Moreno, M.

2010-12-01

This study focuses on understanding seismotectonic segmentation of megathrusts (MT). Recent research suggests elements associated to MT segmentation include: oceanic features, such as seamounts, seismic and aseismic ridges, and fracture zones; thickness and nature of trench sediments; and upper-plate heterogeneities as changes in density, lithology, and presence of splay faults or microplates, features usually manifested in coastline morphology. The 3500-km-long Chilean MT includes all these elements with various amplitudes under fairly constant kinematics and strike. Along the Nazca-South America boundary, the dense GPS network and knowledge of MT geometry allows inverting for the degree of interplate coupling or locking rate. Here we compare locking, historical MT ruptures, and long-term structure. Along-strike changes in locking rate occur at wavelengths of ~100-500 km, and locally correlate with historical ruptures as well as with lower and/or upper plate features, but without a clear systematic pattern. The transition between the 1960 M9.5 and 2010 M8.8 earthquake segments at Arauco (38.5S) has 100 km overlap deduced from land-level changes. Coherent deformation suggest this boundary has been stationary over 4 Myr, and is associated to margin-parallel collision of a forearc microplate along a Paleozoic shear zone. Seismically-active reverse splay faults bound the Peninsula and may absorb coseismic MT slip and stall rupture propagation. To the north, rupture of the 2010 M8.8 event stopped before the prominent J.Fernandez Ridge and its boundary may be associated to the Pichilemu fault, a steep oblique structure that generated a M6.9 aftershock. The change from accretionary to erosive character across this Ridge, from variable thickness of trench sediments, is manifested in narrowing of the coupling zone northwards and a small local decrease in locking rate. This local decrease is coincident with the Maipo orocline axis and a sharp bend in the orogen, which formed at 10 Ma. A sharp decrease in locking rates appears at 32.5S, near the northern end of the 1906 M8.5 earthquake. The 1906 segment appears to be highly coupled in the pre-2010 GPS data. High locking characterizes the southern edge of the 1922 M8.5 event at the Choros Peninsulas, diffusing northward. The Mejillones Peninsula, a prominent discontinuity in the coastline that marks the transition between the 1995 M8 and 1877 M8.7 earthquakes, is associated to a regional lineament of Paleogene paleomagnetic rotation and major discontinuities in Andean structural style along the fore-, intra-, and foreland regions. Minor changes in trench sediment thickness along the erosive segment may be reflected in local variations in locking rate. Two regions with localized decrease in locking rate are spatially associated to the intersection of prominent oceanic ridges at 27.5 and 21.5S, but not to boundaries of historical earthquakes. In general terms, oceanic features seem to have minor influence on earthquake rupture, except for the southern limit of the 1960 event, but are reflected as discrete lows in locking rate. Seismotectonic segmentation along the Chile MT seems to be rather controlled by upper-plate discontinuities such as splay faults and lithological boundaries inherited from the Paleozoic pre-Andean tectonic history of the margin.

Fault creep rates of the Chaman fault (Afghanistan and Pakistan) inferred from InSAR

NASA Astrophysics Data System (ADS)

Barnhart, William D.

2017-01-01

The Chaman fault is the major strike-slip structural boundary between the India and Eurasia plates. Despite sinistral slip rates similar to the North America-Pacific plate boundary, no major (>M7) earthquakes have been documented along the Chaman fault, indicating that the fault either creeps aseismically or is at a late stage in its seismic cycle. Recent work with remotely sensed interferometric synthetic aperture radar (InSAR) time series documented a heterogeneous distribution of fault creep and interseismic coupling along the entire length of the Chaman fault, including an 125 km long creeping segment and an 95 km long locked segment within the region documented in this study. Here I present additional InSAR time series results from the Envisat and ALOS radar missions spanning the southern and central Chaman fault in an effort to constrain the locking depth, dip, and slip direction of the Chaman fault. I find that the fault deviates little from a vertical geometry and accommodates little to no fault-normal displacements. Peak-documented creep rates on the fault are 9-12 mm/yr, accounting for 25-33% of the total motion between India and Eurasia, and locking depths in creeping segments are commonly shallower than 500 m. The magnitude of the 1892 Chaman earthquake is well predicted by the total area of the 95 km long coupled segment. To a first order, the heterogeneous distribution of aseismic creep combined with consistently shallow locking depths suggests that the southern and central Chaman fault may only produce small to moderate earthquakes (

GPS measurement of relative motion of the Cocos and Caribbean Plates and strain accumulation across the Middle America Trench

NASA Astrophysics Data System (ADS)

Dixon, Timothy H.

1993-10-01

Global Positioning System (GPS) measurements in 1988 and 1991 on Cocos Island (Cocos plate), San Andres Island (Caribbean plate), and Liberia (Caribbean plate, mainland Costa Rica) provide an estimate of relative motion between the Cocos and Caribbean plates. The data for Cocos and San Andres Islands, both located more than 400 km from the Middle America Trench, define a velocity that is equivalent within two standard errors (7 mm/yr rate, 5 degrees azimuth) to the NUVEL-1 plate motion model. The data for Liberia, 120 km from the trench, define a velocity that is similar in azimuth but substantially different in rate from NUVEL-1. The discrepancy can be explained with a simple model of elastic strain accumulation with a subduction zone that is locked to a relatively shallow (20±5 km) depth.

Preload Monitoring of Bolted L-Shaped Lap Joints Using Virtual Time Reversal Method.

PubMed

Du, Fei; Xu, Chao; Wu, Guannan; Zhang, Jie

2018-06-13

L-shaped bolt lap joints are commonly used in aerospace and civil structures. However, bolt joints are frequently subjected to loosening, and this has a significant effect on the safety and reliability of these structures. Therefore, bolt preload monitoring is very important, especially at the early stage of loosening. In this paper, a virtual time reversal guided wave method is presented to monitor preload of bolted L-shaped lap joints accurately and simply. In this method, a referenced reemitting signal (RRS) is extracted from the bolted structure in fully tightened condition. Then the RRS is utilized as the excitation signal for the bolted structure in loosening states, and the normalized peak amplitude of refocused wave packet is used as the tightness index (TI A ). The proposed method is experimentally validated by L-shaped bolt joints with single and multiple bolts. Moreover, the selections of guided wave frequency and tightness index are also discussed. The results demonstrate that the relationship between TI A and bolt preload is linear. The detection sensitivity is improved significantly compared with time reversal (TR) method, particularly when bolt loosening is at its embryo stage. The results also show that TR method is an effective method for detection of the number of loosening bolts.

Stress analysis of bolted joints under centrifugal force

NASA Astrophysics Data System (ADS)

Imura, Makoto; Iizuka, Motonobu; Nakae, Shigeki; Mori, Takeshi; Koyama, Takayuki

2014-06-01

Our objective is to develop a long-life rotary machine for synchronous generators and motors. To do this, it is necessary to design a high-strength bolted joint, which is responsible for fixing a salient pole on a rotor shaft. While the rotary machine is in operation, not only centrifugal force but also moment are loaded on a bolted joint, because a point of load is eccentric to a centre of a bolt. We tried to apply the theory proposed in VDI2230-Blatt1 to evaluate the bolted joint under eccentric force, estimate limited centrifugal force, which is the cause of partial separation between the pole and the rotor shaft, and then evaluate additional tension of a bolt after the partial separation has occurred. We analyzed the bolted joint by FEM, and defined load introduction factor in that case. Additionally, we investigated the effect of the variation of bolt preload on the partial separation. We did a full scale experiment with a prototype rotor to reveal the variation of bolt preload against tightening torque. After that, we verified limited centrifugal force and the strength of the bolted joint by the VDI2230-Blatt1 theory and FEM considering the variation of bolt preload. Finally, we could design a high-strength bolted joint verified by the theoretical study and FEM analysis.

Management of comminuted proximal ulna fracture-dislocations using a multiplanar locking intramedullary nail.

PubMed

Edwards, Scott G; Argintar, Evan; Lamb, Joshua

2011-06-01

Intramedullary nails have been used for the fixation of olecranon fractures in an attempt to reduce the soft tissue irritation and resulting need for hardware removal seen with plating and tension banding. Further benefits include preservation of vascular supply, and increase stability and improved compression over some alternative techniques. Most intramedullary nails have been limited to simple olecranon fractures or osteotomies. One novel multiplanar, locking intramedullary nail, however, is indicated to stabilize all fracture patterns of the proximal ulna, including the coronoid. This particular locking nail has screws that radiate in multiple planes and form a fixed-angle lattice throughout the bone. The nail also has fixed-angle screws dedicated to the 3 parts of the coronoid: process tip, medial facet, and medial wall. This allows the nail to secure multiple fragments regardless of the fracture pattern's extent of instability. The objective of this article is to illustrate the recommended steps in reducing and stabilizing a comminuted proximal ulna fracture-dislocation using this multiplanar locking intramedullary nail.

Use of a real-size 3D-printed model as a preoperative and intraoperative tool for minimally invasive plating of comminuted midshaft clavicle fractures.

PubMed

Kim, Hyong Nyun; Liu, Xiao Ning; Noh, Kyu Cheol

2015-06-10

Open reduction and plate fixation is the standard operative treatment for displaced midshaft clavicle fracture. However, sometimes it is difficult to achieve anatomic reduction by open reduction technique in cases with comminution. We describe a novel technique using a real-size three dimensionally (3D)-printed clavicle model as a preoperative and intraoperative tool for minimally invasive plating of displaced comminuted midshaft clavicle fractures. A computed tomography (CT) scan is taken of both clavicles in patients with a unilateral displaced comminuted midshaft clavicle fracture. Both clavicles are 3D printed into a real-size clavicle model. Using the mirror imaging technique, the uninjured side clavicle is 3D printed into the opposite side model to produce a suitable replica of the fractured side clavicle pre-injury. The 3D-printed fractured clavicle model allows the surgeon to observe and manipulate accurate anatomical replicas of the fractured bone to assist in fracture reduction prior to surgery. The 3D-printed uninjured clavicle model can be utilized as a template to select the anatomically precontoured locking plate which best fits the model. The plate can be inserted through a small incision and fixed with locking screws without exposing the fracture site. Seven comminuted clavicle fractures treated with this technique achieved good bone union. This technique can be used for a unilateral displaced comminuted midshaft clavicle fracture when it is difficult to achieve anatomic reduction by open reduction technique. Level of evidence V.

Segmentation of plate coupling, fate of subduction fluids, and modes of arc magmatism in Cascadia, inferred from magnetotelluric resistivity

USGS Publications Warehouse

Wannamaker, Philip E.; Evans, Rob L.; Bedrosian, Paul A.; Unsworth, Martyn J.; Maris, Virginie; McGary, R. Shane

2014-01-01

Five magnetotelluric (MT) profiles have been acquired across the Cascadia subduction system and transformed using 2-D and 3-D nonlinear inversion to yield electrical resistivity cross sections to depths of ∼200 km. Distinct changes in plate coupling, subduction fluid evolution, and modes of arc magmatism along the length of Cascadia are clearly expressed in the resistivity structure. Relatively high resistivities under the coasts of northern and southern Cascadia correlate with elevated degrees of inferred plate locking, and suggest fluid- and sediment-deficient conditions. In contrast, the north-central Oregon coastal structure is quite conductive from the plate interface to shallow depths offshore, correlating with poor plate locking and the possible presence of subducted sediments. Low-resistivity fluidized zones develop at slab depths of 35–40 km starting ∼100 km west of the arc on all profiles, and are interpreted to represent prograde metamorphic fluid release from the subducting slab. The fluids rise to forearc Moho levels, and sometimes shallower, as the arc is approached. The zones begin close to clusters of low-frequency earthquakes, suggesting fluid controls on the transition to steady sliding. Under the northern and southern Cascadia arc segments, low upper mantle resistivities are consistent with flux melting above the slab plus possible deep convective backarc upwelling toward the arc. In central Cascadia, extensional deformation is interpreted to segregate upper mantle melts leading to underplating and low resistivities at Moho to lower crustal levels below the arc and nearby backarc. The low- to high-temperature mantle wedge transition lies slightly trenchward of the arc.

Crustal Deformation and the Seismic Cycle across the Kodiak Islands, Alaska

NASA Technical Reports Server (NTRS)

Sauber, Jeanne; Carver, G.; Cohen, Steven C.; King, Robert

2004-01-01

The Kodiak Islands are located approximately 130 to 250 km from the Alaska-Aleutian Trench where the Pacific plate is underthrusting the North American plate at a rate of about 57 mm/yr. The southern extent of the 1964 Prince William Sound (${M-w}$ = 9.2) earthquake rupture occurred offshore and beneath the eastern portion of the Kodiak Islands. Here we report GPS results (1993-2001) from northern Kodiak Island that span the transition between the 1964 uplift region along the eastern coast and the region of coseismic subsidence further inland. The horizontal velocity vectors range from 22.9 $\\pm$ 2.2 mm/yr at N26.3$\\deg$W $\\pm$ 2.5$\\deg$, about 150 km from the trench, to 5.9 $\\pm$ 1.3 mm/yr at N65.9$\\deg$W $\\pm$ 6.6$\\deg$, about 190 km from the trench. Near the northeastern coast of Kodiak the velocity vector above the shallow, locked main thrust zone is between the orientation of PCFC-NOAM plate motion (N22$/deg$W) and the trench-normal (N3O$\\deg$W). Further west, our geodetic results suggest the accumulation of shear strain that will be released eventually as left-lateral motion on upper plate faults such as the Kodiak Island fault. These results are consistent with the hypothesis that the difference between the Pacific-North American plate motion and the orientation of the down going slab would lead to 4-8 mm/yr of left-lateral slip. Short-term geodetic uplift rates range from 2 - 14 mm/yr, with the maximum uplift located near the axis of maximum subsidence during the 1964 earthquake. We evaluated alternate interseismic models for Kodiak to test the importance of various mechanisms responsible for crustal deformation rates. These models are based on the plate interface slip history inferred from earlier modeling of coseismic and post-seismic geodetic results. The horizontal (trench perpendicular) and vertical deformation rates across Kodiak are consistent with a model that includes the viscoelastic response to : (1) a downgoing Pacific plate interface that is locked at shallow depths,(2) coseismic slip in the 1964 and (3) interseismic creep below the seismogenic zone. The change in orientation of the horizontal velocity vector occurs down-dip from the locked main thrust zone. In southern Kodiak, the coseismic slip in the 1964 earthquake was smaller than in the northern Kodiak region; yet, the horizontal, interseismic velocities as a function of distance from the trench are comparable to those in northern Kodiak. Based on the earthquake history prior to, and following the 1964 earthquake, we hypothesize that the plate interface in southern Kodiak slips in more frequent large earthquakes than in northern Kodiak.

Stable mirror mount

DOEpatents

Cutburth, R.W.

1983-11-04

An improved mirror mount assembly is disclosed. The mirror mount assembly provides a post assembly slidable in a Y-axis orientation and a nut plate assembly slidable in an X-axis orientation and means for simultaneously locking said post assembly and said key assembly in a fixed position.

77 FR 2699 - Foreign-Trade Zone 267-Fargo, ND; Application for Temporary/Interim Manufacturing Authority, CNH...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-19

... and locks (HTSUS 8301.20); metal sign plates (HTSUS 8310.00); fans (HTSUS 8414.59); valves (HTSUS 8413... to choose the duty rates during customs entry procedures that apply to the finished subassemblies and...

19 CFR 10.58 - Bolting cloths; marking.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 19 Customs Duties 1 2010-04-01 2010-04-01 false Bolting cloths; marking. 10.58 Section 10.58... TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. General Provisions Bolting Cloths § 10.58 Bolting cloths; marking. (a) As a prerequisite to the free entry of bolting cloth for milling...

19 CFR 10.58 - Bolting cloths; marking.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 19 Customs Duties 1 2011-04-01 2011-04-01 false Bolting cloths; marking. 10.58 Section 10.58... TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. General Provisions Bolting Cloths § 10.58 Bolting cloths; marking. (a) As a prerequisite to the free entry of bolting cloth for milling...

19 CFR 10.58 - Bolting cloths; marking.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 19 Customs Duties 1 2012-04-01 2012-04-01 false Bolting cloths; marking. 10.58 Section 10.58... TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. General Provisions Bolting Cloths § 10.58 Bolting cloths; marking. (a) As a prerequisite to the free entry of bolting cloth for milling...

19 CFR 10.58 - Bolting cloths; marking.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 19 Customs Duties 1 2014-04-01 2014-04-01 false Bolting cloths; marking. 10.58 Section 10.58... TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. General Provisions Bolting Cloths § 10.58 Bolting cloths; marking. (a) As a prerequisite to the free entry of bolting cloth for milling...

19 CFR 10.58 - Bolting cloths; marking.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 19 Customs Duties 1 2013-04-01 2013-04-01 false Bolting cloths; marking. 10.58 Section 10.58... TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. General Provisions Bolting Cloths § 10.58 Bolting cloths; marking. (a) As a prerequisite to the free entry of bolting cloth for milling...

High-strength bolt corrosion fatigue life model and application.

PubMed

Hui-li, Wang; Si-feng, Qin

2014-01-01

The corrosion fatigue performance of high-strength bolt was studied. Based on the fracture mechanics theory and the Gerberich-Chen formula, the high-strength bolt corrosion fracture crack model and the fatigue life model were established. The high-strength bolt crack depth and the fatigue life under corrosion environment were quantitatively analyzed. The factors affecting high-strength bolt corrosion fatigue life were discussed. The result showed that the high-strength bolt corrosion fracture biggest crack depth reduces along with the material yield strength and the applied stress increases. The material yield strength was the major factor. And the high-strength bolt corrosion fatigue life reduced along with the increase of material strength, the applied stress or stress amplitude. The stress amplitude influenced the most, and the material yield strength influenced the least. Low bolt strength and a low stress amplitude level could extend high-strength bolt corrosion fatigue life.

Analysis of alternatives for using cable bolts as primary support at two low-seam coal mines

PubMed Central

Esterhuizen, Gabriel S.; Tulu, Ihsan B.

2016-01-01

Cable bolts are sometimes used in low-seam coal mines to provide support in difficult ground conditions. This paper describes cable bolting solutions at two low-seam coal mines in similar ground conditions. Both mines used support systems incorporating cable bolts as part of the primary support system. Two original cable bolt based support systems as well as two modified systems are evaluated to estimate their ability to prevent large roof falls. One of the support systems incorporated passive cable bolts, while the other used pre-tensioned cable bolts. The results and experience at the mines showed that the modified systems provided improved stability over the original support systems. The presence of the cable bolts is the most important contribution to stability against large roof falls, rather than the details of the support pattern. It was also found that a heavy steel channel can improve the safety of the system because of the ‘sling’ action it provides. Additionally, the analysis showed that fully-grouted rebar bolts load much earlier than the cable bolts, and pre-tensioning of the cable bolts can result in a more uniform distribution of loading in the roof. PMID:27722019

Analytical Study of the Mechanical Behavior of Fully Grouted Bolts in Bedding Rock Slopes

NASA Astrophysics Data System (ADS)

Liu, C. H.; Li, Y. Z.

2017-09-01

Bolting is widely used as a reinforcement means for rock slopes. The support force of a fully grouted bolt is often provided by the combination of the axial and shear forces acting at the cross section of the bolt, especially for bedding rock slopes. In this paper, load distribution and deformation behavior of the deflecting section of a fully grouted bolt were analyzed, and a structural mechanical model was established. Based on force method equations and deformation compatibility relationships, an analytical approach, describing the contribution of the axial and shear forces acting at the intersection between the bolt and the joint plane to the stability of a rock slope, was developed. Influence of the inclination of the bolt to the joint plane was discussed. Laboratory tests were conducted with different inclinations of the bolt to the joint plane. Comparisons between the proposed approach, the experimental data and a code method were made. The calculation results are in good agreement with the test data. It is shown that transverse shear resistance plays a significant role to the bolting contribution and that the bigger the dip of the bolt to the joint plane, the more significant the dowel effect. It is also shown that the design method suggested in the code overestimates the resistance of the bolt. The proposed model considering dowel effect provides a more precise description on bolting properties of bedding rock slopes than the code method and will be helpful to improve bolting design methods.

Finite element analysis of intramedullary nailing and double locking plate for treating extra-articular proximal tibial fractures.

PubMed

Chen, Fancheng; Huang, Xiaowei; Ya, Yingsun; Ma, Fenfen; Qian, Zhi; Shi, Jifei; Guo, Shuolei; Yu, Baoqing

2018-01-16

Proximal tibia fractures are one of the most familiar fractures. Surgical approaches are usually needed for anatomical reduction. However, no single treatment method has been widely established as the standard care. Our present study aims to compare the stress and stability of intramedullary nails (IMN) fixation and double locking plate (DLP) fixation in the treatment of extra-articular proximal tibial fractures. A three-dimensional (3D) finite element model of the extra-articular proximal tibial fracture, whose 2-cm bone gap began 7 cm from the tibial plateau articular surface, was created fixed by different fixation implants. The axial compressive load on an adult knee during single-limb stance was imitated by an axial force of 2500 N with a distribution of 60% to the medial compartment, while the distal end was fixed effectively. The equivalent von Mises stress and displacement of the model was used as the output measures for analysis. The maximal equivalent von Mises stress value of the system in the IMN model was 293.23 MPa, which was higher comparing against that in the DLP fixation model (147.04 MPa). And the mean stress of the model in the IMN model (9.25 MPa) was higher than that of the DLP fixation system in terms of equivalent von Mises stress (EVMS) (P < 0.0001). The maximal value of displacement (sum) in the IMN system was 8.82 mm, which was lower than that in the DLP fixation system (9.48 mm). This study demonstrated that the stability provided by the locking plate fixation system was superior to the intramedullary nails fixation system and served as an alternative fixation for the extra-articular proximal tibial fractures of young patients.

Short-term Results of Robinson Type 2B2 Clavicular Fractures Treated Conservatively or Surgically.

PubMed

Malkoc, Melih; Korkmaz, Ozgur; Bayram, Erhan; Ormeci, Tugrul; Isyar, Mehmet; Yilmaz, Murat; Seker, Ali

2016-01-01

The most frequently treated injuries, representing approximately 82% of all clavicular fractures, involve the midshaft clavicle. Historically, most acute displaced midshaft clavicular fractures were treated nonsurgically. However, the outcomes of nonsurgical treatment have recently been thought to be not as good as expected in the past, and the trend is to treat these fractures surgically. The goal of this study was to evaluate the short-term clinical outcomes of Robinson type 2B2 clavicular fractures treated conservatively vs with locked plate fixation. Among 59 patients included in the study, 30 patients (mean age, 45±13.7 years; range, 30-62 years) treated conservatively were designated as group A, and 29 patients (mean age, 38.8±11.1 years; range, 20-60 years) treated with locked plate fixation were designated as group B. All patients were evaluated using Oxford and Constant scoring systems at final follow-up. Mean follow-up was 18 months (range, 12-24 months). In group A, mean Constant score was 70.5±15.1 (range, 98-43) and mean Oxford score was 46.6±1.3 (range, 49-44) at final follow-up. In group B, mean Constant score was 89.2±8 (range, 100-77) and mean Oxford score was 46.5±1.2 (range, 48-44) at final follow-up. Callus was detected radiographically in both groups at 6-week follow-up. Patients in groups A and B started active range-of-motion exercises at weeks 6 and 3 after treatment, respectively. Locked plate fixation of Robinson type 2B2 clavicular fractures can be the first treatment option because of good clinical results, low complication rates, and good cosmesis. Copyright 2016, SLACK Incorporated.

Reverse distal femoral locking compression plate a salvage option in nonunion of proximal femoral fractures.

PubMed

Dumbre Patil, Sampat S; Karkamkar, Sachin S; Patil, Vaishali S Dumbre; Patil, Shailesh S; Ranaware, Abhijeet S

2016-01-01

When primary fixation of proximal femoral fractures with implants fails, revision osteosynthesis may be challenging. Tracts of previous implants and remaining insufficient bone stock in the proximal femur pose unique problems for the treatment. Intramedullary implants like proximal femoral nail (PFN) or surface implants like Dynamic Condylar Screw (DCS) are few of the described implants for revision surgery. There is no evidence in the literature to choose one implant over the other. We used the reverse distal femur locking compression plate (LCP) of the contralateral side in such cases undergoing revision surgery. This implant has multiple options of fixation in proximal femur and its curvature along the length matches the anterior bow of the femur. We aimed to evaluate the efficacy of this implant in salvage situations. Twenty patients of failed primary proximal femoral fractures who underwent revision surgery with reverse distal femoral locking plate from February 2009 to November 2012 were included in this retrospective study. There were 18 subtrochanteric fractures and two ipsilateral femoral neck and shaft fractures, which exhibited delayed union or nonunion. The study included 14 males and six females. The mean patient age was 43.6 years (range 22-65 years) and mean followup period was 52.1 months (range 27-72 months). Delayed union was considered when clinical and radiological signs of union failed to progress at the end of four months from initial surgery. All fractures exhibited union without any complications. Union was assessed clinically and radiologically. One case of ipsilateral femoral neck and shaft fracture required bone grafting at the second stage for delayed union of the femoral shaft fracture. Reverse distal femoral LCP of the contralateral side can be used as a salvage option for failed fixation of proximal femoral fractures exhibiting nonunion.

Mid-term functional outcome after the internal fixation of distal radius fractures

PubMed Central

2012-01-01

Background Distal radius fracture is a common injury with a variety of operative and non-operative management options. There remains debate as to the optimal treatment for a given patient and fracture. Despite the popularity of volar locking plate fixation, there are few large cohort or long term follow up studies to justify this modality. Our aim was to report the functional outcome of a large number of patients at a significant follow up time after fixation of their distal radius with a volar locking plate. Methods 180 patients with 183 fractures and a mean age of 62.4 years were followed up retrospectively at a mean of 30 months (Standard deviation = 10.4). Functional assessment was performed using the Disabilities of the Arm, Shoulder and Hand (DASH) and modified MAYO wrist scores. Statistical analysis was performed to identify possible variables affecting outcome and radiographs were assessed to determine time to fracture union. Results The median DASH score was 2.3 and median MAYO score was 90 for the whole group. Overall, 133 patients (74%) had a good or excellent DASH and MAYO score. Statistical analysis showed that no specific variable including gender, age, fracture type, post-operative immobilisation or surgeon grade significantly affected outcome. Complications occurred in 27 patients (15%) and in 11 patients were major (6%). Conclusion This single centre large population series demonstrates good to excellent results in the majority of patients after volar locking plate fixation of the distal radius, with complication rates comparable to other non-operative and operative treatment modalities. On this basis we recommend this mode of fixation for distal radius fractures requiting operative intervention. PMID:22280557

Mid-term functional outcome after the internal fixation of distal radius fractures.

PubMed

Phadnis, Joideep; Trompeter, Alex; Gallagher, Kieran; Bradshaw, Lucy; Elliott, David S; Newman, Kevin J

2012-01-26

Distal radius fracture is a common injury with a variety of operative and non-operative management options. There remains debate as to the optimal treatment for a given patient and fracture. Despite the popularity of volar locking plate fixation, there are few large cohort or long term follow up studies to justify this modality. Our aim was to report the functional outcome of a large number of patients at a significant follow up time after fixation of their distal radius with a volar locking plate. 180 patients with 183 fractures and a mean age of 62.4 years were followed up retrospectively at a mean of 30 months (Standard deviation=10.4). Functional assessment was performed using the Disabilities of the Arm, Shoulder and Hand (DASH) and modified MAYO wrist scores. Statistical analysis was performed to identify possible variables affecting outcome and radiographs were assessed to determine time to fracture union. The median DASH score was 2.3 and median MAYO score was 90 for the whole group. Overall, 133 patients (74%) had a good or excellent DASH and MAYO score. Statistical analysis showed that no specific variable including gender, age, fracture type, post-operative immobilisation or surgeon grade significantly affected outcome. Complications occurred in 27 patients (15%) and in 11 patients were major (6%). This single centre large population series demonstrates good to excellent results in the majority of patients after volar locking plate fixation of the distal radius, with complication rates comparable to other non-operative and operative treatment modalities. On this basis we recommend this mode of fixation for distal radius fractures requiting operative intervention.

Immediate Weightbearing After First Metatarsophalangeal Joint Arthrodesis With Screw and Locking Plate Fixation: A Short-Term Review.

PubMed

Abben, Kyle W; Sorensen, Matthew D; Waverly, Brett J

2018-05-08

Historically, the postoperative protocol for patients undergoing first metatarsophalangeal joint arthrodesis has included 6 weeks of non-weightbearing, followed by protected weightbearing in a below-the-knee cast boot or postoperative shoe. This prolonged period of non-weightbearing predisposes the patient to disuse atrophy, osteopenia, deep vein thrombosis risk, and, overall, a prolonged time to recovery. The present study reports a retrospective review of a patient cohort that underwent first metatarsophalangeal joint fusion with immediate full weightbearing postoperatively. Thirty consecutive first metatarsophalangeal joint arthrodeses were performed during the study period. Five patients were excluded secondary to insufficient postoperative follow-up data or a lack of adequate radiographic evaluation at regular postoperative intervals. Conical reamers were used for joint preparation. Internal fixation, consisting of a single cannulated interfragmentary compression screw and a dorsal locking plate, was used in all patients. The results showed that patients achieved clinical healing at an average of 5.92 weeks and showed radiographic fusion at an average of 6.83 weeks. The patients in the present study had an overall union rate of 96%. Complications included 1 nonunion, 1 superficial wound infection, 1 wound dehiscence, 1 case of symptomatic hardware, and 2 patients with symptomatic hallux interphalangeal joint arthralgia. The mean visual analog pain score preoperatively was 6.64 (range 4 to 8) and postoperatively was 0.6 (range 0 to 4). In conclusion, we found that immediate full weightbearing after first metatarsophalangeal joint fusion in the context of interfragmentary compression and locked plating techniques is a safe, predictable postoperative protocol that allows for a successful fusion interval and an early return to regular activity. Copyright © 2018 The American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Using the Vertical Component of the Surface Velocity Field to Map the Locked Zone at Cascadia Subduction Zone

NASA Astrophysics Data System (ADS)

Moulas, E.; Brandon, M. T.; Podladchikov, Y.; Bennett, R. A.

2014-12-01

At present, our understanding of the locked zone at Cascadia subduction zone is based on thermal modeling and elastic modeling of horizontal GPS velocities. The thermal model by Hyndman and Wang (1995) provided a first-order assessment of where the subduction thrust might be cold enough for stick-slip behavior. The alternative approach by McCaffrey et al. (2007) is to use a Green's function that relates horizontal surface velocities, as recorded by GPS, to interseismic elastic deformation. The thermal modeling approach is limited by a lack of information about the amount of frictional heating occurring on the thrust (Molnar and England, 1990). The GPS approach is limited in that the horizontal velocity component is fairly insensitive to the structure of the locked zone. The vertical velocity component is much more useful for this purpose. We are fortunate in that vertical velocities can now be measured by GPS to a precision of about 0.2 mm/a. The dislocation model predicts that vertical velocities should range up to about 20 percent of the subduction velocity, which means maximum values of ~7 mm/a. The locked zone is generally entirely offshore at Cascadia, except for the Olympic Peninsula region, where the underlying Juan De Fuca plate has an anomalously low dip. Previous thermal and GPS modeling, as well as tide gauge data and episodic tremors indicate the locked zone there extends about 50 to 75 km onland. This situation provides an opportunity to directly study the locked zone. With that objective in mind, we have constructed a full 3D geodynamic model of the Cascadia subduction zone. At present, the model provides a full representation of the interseismic elastic deformation due to variations of slip on the subduction thrust. The model has been benchmarked against the Savage (2D) and Okada (3D) analytical solutions. This model has an important advantage over traditional dislocation modeling in that we include temperature-sensitive viscosity for the upper and lower plates, and also use realistic constitutive models to represent the locked zone. Another important advantage is that the 3D model provides a full representation of the interseismic deformation, which is important for interpreting GPS data.

Are Locking Constructs in Distal Femoral Fractures Always Best? A Prospective Multicenter Randomized Controlled Trial Comparing the Less Invasive Stabilization System With the Minimally Invasive Dynamic Condylar Screw System.

PubMed

2016-01-01

The purpose of this clinical study is to determine whether the rate of fracture healing and fracture union, repaired with a locked device, will be as good as or better than standard nonlocking bicortical fixation in distal femoral fractures. Institutional review board-approved, multicenter prospective randomized controlled trial. Seven level 1 trauma centers across Canada. Fifty-two patients with distal femoral fractures (AO/OTA 33A1 to 33C2) were enrolled in the randomized trial. Twelve AO/OTA 33C3 fractures were excluded from the randomized trial but followed up as a nonrandomized cohort. Patients were treated through a standardized minimally invasive approach. Fractures were randomized 1:1 to treatment with the locked Less Invasive Stabilization System (LISS; Synthes, Paoli, PA) or the dynamic condylar screw (DCS). The nonrandomized cohort was treated at the surgeon's discretion. Primary outcomes were time to radiological union and number of delayed/nonunions at 12 months. Secondary outcomes were postoperative function and complications. Fifty-two patients were randomized including 34 women and 18 men. The mean age was 59 years. Twenty-eight patients were treated with the LISS and 24 with the DCS. There was no statistically significant difference between the LISS and the DCS in terms of the number of fractures healed, time to union, or functional scores. Complications and revisions were more common in the LISS group. There were 7 reoperations in the LISS group and one in the DCS group. Only 52% of the LISS group healed without intervention by 12 months compared with 91% in the DCS group. There was no advantage to the locking plate design in the management of distal femoral fractures in this study. The higher cost of the locking plates, challenges in technique, and lack of superiority have led the authors to discontinue the use of this lateral unicortical locking device in favor of other devices that allow locked or nonlocked bicortical fixation, articular compression, and bridging of the comminuted fracture segments. The cost-effective treatment for a subgroup or periarticular fractures may be a fixed-angle nonlocked device in patients with reasonable bone quality. Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

A new design concept of fully grouted rock bolts in underground construction

NASA Astrophysics Data System (ADS)

Phich Nguyen, Quang; Nguyen, Van Manh; Tuong Nguyen, Ke

2018-04-01

The main problem after excavating an underground excavation is to maintain the stability of the excavation for a certain period of time. Failure in meeting this demand is a threat to safety of men and equipment. Support and reinforcement are different instruments with different mechanisms. Among the common support systems in tunnelling and mining, rock bolts have been widely used to reinforce rock mass and also to reduce geological hazards. Furthermore rock bolts can be applied under varying different geological conditions with cost-effectiveness. Although different methods are developed for grouted rock bolts design until now, the interaction mechanism of the rock bolts and rock mass is still very complicated issue. The paper addresses an analytical model for the analysis and design of fully grouted rock bolts based on the reinforcement principle. According to this concept the jointed rock mass reinforced by grouted rock bolts is considered as composite material which includes rock mass, the grout material and the bolt shank. The mechanical properties of this composite material depend on the ratio of the components. The closed-form solution was developed based on the assumption that the rock mass arround a circular tunnel remained elastic after installing fully grouted rock bolts. The main parameters of the rock-bolt system (the diameter and length of bolt shank, the space between the bolts) are then easily estimated from the obtained solution.

49 CFR 571.209 - Standard No. 209; Seat belt assemblies.

Code of Federal Regulations, 2010 CFR

2010-10-01

.... (1) Eye bolts, shoulder bolts, or other bolt used to secure the pelvic restraint of seat belt... connecting webbing to an eye bolt shall be provided with a retaining latch or keeper which shall not move...) Single attachment hook for connecting webbing to any eye bolt shall be tested in the following manner...

7. VIEW OF INTERIOR OF BUILDING 220 FIRST FLOOR, DENTAL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. VIEW OF INTERIOR OF BUILDING 220 FIRST FLOOR, DENTAL FACILITY AREA (ORIGINALLY THE ARSENAL ROOM). THE ORIGINAL DOOR, SHOWN ON THE LEFT OF PHOTO, IS CONSTRUCTED OF 2' THICK HARDWOOD SANDWICHED BY 1/4' THICK STEEL PLATES WHICH ARE BOLTED TOGETHER. THE DOOR SHOWN ON THE RIGHT OF PHOTO, WAS ADDED DURING THE RENOVATION INTO A DENTAL FACILITY. THE TEXTURED WALLS DISPLAY THE IMPRESSION OF THE WOOD FORMS (5' WIDE PLANKS) USED TO CAST THE 12' THICK CONCRETE WALLS. - U.S. Naval Base, Pearl Harbor, Brig, Neville Way near Ninth Street at Marine Barracks, Pearl City, Honolulu County, HI

An Introductory Characterization of a Combat-Casualty-Care Relevant Swine Model of Closed Head Injury Resulting from Exposure to Explosive Blast

DTIC Science & Technology

2009-07-08

into the crew compartment, the steel top of the frame was bolted to the top of the surrogate and the sling was anchored to the bottom steel plate of...subcutaneously from near the right scapula to the skull surface, where the ends of these leads were attached to the screws, the ends of which rested on...dis- sected near the right scapula , and the positive lead for channel 3 was advanced within this pocket under the skin around the left rib cage to a

An advanced EM railgun design

NASA Astrophysics Data System (ADS)

Hallse, R. L.; Weiman, S. M.

1986-11-01

A progress report is presented from a study of structural design concepts for a large, square-bore, multi-shot railgun. The railgun is to have multi-MA current, a barrel longer than 15 ft, a thermally-managed breech 3 ft long, and pre-stressed internal components. The design, as of early 1986, had a one-piece monolithic circular shell, S-glass/epoxy insulators, and bolt-loaded steel pre-stressed plates. Thermal management is achieved with longitudinal cooling slots with numerous water and air inlets. The device is instrumented for gun current, voltage, bore velocity, magnetic field, rail and armature current, bore dimensions and coolant temperature.

Experimental research on the seismic behavior of CSPSWs connected to frame beams

NASA Astrophysics Data System (ADS)

Guo, Lanhui; Ma, Xinbo; Li, Ran; Zhang, Sumei

2011-03-01

The seismic performance of composite steel plate shear walls (CSPSWs) that consist of a steel plate shear wall (SPSW) with reinforced concrete (RC) panels attached to one or both sides by means of bolts or connectors is experimentally studied. The shear wall is connected to the frame beams but not to the columns. This arrangement restrains the possible out-of-plane buckling of the thin-walled steel plate, thus significantly increasing the bearing capacity and ductility of the overall wall, and prevents the premature overall or local buckling failure of the frame columns. From a practical viewpoint, these solutions can provide open space in a floor as this type of composite shear walls with a relatively small aspect ratio can be placed parallel along a bay. In this study, four CSPSWs and one SPSW were tested and the results showed that both CSPSWs and SPSW possessed good ductility. For SPSW alone, the buckling appeared and resulted in a decrease of bearing capacity and energy dissipation capacity. In addition, welding stiffeners at corners were shown to be an effective way to increase the energy dissipation capacity of CSPSWs.

The extent of slits at the interfaces between luting cements and enamel, dentin and alloy.

PubMed

Oilo, G

1978-01-01

Four different cements were used to assess the presence of slits at the cement/tooth or the cement/alloy interfaces using a tooth-crown model. The model consisted of ground sections of teeth and plane plates of silver/palladium alloy. The plates were fixed with bolts between two brass plates and with three different dimensions of the cement film between tooth and alloy, i.e. 50 micrometer, 100 micrometer and 200 micrometer. The tooth-alloy specimens were sectioned and the adaption of cements was studied with an indirect technique (replica) in a scanning electron microscope. The extent of slits was expressed as the length of all slits relative to the total length of the interface in each specimen. The results showed that the zinc phosphate cement and polycarboxylate cement exhibited a slight to moderate tendency to formation of slits at the interfaces. The EBA cement had a small extent of slits adjacent to thin cement films, but more slits were observed with increasing film thickness. The composite resin cement had a marked tendency to slit formation independent of the cement film thickness.

New constraints on slip rates and locking depths of the San Andreas Fault System from Sentinel-1A InSAR and GAGE GPS observations

NASA Astrophysics Data System (ADS)

Ward, L. A.; Smith-Konter, B. R.; Higa, J. T.; Xu, X.; Tong, X.; Sandwell, D. T.

2017-12-01

After over a decade of operation, the EarthScope (GAGE) Facility has now accumulated a wealth of GPS and InSAR data, that when successfully integrated, make it possible to image the entire San Andreas Fault System (SAFS) with unprecedented spatial coverage and resolution. Resulting surface velocity and deformation time series products provide critical boundary conditions needed for improving our understanding of how faults are loaded across a broad range of temporal and spatial scales. Moreover, our understanding of how earthquake cycle deformation is influenced by fault zone strength and crust/mantle rheology is still developing. To further study these processes, we construct a new 4D earthquake cycle model of the SAFS representing the time-dependent 3D velocity field associated with interseismic strain accumulation, co-seismic slip, and postseismic viscoelastic relaxation. This high-resolution California statewide model, spanning the Cerro Prieto fault to the south to the Maacama fault to the north, is constructed on a 500 m spaced grid and comprises variable slip and locking depths along 42 major fault segments. Secular deep slip is prescribed from the base of the locked zone to the base of the elastic plate while episodic shallow slip is prescribed from the historical earthquake record and geologic recurrence intervals. Locking depths and slip rates for all 42 fault segments are constrained by the newest GAGE Facility geodetic observations; 3169 horizontal GPS velocity measurements, combined with over 53,000 line-of-sight (LOS) InSAR velocity observations from Sentinel-1A, are used in a weighted least-squares inversion. To assess slip rate and locking depth sensitivity of a heterogeneous rheology model, we also implement variations in crustal rigidity throughout the plate boundary, assuming a coarse representation of shear modulus variability ranging from 20-40 GPa throughout the (low rigidity) Salton Trough and Basin and Range and the (high rigidity) Central Valley and ocean lithosphere.

Surgical Fixation of Sternal Fractures: Preoperative Planning and a Safe Surgical Technique Using Locked Titanium Plates and Depth Limited Drilling

PubMed Central

Schulz-Drost, Stefan; Oppel, Pascal; Grupp, Sina; Schmitt, Sonja; Carbon, Roman Th.; Mauerer, Andreas; Hennig, Friedrich F.; Buder, Thomas

2015-01-01

Different ways to stabilize a sternal fracture are described in literature. Respecting different mechanisms of trauma such as the direct impact to the anterior chest wall or the flexion-compression injury of the trunk, there is a need to retain each sternal fragment in the correct position while neutralizing shearing forces to the sternum. Anterior sternal plating provides the best stability and is therefore increasingly used in most cases. However, many surgeons are reluctant to perform sternal osteosynthesis due to possible complications such as difficulties in preoperative planning, severe injuries to mediastinal organs, or failure of the performed method. This manuscript describes one possible safe way to stabilize different types of sternal fractures in a step by step guidance for anterior sternal plating using low profile locking titanium plates. Before surgical treatment, a detailed survey of the patient and a three dimensional reconstructed computed tomography is taken out to get detailed information of the fracture’s morphology. The surgical approach is usually a midline incision. Its position can be described by measuring the distance from upper sternal edge to the fracture and its length can be approximated by the summation of 60 mm for the basis incision, the thickness of presternal soft tissue and the greatest distance between the fragments in case of multiple fractures. Performing subperiosteal dissection along the sternum while reducing the fracture, using depth limited drilling, and fixing the plates prevents injuries to mediastinal organs and vessels. Transverse fractures and oblique fractures at the corpus sterni are plated longitudinally, whereas oblique fractures of manubrium, sternocostal separation and any longitudinally fracture needs to be stabilized by a transverse plate from rib to sternum to rib. Usually the high convenience of a patient is seen during follow up as well as a precise reconstruction of the sternal morphology. PMID:25590989

Ultrasonic measurement and monitoring of loads in bolts used in structural joints

NASA Astrophysics Data System (ADS)

Koshti, Ajay M.

2015-04-01

The paper is an overview of work by the author in measuring and monitoring loads in bolts using an ultrasonic extensometer. A number of cases of bolted joints are covered. These include, a clamped joint with clearance fit between the bolt and hole, a clamped joint with bolt in an interference fit with the hole, a flanged joint which allows the flange and bolt to bend; and a shear joint in a clevis and tang configuration. These applications were initially developed for measuring and monitoring preload in National Aeronautics and Space Administration (NASA) Space Shuttle Orbiter critical joints but are also applicable for monitoring loads in other critical bolted joints of structures such as transportation bridges and other aerospace structures. The papers cited here explain how to set-up a model to estimate the ultrasonic load factor and accuracy for the ultrasonic preload application in a clamped joint with clearance fit. The ultrasonic preload application for clamped joint with bolt in an interference fit can also be used to measure diametrical interference between the bolt shank and hole, as well as interference pressure on the bolt shank. Results of simulation and experimental data are given to demonstrate use of ultrasonic measurements in a shear joint. A bolt in a flanged joint experiences both tensile and bending loads. This application involves measurement of bending and tensile preload in a bolt. The ultrasonic beam bends due to bending load on the bolt. Results of a numerical technique to compute the trace of ultrasonic ray are presented.

Stable mirror mount

DOEpatents

Cutburth, Ronald W.

1990-01-01

An improved mirror mount assembly is disclosed. The mirror mount assembly provides a post assembly slidable in a Y-axis orientation and a nut plate assembly slidable in an X-axis orientation and a device for simultaneously locking the post assembly and the key assembly in a fixed position.

Diode-pumped continuous-wave and femtosecond Cr:LiCAF lasers with high average power in the near infrared, visible and near ultraviolet.

PubMed

Demirbas, Umit; Baali, Ilyes; Acar, Durmus Alp Emre; Leitenstorfer, Alfred

2015-04-06

We demonstrate continuous-wave (cw), cw frequency-doubled, cw mode-locked and Q-switched mode-locked operation of multimode diode-pumped Cr:LiCAF lasers with record average powers. Up to 2.54 W of cw output is obtained around 805 nm at an absorbed pump power of 5.5 W. Using intracavity frequency doubling with a BBO crystal, 0.9 W are generated around 402 nm, corresponding to an optical-to-optical conversion efficiency of 12%. With an intracavity birefringent tuning plate, the fundamental and frequency-doubled laser output is tuned continuously in a broad wavelength range from 745 nm to 885 nm and from 375 to 440 nm, respectively. A saturable Bragg reflector is used to initiate and sustain mode locking. In the cw mode-locked regime, the Cr:LiCAF laser produces 105-fs long pulses near 810 nm with an average power of 0.75 W. The repetition rate is 96.4 MHz, resulting in pulse energies of 7.7 nJ and peak powers of 65 kW. In Q-switched mode-locked operation, pulses with energies above 150 nJ are generated.

Feasibility of fiberglass-reinforced bolted wood connections

Treesearch

D. F. Windorski; L. A. Soltis; R. J. Ross

Bolted connections often fail by a shear plug or a splitting beneath the bolt caused by tension perpendicular-to-grain stresses as the bolt wedges its way through the wood. Preventing this type of failure would enhance the capacity and reliability of the bolted connection, thus increasing the overall integrity of a timber structure and enabling wood to compete...

21 CFR 137.280 - Bolted yellow corn meal.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Bolted yellow corn meal. 137.280 Section 137.280... Flours and Related Products § 137.280 Bolted yellow corn meal. Bolted yellow corn meal conforms to the definition and standard of identity prescribed by § 137.255 for bolted white corn meal except that cleaned...

21 CFR 137.280 - Bolted yellow corn meal.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Bolted yellow corn meal. 137.280 Section 137.280... Flours and Related Products § 137.280 Bolted yellow corn meal. Bolted yellow corn meal conforms to the definition and standard of identity prescribed by § 137.255 for bolted white corn meal except that cleaned...

Simulation and experiment for the inspection of stainless steel bolts in servicing using an ultrasonic phased array

NASA Astrophysics Data System (ADS)

Chen, Jinzhong; He, Renyang; Kang, Xiaowei; Yang, Xuyun

2015-10-01

The non-destructive testing of small-sized (M12-M20) stainless steel bolts in servicing is always a technical problem. This article focuses on the simulation and experimental research of stainless steel bolts with an artificial defect reflector using ultrasonic phased array inspection. Based on the observation of the sound field distribution of stainless steel bolts in ultrasonic phased array as well as simulation modelling and analysis of the phased array probes' detection effects with various defect sizes, different artificial defect reflectors of M16 stainless steel bolts are machined in reference to the simulation results. Next, those bolts are tested using a 10-wafer phased array probe with 5 MHz. The test results finally prove that ultrasonic phased array can detect 1-mm cracks in diameter with different depths of M16 stainless steel bolts and a metal loss of Φ1 mm of through-hole bolts, which provides technical support for future non-destructive testing of stainless steel bolts in servicing.

46 CFR 56.25-20 - Bolting.

Code of Federal Regulations, 2010 CFR

2010-10-01

... chapter for exceptions on bolting used in fluid power and control systems. (b) Carbon steel bolts or bolt... less than that at the root of the threads. They must have heavy semifinished hexagonal nuts in...

Bolt failure detection

DOEpatents

Sutton, Jr., Harry G.

1984-01-01

Bolts of a liquid metal fast breeder reactor, each bolt provided with an internal chamber filled with a specific, unique radioactive tag gas. Detection of the tag gas is indicative of a crack in an identifiable bolt.

Contact acoustic nonlinearity (CAN)-based continuous monitoring of bolt loosening: Hybrid use of high-order harmonics and spectral sidebands

NASA Astrophysics Data System (ADS)

Zhang, Zhen; Liu, Menglong; Liao, Yaozhong; Su, Zhongqing; Xiao, Yi

2018-03-01

The significance of evaluating bolt tightness in engineering structures, preferably in a continuous manner, cannot be overemphasized. With hybrid use of high-order harmonics (HOH) and spectral sidebands, a contact acoustic nonlinearity (CAN)-based monitoring framework is developed for detecting bolt loosening and subsequently evaluating the residual torque on a loose bolt. Low-frequency pumping vibration is introduced into the bolted joint to produce a "breathing" effect at the joining interface that modulates the propagation characteristics of a high-frequency probing wave when it traverses the bolt, leading to the generation of HOH and vibro-acoustic nonlinear distortions (manifested as sidebands in the signal spectrum). To gain insight into the mechanism of CAN generation and to correlate the acquired nonlinear responses of a loose joint with the residual torque remaining on the bolt, an analytical model based on micro-contact theory is established. Two types of nonlinear index, respectively exploiting the induced HOH and spectral sidebands, are defined without dependence on excitation intensity and are experimentally demonstrated to be effective in continuously monitoring bolt loosening in both aluminum-aluminum and composite-composite bolted joints. Taking a step further, variation of the index pair is quantitatively associated with the residual torque on a loose bolt. The approach developed provides a reliable method of continuous evaluation of bolt tightness in both composite and metallic joints, regardless of their working conditions, from early awareness of bolt loosening at an embryonic stage to quantitative estimation of residual torque.

A Modelling Method of Bolt Joints Based on Basic Characteristic Parameters of Joint Surfaces

NASA Astrophysics Data System (ADS)

Yuansheng, Li; Guangpeng, Zhang; Zhen, Zhang; Ping, Wang

2018-02-01

Bolt joints are common in machine tools and have a direct impact on the overall performance of the tools. Therefore, the understanding of bolt joint characteristics is essential for improving machine design and assembly. Firstly, According to the experimental data obtained from the experiment, the stiffness curve formula was fitted. Secondly, a finite element model of unit bolt joints such as bolt flange joints, bolt head joints, and thread joints was constructed, and lastly the stiffness parameters of joint surfaces were implemented in the model by the secondary development of ABAQUS. The finite element model of the bolt joint established by this method can simulate the contact state very well.

Failure Analysis on Tail Rotor Teeter Pivot Bolt on a Helicopter

NASA Astrophysics Data System (ADS)

Qiang, WANG; Zi-long, DONG

2018-03-01

Tail rotor teeter pivot bolt of a helicopter fractured when in one flight. Failure analysis on the bolt was finished in laboratory. Macroscopic observation of the tailor rotor teeter pivot bolt, macro and microscopic inspection on the fracture surface of the bolt was carried out. Chemical components and metallurgical structure was also carried out. Experiment results showed that fracture mode of the tail rotor teeter pivot bolt is fatigue fracture. Fatigue area is over 80% of the total fracture surface, obvious fatigue band characteristics can be found at the fracture face. According to the results were analyzed from the macroscopic and microcosmic aspects, fracture reasons of the tail rotor teeter pivot bolt were analyzed in detail

[Augmentation technique on the proximal humerus].

PubMed

Scola, A; Gebhard, F; Röderer, G

2015-09-01

The treatment of osteoporotic fractures is still a challenge. The advantages of augmentation with respect to primary in vitro stability and the clinical use for the proximal humerus are presented in this article. In this study six paired human humeri were randomized into an augmented and a non-augmented group. Osteosynthesis was performed with a PHILOS plate (Synthes®). In the augmented group the two screws finding purchase in the weakest cancellous bone were augmented. The specimens were tested in a 3-part fracture model in a varus bending test. The augmented PHILOS plates withstood significantly more load cycles until failure. The correlation to bone mineral density (BMD) showed that augmentation could partially compensate for low BMD. The augmentation of the screws in locked plating in a proximal humerus fracture model is effective in improving the primary stability in a cyclic varus bending test. The targeted augmentation of two particular screws in a region of low bone quality within the humeral head was almost as effective as four screws with twice the amount of bone cement. Screw augmentation combined with a knowledge of the local bone quality could be more effective in enhancing the primary stability of a proximal humerus locking plate because the effect of augmentation can be exploited more effectively limiting it to the degree required. The technique of augmentation is simple and can be applied in open and minimally invasive procedures. When the correct procedure is used, complications (cement leakage into the joint) can be avoided.

Minimally invasive locked plating of distal tibia fractures is safe and effective.

PubMed

Ronga, Mario; Longo, Umile Giuseppe; Maffulli, Nicola

2010-04-01

Distal tibial fractures are difficult to manage. Limited soft tissue and poor vascularity impose limitations for traditional plating techniques that require large exposures. The nature of the limitations for traditional plating techniques is intrinsic to the large exposure required to approach distal tibia, a bone characterized by limited soft tissue coverage and poor vascularity. The locking plate (LP) is a new device for treatment of fractures. We assessed the bone union rate, deformity, leg-length discrepancy, ankle range of motion, return to preinjury activities, infection, and complication rate in 21 selected patients who underwent minimally invasive osteosynthesis of closed distal tibia fractures with an LP. According to the AO classification, there were 12 Type A, 5 Type B, and 4 Type C fractures. The minimum followup was 2 years (average, 2.8 years; range, 2-4 years). Two patients were lost to followup. Union was achieved in all but one patient by the 24th postoperative week. Four patients had angular deformity less than 7 degrees . No patient had a leg-length discrepancy more than 1.1 cm. Five patients had ankle range of motion less than 20 degrees compared with the contralateral side. Sixteen patients had not returned to their preinjury sporting or leisure activities. Three patients developed a delayed infection. We judge the LP a reasonable device for treating distal tibia fractures. The level of physical activities appears permanently reduced in most patients. Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Finite element analysis of locking plate and two types of intramedullary nails for treating mid-shaft clavicle fractures.

PubMed

Ni, Ming; Niu, Wenxin; Wong, Duo Wai-Chi; Zeng, Wei; Mei, Jiong; Zhang, Ming

2016-08-01

Both plate and intramedullary nail fixations, including straight and anatomic nails, have been clinically adopted for the treatment of displaced mid-shaft clavicle fractures. However, the biomechanical performances of these fixations and implants have not been well evaluated. This study aims to compare the construct stability, stress distribution and fracture micro-motion of three fixations based on finite element (FE) method. The FE model of clavicle was reconstructed from CT images of a male volunteer. A mid-shaft fracture gap was created in the intact clavicle. Three fixation styles were simulated including locking plate (LP), anatomic intramedullary nail (CRx), and straight intramedullary nail (RCP). Two loading scenarios (axial compression and inferior bending) were applied at the distal end of the clavicle to simulate arm abduction, while the sternal end was fixed. Under both conditions, the LP was the stiffest, followed by the CRx, and the RCP was the weakest. LP also displayed a more evenly stress distribution for both implant and bone. RCP had a higher stress compared with CRx in both conditions. Moreover, all implants sustained higher stress level under the loading condition of bending than compression. The plate fixation significantly stabilizes the fracture gap, reduces the implant stress, and serves as the recommended fixation for the mid-shaft clavicle fracture. The CRx is an alternative device to treat clavicle shaft fracture, but the shoulder excessive activities should be avoided after operation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of fiberglass reinforcement on the behavior of bolted wood connections

Treesearch

Lawrence A. Soltis; Robert J. Ross; Daniel E. Windorski

1997-01-01

Bolted connections often fail by a shear plug or by splitting beneath the bolt caused by tension perpendicular-to-grain stress as the bolt wedges its way through the wood. Preventing this type of failure enhances both the capacity and reliability of bolted connections. This research investigated the use of fiberglass reinforcement to enhance the load-carrying capacity...

A simple method to ensure proper screw position and plate size selection using the Morscher cervical spine locking plate. Technical note.

PubMed

Ball, P A; Benzel, E C; Baldwin, N G

1994-04-01

The use of bone plate instrumentation with screw fixation has proved to be a useful adjunctive measure in anterior cervical spine fusion surgery. Proper fitting, positioning, and attachment of this instrumentation have been shown to be frequently suboptimal if done without radiographic guidance. The most commonly used method of radiographic assistance for placement of this instrumentation is fluoroscopy. While this gives satisfactory technical results, it is expensive and time-consuming, and exposes the patient and the operating room personnel to ionizing radiation. The authors present a simple technique to ensure screw placement and plate fitting using Kirschner wires and a single lateral radiograph. This technique saves time, reduces exposure to radiation, and has led to satisfactory results in over 20 operative cases.

[Tibiotalocalcaneal arthrodesis using a distally introduced femur nail (DFN)].

PubMed

Grass, René

2005-10-01

Simultaneous arthrodesis of ankle and subtalar joints and, at the same sitting, correction of axial malalignment of hindfoot, treatment of bony defects and of sequelae of circulatory disturbances after multiple previous interventions. Internal stabilization with a short distal femur nail. Restitution of a pain-free weight bearing. Failure of arthrodesis of ankle and subtalar joint causing pain in patients with severely altered bone structures particularly at the level of the talar dome. Malalignment of hind- and/or forefoot after previous arthrodesis of ankle and subtalar joint. Failure of conservative therapy in both above-enumerated conditions. Poor skin or soft-tissue conditions. Reflex sympathetic dystrophy. Acute osteitis/osteomyelitis. Posterolateral approach. Resection of the articular cartilage and the areas of sclerosis of the ankle and of the posterior facet of the subtalar joint. Interposition of bone grafts harvested from the iliac crest. Correction of malalignment of hind- and forefoot. Locked nailing with a short distal femur nail. Fitting of a flexible custom-made arthrodesis boot; weight bearing in boot not exceeding half of body weight until the 8th week. Gait training. After 12 weeks wearing of normal shoes. Radiographs after 6 and 12 weeks. Between February 1, 2002 and September 1, 2003 this technique was performed on 18 feet in 17 patients (three women, 14 men, average age 53 years [38.9-73.7 years]). Average duration of follow-up: 1.2 years (0.6-2.1 years). The goal of surgery was reached in all patients. Subjective assessment: 14 times good, three times satisfactory. Four complications: one loss of nail purchase, one dislocation of locking screw, one breakage of locking bolt, one prolonged bone healing.

Fastener stretcher

NASA Technical Reports Server (NTRS)

Oconnor, J. W.; Orem, V. C. (Inventor)

1973-01-01

A description is given of a fastener stretcher used to apply a substantial pure axial tensile force to a structural bolt or similar fastening element. The system is comprised of a pair of telescoping elements, one of which is temporarily secured to the bolt. By spreading the telescoping elements axially, the bolt is tensioned axially to permit a nut or the like to be threaded with a minimum of torque; when the elements are then removed from the bolt, the axial forces on the bolt are taken up by the nut to retain the bolt in its stressed state.

The Fatigue Characteristics of Bolted Lap Joints of 24S-T Alclad Sheet Materials

DTIC Science & Technology

1946-10-01

extremely close bolt fits are needed to o%tain maximum life of bolt ~oint~ under repeated etreseeci. -. Szvzral ty~+?+s of bolt patterns hava been tegted...Memorial Institute on spec~meris of 0.102-i.nch sheet. In particular, figure 4 shows, on a load- life diagram, . results of tests Qn single-bolt...results of tests at the Univer- sity of’ il~~nols on single—bolt specimens, Tables 10 and 11 give reeults of tests, made at the U“ uiversity of Illino~8 , on