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Sample records for endplate welding technology

  1. Automated and aluminum welding technology

    NASA Astrophysics Data System (ADS)

    Jones, Clyde S.

    1994-10-01

    Automated welding technology and techniques for welding advanced aluminum alloys with potential for industrial and commercial applications have been developed by the National Aeronautics and Space Administration at the Marshall Space Flight Center. These technologies are being offered to private companies for commercial development, and include: Variable polarity plasma arc welding, a welding process that produces high-quality aluminum welds for fabrication of the space shuttle external tank and space station common module structures. This process uses reverse polarity pulses to produce welds virtually free of internal defects. Advanced weld sensor technology, comprised of machine vision-based weld seam tracking that uses both structured and global laser illumination for finding weld joints, even those difficult to discern by the human eye. Weld pool feedback is accomplished with a vision system to measure arc symmetry and molten weld pool geometry. A weld bead profiler trails the welding torch. It provides feedback to the process control system, which records quality control data.

  2. Welding space vacuum technology

    NASA Technical Reports Server (NTRS)

    Johnson, R. Barry

    1991-01-01

    The objective was to assist the EH 42 Division in putting together a vacuum system that could attain the desired pressure and be large enough to accommodate the gas-metal arc (GMA) welding fixture apparatus. A major accomplishment was the design and fabrication of the controller/annunciator for the 4' by 8' system. It contains many safety features such as thermocouple set point relays that will only allow inlet and exit gas and vacuum valves to be operated at pre-selected system pressures, and a fail safe mode for power interruptions and operator mistakes. It is felt that significant progress was made in this research effort to weld in a vacuum environment. With continued efforts to increase the pump speeds for vacuum chambers and further studies on weld fixtures and gas inlet pressures, the NASA program will be successful.

  3. TAT Welding Technology Training Program.

    ERIC Educational Resources Information Center

    Rogers, Everette N.; Cook, Jerry L.

    The Training and Technology (TAT) Welding Technology Training Program is an intensive industrial training program conducted by Oak Ridge Associated Universities and Union Carbide Corporation designed to upgrade the skills of unemployed and underemployed individuals so they can command good jobs in industry. The document provides an introduction…

  4. Welding technology. [technology transfer of NASA developments to commercial organizations

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Welding processes which have been developed during NASA space program activities are discussed. The subjects considered are: (1) welding with an electron gun, (2) technology of welding special alloys, and (3) welding shop techniques and equipment. The material presented is part of the combined efforts of NASA and the Small Business Administration to provide technology transfer of space-related developments to the benefit of commercial organizations.

  5. Welding technologies as applied to nuclear manufacturing

    NASA Astrophysics Data System (ADS)

    Roper, J. R.

    1992-10-01

    This is the trip report of John R. Roper, who traveled to England 25 Sep. through 8 Oct. 1992. Dr. Roper attended the US/UK JOWOG 22-D Joining Technical Exchange meeting and gave a presentation on Welding Finite Element Analysis and the Precision Joining Center at the Atomic Weapons Establishment in Aldermaston, United Kingdom. Dr. Roper also toured the Welding Institute in Abington, UK and discussed technology exchange of weld thermal and mechanical material responses.

  6. The technology and welding joint properties of hybrid laser-tig welding on thick plate

    NASA Astrophysics Data System (ADS)

    Shenghai, Zhang; Yifu, Shen; Huijuan, Qiu

    2013-06-01

    The technologies of autogenous laser welding and hybrid laser-TIG welding are used on thick plate of high strength lower alloy structural steel 10CrNiMnMoV in this article. The unique advantages of hybrid laser-TIG welding is summarized by comparing and analyzing the process parameters and welding joints of autogenous laser welding laser welding and hybrid laser-TIG welding. With the optimal process parameters of hybrid welding, the good welding joint without visible flaws can be obtained and its mechanical properties are tested according to industry standards. The results show that the hybrid welding technology has certain advantages and possibility in welding thick plates. It can reduce the demands of laser power, and it is significant for lowering the aspect ratio of weld during hybrid welding, so the gas in the molten pool can rise and escape easily while welding thick plates. Therefore, the pores forming tendency decreases. At the same time, hybrid welding enhances welding speed, and optimizes the energy input. The transition and grain size of the microstructure of hybrid welding joint is better and its hardness is higher than base material. Furthermore, its tensile strength and impact toughness is as good as base material. Consequently, the hybrid welding joint can meet the industry needs completely.

  7. Applied Welding Technology Curriculum Guide.

    ERIC Educational Resources Information Center

    Idaho State Dept. of Education, Boise. Div. of Vocational Education.

    This Idaho state curriculum guide provides lists of tasks, performance objectives, and enabling objectives for instruction in welding. Following an introduction and a list of tasks, the bulk of the document consists of 10 modules, each of which is a list of tasks and the performance objectives and enabling objectives that pertain to each task. The…

  8. Applied Welding Technology. Technical Committee Report.

    ERIC Educational Resources Information Center

    Idaho State Dept. of Education, Boise. Div. of Vocational Education.

    This Technical Committee Report prepared by industry representatives in Idaho lists the skills currently necessary for an employee in that state to obtain a job in applied welding technology, retain a job once hired, and advance in that occupational field. (Task lists are grouped according to duty areas generally used in industry settings, and are…

  9. Virtual Welded - Joint Design Integrating Advanced Materials and Processing Technology

    SciTech Connect

    Yang, Zhishang; Ludewig, Howard W.; Babu, S. Suresh

    2005-06-30

    Virtual Welede-Joint Design, a systematic modeling approach, has been developed in this project to predict the relationship of welding process, microstructure, properties, residual stress, and the ultimate weld fatique strength. This systematic modeling approach was applied in the welding of high strength steel. A special welding wire was developed in this project to introduce compressive residual stress at weld toe. The results from both modeling and experiments demonstrated that more than 10x fatique life improvement can be acheived in high strength steel welds by the combination of compressive residual stress from the special welding wire and the desired weld bead shape from a unique welding process. The results indicate a technology breakthrough in the design of lightweight and high fatique performance welded structures using high strength steels.

  10. Comparing Laser Welding Technologies with Friction Stir Welding for Production of Aluminum Tailor-Welded Blanks

    SciTech Connect

    Hovanski, Yuri; Carsley, John; Carlson, Blair; Hartfield-Wunsch, Susan; Pilli, Siva Prasad

    2014-01-15

    A comparison of welding techniques was performed to determine the most effective method for producing aluminum tailor-welded blanks for high volume automotive applications. Aluminum sheet was joined with an emphasis on post weld formability, surface quality and weld speed. Comparative results from several laser based welding techniques along with friction stir welding are presented. The results of this study demonstrate a quantitative comparison of weld methodologies in preparing tailor-welded aluminum stampings for high volume production in the automotive industry. Evaluation of nearly a dozen welding variations ultimately led to down selecting a single process based on post-weld quality and performance.

  11. Development of New Materials and Technologies for Welding and Surfacing at Research and Production Center "Welding Processes and Technologies"

    NASA Astrophysics Data System (ADS)

    Kozyrev, N. A.; Kryukov, R. E.; Galevsky, G. V.; Titov, D. A.; Shurupov, V. M.

    2015-09-01

    The paper provides description of research into the influence of new materials and technologies on quality parameters of welds and added metal carried out at research and production center «Welding processes and technologies». New welding technologies of tanks for northern conditions are considered, as well as technologies of submerged arc welding involving fluxing agents AN - 348, AN - 60, AN - 67, OK. 10.71 and carbon-fluorine containing additives, new flux cored wires and surfacing technologies, teaching programs and a trainer for welders are designed.

  12. The course of solar array welding technology development

    NASA Technical Reports Server (NTRS)

    Stella, P. M.

    1982-01-01

    Solar array welding technology is examined from its beginnings in the late 1960's to the present. The U.S. and European efforts are compared, and significant similarities are highlighted. The utilization of welding technology for space use is shown to have been influenced by a number of subtle, secondary factors.

  13. Gas Shielding Technology for Welding and Brazing

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur J.; Gradl, Paul R.

    2012-01-01

    Welding is a common method that allows two metallic materials to be joined together with high structural integrity. When joints need to be leak-tight, light-weight, or free of contaminant-trapping seams or surface asperities, welding tends to be specified. There are many welding techniques, each with its own advantages and disadvantages. Some of these techniques include Forge Welding, Gas Tungsten Arc Welding, Friction Stir Welding, and Laser Beam Welding to name a few. Whichever technique is used, the objective is a structural joint that meets the requirements of a particular component or assembly. A key practice in producing quality welds is the use of shielding gas. This article discusses various weld techniques, quality of the welds, and importance of shielding gas in each of those techniques. Metallic bonds, or joints, are produced when metals are put into intimate contact. In the solid-state "blacksmith welding" process, now called Forge Welding (FOW), the site to be joined is pounded into intimate contact. The surfaces to be joined usually need to be heated to make it easier to deform the metal. The surfaces are sprinkled with a flux to melt surface oxides and given a concave shape so that surface contamination can be squeezed out of the joint as the surfaces are pounded together; otherwise the surface contamination would be trapped in the joint and would weaken the weld. In solid-state welding processes surface oxides or other contamination are typically squeezed out of the joint in "flash."

  14. Welding technology transfer task/laser based weld joint tracking system for compressor girth welds

    NASA Technical Reports Server (NTRS)

    Looney, Alan

    1991-01-01

    Sensors to control and monitor welding operations are currently being developed at Marshall Space Flight Center. The laser based weld bead profiler/torch rotation sensor was modified to provide a weld joint tracking system for compressor girth welds. The tracking system features a precision laser based vision sensor, automated two-axis machine motion, and an industrial PC controller. The system benefits are elimination of weld repairs caused by joint tracking errors which reduces manufacturing costs and increases production output, simplification of tooling, and free costly manufacturing floor space.

  15. Virtual Reality Simulator Developed Welding Technology Skills

    ERIC Educational Resources Information Center

    Yunus, Faizal Amin Nur; Baser, Jamil Abd; Masran, Saiful Hadi; Razali, Nizamuddin; Rahim, Bekri

    2011-01-01

    The purpose of this study was to identify the suitability of VR welding simulator application towards CBT in developing welding skills upon new trainees at the Centre of Instructor and Advanced Skills Training (CIAST) Shah Alam Selangor and National Youth Skills Institute (IKBN) Pagoh Johor. The significance of the study was to create a…

  16. Welding.

    ERIC Educational Resources Information Center

    Baldwin, Harold; Whitney, Gregory

    This curriculum guide is intended to assist vocational instructors in preparing students for entry-level employment as welders and preparing them for advanced training in the workplace. The package contains an overview of new and emerging welding technologies, a competency/skill and task list, an instructor's guide, and an annotated bibliography.…

  17. Laser-Hybrid welding, an innovative technology to join automotive body parts

    NASA Astrophysics Data System (ADS)

    Sieben, Manuel; Brunnecker, Frank

    The design of Tail lamps has been changed dramatically since cars built. At modern lamps, the lenses are absolutely transparent and allow a direct view onto the weld seam. Conventional welding technologies, such as vibration and hot plate welding cannot compete with this demand. Focused on this targeted application, LPKF Laser & Electronics AG has developed in cooperation with the Bavarian Laser Centre a unique Laser welding technology called hybrid welding.

  18. Welding.

    ERIC Educational Resources Information Center

    South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

    This curriculum guide is designed for use by South Carolina vocational education teachers as a continuing set of lesson plans for a two-year course on welding. Covered in the individual sections of the guide are the following topics: an orientation to welding, oxyacetylene welding, advanced oxyacetylene welding, shielded metal arc welding, TIG…

  19. FRICTION STIR LAP WELDING OF ALUMINUM - POLYMER USING SCRIBE TECHNOLOGY

    SciTech Connect

    Upadhyay, Piyush; Hovanski, Yuri; Fifield, Leonard S.; Simmons, Kevin L.

    2015-02-16

    Friction Stir Scribe (FSS) technology is a relatively new variant of Friction Stir Welding (FSW) which enables lap joining of dissimilar material with very different melting points and different high temperature flow behaviors. The cutter scribe attached at the tip of FSW tool pin effectively cuts the high melting point material such that a mechanically interlocking feature is created between the dissimilar materials. The geometric shape of this interlocking feature determines the shear strength attained by the lap joint. This work presents first use of scribe technology in joining polymers to aluminum alloy. Details of the several runs of scribe welding performed in lap joining of ~3.175mm thick polymers including HDPE, filled and unfilled Nylon 66 to 2mm thick AA5182 are presented. The effect of scribe geometry and length on weld interlocking features is presented along with lap shear strength evaluations.

  20. Welding.

    ERIC Educational Resources Information Center

    Lehigh County Area Vocational-Technical School, Schnecksville, PA.

    This curriculum guide provides materials for a 12-unit secondary course in welding. Purpose stated for the flexible entry and exit course is to help students master manipulative skills to develop successful welding techniques and to gain an understanding of the specialized tools and equipment used in the welding field. Units cover oxyacetylene…

  1. Welding of titanium and nickel alloy by combination of explosive welding and spark plasma sintering technologies

    SciTech Connect

    Malyutina, Yu. N. Bataev, A. A. Shevtsova, L. I.; Mali, V. I. Anisimov, A. G.

    2015-10-27

    A possibility of titanium and nickel-based alloys composite materials formation using combination of explosive welding and spark plasma sintering technologies was demonstrated in the current research. An employment of interlayer consisting of copper and tantalum thin plates makes possible to eliminate a contact between metallurgical incompatible titanium and nickel that are susceptible to intermetallic compounds formation during their interaction. By the following spark plasma sintering process the bonding has been received between titanium and titanium alloy VT20 through the thin powder layer of pure titanium that is distinguished by low defectiveness and fine dispersive structure.

  2. Welding of titanium and nickel alloy by combination of explosive welding and spark plasma sintering technologies

    NASA Astrophysics Data System (ADS)

    Malyutina, Yu. N.; Bataev, A. A.; Mali, V. I.; Anisimov, A. G.; Shevtsova, L. I.

    2015-10-01

    A possibility of titanium and nickel-based alloys composite materials formation using combination of explosive welding and spark plasma sintering technologies was demonstrated in the current research. An employment of interlayer consisting of copper and tantalum thin plates makes possible to eliminate a contact between metallurgical incompatible titanium and nickel that are susceptible to intermetallic compounds formation during their interaction. By the following spark plasma sintering process the bonding has been received between titanium and titanium alloy VT20 through the thin powder layer of pure titanium that is distinguished by low defectiveness and fine dispersive structure.

  3. Aviation Maintenance Technology. Airframe. A204. Aircraft Welding. Instructor Material.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This teacher's guide is designed to aid teachers in leading students through a module on aircraft welding on airframes. The module contains four units that cover the following topics: (1) gas welding and cutting; (2) brazing and soldering; (3) shielded metal arc welding; and (4) gas tungsten arc welding. Each unit follows a standardized format…

  4. New Technology In Laser Welding Of Thin Filaments

    NASA Astrophysics Data System (ADS)

    Li, Yongzeng; Zhang, Qiu'e.; Ma, Shulin; Li, Yongda; Tian, Fenggui

    1987-01-01

    It is difficult to get a good welding spot and nearly impossible to weld a 10 micron diameter filament (e.g. NiCr) onto a foreign workpiece over 1000 times larger in size. In this paper we introduce the laser powder-covered welding technique. The first step is to laser- weld a metal powder onto a small area of interest of a larger-sized workpiece. This changes the nature of the larger-sized material. The second step is to position the thin filament in contact with the larger workpiece and to apply the pulsed laser so a round and smooth welding spot forms. This should form a good alloy combination. This welding technique has a high success rate for welding minute electrical heat source, independent of the material of the larger workpiece. This technique also solves the problems of unstable quality in tin welding, burrs in pressure welding, and eliminates the problem of welding flux corrosion. This same technique is applied to the laser-welding of a super-thin piece to a foreign workpiece, where the welding spot forms a "micro-rivet': In the paper we present specific conditions required, the analysis data of the welding quality and the specific structure of the laser-welding workstation.

  5. Simulation and Technology of Hybrid Welding of Thick Steel Parts with High Power Fiber Laser

    NASA Astrophysics Data System (ADS)

    Turichin, Gleb; Valdaytseva, Ekaterina; Tzibulsky, Igor; Lopota, Alexander; Velichko, Olga

    The article devoted to steady state and dynamic simulation of melt pool behavior during hybrid laser-arc welding of pipes and shipbuilding sections. The quasi-stationary process-model was used to determine an appropriate welding mode. The dynamical model of laser welding was used for investigation of keyhole depth and width oscillations. The experiments of pipe steel and stainless steel hybrid laser-MAG welding have been made with 15-kW fiber laser in wide range of welding mode parameters. Comparison of experimentally measured and simulated behavior of penetration depth as well as their oscillation spectra approved the self-oscillation nature of melt pool behavior. The welding mode influence of melt pool stability has also been observed. The technological peculiarities, which allow provide high quality weld seam, has been discussed also.

  6. Gallium Arsenide welded panel technology for advanced spaceflight applications

    NASA Technical Reports Server (NTRS)

    Lillington, D. R.; Gillanders, M. S.; Garlick, G. F. J.; Cavicchi, B. T.; Glenn, G. S.; Tobin, S. P.

    1989-01-01

    A significant impediment to the widespread use of GaAs solar cells in space is the cost and weight of the GaAs substrate. In order to overcome these problems, Spectrolab is pursuing thin cell technologies encompassing both liquid phase epitaxy (LPE) GaAs on GaAs and MOCVD GaAs on Ge cells. Spectrolab's experience in the manufacture of 4 to 6 mil 2 cm x 4 cm GaAs cells on a LPE production line is discussed. By thinning the cells at a late state of processing, production yields comparable to 12 mil cells have been achieved. Data are presented showing that GaAs cells can be welded without degradation and have achieved minimum average efficiencies of 18 percent AM0, 28 C with efficiencies up to 20 percent. Spectrolab, in conjunction with Spire Corporation has also been pursuing GaAs on Ge cell technology in support of larger area lighter weight power systems. Data are presented showing that individual 2 cm x 2 cm, 8 mil cell efficiencies up to 21.7 percent have been achieved. Efficiencies up to 24 percent AM0 will be possible by optimizing the GaAs/Ge interface. Cells have been welded without degradation using silver interconnects and have been laid down on an aluminum honeycomb/graphite facesheet substrate to produce a small coupon. The efficiency was 18.1 percent at AM0, 28 C.

  7. Investigation of the technology of laser welding of aluminum alloy 1424

    NASA Astrophysics Data System (ADS)

    Annin, B. D.; Fomin, V. M.; Antipov, V. V.; Ioda, E. N.; Karpov, E. V.; Malikov, A. G.; Orishich, A. M.; Cherepanov, A. N.

    2015-12-01

    In this study, certain technological variants of the laser welding of alloy 1424 of the Al-Mg-Li-Zr system are considered with the purpose of obtaining the durability level of the welded joint, which is close to that of the basic metal. It is shown that, in the case of using various types of plastic deformation of the welded joint, its durability can be increased considerably to 0.85-0.95 from that of the basic metal.

  8. A theoretical study of the influence of technological friction stir welding parameters on weld structures

    NASA Astrophysics Data System (ADS)

    Astafurov, Sergey; Shilko, Evgeny; Kolubaev, Evgeny; Psakhie, Sergey

    2015-10-01

    Computer simulation by the movable cellular automaton method was performed to study the dynamics of friction stir welding of duralumin plates. It was shown that the ratio of the rotation rate to the translational velocity of the rotating tool has a great influence on the quality of the welded joint. A suitably chosen ratio of these parameters combined with an additional ultrasonic impact reduces considerably the porosity and the amount of microcracks in the weld.

  9. THE NEED FOR A NEW JOINING TECHNOLOGY FOR THE CLOSURE WELDING OF RADIOACTIVE MATERIALS CONTAINERS

    SciTech Connect

    CANNELL GR; HILL BE; GRANT GJ

    2008-10-29

    One of the activities associated with cleanup throughout the Department of Energy (DOE) complex is packaging radioactive materials into storage containers. Much of this work will be performed in high-radiation environments requiring fully remote operations, for which existing, proven systems do not currently exist. These conditions demand a process that is capable of producing acceptable (defect-free) welds on a consistent basis; the need to perform weld repair, under fully-remote operations, can be extremely costly and time consuming. Current closure welding technology (fusion welding) is not well suited for this application and will present risk to cleanup cost and schedule. To address this risk, Fluor and the Pacific Northwest National Laboratory (PNNL), are proposing that a new and emerging joining technology, Friction Stir Welding (FSW), be considered for this work. FSW technology has been demonstrated in other industries (aerospace and marine) to produce near flaw-free welds on a consistent basis. FSW is judged capable of providing the needed performance for fully-remote closure welding of containers for radioactive materials for the following reasons: FSW is a solid-state process; material is not melted. As such, FSW does not produce the type of defects associated with fusion welding, e.g., solidification-induced porosity, cracking, distortion due to weld shrinkage, and residual stress. In addition, because FSW is a low-heat input process, material properties (mechanical, corrosion and environmental) are preserved and not degraded as can occur with 'high-heat' fusion welding processes. When compared to fusion processes, FSW produces extremely high weld quality. FSW is performed using machine-tool technology. The equipment is simple and robust and well-suited for high radiation, fully-remote operations compared to the relatively complex equipment associated with the fusion-welding processes. Additionally, for standard wall thicknesses of radioactive materials

  10. Welding Research

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Welding fabrication and welding processes were studied. The following research projects are reported: (1) welding fabrication; (2) residual stresses and distortion in structural weldments in high strength steels; (3) improvement of reliability of welding by in process sensing and control (development of smart welding machines for girth welding of pipes); (4) development of fully automated and integrated welding systems for marine applications; (5) advancement of welding technology; (6) research on metal working by high power laser (7) flux development; (8) heat and fluid flow; (9) mechanical properties developments.

  11. Joining technologies for the 1990s: Welding, brazing, soldering, mechanical, explosive, solid-state, adhesive

    NASA Technical Reports Server (NTRS)

    Buckley, John D. (Editor); Stein, Bland A. (Editor)

    1986-01-01

    A compilation of papers presented in a joint NASA, American Society for Metals, The George Washington University, American Welding Society, and Society of Manufacturing Engineers Conference on Welding, Bonding, and Fastening at Langley Research Center, Hampton, VA, on October 23 to 25, 1984 is given. Papers were presented on technology developed in current research programs relevant to welding, bonding, and fastening of structural materials required in fabricating structures and mechanical systems used in the aerospace, hydrospace, and automotive industries. Topics covered in the conference included equipment, hardware and materials used when welding, brazing, and soldering, mechanical fastening, explosive welding, use of unique selected joining techniques, adhesives bonding, and nondestructive evaluation. A concept of the factory of the future was presented, followed by advanced welding techniques, automated equipment for welding, welding in a cryogenic atmosphere, blind fastening, stress corrosion resistant fasteners, fastening equipment, explosive welding of different configurations and materials, solid-state bonding, electron beam welding, new adhesives, effects of cryogenics on adhesives, and new techniques and equipment for adhesive bonding.

  12. Repairing an implant titanium milled framework using laser welding technology: a clinical report.

    PubMed

    Prasad, Soni; Monaco, Edward A

    2009-04-01

    The application of laser welding technology allows titanium to be welded predictably and precisely to achieve accurate fit of a milled framework. Laser energy results in localized heat production, thereby reducing thermal expansion. Unlike soldering, laser energy can be directed to a small area, making it possible to laser weld close to acrylic resin or ceramic. This article describes the use of laser welding to repair an implant titanium milled fixed denture. A quick, cost-effective, accurate repair was accomplished, and the repaired framework possessed adequate strength and the same precise fit as the original framework. PMID:19328274

  13. Assessment of weld quality of aerospace grade metals by using ultrasonic matrix phased array technology

    NASA Astrophysics Data System (ADS)

    Na, Jeong K.; Gleeson, Sean T.

    2014-03-01

    Advantages of two dimensional electronic ultrasonic beam focusing, steering and scanning with the matrix phased array (MPA) technology has been used to visualize the conditions of resistance spot welds in auto vehicle grade advanced high strength steel carbon steels nondestructively. Two of the commonly used joining techniques, resistance spot welding and resistance seam welding, for thin aerospace grade plates made of aluminum, titanium, and stainless steels have also been inspected with the same MPA NDE system. In this study, a detailed discussions of the current MPA based ultrasonic real time imaging methodology has been made followed by some of the NDT results obtained with various welded test coupons.

  14. The Impact of Information Technology on "Traditional" Occupations: The Case of Welding.

    ERIC Educational Resources Information Center

    Mutch, Alistair

    1998-01-01

    Using the example of welding, the author critiques the work of Casey and Zuboff, arguing that welding has not been as dramatically affected by information technology as some analysts suggest. A temporal dimension in sociological analysis is recommended. (Author/SK)

  15. Classification of weld defect based on information fusion technology for radiographic testing system

    NASA Astrophysics Data System (ADS)

    Jiang, Hongquan; Liang, Zeming; Gao, Jianmin; Dang, Changying

    2016-03-01

    Improving the efficiency and accuracy of weld defect classification is an important technical problem in developing the radiographic testing system. This paper proposes a novel weld defect classification method based on information fusion technology, Dempster-Shafer evidence theory. First, to characterize weld defects and improve the accuracy of their classification, 11 weld defect features were defined based on the sub-pixel level edges of radiographic images, four of which are presented for the first time in this paper. Second, we applied information fusion technology to combine different features for weld defect classification, including a mass function defined based on the weld defect feature information and the quartile-method-based calculation of standard weld defect class which is to solve a sample problem involving a limited number of training samples. A steam turbine weld defect classification case study is also presented herein to illustrate our technique. The results show that the proposed method can increase the correct classification rate with limited training samples and address the uncertainties associated with weld defect classification.

  16. Classification of weld defect based on information fusion technology for radiographic testing system.

    PubMed

    Jiang, Hongquan; Liang, Zeming; Gao, Jianmin; Dang, Changying

    2016-03-01

    Improving the efficiency and accuracy of weld defect classification is an important technical problem in developing the radiographic testing system. This paper proposes a novel weld defect classification method based on information fusion technology, Dempster-Shafer evidence theory. First, to characterize weld defects and improve the accuracy of their classification, 11 weld defect features were defined based on the sub-pixel level edges of radiographic images, four of which are presented for the first time in this paper. Second, we applied information fusion technology to combine different features for weld defect classification, including a mass function defined based on the weld defect feature information and the quartile-method-based calculation of standard weld defect class which is to solve a sample problem involving a limited number of training samples. A steam turbine weld defect classification case study is also presented herein to illustrate our technique. The results show that the proposed method can increase the correct classification rate with limited training samples and address the uncertainties associated with weld defect classification. PMID:27036822

  17. Nuclear Technology. Course 28: Welding Inspection. Module 28-2, Shielded Metal Arc and Oxyacetylene Welding.

    ERIC Educational Resources Information Center

    Espy, John; Selleck, Ben

    This second in a series of ten modules for a course titled Welding Inspection describes the key features of the oxyacetylene and shielded metal arc welding process. The apparatus, process techniques, procedures, applications, associated defects, and inspections are presented. The module follows a typical format that includes the following…

  18. Welding.

    ERIC Educational Resources Information Center

    Cowan, Earl; And Others

    The curriculum guide for welding instruction contains 16 units presented in six sections. Each unit is divided into the following areas, each of which is color coded: terminal objectives, specific objectives, suggested activities, and instructional materials; information sheet; transparency masters; assignment sheet; test; and test answers. The…

  19. Method of cold welding using ion beam technology

    NASA Technical Reports Server (NTRS)

    Sater, B. L. (Inventor)

    1981-01-01

    A method for cold welding metal joints is described. In order to remove the contamination layer on the surface of the metal, an ion beam generator is used in a vacuum environment. A gas, such as xenon or argon, is ionized and accelerated toward the metal surface. The beam of gas effectively sputters away the surface oxides and contamination layer so that clean underlying metal is exposed in the area to be welded. The use of this method allows cold welding with minimal deformation. Both similar and dissimilar metals can be cold welded with this method.

  20. Development of technologies for welding interconnects to fifty-micron thick silicon solar cells

    NASA Technical Reports Server (NTRS)

    Patterson, R. E.

    1982-01-01

    A program was conducted to develop technologies for welding interconnects to 50 microns thick, 2 by 2 cm solar cells. The cells were characterized with respect to electrical performance, cell thickness, silver contact thickness, contact waviness, bowing, and fracture strength. Weld schedules were independently developed for each of the three cell types and were coincidentally identical. Thermal shock tests (100 cycles from 100 C to -180 C) were performed on 16 cell coupons for each cell type without any weld joint failures or electrical degradation. Three 48 cell modules (one for each cell type) were assembled with 50 microns thick cells, frosted fused silica covers, silver clad Invar interconnectors, and Kapton substrates.

  1. Feasibility of remotely manipulated welding in space: A step in the development of novel joining technologies

    NASA Technical Reports Server (NTRS)

    Masubuchi, K.; Agapakis, J. E.; Debiccari, A.; Vonalt, C.

    1985-01-01

    A six month research program entitled Feasibility of Remotely Manipulated Welding in Space - A Step in the Development of Novel Joining Technologies is performed at the Massachusetts Institute of Technology for the Office of Space Science and Applications, NASA, under Contract No. NASW-3740. The work is performed as a part of the Innovative Utilization of the Space Station Program. The final report from M.I.T. was issued in September 1983. This paper presents a summary of the work performed under this contract. The objective of this research program is to initiate research for the development of packaged, remotely controlled welding systems for space construction and repair. The research effort includes the following tasks: (1) identification of probable joining tasks in space; (2) identification of required levels of automation in space welding tasks; (3) development of novel space welding concepts; (4) development of recommended future studies; and (5) preparation of the final report.

  2. Matrix phased array (MPA) imaging technology for resistance spot welds

    SciTech Connect

    Na, Jeong K.; Gleeson, Sean T.

    2014-02-18

    A three-dimensional MPA probe has been incorporated with a high speed phased array electronic board to visualize nugget images of resistance spot welds. The primary application area of this battery operated portable MPA ultrasonic imaging system is in the automotive industry which a conventional destructive testing process is commonly adopted to check the quality of resistance spot welds in auto bodies. Considering an average of five-thousand spot welds in a medium size passenger vehicle, the amount of time and effort given to popping the welds and measuring nugget size are immeasurable in addition to the millions of dollars' worth of scrap metals recycled per plant per year. This wasteful labor intensive destructive testing process has become less reliable as auto body sheet metal has transitioned from thick and heavy mild steels to thin and light high strength steels. Consequently, the necessity of developing a non-destructive inspection methodology has become inevitable. In this paper, the fundamental aspects of the current 3-D probe design, data acquisition algorithms, and weld nugget imaging process are discussed.

  3. Matrix phased array (MPA) imaging technology for resistance spot welds

    NASA Astrophysics Data System (ADS)

    Na, Jeong K.; Gleeson, Sean T.

    2014-02-01

    A three-dimensional MPA probe has been incorporated with a high speed phased array electronic board to visualize nugget images of resistance spot welds. The primary application area of this battery operated portable MPA ultrasonic imaging system is in the automotive industry which a conventional destructive testing process is commonly adopted to check the quality of resistance spot welds in auto bodies. Considering an average of five-thousand spot welds in a medium size passenger vehicle, the amount of time and effort given to popping the welds and measuring nugget size are immeasurable in addition to the millions of dollars' worth of scrap metals recycled per plant per year. This wasteful labor intensive destructive testing process has become less reliable as auto body sheet metal has transitioned from thick and heavy mild steels to thin and light high strength steels. Consequently, the necessity of developing a non-destructive inspection methodology has become inevitable. In this paper, the fundamental aspects of the current 3-D probe design, data acquisition algorithms, and weld nugget imaging process are discussed.

  4. Technology of ultrasonic control of gas-shielded welding process

    NASA Astrophysics Data System (ADS)

    Solodsky, S. A.; Sarychev, V. D.; Borisov, I. S.

    2016-04-01

    A new approach to implementation of electrode metal transfer control under MAG, MIG welding is suggested. The process ensures control of thermal and crystallization processes, stabilizes the time of electrode metal drop formation. The results of the research allow formulating the basic criteria of electrode metal transfer control via ultrasonic exposure, determining the conditions of producing a more equilibrium structure of deposit metal.

  5. Optimized design on condensing tubes high-speed TIG welding technology magnetic control based on genetic algorithm

    NASA Astrophysics Data System (ADS)

    Lu, Lin; Chang, Yunlong; Li, Yingmin; Lu, Ming

    2013-05-01

    An orthogonal experiment was conducted by the means of multivariate nonlinear regression equation to adjust the influence of external transverse magnetic field and Ar flow rate on welding quality in the process of welding condenser pipe by high-speed argon tungsten-arc welding (TIG for short). The magnetic induction and flow rate of Ar gas were used as optimum variables, and tensile strength of weld was set to objective function on the base of genetic algorithm theory, and then an optimal design was conducted. According to the request of physical production, the optimum variables were restrained. The genetic algorithm in the MATLAB was used for computing. A comparison between optimum results and experiment parameters was made. The results showed that the optimum technologic parameters could be chosen by the means of genetic algorithm with the conditions of excessive optimum variables in the process of high-speed welding. And optimum technologic parameters of welding coincided with experiment results.

  6. ARC+(Registered Trademark) and ARC PC Welding Simulators: Teach Welders with Virtual Interactive 3D Technologies

    NASA Technical Reports Server (NTRS)

    Choquet, Claude

    2011-01-01

    123 Certification Inc., a Montreal based company, has developed an innovative hands-on welding simulator solution to help build the welding workforce in the most simple way. The solution lies in virtual reality technology, which has been fully tested since the early 90's. President and founder of 123 Certification Inc., Mr. Claude Choquet Ing. Msc. IWE. acts as a bridge between the welding and the programming world. Working in these fields for more than 20 years. he has filed 12 patents world-wide for a gesture control platform with leading edge hardware related to simulation. In the summer of 2006. Mr Choquet was proud to be invited to the annual IIW International Weld ing Congress in Quebec City to launch the ARC+ welding simulator. A 100% virtual reality system and web based training center was developed to simulate multi process. multi-materiaL multi-position and multi pass welding. The simulator is intended to train welding students and apprentices in schools or industries. The welding simulator is composed of a real welding e[eetrode holder (SMAW-GTAW) and gun (GMAW-FCAW). a head mounted display (HMD), a 6 degrees of freedom tracking system for interaction between the user's hands and head. as well as external audio speakers. Both guns and HMD are interacting online and simultaneously. The welding simulation is based on the law of physics and empirical results from detailed analysis of a series of welding tests based on industrial applications tested over the last 20 years. The simulation runs in real-time, using a local logic network to determine the quality and shape of the created weld. These results are based on the orientation distance. and speed of the welding torch and depth of penetration. The welding process and resulting weld bc.1d are displayed in a virtual environment with screenplay interactive training modules. For review. weld quality and recorded process values can be displayed and diagnosed after welding. To help in the le.tming process, a

  7. Development of a technology for laser welding of the 1424 aluminum alloy with a high strength of the welded joint

    NASA Astrophysics Data System (ADS)

    Annin, B. D.; Fomin, V. M.; Karpov, E. V.; Malikov, A. G.; Orishich, A. M.; Cherepanov, A. N.

    2015-11-01

    Results of an experimental study of properties of joints obtained by using different regimes of laser welding of the 1424 alloy (Al-Mg-Li) are reported. The strength and structure of the welded joints are determined. The influence of various types of welded joint straining on its strength is studied. It is demonstrated that the joint strength increases in the case of plastic straining.

  8. Lightweight solar array blanket tooling, laser welding and cover process technology

    NASA Technical Reports Server (NTRS)

    Dillard, P. A.

    1983-01-01

    A two phase technology investigation was performed to demonstrate effective methods for integrating 50 micrometer thin solar cells into ultralightweight module designs. During the first phase, innovative tooling was developed which allows lightweight blankets to be fabricated in a manufacturing environment with acceptable yields. During the second phase, the tooling was improved and the feasibility of laser processing of lightweight arrays was confirmed. The development of the cell/interconnect registration tool and interconnect bonding by laser welding is described.

  9. Human Disc Nucleus Properties and Vertebral Endplate Permeability

    PubMed Central

    Rodriguez, Azucena G.; Slichter, Chloe K.; Acosta, Frank L.; Rodriguez-Soto, Ana E.; Burghardt, Andrew J.; Majumdar, Sharmila; Lotz, Jeffrey C.

    2010-01-01

    Study of human cadaveric discs quantifying endplate permeability and porosity and correlating these with measures of disc quality: cell density, proteoglycan content, and overall degeneration. Permeability and porosity increased with age and were not correlated with cell density or overall degeneration, suggesting that endplate calcification may not accelerate disc degeneration. Study Design Experimental quantification of relationships between vertebral endplate morphology, permeability, disc cell density, glycosaminoglycan content and degeneration in samples harvested from human cadaveric spines. Objective To test the hypothesis that variation in endplate permeability and porosity contribute to changes in intervertebral disc cell density and overall degeneration. Summary of Background Data Cells within the intervertebral disc are dependent on diffusive exchange with capillaries in the adjacent vertebral bone. Previous findings suggest that blocked routes of transport negatively affect disc quality, yet there are no quantitative relationships between human vertebral endplate permeability, porosity, cell density and disc degeneration. Such relationships would be valuable for clarifying degeneration risk factors, and patient features that may impede efforts at disc tissue engineering. Methods Fifty-one motion segments were harvested from 13 frozen cadaveric human lumbar spines (32 to 85 years) and classified for degeneration using the MRI-based Pfirrmann scale. A cylindrical core was harvested from the center of each motion segment that included vertebral bony and cartilage endplates along with adjacent nucleus tissue. The endplate mobility, a type of permeability, was measured directly using a custom-made permeameter before and after the cartilage endplate was removed. Cell density within the nucleus tissue was estimated using the picogreen method while the nuclear GAG content was quantified using the DMMB technique. Specimens were imaged at 8 μm resolution using

  10. The spectrum of mutations causing end-plate acetylcholinesterase deficiency.

    PubMed

    Ohno, K; Engel, A G; Brengman, J M; Shen, X M; Heidenreich, F; Vincent, A; Milone, M; Tan, E; Demirci, M; Walsh, P; Nakano, S; Akiguchi, I

    2000-02-01

    The end-plate species of acetylcholinesterase (AChE) is an asymmetric enzyme consisting of a collagenic tail subunit composed of three collagenic strands (ColQ), each attached to a tetramer of the T isoform of the catalytic subunit (AChE(T)) via a proline-rich attachment domain. The principal function of the tail subunit is to anchor asymmetric AChE in the synaptic basal lamina. Human end-plate AChE deficiency was recently shown to be caused by mutations in COLQ. We here report nine novel COLQ mutations in 7 patients with end-plate AChE deficiency. We examine the effects of the mutations on the assembly of asymmetric AChE by coexpressing each genetically engineered COLQ mutant with ACHE(T) in COS cells. We classify the newly recognized and previously reported COLQ mutations into four classes according to their position in ColQ and their effect on AChE expression. We find that missense mutations in the proline-rich attachment domain abrogate attachment of catalytic subunits, that truncation mutations in the ColQ collagen domain prevent the assembly of asymmetric AChE, that hydrophobic missense residues in the C-terminal domain prevent triple helical assembly of the ColQ collagen domain, and that other mutations in the C-terminal region produce asymmetric species of AChE that are likely insertion incompetent. PMID:10665486

  11. Welding and joining: A compilation

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A compilation is presented of NASA-developed technology in welding and joining. Topics discussed include welding equipment, techniques in welding, general bonding, joining techniques, and clamps and holding fixtures.

  12. Virtual Welded-Joint Design Integrating Advanced Materials and Processing Technologies

    SciTech Connect

    Yang, Z.; Dong, P.; Liu, S.; Babu, S.; Olson, G.; DebRoy, T.

    2005-04-15

    The primary goal of this project is to increase the fatigue life of a welded-joint by 10 times and to reduce energy use by 25% through product performance and productivity improvements using an integrated modeling approach. The fatigue strength of a welded-joint is currently the bottleneck to design high performance and lightweight welded structures using advanced materials such as high strength steels. In order to achieve high fatigue strength in a welded-joint it is necessary to manage the weld bead shape for lower stress concentration, produce preferable residual stress distribution, and obtain the desired microstructure for improved material toughness and strength. This is a systems challenge that requires the optimization of the welding process, the welding consumable, the base material, as well as the structure design. The concept of virtual welded-joint design has been proposed and established in this project. The goal of virtual welded-joint design is to develop a thorough procedure to predict the relationship of welding process, microstructure, property, residual stress, and the ultimate weld fatigue strength by a systematic modeling approach. The systematic approach combines five sub-models: weld thermal-fluid model, weld microstructure model, weld material property model, weld residual stress model, and weld fatigue model. The systematic approach is thus based on interdisciplinary applied sciences including heat transfer, computational fluid dynamics, materials science, engineering mechanics, and material fracture mechanics. The sub-models are based on existing models with further development. The results from modeling have been validated with critical experiments. The systematic modeling approach has been used to design high fatigue resistant welds considering the combined effects of weld bead geometry, residual stress, microstructure, and material property. In particular, a special welding wire has been developed in this project to introduce

  13. Nuclear Technology. Course 28: Welding Inspection. Module 28-8, Filler Metal Control.

    ERIC Educational Resources Information Center

    Espy, John

    This eighth in a series of ten modules for a course titled Welding Inspection describes controls necessary to place the proper electrode or rod at each welding station. More specifically, the module describes use of the American Welding Society specifications, control of weld filler material after receipt from the supplier, and methods of ensuring…

  14. Variable polarity arc welding

    NASA Technical Reports Server (NTRS)

    Bayless, E. O., Jr.

    1991-01-01

    Technological advances generate within themselves dissatisfactions that lead to further advances in a process. A series of advances in welding technology which culminated in the Variable Polarity Plasma Arc (VPPA) Welding Process and an advance instituted to overcome the latest dissatisfactions with the process: automated VPPA welding are described briefly.

  15. Lumbar spine endplate fractures: Biomechanical evaluation and clinical considerations through experimental induction of injury.

    PubMed

    Curry, William H; Pintar, Frank A; Doan, Ninh B; Nguyen, Ha Son; Eckardt, Gerald; Baisden, Jamie L; Maiman, Dennis J; Paskoff, Glenn R; Shender, Barry S; Stemper, Brian D

    2016-06-01

    Lumbar endplate fractures were investigated in different experimental scenarios, however the biomechanical effect of segmental alignment was not outlined. The objectives of this study were to quantify effects of spinal orientation on lumbar spine injuries during single-cycle compressive loads and understand lumbar spine endplate injury tolerance. Twenty lumbar motion segments were compressed to failure. Two methods were used in the preparation of the lumbar motion segments. Group 1 (n = 7) preparation maintained pre-test sagittal lordosis, whereas Group 2 (n = 13) specimens had a free-rotational end condition for the cranial vertebra, allowing sagittal rotation of the cranial vertebra to create parallel endplates. Five Group 1 specimens experienced posterior vertebral body fracture prior to endplate fracture, whereas two sustained endplate fracture only. Group 2 specimens sustained isolated endplate fractures. Group 2 fractures occurred at approximately 41% of the axial force required for Group 1 fracture (p < 0.05). Imaging and specimen dissection indicate endplate injury consistently took place within the confines of the endplate boundaries, away from the vertebral periphery. These findings indicate that spinal alignment during compressive loading influences the resulting injury pattern. This investigation identified the specific mechanical conditions under which an endplate breach will take place. Development of endplate injuries has significant clinical implication as previous research identified internal disc disruption (IDD) and degenerative disc disease (DDD) as long-term consequences of the axial load-shift that occurs following a breach of the endplate. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1084-1091, 2016. PMID:26610067

  16. In vivo measurement of vertebral endplate surface area along the whole-spine.

    PubMed

    Kishimoto, Maho; Akeda, Koji; Sudo, Akihiro; Espinoza Orías, Alejandro A; Inoue, Nozomu

    2016-08-01

    Accurate determination of vertebral endplate surface area and diameters plays an important role in surgical procedures, spinal implant design and sizing. The objective of this study was to contribute with baseline information on the endplate geometrical parameters using subject-based 3D whole-spine computed tomography (CT) models based on myelogram CT images taken of 49 patients with spinal disorders. Superior and inferior bony endplate mesh-models were created from said 3D CT models and endplate geometrical parameters including total polygon-mesh areas, projected areas and antero posterior and transverse diameters of each endplate were measured. The position of each endplate was determined by the cumulative distance along the spinal column with respect to C2. Endplate area and diameters were analyzed by gender, spinal level, age and correlation with spinal position. Males had larger endplates than females at all levels (p < 0.05) but S1. While endplate areas and transverse diameters increased with age at C3-L5 in females, these increases were not consistent through the whole-spine and even decreases with age were found at T1-T3 in males. There was a strong linear correlation between endplate area and spinal position in males and females with correlation coefficient values of r = 0.938 and r = 0.911, respectively. However, multiple comparisons of the geometrical parameters through the whole-spine revealed localized reduction of the anteroposterior or transverse diameters at T4 and L5-S1 levels. These regional and age-related changes in endplate dimensions should be taken into account for safe interventional treatments at these sites. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1418-1430, 2016. PMID:27346338

  17. A quantitative analysis of local anaesthetic alteration of miniature end-plate currents and end-plate current fluctuations.

    PubMed Central

    Ruff, R L

    1977-01-01

    1. The effect of the local anaesthetic QX222 on the kinetics of miniature end-plate currents (m.e.p.c.s) and acetylcholine (ACh) induced end-plate current (e.p.c) fluctuations was studied in voltage-clamped frog cutaneous pectoris neuromuscular junctions made visible with Nomarski differential interference contrast optics. 2. In Ringer solution the m.e.p.c.s decayed with a single exponential time course and the e.p.c. fluctuation spectra were characterized by single Lorentzian functions, with the spectral cut-off frequency well predicted by the m.e.p.c. decay rate. 3. In the presence of 0-1-0-5 mm QX222 at-50 to -100 mV holding potential both the e.p.c. fluctuation spectrum and the m.e.p.c. decay consisted of a fast and a slow component, with the cut-off frequency of each spectral component predicted by the decay rate of the corresponding constituent of the m.e.p.c. 4. Hyperpolarization increased the decay rate and relative amplitude of the fast component of the m.e.p.c. and decreased the decay rate of the slow m.e.p.c. component. 5. With 0-05 mm QX222 and -70 mV holding potential the m.e.p.c.s. and e.p.c. fluctuation spectra consisted of three components. The third component of the m.e.p.c. and e.p.c. spectra had nearly the same decay rate and cut-off frequency as was found at the same end-plate under equivalent conditions before drug exposure. 6. The kinetic predictions of four different schemes for local anaesthetic action were compared with observed m.e.p.c.s. and e.p.c. fluctuations. 7. Schemes in which the local anaesthetic acted by creating two kinetically distinct populations of acetylcholine receptors or by interacting with ACh receptor to produce a biphasic exponential decay of the end-plate channel conductance did not accurately predict the e.p.c. fluctuation spectrum. 8. The variance of the e.p.c. fluctuations vanished at the reversal potential indicating that local anaesthetic action was not due to the presence of different ion selective end-plate

  18. Feasibility of remotely manipulated welding in space. A step in the development of novel joining technologies

    NASA Technical Reports Server (NTRS)

    Masubuchi, K.; Agapakis, J. E.; Debiccari, A.; Vonalt, C.

    1983-01-01

    In order to establish permanent human presence in space technologies of constructing and repairing space stations and other space structures must be developed. Most construction jobs are performed on earth and the fabricated modules will then be delivered to space by the Space Shuttle. Only limited final assembly jobs, which are primarily mechanical fastening, will be performed on site in space. Such fabrication plans, however, limit the designs of these structures, because each module must fit inside the transport vehicle and must withstand launching stresses which are considerably high. Large-scale utilization of space necessitates more extensive construction work on site. Furthermore, continuous operations of space stations and other structures require maintenance and repairs of structural components as well as of tools and equipment on these space structures. Metal joining technologies, and especially high-quality welding, in space need developing.

  19. END-PLATE ACETYLCHOLINE RECEPTOR: STRUCTURE, MECHANISM, PHARMACOLOGY, AND DISEASE

    PubMed Central

    Sine, Steven M.

    2012-01-01

    The synapse is a localized neurohumoral contact between a neuron and an effector cell and may be considered the quantum of fast intercellular communication. Analogously, the postsynaptic neurotransmitter receptor may be considered the quantum of fast chemical to electrical transduction. Our understanding of postsynaptic receptors began to develop about a hundred years ago with the demonstration that electrical stimulation of the vagus nerve released acetylcholine and slowed the heart beat. During the past 50 years, advances in understanding postsynaptic receptors increased at a rapid pace, owing largely to studies of the acetylcholine receptor (AChR) at the motor endplate. The endplate AChR belongs to a large superfamily of neurotransmitter receptors, called Cys-loop receptors, and has served as an exemplar receptor for probing fundamental structures and mechanisms that underlie fast synaptic transmission in the central and peripheral nervous systems. Recent studies provide an increasingly detailed picture of the structure of the AChR and the symphony of molecular motions that underpin its remarkably fast and efficient chemoelectrical transduction. PMID:22811427

  20. Single crystals for welding research

    SciTech Connect

    David, S.A.; Boatner, L.A.

    1991-01-01

    Most welds last for many years, but a few fail after a relatively short time. Knowing the reasons why welds fail is important because cracks in welds can threaten the safety of people in buildings, airplanes, ships, automobiles, and power plants. Bad welds can lead to costly, extended shutdowns of industrial facilities such as petroleum refineries. Thus, research on this very important fabrication technology is critical to the multibillion-dollar welding industry. Research at ORNL and elsewhere strives to determine the structural features that make some welds strong and others weak. The goals are to find cost-effective ways to characterize the structure and strength of a new weld, correctly predict whether it will last a long time, and determine the welding conditions most likely to produce high-quality welds. There is more to welding than meets the eye. The cracks that make welds fail result from the complexities of microstructures formed during welding. Thus weld microstructure is linked to weld properties such as mechanical strength. As the hot weld material cools from a liquid into a solid, the crystalline grains grow at different speeds and in different directions, forming a new microstructure. By using single crystals rather than polycrystalline alloys to study different weld microstructures, scientists at ORNL have developed a way to predict more accurately the microstructures of various welds. The results could guide welders in providing the right conditions (correct welding speed, heat input, and weld thickness) for producing safer, higher-quality, and longer-lasting welds.

  1. Prediction of Cervical Endplate Size: One Size Does Not Fit All.

    PubMed

    Soo, Adrianne Elizabeth; Olsson, Eric; Lim, Moe

    2016-05-01

    Significant variations exist in the footprint size of cervical vertebral endplates. In anterior cervical spine surgery, an implant that maximizes coverage of the endplate and contacts the apophyses may reduce subsidence and decrease risk of endplate fracture. The ability to accurately predict a patient's vertebral endplate size may be helpful for surgeons to preoperatively choose the optimal implant for the patient's specific anatomy. The purpose of this study was to (1) demonstrate the range of vertebral endplate sizes between individual patients and cervical levels and (2) determine if vertebral endplate size can be predicted based on patient characteristics and vertebral level. Fifty cervical computed tomography scans of patients 18 to 65 years old were selected for analysis. Superior vertebral endplate sizes of C3-C7 were measured medial-laterally and anteriorly-posteriorly. The medial-laterally measurement was taken from the midbody coronal view at the flat central region of the superior endplate, and the anteriorly-posteriorly measurement was taken at the midbody axial view from the front to back edge of the vertebral body. Age, height, weight, gender, and race were recorded for all patients. One-way analysis of variance, linear regressions, and multivariate regressions were performed. Patient height, age, gender, and race accounted for 51% to 71% of the variance between individuals, and endplate size increased by 1 mm in width and 0.6 mm in depth for each progressively more caudal vertebral level. Vertebral endplate size could be reliably calculated based on patient height, age, gender, and vertebral level. These data may be useful to assist surgeons in preoperative planning for patient-specific implant selection. [Orthopedics. 2016; 39(3):e526-e531.]. PMID:27135446

  2. Does Vertebral Endplate Morphology Influence Outcomes in Lumbar Disc Arthroplasty? Part I: An Initial Assessment of a Novel Classification System of Lumbar Endplate Morphology

    PubMed Central

    Yue, James J.; Oetgen, Matthew E.; la Torre, Jorge J. Jaramillo-de; Bertagnoli, Rudolf

    2008-01-01

    Background The influence of lumbar endplate morphology on the clinical and radiographic outcomes of lumbar disc arthroplasty has not been evaluated to the best of our knowledge. Study Design and Objective In this observational study of 80 patients, the objective was to formulate a reproducible and valid lumbar endplate classification system to be used in evaluating lumbar total disc replacement patients. Methods A novel vertebral endplate morphology classification system was formulated after review of data related to 80 patients enrolled in a prospective, randomized clinical trial in conjunction with an application for a US Food and Drug Administration investigational device exemption. Intraobserver and interobserver analyses of the classification system were performed on the same 80 patients utilizing the classification system. Results The initial review of the radiographs revealed 5 types of endplates: Type I (n = 82) flat endplates; Type II (n = 26) posterior lip; Type III (n = 5) central concavity; Type IV (n = 4) anterior sloping endplate; and Type V (n = 2) combination of Types I—IV. The intraobserver kappa was 0.66 and the interobserver kappa was 0.51. These kappa values indicate “substantial” to “moderate” reproducibility, respectively. Conclusions In this study, we propose a lumbar endplate classification system to be used in the preoperative assessment of patients undergoing lumbar disc arthroplasty. The classification can function as a basis for comparison and discussion among arthroplasty clinicians, and serve as a possible exclusionary screening tool for disc arthroplasty. Special consideration should be given to Type II endplates to optimize proper positioning and functioning of a total disc replacement (TDR) implant. Further outcome studies are warranted to assess the clinical significance of this classification system. The key points of our study are: (1) We present a novel lumbar vertebral endplate classification system; (2) Five types of

  3. A review of computer aided interpretation technology for the evaluation of radiographs of aluminum welds

    NASA Technical Reports Server (NTRS)

    Lloyd, J. F., Sr.

    1987-01-01

    Industrial radiography is a well established, reliable means of providing nondestructive structural integrity information. The majority of industrial radiographs are interpreted by trained human eyes using transmitted light and various visual aids. Hundreds of miles of radiographic information are evaluated, documented and archived annually. In many instances, there are serious considerations in terms of interpreter fatigue, subjectivity and limited archival space. Quite often it is difficult to quickly retrieve radiographic information for further analysis or investigation. Methods of improving the quality and efficiency of the radiographic process are being explored, developed and incorporated whenever feasible. High resolution cameras, digital image processing, and mass digital data storage offer interesting possibilities for improving the industrial radiographic process. A review is presented of computer aided radiographic interpretation technology in terms of how it could be used to enhance the radiographic interpretation process in evaluating radiographs of aluminum welds.

  4. Does Vertebral Endplate Morphology Influence Outcomes in Lumbar Total Disc Arthroplasty? Part II: Clinical and Radiographic Results as Evaluated Utilizing the Vertebral Endplate Yue-Bertagnoli (VEYBR) Classification

    PubMed Central

    Oetgen, Matthew E.; la Torre, Jorge J. Jaramillo-de; Bertagnoli, Rudolf

    2008-01-01

    Study Design This study was a prospective study with a minimum patient follow-up of 2 years. Objective The purpose of this study was to evaluate the clinical usefulness of a vertebral endplate classification system (VEYBR) in predicting outcomes following lumbar arthroplasty. Background In the present study, our previously described endplate classification system was evaluated to determine its clinical usefulness in patients undergoing lumbar arthroplasty. Methods The patient cohort in this study consisted of 80 patients who had been enrolled in the US FDA ProDisc clinical trial. Radiographs were classified using the VEYBR classification. The preoperative categories (Types I to V) were then correlated with the patients’ visual analogue scores (VAS) and Oswestry Disability Index (ODI) scores and radiographic outcomes at an average follow-up point of 28 months. Results The rank order of total change in VAS based on preoperative VEYBR classification was Type IV, III, I II, and V, with Type IV having the greatest improvement in VAS and Type V having the least improvement. The rank order of total change in ODI was Type IV, II, III, I, and V. We found no differences in clinical outcomes among the 5 vertebral endplate types. Type II endplates had least optimal sagittal positioning. Conclusions Although not statistically significant, there was a strong trend for Type V endplates to have the least improvements in VAS and Oswestry clinical outcome scores. Knowledge and use of the endplate classification system did lead to consistent implant placement across endplate classes which may indicate the usefulness of this classification system in preoperative planning, especially for physicians in the “learning curve” phase of this procedure. Level of Evidence Case series (Level IV). PMID:25802609

  5. Welds in thermoplastic composite materials

    NASA Astrophysics Data System (ADS)

    Taylor, N. S.

    Welding methods are reviewed that can be effectively used for joining of thermoplastic composites and continuous-fiber thermoplastics. Attention is given to the use of ultrasonic, vibration, hot-plate, resistance, and induction welding techniques. The welding techniques are shown to provide complementary weld qualities for the range of thermoplastic materials that are of interest to industrial and technological applications.

  6. Influences of Endplate Removal and Bone Mineral Density on the Biomechanical Properties of Lumbar Spine

    PubMed Central

    Yuan, Wen; Liu, Yang

    2013-01-01

    Purpose To investigate (1) effects of endplate removal and bone mineral density (BMD) on biomechanical properties of lumbar vertebrae (2) whether the distributions of mechanical strength and stiffness of endplate are affected by BMD. Methods A total of thirty-one lumbar spines (L1-L5) collected from fresh cadavers were used in this study. Bone density was measured using lateral DEXA scans and parts of samples were performed with partial or entire endplate removal. All the specimens were divided into three BMD groups. According to endplate integrity of the lumbar vertebrae, each BMD group was then divided into three subgroups: subgroup A: intact endplate; subgroup B: central region of endplate removal; subgroup C: entire endplate removal. The axial compression test was conducted with material testing system at a speed of 2mm/min. The experimental results were statistically analyzed using SPSS 17.0. Results (1) Significant differences of biomechanical properties occurred among normal BMD, osteoporotic and serious osteoporotic group (P<0.05). (2) Spearman analysis showed that BMD was positively correlated with the failure load and stiffness of lumbar vertebrae. (3) For each BMD group, significant differences of biomechanical properties were found between subgroup A and C, and between subgroup B and C (P<0.05). (4) For each BMD group, there was no statistical difference of biomechanical properties between subgroup A and B (P>0.05). Conclusions Entire endplate removal can significantly decrease the structural properties of lumbar vertebrae with little change in biomechanical properties by preservation of peripheral region of the endplate. BMD is positively correlated to the structural properties of the lumbar vertebrae. PMID:24244269

  7. U.S. welding technology - Constraints to space implementation. [for solar arrays

    NASA Technical Reports Server (NTRS)

    Stella, P. M.

    1982-01-01

    U.S. and European efforts to develop welding techniques for satellite solar arrays are described. Soldering practices in the U.S. have benefitted from Mo solders, which are well fitted to Si solar cell material thermal characteristics. Analyses have indicated that welds are the preferred method for interconnections and bonds. Extensive work has been done with the parallel gap resistance method (RW), which involves process heat generated by passing a current through resistive layers. Confining the primary heat input to the interconnector/cell contact interface results in welds being formed beneath both electrodes. Pulse welding has become the dominant RW technique in Europe, while ultrasonic welding is used in the U.S.; silver is employed as the interconnect material on both continents. The bonding techniques have been developed empirically instead of theoretically. An IR inspection technique has been produced for monitoring the weld temperature.

  8. Endplate structure and parameters of neuromuscular transmission in sporadic centronuclear myopathy associated with myasthenia.

    PubMed

    Liewluck, Teerin; Shen, Xin-Ming; Milone, Margherita; Engel, Andrew G

    2011-06-01

    Centronuclear myopathy is a pathologically diagnosed congenital myopathy. The disease genes encode proteins with membrane modulating properties (MTM1, DNM2, and BIN1) or alter excitation-contraction coupling (RYR1). Some patients also have myasthenic symptoms but electrodiagnostic and endplate studies in these are limited. A sporadic patient had fatigable weakness and a decremental EMG response. Analysis of centronuclear myopathy disease- and candidate-genes identified no mutations. Quantitative endplate electron microscopy studies revealed simplified postsynaptic regions, endplate remodeling with normal nerve terminal size, normal synaptic vesicle density, and mild acetylcholine receptor deficiency. The amplitude of the miniature endplate potential was decreased to 60% of normal. Quantal release by nerve impulse was reduced to 40% of normal due to a decreased number of releasable quanta. The safety margin of neuromuscular transmission is compromised by decreased quantal release by nerve impulse and by a reduced postsynaptic response to the released quanta. PMID:21482111

  9. Correlation of cervical endplate strength with CT measured subchondral bone density

    PubMed Central

    Ordway, Nathaniel R.; Lu, Yen-Mou; Zhang, Xingkai; Cheng, Chin-Chang; Fang, Huang

    2007-01-01

    Cervical interbody device subsidence can result in screw breakage, plate dislodgement, and/or kyphosis. Preoperative bone density measurement may be helpful in predicting the complications associated with anterior cervical surgery. This is especially important when a motion preserving device is implanted given the detrimental effect of subsidence on the postoperative segmental motion following disc replacement. To evaluate the structural properties of the cervical endplate and examine the correlation with CT measured trabecular bone density. Eight fresh human cadaver cervical spines (C2–T1) were CT scanned and the average trabecular bone densities of the vertebral bodies (C3–C7) were measured. Each endplate surface was biomechanically tested for regional yield load and stiffness using an indentation test method. Overall average density of the cervical vertebral body trabecular bone was 270 ± 74 mg/cm3. There was no significant difference between levels. The yield load and stiffness from the indentation test of the endplate averaged 139 ± 99 N and 156 ± 52 N/mm across all cervical levels, endplate surfaces, and regional locations. The posterior aspect of the endplate had significantly higher yield load and stiffness in comparison to the anterior aspect and the lateral aspect had significantly higher yield load in comparison to the midline aspect. There was a significant correlation between the average yield load and stiffness of the cervical endplate and the trabecular bone density on regression analysis. Although there are significant regional variations in the endplate structural properties, the average of the endplate yield loads and stiffnesses correlated with the trabecular bone density. Given the morbidity associated with subsidence of interbody devices, a reliable and predictive method of measuring endplate strength in the cervical spine is required. Bone density measures may be used preoperatively to assist in the prediction of the strength

  10. Activation of endplate nicotinic acetylcholine receptors by agonists.

    PubMed

    Auerbach, Anthony

    2015-10-15

    The interaction of a small molecule made in one cell with a large receptor made in another is the signature event of cell signaling. Understanding the structure and energy changes associated with agonist activation is important for engineering drugs, receptors and synapses. The nicotinic acetylcholine receptor (AChR) is a ∼300kD ion channel that binds the neurotransmitter acetylcholine (ACh) and other cholinergic agonists to elicit electrical responses in the central and peripheral nervous systems. This mini-review is in two sections. First, general concepts of skeletal muscle AChR operation are discussed in terms of energy landscapes for conformational change. Second, adult vs. fetal AChRs are compared with regard to interaction energies between ACh and agonist-site side chains, measured by single-channel electrophysiology and molecular dynamics simulations. The five aromatic residues that form the core of each agonist binding site can be divided into two working groups, a triad (led by αY190) that behaves similarly at all sites and a coupled pair (led by γW55) that has a large influence on affinity only in fetal AChRs. Each endplate AChR has 5 homologous subunits, two of α(1) and one each of β, δ, and either γ (fetal) or ϵ (adult). These nicotinic AChRs have only 2 functional agonist binding sites located in the extracellular domain, at αδ and either αγ or αϵ subunit interfaces. The receptor undergoes a reversible, global isomerization between structures called C and O. The C shape does not conduct ions and has a relatively low affinity for ACh, whereas O conducts cations and has a higher affinity. When both agonist sites are empty (filled only with water) the probability of taking on the O conformation (PO) is low, <10(-6). When ACh molecules occupy the agonist sites the C→O opening rate constant and C↔O gating equilibrium constant increase dramatically. Following a pulse of ACh at the nerve-muscle synapse, the endplate current rises rapidly

  11. Influence of Biochemical Composition on Endplate Cartilage Tensile Properties in the Human Lumbar Spine

    PubMed Central

    Fields, Aaron J.; Rodriguez, David; Gary, Kaitlyn N.; Liebenberg, Ellen C.; Lotz, Jeffrey C.

    2014-01-01

    Endplate cartilage integrity is critical to spine health and is presumably impaired by deterioration in biochemical composition. Yet, quantitative relationships between endplate biochemical composition and biomechanical properties are unavailable. Using endplate cartilage harvested from human lumbar spines (six donors, ages 51–67 years) we showed that endplate biochemical composition has a significant influence on its equilibrium tensile properties and that the presence of endplate damage associates with a diminished composition–function relationship. We found that the equilibrium tensile modulus (5.9±5.7 MPa) correlated significantly with collagen content (559±147 μg/mg dry weight, r2=0.35) and with the collagen/GAG ratio (6.0±2.1, r2=0.58). Accounting for the damage status of the adjacent cartilage improved the latter correlation (r2=0.77) and indicated that samples with adjacent damage such as fissures and avulsions had a diminished modulus–collagen/GAG relationship (p=0.02). Quasi-linear viscoelastic relaxation properties (C, t1, and t2) did not correlate with biochemical composition. We conclude that reduced matrix quantity decreases the equilibrium tensile modulus of human endplate cartilage and that characteristics of biochemical composition that are independent of matrix quantity, that is, characteristics related to matrix quality, may also be important. PMID:24273192

  12. Recent advances in the welding technology on the fabrication of jackup drilling rig

    SciTech Connect

    Akahide, K.; Hashimoto, O.; Kikukawa, S.; Shimizu, T.

    1983-05-01

    This paper presents new techniques in the fabrication of rig components that satisfy various requirements for use in cold and/or deep waters such as the North Sea. Details discussed include: improving the toughness of heavy-walled HSLA steel pipes (700-800 MPa class) for the chords and legs of rigs, method of controlling welding deformation in the fabrication of chords, and the effect of post weld heat treatment (PWHT) on the toughness of welded joints. Data are presented from both field operations and laboratory tests of actual size specimens manufactured by industrial processes.

  13. Explosive welding of pipes

    NASA Astrophysics Data System (ADS)

    Drennov, O.; Burtseva, O.; Kitin, A.

    2006-08-01

    For connection by welding it is suggested to use the explosive welding method. This method is rather new. Nevertheless, it has become commonly used among the technological developments. This method can be advantageous (saving material and physical resources) comparing to its statical analogs (electron-beam welding, argon-arc welding, plasma welding, gas welding, etc.), in particular, in hard-to-reach areas due to their geographic and climatic conditions. The suggestion is to use water as filler. The principle of non-compressibility of liquid under quasi-dynamic loading is used. In one-dimensional gasdynamic and elastic-plastic calculations we determined non-deformed mass of water. Model experiments with pipes having radii R = 57 mm confirmed results of the calculations and the possibility in principle to weld pipes by explosion with use of water as filler.

  14. Welding arc plasma physics

    NASA Technical Reports Server (NTRS)

    Cain, Bruce L.

    1990-01-01

    The problems of weld quality control and weld process dependability continue to be relevant issues in modern metal welding technology. These become especially important for NASA missions which may require the assembly or repair of larger orbiting platforms using automatic welding techniques. To extend present welding technologies for such applications, NASA/MSFC's Materials and Processes Lab is developing physical models of the arc welding process with the goal of providing both a basis for improved design of weld control systems, and a better understanding of how arc welding variables influence final weld properties. The physics of the plasma arc discharge is reasonably well established in terms of transport processes occurring in the arc column itself, although recourse to sophisticated numerical treatments is normally required to obtain quantitative results. Unfortunately the rigor of these numerical computations often obscures the physics of the underlying model due to its inherent complexity. In contrast, this work has focused on a relatively simple physical model of the arc discharge to describe the gross features observed in welding arcs. Emphasis was placed of deriving analytic expressions for the voltage along the arc axis as a function of known or measurable arc parameters. The model retains the essential physics for a straight polarity, diffusion dominated free burning arc in argon, with major simplifications of collisionless sheaths and simple energy balances at the electrodes.

  15. Effects on the vertebral end-plate of uncomplicated lumbar discography: an MRI study.

    PubMed

    Saifuddin, A; Renton, P; Taylor, B A

    1998-01-01

    The study aimed to identify and characterise changes occurring in the vertebral end-plate on MRI following uncomplicated lumbar discography. MRI was performed immediately before and within 2 h after uncomplicated lumbar discography in 20 consecutive patients undergoing the study as a precursor to possible spinal fusion. Of these, seven patients underwent a further MRI study at a mean of 72 days after discography (range 19-183 days). The MRI scans were assessed for the presence of any changes in the end-plates prior to and following discography. End-plate changes were identified in eight patients (40%) prior to discography. No new changes in end-plate signal intensity (SI) were identified in either the immediate or delayed MRI studies. The study suggests that any changes occurring in the vertebral end-plate following discography should be considered due to infectious discitis. There is no support for the concept of chemical discitis, chemical irritation of bone or microfracture of subchondral trabeculae as a cause of pain at discography. PMID:9548356

  16. Nuclear Technology. Course 28: Welding Inspection. Module 28-3, Tungsten Inert Gas (TIG), Metal Inert Gas (MIG) and Submerged Arc Welding.

    ERIC Educational Resources Information Center

    Espy, John

    This third in a series of ten modules for a course titled Welding Inspection presents the apparatus, process techniques, procedures, applications, associated defects, and inspection for the tungsten inert gas, metal inert gas, and submerged arc welding processes. The module follows a typical format that includes the following sections: (1)…

  17. Design of asymmetrically loaded end-plates with vacuum seal surfaces for the Navy Prototype Optical Interferometer

    NASA Astrophysics Data System (ADS)

    Walton, Joshua P.; Clark, James H., III; Penado, F. Ernesto

    2007-09-01

    Engineering specifications for O-ring seal surfaces are well documented. However, when seal surfaces are located on asymmetrically loaded vacuum end-plates, consideration must be given not only to surface finish and flatness, but also to load-induced deflections. When deflections are significant, O-ring compression can relax and potentially cause vacuum leaks. Large vacuum systems, such as the 9000 cubic foot system at the Navy Prototype Optical Interferometer (NPOI), cannot afford costly vacuum leaks due to improper end-plate design. The NPOI employs vacuum end-plates that serve both as structural members, and as vacuum system entrance and exit ports for stellar light. These ports consist of vacuum components attached directly to the end-plate via static O-ring sealing techniques. Optical geometry dictates off-center port locations, which create asymmetric end-plate loading. This paper details the behavior of a 22 inch diameter, multi-port, end-plate for the NPOI Fast Delay Line subsystem. In depth CAD modeling and finite element analysis techniques were used to determine load-induced stress distributions and deflections in the end-plate. After several design iterations, an end-plate design was substantiated that maintains vacuum seal integrity under loading, exhibits a conservative factor of safety, and is readily manufacturable.

  18. In-situ weld quality inspection with matrix phased array (MPA) ultrasonic technology

    NASA Astrophysics Data System (ADS)

    Gleeson, Sean; Dao, Gavin; Na, Jeong K.

    2014-02-01

    In the Oil and Gas industry, it is very common to make welds on pipes in the field. For straight pipes, most of the time, welds are inspected with an automated ultrasonic testing (AUT) system. However, pipes having non-traditional geometric constraints such as a slanted corrugation feature prohibit the use of an AUT method. As an effort to develop a field deployable in-situ weld inspection system, a high-speed MPA circuit board (purchased from Advanced OEM Solutions) has been used to drive a 32-element MPA probe operating at 3 MHz. The goal of the most recent phase of this development was to achieve a minimum of 200 inches per minute real-time inspection speed to match a welding process developed simultaneously at EWI. In order to meet the speed requirement, it was necessary to maximize the data acquisition rate as close as possible to the data transfer rate the MPA circuit board could support. A customized ultrasonic imaging algorithm developed using the Python programming language proved to be effective enough to achieve a maximum of 220 inches per minute inspection speed. In this paper, detailed discussions on the development of imaging algorithm and the results of real-time imaging inspection performed on a test specimen are presented.

  19. Fine welding with lasers.

    PubMed

    MacLellan, D

    2008-01-01

    The need for micro joining metallic alloys for surgical instruments, implants and advanced medical devices is driving a rapid increase in the implementation of laser welding technology in research, development and volume production. This article discusses the advantages of this welding method and the types of lasers used in the process. PMID:18557404

  20. Wind-tunnel Investigation of End-plate Effects of Horizontal Tails on a Vertical Tail Compared with Available Theory

    NASA Technical Reports Server (NTRS)

    Murray, Harry E

    1946-01-01

    A vertical-tail model with stub fuselage was tested in combination with various simulated horizontal tails to determine the effect of horizontal-tail span and location on the aerodynamic characteristics of the vertical tail. Available theoretical data on end-plate effects were collected and presented in the form most suitable for design purposes. Reasonable agreement was obtained between the measured and theoretical end-plate effects of horizontal tails on vertical tails, and the data indicated that the end-plate effect was determined more by the location of the horizontal tail than by the span of the horizontal tail. The horizontal tail gave most end-plate effect when located near either tip of the vertical tail and, when located near the base of the vertical tail, the end-plate effect was increased by moving the horizontal tail rearward.

  1. Biomechanical evaluation of an endplate-conformed polycaprolactone-hydroxyapatite intervertebral fusion graft and its comparison with a typical nonconformed cortical graft.

    PubMed

    Agarwal, Aakash; Palepu, Vivek; Agarwal, Anand K; Goel, Vijay K; Yildirim, Eda D

    2013-06-01

    In the thoracolumbar region, between 7% and 30% of spinal fusion failures are at risk for pseudarthrosis. From a biomechanical perspective, the nonconformity of the intervertebral graft to the endplate surface could contribute to pseudarthrosis, given suboptimal stress distributions. The objective of this study was to quantify the effect of endplate-graft conformation on endplate stress distribution, maximum Von Mises stress development, and stability. The study design used an experimentally validated finite element (FE) model of the L4-L5 functional spinal unit to simulate two types of interbody grafts (cortical bone and polycaprolactone (PCL)-hydroxyapatite (HA) graft), with and without endplate-conformed surfaces. Two case studies were completed. In Case Study I, the endplate-conformed grafts and nonconformed grafts were compared under without posterior instrumentation condition, while in Case Study II, the endplate-conformed and nonconformed grafts were compared with posterior instrumentation. In both case studies, the results suggested that the increased endplate-graft conformity reduced the maximum stress on the endplate, created uniform stress distribution on endplate surfaces, and reduced the range of motion of L4-L5 segments by increasing the contact surface area between the graft and the endplate. The stress distributions in the endplate suggest that the load sharing is greater with the endplate-conformed PCL-HA graft, which might reduce the graft subsidence possibility. PMID:23699717

  2. Development of welding technologies for the manufacturing of European Tritium Breeder blanket modules

    NASA Astrophysics Data System (ADS)

    Poitevin, Y.; Aubert, Ph.; Diegele, E.; de Dinechin, G.; Rey, J.; Rieth, M.; Rigal, E.; von der Weth, A.; Boutard, J.-L.; Tavassoli, F.

    2011-10-01

    Europe has developed two reference Tritium Breeder Blankets concepts for a DEMO fusion reactor: the Helium-Cooled Lithium-Lead and the Helium-Cooled Pebble-Bed. Both are using the reduced-activation ferritic-martensitic EUROFER-97 steel as structural material and will be tested in ITER under the form of test blanket modules. The fabrication of their EUROFER structures requires developing welding processes like laser, TIG, EB and diffusion welding often beyond the state-of-the-art. The status of European achievements in this area is reviewed, illustrating the variety of processes and key issues behind retained options, in particular with respect to metallurgical aspects and mechanical properties. Fabrication of mock-ups is highlighted and their characterization and performances with respect to design requirements are reviewed.

  3. The origin of spontaneous electrical activity at the end-plate zone.

    PubMed

    Brown, W F; Varkey, G P

    1981-12-01

    Two types of spontaneous electrical activity are present at the end-plate zone: low-voltage negative potentials that correspond to miniature end-plate potentials, and larger voltage negative-positive potentials. The electrogenic origin of the latter has been uncertain. The origin of these larger potentials was investigated in the rat phrenic nerve diaphragm preparation and in human gastrocnemius muscle just prior to intubation during administration of preoperative anesthesia. In the hemidiaphragm the larger voltage negative-positive potentials were rarely triggered by intracellular or tungsten microelectrodes. The negative-positive potentials, however, were clearly triggered by contact of the concentric needle electrode with muscle hemidiaphragm at the end-plate region. The potentials were abolished by curare. Likewise, the equivalent potentials observed at the human gastrocnemius end-plate zone were blocked by neuromuscular blocking agents. Therefore, these positive-negative discharges represent postsynaptic muscle fiber action potentials and not nerve fiber activity. They were probably presynaptically activated by mechanical irritation of the motor axon terminal and preterminal branches. PMID:6275771

  4. Finite element analysis of an extended end-plate connection using the T-stub approach

    SciTech Connect

    Muresan, Ioana Cristina; Balc, Roxana

    2015-03-10

    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 by 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.

  5. Space processing applications of ion beam technology. [surface finishing, welding, milling and film deposition

    NASA Technical Reports Server (NTRS)

    Grodzka, P. G.

    1977-01-01

    Ion thruster engines for spacecraft propulsion can serve as ion beam sources for potential space processing applications. The advantages of space vacuum environments and the possible gravity effects on thruster ion beam materials operations such as thin film growth, ion milling, and surface texturing were investigated. The direct gravity effect on sputter deposition and vapor deposition processes are discussed as well as techniques for cold and warm welding.

  6. Explosive Welding of Pipes

    NASA Astrophysics Data System (ADS)

    Drennov, Oleg; Drennov, Andrey; Burtseva, Olga

    2013-06-01

    For connection by welding it is suggested to use the explosive welding method. This method is rather new. Nevertheless, it has become commonly used among the technological developments. This method can be advantageous (saving material and physical resources) comparing to its statical analogs (electron-beam welding, argon-arc welding, plasma welding, gas welding, etc.), in particular, in hard-to-reach areas due to their geographic and climatic conditions. Explosive welding of cylindrical surfaces is performed by launching of welded layer along longitudinal axis of construction. During this procedure, it is required to provide reliable resistance against radial convergent strains. The traditional method is application of fillers of pipe cavity, which are dense cylindrical objects having special designs. However, when connecting pipes consecutively in pipelines by explosive welding, removal of the fillers becomes difficult and sometimes impossible. The suggestion is to use water as filler. The principle of non-compressibility of liquid under quasi-dynamic loading is used. In one-dimensional gasdynamic and elastic-plastic calculations we determined non-deformed mass of water (perturbations, which are moving in the axial direction with sound velocity, should not reach the layer end boundaries for 5-7 circulations of shock waves in the radial direction). Linear dimension of the water layer from the zone of pipe coupling along axis in each direction is >= 2R, where R is the internal radius of pipe.

  7. [Histochemical findings of and fine structural changes in motor endplates in diseases with neuromuscular transmission abnormalities].

    PubMed

    Yoshimura, Toshiro; Motomura, Masakatsu; Tsujihata, Mitsuhiro

    2011-07-01

    We herein review the histochemical findings and fine structural changes of motor endplates associated with diseases causing neuromuscular transmission abnormalities. In anti-acetylcholine receptor (AChR) antibody-positive myasthenia gravis (MG), type 2 fiber atrophy is observed, and the motor endplates show a reduction in the nerve terminal area, simplification of the postsynaptic membrane, decreased number of acetylcholine receptors, and deposition of immune complexes. In anti-MuSK antibody-positive MG, the fine structure shows a decrease in the postsynaptic membrane length, but the secondary synaptic cleft is preserved. There is no decrease in the number of AChRs, and there are no deposits of immune complexes at the motor endplates. Patients with Lambert-Eaton myasthenic syndrome show type 2 fiber atrophy, their motor endplates show a decrease in both the mean postsynaptic area and postsynaptic membrane length in the brachial biceps muscle. Congenital myasthenic syndrome with episodic apnea is characterized only by small-sized synaptic vesicles; the postsynaptic area is preserved. In subjects with congenital myasthenic syndrome with acetylcholinesterase deficiency, quantitative electron microscopy reveals a significant decrease in the nerve terminal size and presynaptic membrane length; further, the Schwann cell processes extend into the primary synaptic cleft, and partially or completely occlude the presynaptic membrane. The postsynaptic folds are degenerated, and associated with pinocytotic vesicles and labyrinthine membranous networks. Patients with slow-channel congenital myasthenia syndrome show type 1 fiber predominance, and their junctional folds are typically degenerated with widened synaptic space and loss of AChRs. Patients with AChR deficiency syndrome caused by recessive mutations in AChR subunits also show type 1 fiber predominance, and while most junctional folds are normal, some are simplified and have smaller than normal endplates. Rapsin and Mu

  8. Laser Welding in Space

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Kaukler, William F.

    1989-01-01

    Solidification type welding process experiments in conditions of microgravity were performed. The role of convection in such phenomena was examined and convective effects in the small volumes obtained in the laser weld zone were observed. Heat transfer within the weld was affected by acceleration level as indicated by the resulting microstructure changes in low gravity. All experiments were performed such that both high and low gravity welds occurred along the same weld beam, allowing the effects of gravity alone to be examined. Results indicate that laser welding in a space environment is feasible and can be safely performed IVA or EVA. Development of the hardware to perform the experiment in a Hitchhiker-g platform is recomended as the next step. This experiment provides NASA with a capable technology for welding needs in space. The resources required to perform this experiment aboard a Shuttle Hitchhiker-pallet are assessed. Over the four year period 1991 to 1994, it is recommended that the task will require 13.6 manyears and $914,900. In addition to demonstrating the technology and ferreting out the problems encountered, it is suggested that NASA will also have a useful laser materials processing facility for working with both the scientific and the engineering aspects of materials processing in space. Several concepts are also included for long-term optimization of available solar power through solar pumping solid state lasers directly for welding power.

  9. A path to in-space welding and to other in-space metal processing technologies using Space Shuttle small payloads

    NASA Technical Reports Server (NTRS)

    Tamir, David

    1992-01-01

    As we venture into space, it becomes necessary to assemble, expand, and repair space-based structures for our housing, research, and manufacturing. The zero gravity-vacuum of space challenges us to employ construction options which are commonplace on Earth. Rockwell International (RI) has begun to undertake the challenge of space-based construction via numerous options, of which one is welding. As of today, RI divisions have developed appropriate resources and technologies to bring space-based welding within our grasp. Further work, specifically in the area of developing space experiments to test RI technology, is required. RI Space Welding Project's achievements to date, from research and development (R&E) efforts in the areas of microgravity, vacuum, intra- / extra- vehicular activity and spinoff technologies, are reviewed. Special emphasis is given to results for G-169's (Get Away Special) microgravity flights aboard a NASA KC-135. Based on these achievements, a path to actual development of a space welding system is proposed with options to explore spinoff in-space metal processing technologies. This path is constructed by following a series of milestone experiments, of which several are to utilize NASA's Shuttle Small Payload Programs. Conceptual designs of the proposed shuttle payload experiments are discussed with application of lessons learned from G-169's design, development, integration, testing, safety approval process, and KC-135 flights.

  10. Welding Curriculum.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau. Div. of Adult and Vocational Education.

    This competency-based curriculum guide is a handbook for the development of welding trade programs. Based on a survey of Alaskan welding employers, it includes all competencies a student should acquire in such a welding program. The handbook stresses the importance of understanding the principles associated with the various elements of welding.…

  11. Welding IV.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding IV, a competency-based course in advanced arc welding offered at the Community College of Allegheny County to provide students with proficiency in: (1) single vee groove welding using code specifications established by the American Welding Society…

  12. Explosive Welding of Pipes

    NASA Astrophysics Data System (ADS)

    Burtseva, Olga

    2007-06-01

    For connection by welding it is suggested to use the explosive welding method. This method is rather new. Nevertheless, it has become commonly used among the technological developments. This method can be advantageous (saving material and physical resources) comparing to its statical analogs (electron-beam welding, argon-arc welding, plasma welding, gas welding, etc.), in particular, in hard-to-reach areas due to their geographic and climatic conditions. The suggestion is to use water as filler. The principle of non-compressibility of liquid under quasi-dynamic loading is used. In one-dimensional gasdynamic and elastic-plastic calculations we determined non-deformed mass of water (perturbations, which are moving in the axial direction with sound velocity, should not reach the layer end boundaries for 5-7 circulations of shock waves in the radial direction). Linear dimension of the water layer from the zone of pipe coupling along axis in each direction is >= 2R, where R is the internal radius of pipe. Model experiments with pipes having radii R = 57 mm confirmed results of the calculations and the possibility in principle to weld pipes by explosion with use of water as filler. Reduction of pipe diameter after dynamic loading and explosive welding was ˜2%.

  13. Online Visual Quality Inspection for Weld Seams

    NASA Astrophysics Data System (ADS)

    Löhndorf, Maike; Ramoser, Herbert; Cambrini, Luigi

    2007-12-01

    Arc welding is a widely used technology in almost all sectors of industrial production. Many tasks are automatically performed by robots. This paper presents a flexible vision based quality management system to detect defects online during the weld process.

  14. Weld cladding of hard surfaces

    NASA Astrophysics Data System (ADS)

    Habrekke, T.

    1993-02-01

    A literature study about clad welding of hard surfaces on steel is performed. The purpose was to see what kind of methods are mainly used, and particular attention is paid to clad welding of rolls. The main impression from this study is that several methods are in use. Some of these must be considered as 'too exotic' for the aim of the program, such as laser build-up welding. However, clad welding of hard surfaces to rolls is widely used around the world, and there is no need for particularly advanced welding methods to perform the work. The welding consumables and the way the welding is carried out is of more important character. The report will give some comments to this, and hopefully will give a short review of the current technology in this field.

  15. Advanced Welding Concepts

    NASA Technical Reports Server (NTRS)

    Ding, Robert J.

    2010-01-01

    Four advanced welding techniques and their use in NASA are briefly reviewed in this poster presentation. The welding techniques reviewed are: Solid State Welding, Friction Stir Welding (FSW), Thermal Stir Welding (TSW) and Ultrasonic Stir Welding.

  16. Weld Wire Investigation Summary

    SciTech Connect

    Cunningham, M.A.

    1999-03-22

    After GTA welding reservoir A production/process prove-in assemblies, X-ray examination detected a lack of sidewall fusion. After examining several possible causes, it was determined that the weld wire filler metal was responsible, particularly the wire cleaning process. The final conclusion was that the filler wire must be abrasively cleaned in a particular manner to perform as required. The abrasive process was incorporated into the wire material specification, ensuring consistency for all reservoir GTA welding at AlliedSignal Federal Manufacturing and Technologies (FM and T).

  17. Effect of Cartilage Endplate on Cell Based Disc Regeneration: A Finite Element Analysis

    PubMed Central

    Wu, Yongren; Cisewski, Sarah; Sachs, Barton L.; Yao, Hai

    2015-01-01

    This study examines the effects of cartilage endplate (CEP) calcification and the injection of intervertebral disc (IVD) cells on the nutrition distributions inside the human IVD under physiological loading conditions using multiphasic finite element modeling. The human disc was modeled as an inhomogeneous mixture consisting of a charged elastic solid, water, ions (Na+ and Cl−), and nutrient solute (oxygen, glucose and lactate) phases. The effect of the endplate calcification was simulated by a reduction of the tissue porosity (i.e., water volume faction) from 0.60 to 0.48. The effect of cell injection was simulated by increasing the cell density in the NP region by 50%, 100%, and 150%. Strain-dependent transport properties (e.g., hydraulic permeability and solute diffusivities) were considered to couple the solute transport and the mechanical loading. The simulation results showed that nutrient solute distribution inside the disc is maintained at a stable state during the day and night. The physiological diurnal cyclic loading does not change the nutrient environment in the human IVD. The cartilage endplate plays a significant role in the nutrient supply to human IVD. Calcification of the cartilage endplate significantly reduces the nutrient levels in human IVD. Therefore, in cell based therapy for IVD regeneration, the increased nutrient demand as a result of cell injection needs to be addressed. Excessive numbers of injected cells may cause further deterioration of the nutrient environment in the degenerated disc. This study is important for understanding the pathology of IVD degeneration and providing new insights into cell based therapies for low back pain. PMID:24015481

  18. Mineralization and collagen orientation throughout aging at the vertebral endplate in the human lumbar spine.

    PubMed

    Paietta, Rachel C; Burger, Evalina L; Ferguson, Virginia L

    2013-11-01

    The human vertebral body and intervertebral disc interface forms the region where the cartilaginous endplate, annulus fibrosis and bone of the vertebral body are connected through an intermediate calcified cartilage layer. While properties of both the vertebral body and components of the disc have been extensively studied, limited quantitative data exists describing the microstructure of the vertebral body-intervertebral disc interface in the spine throughout development and degeneration. Quantitative backscattered scanning electron and second harmonic generation confocal imaging were used to collect quantitative data describing the mineral content and collagen fiber orientation across the interface, respectively. Specimens spanned ages 56 days to 84 years and measurements were taken across the vertebral endplate at the outer annulus, inner annulus and nucleus pulposis. In mature and healthy endplates, collagen fibers span the calcified cartilage layer in all regions, including the endplate adjacent to the central nucleus pulposis. We also observed an abrupt transition from high mineral volume fractions (35-50%) to 0% over short distances measuring 3-15 microns in width across the transition from calcified cartilage to unmineralized cartilage. The alignment of collagen fibers at the outer annulus and thickness of the CC layer indicated that collagen fiber mineralization adjacent to the bone may serve to anchor the soft tissue without a gradual change in material properties. Combining backscattered scanning electron microscopy and second harmonic generation imaging on the same sections thus enable a novel assessment of morphology and properties in both mineralized and soft tissues at the vertebral body-intervertebral disc throughout development and aging. PMID:23999190

  19. Automatic detection and tracking of the weld area on erw pipes using phased-array inspection technology

    NASA Astrophysics Data System (ADS)

    Zottig, Federico; Zhang, Jinchi; Imbert, Christophe

    2012-05-01

    This paper presents a phased-array method for tracking the scarfing area on ERW pipes. The time-of-flight C-Scan image generated by the phased-array system is processed by an algorithm that detects the center of the scarfing area. The weld centerline, which is of interest to the inspection, is identified and tracked. The information relative to the position of the weld line is used to control the position of the PA probes, which automatically track the weld seam during flaw inspection. If loss of detection occurs, the algorithm disengages tracking of the weld, and the operator is prompted to continue the task manually.

  20. EMAT weld inspection and weld machine diagnostic system for continuous coil processing lines

    NASA Astrophysics Data System (ADS)

    Latham, Wayne M.; MacLauchlan, Daniel T.; Geier, Dan P.; Lang, Dennis D.

    1996-11-01

    Weld breaks of steel coil during cold rolling and continuous pickling operations are a significant source of lost productivity and product yield. Babcock and Wilcox Innerspec Technologies has developed a weld process control system which monitors the key variables of the welding process and determines the quality of the welds generated by flash butt welding equipment. This system is known as the Temate 2000 Automated Flash Butt Weld Inspection and Weld Machine Diagnostic System. The Temate 2000 system utilizes electro- magnetic acoustic transducer (EMAT) technology as the basis for performing on-line, real-time, nondestructive weld quality evaluation. This technique accurately detects voids, laps, misalignment and over/under trim conditions in the weld. Results of the EMAT weld inspection are immediately presented to the weld machine operator for disposition. Welding process variables such as voltage, current, platen movements and upset pressures are monitored and collected with the high speed data acquisition system. This data is processed and presented in real-time display to indicate useful welding process information such as platen crabbing, upset force, peak upset current, and many others. Alarming for each variable is provided and allows detailed maintenance reports and summary information to be generated. All weld quality and process parameter data are stored, traceable to each unique weld, and available for post process evaluation. Installation of the Temate 2000 system in a major flat rolled steel mill has contributed to near elimination of weld breakage and increased productivity at this facility.

  1. Welding Technician

    ERIC Educational Resources Information Center

    Smith, Ken

    2009-01-01

    About 95% of all manufactured goods in this country are welded or joined in some way. These welded products range in nature from bicycle handlebars and skyscrapers to bridges and race cars. The author discusses what students need to know about careers for welding technicians--wages, responsibilities, skills needed, career advancement…

  2. Advanced cell designs for welded arrays

    SciTech Connect

    Giuliano, M.; Wohlgemuth, J.

    1982-08-01

    In this paper the authors present some solar cell design innovations and associated process technology which can result in practical welded contacts for interconnection into arrays. The principal problem with welded contacts on solar cells relates to electrical and mechanical damage to the shallow diffused front junction of the cell. Design approaches are presented which result in a deeper pn junction under the weld contact point. This moves the location of the junction to a safer distance below the region of heat and pressure resulting from the welding operation. The methods presented can be used with various welding techniques including parallel gap welding, ultrasonic welding, laser spot welding or thermo-compression bonding. Design approaches include the development of a eutectic bonding technique to provide weldable contacts on front and back of the solar cell, as well as a novel integral feedthrough approach which permits welding of both contacts on the back of the cell.

  3. Automatic Welding System

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Robotic welding has been of interest to industrial firms because it offers higher productivity at lower cost than manual welding. There are some systems with automated arc guidance available, but they have disadvantages, such as limitations on types of materials or types of seams that can be welded; susceptibility to stray electrical signals; restricted field of view; or tendency to contaminate the weld seam. Wanting to overcome these disadvantages, Marshall Space Flight Center, aided by Hayes International Corporation, developed system that uses closed-circuit TV signals for automatic guidance of the welding torch. NASA granted license to Combined Technologies, Inc. for commercial application of the technology. They developed a refined and improved arc guidance system. CTI in turn, licensed the Merrick Corporation, also of Nashville, for marketing and manufacturing of the new system, called the CT2 Optical Trucker. CT2 is a non-contracting system that offers adaptability to broader range of welding jobs and provides greater reliability in high speed operation. It is extremely accurate and can travel at high speed of up to 150 inches per minute.

  4. Friction welding.

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1972-01-01

    Results of an exploratory study of the structure and properties of friction welds in Udimet 700 (U-700) and TD-nickel (TD-Ni) bar materials, as well as dissimilar U-700/TD-Ni friction welds. Butt welds were prepared by friction welding 12.7-mm-diam U-700 bars and TD-Ni bars. Specimens for elevated temperature tensile and stress rupture testing were machined after a postweld heat treatment. Friction welding of U-700 shows great potential because the welds were found to be as strong as the parent metal in stress rupture and tensile tests at 760 and 980 C. In addition, the weld line was not detectable by metallographic examination after postheating. Friction welds in TD-Ni or between U-700 and TD-Ni were extremely weak at elevated temperatures. The TD-Ni friction welds could support only 9% as much stress as the base metal for 10-hour stress rupture life at 1090 C. The U-700/TD-Ni weld could sustain only 15% as much stress as the TD-Ni parent metal for a 10-hour stress rupture life at 930 C. Thus friction welding is not a suitable joining method for obtaining high-strength TD-Ni or U-700/TD-Ni weldments.

  5. Welding, Bonding and Fastening, 1984

    NASA Technical Reports Server (NTRS)

    Buckley, J. D. (Editor); Stein, B. A. (Editor)

    1985-01-01

    A compilation of papers presented in a joint NASA, American Society for Metals, The George Washington University, American Welding Soceity, and Society of Manufacturing Engineers conference on Welding, Bonding, and Fastening at Langley Research Center, Hampton, VA, on October 23 to 25, 1984 is given. Papers were presented on technology developed in current research programs relevant to welding, bonding, and fastening of structural materials required in fabricating structures and mechanical systems used in the aerospace, hydrospace, and automotive industries. Topics covered in the conference included equipment, hardware and materials used when welding, brazing, and soldering, mechanical fastening, explosive welding, use of unique selected joining techniques, adhesives bonding, and nondestructive evaluation. A concept of the factory of the future was presented, followed by advanced welding techniques, automated equipment for welding, welding in a cryogenic atmosphere, blind fastening, stress corrosion resistant fasteners, fastening equipment, explosive welding of different configurations and materials, solid-state bonding, electron beam welding, new adhesives, effects of cryogenics on adhesives, and new techniques and equipment for adhesive bonding.

  6. Laser welding of aluminum alloys

    SciTech Connect

    Leong, K.H.; Sabo, K.R.; Sanders, P.G.; Spawr, W.J.

    1997-03-01

    Recent interest in reducing the weight of automobiles to increase fuel mileage has focused attention on the use of aluminum and associated joining technologies. Laser beam welding is one of the more promising methods for high speed welding of aluminum. Consequently, substantial effort has been expended in attempting to develop a robust laser beam welding process. Early results have not been very consistent in the process requirements but more definitive data has been produced recently. This paper reviews the process parameters needed to obtain consistent laser welds on 5,000 series aluminum alloys and discusses the research necessary to make laser processing of aluminum a reality for automotive applications.

  7. Large Spun Formed Friction-Stir Welded Tank Domes for Liquid Propellant Tanks Made from AA2195: A Technology Demonstration for the Next Generation of Heavy Lift Launchers

    NASA Technical Reports Server (NTRS)

    Stachulla, M.; Pernpeinter, R.; Brewster J.; Curreri, P.; Hoffman, E.

    2010-01-01

    Improving structural efficiency while reducing manufacturing costs are key objectives when making future heavy-lift launchers more performing and cost efficient. The main enabling technologies are the application of advanced high performance materials as well as cost effective manufacture processes. This paper presents the status and main results of a joint industrial research & development effort to demonstrate TRL 6 of a novel manufacturing process for large liquid propellant tanks for launcher applications. Using high strength aluminium-lithium alloy combined with the spin forming manufacturing technique, this development aims at thinner wall thickness and weight savings up to 25% as well as a significant reduction in manufacturing effort. In this program, the concave spin forming process is used to manufacture tank domes from a single flat plate. Applied to aluminium alloy, this process allows reaching the highest possible material strength status T8, eliminating numerous welding steps which are typically necessary to assemble tank domes from 3D-curved panels. To minimize raw material costs for large diameter tank domes for launchers, the dome blank has been composed from standard plates welded together prior to spin forming by friction stir welding. After welding, the dome blank is contoured in order to meet the required wall thickness distribution. For achieving a material state of T8, also in the welding seams, the applied spin forming process allows the required cold stretching of the 3D-curved dome, with a subsequent ageing in a furnace. This combined manufacturing process has been demonstrated up to TRL 6 for tank domes with a 5.4 m diameter. In this paper, the manufacturing process as well as test results are presented. Plans are shown how this process could be applied to future heavy-lift launch vehicles developments, also for larger dome diameters.

  8. Advances in welding science - a perspective

    SciTech Connect

    David, S.A.; Vitek, J.M.; Babu, S.S.; DebRoy, T.

    1995-02-01

    The ultimate goal of welding technology is to improve the joint integrity and increase productivity. Over the years, welding has been more of an art than a science, but in the last few decades major advances have taken place in welding science and technology. With the development of new methodologies at the crossroads of basic and applied sciences, enormous opportunities and potential exist to develop a science-based tailoring of composition, structure, and properties of welds with intelligent control and automation of the welding processes.

  9. Study on visual image information detection of external angle weld based on arc welding robot

    NASA Astrophysics Data System (ADS)

    Liu, Xiaorui; Liu, Nansheng; Sheng, Wei; Hu, Xian; Ai, Xiaopu; Wei, Yiqing

    2009-11-01

    Nowadays, the chief development trend in modern welding technology is welding automation and welding intelligence. External angle weld has a certain proportion in mechanical manufacture industries. In the real-time welding process, due to hot deformation and the fixture of workpieces used frequently, torch will detach welding orbit causes deviation, which will affect welding quality. Therefore, elimination weld deviation is the key to the weld automatic tracking system. In this paper, the authors use the self-developed structured light vision sensor system which has significant advantage compared with arc sensors to capture real-time weld images. In the project of VC++6.0 real-time weld image processing, after binaryzation with threshold value seventy, 3*1 median filter, thinning, obtain weld main stripe. Then, using the extraction algorithm this paper proposed to obtain weld feature points, and compute position of weld. Experiment result verified that the extraction algorithm can locate feature points rapidly and compute the weld deviation accurately.

  10. Enhancing the mechanical integrity of the implant-bone interface with BoneWelding technology: determination of quasi-static interfacial strength and fatigue resistance.

    PubMed

    Ferguson, Stephen J; Weber, Urs; von Rechenberg, Brigitte; Mayer, Joerg

    2006-04-01

    The BoneWelding technology is an innovative bonding method, which offers new alternatives in the treatment of fractures and other degenerative disorders of the musculoskeletal system. The BoneWelding process employs ultrasonic energy to liquefy a polymeric interface between orthopaedic implants and the host bone. Polymer penetrates the pores of the surrounding bone and, following a rapid solidification, forms a strong and uniform bond between implant and bone. Biomechanical testing was performed to determine the quasi-static push-out strength and fatigue performance of 3.5-mm-diameter polymeric dowels bonded to a bone surrogate material (Sawbones solid and cellular polyurethane foam) using the BoneWelding process. Fatigue tests were conducted over 100,000 cycles of 20-100 N loading. Mechanical test results were compared with those obtained with a comparably-sized, commercial metallic fracture fixation screw. Tests in surrogate bone material of varying density demonstrated significantly superior mechanical performance of the bonded dowels in comparison to conventional bone screws (p < 0.01), with holding strengths approaching 700 N. Even in extremely porous host material, the performance of the bonded dowels was equivalent to that of the bone screws. For both cellular and solid bone analog materials, failure always occurred within the bone analog material surrounding and distant to the implant; the infiltrated interface was stronger than the surrounding bone analog material. No significant decrease in interfacial strength was observed following conditioning in a physiological saline solution for a period of 1 month prior to testing. Ultrasonically inserted implants migrated, on average, less than 20 microm over, and interfacial stiffness remained constant the full duration of fatigue testing. With further refinement, the BoneWelding technology may offer a quicker, simpler, and more effective method for achieving strong fixation and primary stability for fracture

  11. The upregulation of acetylcholine release at endplates of alpha-bungarotoxin-treated rats: its dependency on calcium.

    PubMed Central

    Plomp, J J; van Kempen, G T; Molenaar, P C

    1994-01-01

    1. The presynaptic component of an adaptive feedback mechanism leading to increased acetylcholine (ACh) release was studied in endplates of diaphragms from rats treated chronically with alpha-bungarotoxin (alpha BTX). 2. Quantal contents were calculated 'directly' from the amplitude of miniature endplate potentials (MEPPs) and endplate potentials (EPPs) which were recorded after mu-conotoxin treatment to prevent muscle action potentials. 3. In vitro application of the Ca2+ channel blockers nifedipine (10 microM) or omega-conotoxin (40 nM) had no significant effect on the increased quantal content of endplates from alpha BTX-treated rats. 4. At control endplates, in vitro block of presynaptic K+ channels by 5 microM 3,4-diaminopyridine did increase the quantal content to a level which was similar to that found in endplates of alpha BTX-treated rats but also induced a broadening of EPPs, which was not found at endplates after alpha BTX treatment. 5. The difference between quantal contents of alpha BTX-treated and control rats was highly dependent on the [Ca2+]o/[Mg2+]o ratio when [Mg2+]o was fixed at 1 mM. At low [Ca2+]o, the quantal content of endplates from alpha BTX-treated rats was lower than that of controls while at [Ca2+]o in the normal and high range this was reversed. However, changing the [Ca2+]o/[Mg2+]o ratio by means of [Mg2+]o, at a fixed [Ca2+]o of 2 mM, did not influence the relative increase of quantal contents at endplates from alpha BTX-treated rats. Double logarithmic plots of the 'toxin-induced' myasthenia gravis (TIMG) and control quantal content versus [Ca2+]o had an approximately linear part between 0.2 and 1.5 mM [Ca2+]o. The slopes of the TIMG and control lines were 1.81 and 0.96, indicating that the ACh release in TIMG muscles was more sensitive to changes of [Ca2+]o than controls. 6. At normal [Ca2+]o and [Mg2+]o, the depression of EPP amplitude during stimulation of the phrenic nerve at 30-50 Hz was somewhat larger at endplates from alpha

  12. Soldadura (Welding). Spanish Translations for Welding.

    ERIC Educational Resources Information Center

    Hohhertz, Durwin

    Thirty transparency masters with Spanish subtitles for key words are provided for a welding/general mechanical repair course. The transparency masters are on such topics as oxyacetylene welding; oxyacetylene welding equipment; welding safety; different types of welds; braze welding; cutting torches; cutting with a torch; protective equipment; arc…

  13. WELDING TORCH

    DOEpatents

    Correy, T.B.

    1961-10-01

    A welding torch into which water and inert gas are piped separately for cooling and for providing a suitable gaseous atmosphere is described. A welding electrode is clamped in the torch by a removable collet sleeve and a removable collet head. Replacement of the sleeve and head with larger or smaller sleeve and head permits a larger or smaller welding electrode to be substituted on the torch. (AEC)

  14. Plasma arc welding weld imaging

    NASA Technical Reports Server (NTRS)

    Rybicki, Daniel J. (Inventor); Mcgee, William F. (Inventor)

    1994-01-01

    A welding torch for plasma arc welding apparatus has a transparent shield cup disposed about the constricting nozzle, the cup including a small outwardly extending polished lip. A guide tube extends externally of the torch and has a free end adjacent to the lip. First and second optical fiber bundle assemblies are supported within the guide tube. Light from a strobe light is transmitted along one of the assemblies to the free end and through the lip onto the weld site. A lens is positioned in the guide tube adjacent to the second assembly and focuses images of the weld site onto the end of the fiber bundle of the second assembly and these images are transmitted along the second assembly to a video camera so that the weld site may be viewed continuously for monitoring the welding process.

  15. Gap and stagger effects on the aerodynamic performance and the wake behind a biplane with endplates

    NASA Astrophysics Data System (ADS)

    Kang, Hantae

    Modern flow diagnostics applied to a very old aerodynamic problem has produced a number of intriguing new results and new insight into previous results. The aerodynamic performance and associated flow physics of the biplane with endplates as a function of variation in gap and stagger were analytically and experimentally investigated. A combination of vortex lattice method, integrated force measurement, streamwise PIV, and Trefftz plane Stereo PIV were used to better understand the flowfield around the biplane with endplates. This study was performed to determine the configuration with the optimal aerodynamic performance and to understand the fluid mechanics behind optimal and suboptimal performance of the configuration. The Vortex Lattice code (AVL) shows that the gap and stagger have the most dramatic effects out of the six parameters studied: gap, stagger, dihedral, decalage, sweep and overhang. The force balance measurements with fourteen biplane configurations of different gaps and staggers show that as gap and stagger increase, the lift efficiency also increases at all angles of attack tested at both Re 60,000 and 120,000. Using the force balance data, a generalized empirical method for the prediction of lift coefficient as a function of gap, stagger and angle of attack has been determined and validated when combined with existing relations for CL--α adjustments for AR and taper effects. The resulting empirical approach allows for a rapid determination of CL for a biplane having different gap, stagger, AR and taper without the need for a complete flowfield analysis. Two Dimensional PIV results show a distinctive pattern in the downwash angle for the different gap and stagger configurations tested. The downwash angle increases with increasing gap and stagger. It is also evident that the change in downwash angle is directly proportional to the change in lift coefficient as would be expected. Increasing gap spacing increases the downwash angle as well. Based on

  16. An Ultrasound Assisted Anchoring Technique (BoneWelding® Technology) for Fixation of Implants to Bone – A Histological Pilot Study in Sheep

    PubMed Central

    Langhoff, Jens D; Kuemmerle, Jan M; Mayer, Joerg; Weber, Urs; Berra, Milica; Mueller, Jessika M; Kaestner, Sabine B; Zlinszky, Katalin; Auer, Joerg A; von Rechenberg, Brigitte

    2009-01-01

    The BoneWelding® Technology offers new opportunities to anchor implants within bone. The technology melted the surface of biodegradable polymer pins by means of ultrasound energy to mould material into the structures of the predrilled bone. Temperature changes were measured at the sites of implantation in an in vitro experiment. In the in vivo part of the study two types of implants were implanted in the limb of sheep to investigate the biocompatibility of the method. One implant type was made of PL-DL-lactide (PLA), the second one was a titanium core partially covered with PLA. Healing period was 2 and 6 months, with 3 sheep per group. Bone samples were evaluated radiologically, histologically and histomorphometrically for bone remodeling and inflammatory reactions. Results demonstrated mild and short temperature increase during insertion. New bone formed at the implant without evidence of inflammatory reaction. The amount of adjacent bone was increased compared to normal cancellous bone. It was concluded that the BoneWelding® Technology proved to be a biocompatible technology to anchor biodegradable as well as titanium-PLA implants in bone. PMID:19572033

  17. Welding II.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding II, a performance-based course offered at the Community College of Allegheny County to introduce students to out-of-position shielded arc welding with emphasis on proper heats, electrode selection, and alternating/direct currents. After introductory…

  18. Welding Curriculum.

    ERIC Educational Resources Information Center

    EASTCONN Regional Educational Services Center, North Windham, CT.

    The purpose of this welding program is to provide students with skills and techniques to become employed as advanced apprentice welders. The welding program manual includes the following sections: (1) course description; (2) general objectives; (3) competencies; (4) curriculum outline for 13 areas; (5) 13 references; and (6) student progress…

  19. Welding III.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding III, an advanced course in arc welding offered at the Community College of Allegheny County to provide students with the proficiency necessary for industrial certification. The course objectives, which are outlined first, specify that students will…

  20. Robotic Vision for Welding

    NASA Technical Reports Server (NTRS)

    Richardson, R. W.

    1986-01-01

    Vision system for robotic welder looks at weld along axis of welding electrode. Gives robot view of most of weld area, including yet-unwelded joint, weld pool, and completed weld bead. Protected within welding-torch body, lens and fiber bundle give robot closeup view of weld in progress. Relayed to video camera on robot manipulator frame, weld image provides data for automatic control of robot motion and welding parameters.

  1. WELDING METHOD

    DOEpatents

    Cornell, A.A.; Dunbar, J.V.; Ruffner, J.H.

    1959-09-29

    A semi-automatic method is described for the weld joining of pipes and fittings which utilizes the inert gasshielded consumable electrode electric arc welding technique, comprising laying down the root pass at a first peripheral velocity and thereafter laying down the filler passes over the root pass necessary to complete the weld by revolving the pipes and fittings at a second peripheral velocity different from the first peripheral velocity, maintaining the welding head in a fixed position as to the specific direction of revolution, while the longitudinal axis of the welding head is disposed angularly in the direction of revolution at amounts between twenty minutas and about four degrees from the first position.

  2. Tailoring defect free fusion welds based on phenomenological modeling

    NASA Astrophysics Data System (ADS)

    Kumar, Amit

    principles still remains an important milestone in changing welding from almost an empirical art to a mainstream science-based technology. The ability to determine multiple welding variable sets to achieve desired weld attributes, based on scientific principles, would be an important step to achieve this goal. Furthermore, no comprehensive unified theoretical model exists today that can predict the formation of commonly occurring humping defects considering the effects of important welding variables such as the arc current, voltage, welding speed, nature of the shielding gas, electrode geometry, torch angle and ambient pressure. In this research work, a model is developed to achieve desired weld attributes and avoid high speed weld defects like humping. (Abstract shortened by UMI.)

  3. Unique Cryogenic Welded Structures

    NASA Astrophysics Data System (ADS)

    Yushchenko, K. A.; Monko, G. G.

    2004-06-01

    For the last few decades, the E. O. Paton Electric Welding Institute has been active in the field of cryogenic materials science. Integrated research on development of new grades of steels and alloys for cryogenic engineering was carried out in collaboration with the leading institutions of Russia, Ukraine, and Georgia. Commercially applied welding technologies and consumables were developed. They include large, spherical tanks for storage of liquefied gases (from oxygen to helium) under high pressures; space simulators with a capacity of 10 000 m3 and more; and load-carrying elements of superconducting fusion magnetic systems for the TOKAMAK, MGD, and ITER series.

  4. Unique Cryogenic Welded Structures

    SciTech Connect

    Yushchenko, K.A.; Monko, G.G.

    2004-06-28

    For the last few decades, the E. O. Paton Electric Welding Institute has been active in the field of cryogenic materials science. Integrated research on development of new grades of steels and alloys for cryogenic engineering was carried out in collaboration with the leading institutions of Russia, Ukraine, and Georgia. Commercially applied welding technologies and consumables were developed. They include large, spherical tanks for storage of liquefied gases (from oxygen to helium) under high pressures; space simulators with a capacity of 10 000 m3 and more; and load-carrying elements of superconducting fusion magnetic systems for the TOKAMAK, MGD, and ITER series.

  5. The influence of cortical end-plate on broadband ultrasound attenuation measurements at the human calcaneus using scanning confocal ultrasound

    NASA Astrophysics Data System (ADS)

    Xia, Yi; Lin, Wei; Qin, Yi-Xian

    2005-09-01

    Quantitative ultrasound (QUS) assessment, including broadband ultrasound attenuation (BUA), is an efficient technique for assessing bone quality in various statuses, e.g., osteoporosis. While assessing trabecular bone loss is essential to bone quality, the existence of cortical bone can substantially reduce the accuracy of BUA measurement. In this study, we developed an approach to quantify the influence of the cortical end-plate in the QUS on 18 cadaver calcanei using both analytical and experimental analyses. A simplified cortical-trabecular-cortical sandwich model has been developed for simulation of wave propagations. Results show that the cortical end-plate has a significant effect on BUA (yielding 8.5+/-3.6 dB/MHz in cortical bone alone), approximately 15% of the BUA value over the whole bone BUA measurement (54.1+/-20.1 dB/MHz). The phenomenon has been predicted by the developed analytical model with a high correlation (r2=0.63,p<0.0001). The data have suggested that the mechanism of the BUA attributed to the cortical end-plate is primarily due to the ultrasonic wave transmission and reflection within the cortical layers. Therefore, the influence of the cortical end-plate in BUA can be quantified and incorporated into the QUS assessment for bone quality, which may provide insight into BUA measurement for accurate diagnosis of bone diseases.

  6. Effects of length changes on Na+ current amplitude and excitability near and far from the end-plate.

    PubMed

    Ruff, R L

    1996-09-01

    Na+ current (INa), membrane capacitance (Cm), action potential (AP) properties, and cable properties were studied on the end-plate (E), the end-plate border (EB), and extrajunctional (EJ) membrane of rat fast twitch muscle fibers. INa normalized to Cm, which is proportional to the density of Na+ channels, was the same on the E and the EB and smallest on EJ membrane. The AP threshold was lower and rate of rise of the AP was larger at the EB compared with EJ membrane. On the E and the EB, Cm and INa did not change in response to changes in fiber length. On EJ membrane, INa, Cm, and membrane cable properties changed in a manner consistent with folding and unfolding of the sarcolemma during length changes. The stiffness of the E membrane may add mechanical stability of the neuromuscular junction so that the electrical properties of the end-plate do not change with fiber length. The higher density of Na+ channels near the end-plate increases the safety factor for neuromuscular transmission by lowering the AP threshold. PMID:8761263

  7. MiR-34a promotes Fas-mediated cartilage endplate chondrocyte apoptosis by targeting Bcl-2.

    PubMed

    Chen, Huajiang; Wang, Jianxi; Hu, Bo; Wu, Xiaodong; Chen, Yu; Li, Renhu; Yuan, Wen

    2015-08-01

    Apoptosis of cartilage endplate (CEP) chondrocytes is associated with the pathogenesis of intervertebral disk degeneration (IDD). Recent studies have shown that miR-34a is crucially involved in chondrocyte apoptosis during osteoarthritic cartilage. Here, we investigated the involvement of miR-34a in CEP chondrocyte apoptosis in IDD. In human degenerated CEP chondrocytes, miRNA (miR)-34a was markedly elevated in association with increased apoptosis. Bioinformatics target prediction identified Bcl-2 as a putative target of miR-34a. Furthermore, miR-34a inhibited Bcl-2 expression by directly targeting their 3'-untranslated regions, and this inhibition was abolished by mutation of the miR-34a binding sites. In vitro, knockdown of miR-34a in human endplate chondrocytes resulted in overexpression of Bcl-2, whereas upregulation of miR-34a led to repression of Bcl-2. Fas-mediated apoptosis was decreased when antagonizing miR-34a with locked nucleotide analog-miR-34a in human endplate chondrocytes. Taken together, our results demonstrate that upregulated miR-34a potentiates Fas-mediated endplate chondrocyte apoptosis, which is associated with IDD. PMID:25910896

  8. The evidence and the possible significance of autophagy in degeneration model of human cervical end-plate cartilage

    PubMed Central

    XU, HONGGUANG; XIONG, SHOULIANG; WANG, HONG; ZHANG, MIN; YU, YUNFEI

    2014-01-01

    The aim of this study was to observe autophagy in chondrocytes from degenerative human cervical vertebral end-plates and to investigate the significance of variations in autophagy in the degeneration of cervical vertebral end-plate chondrocytes. Cartilage end-plates were obtained from 48 inpatients admitted to hospital between February 2011 and August 2012. The patients were divided into the control group (n=17) with cervical vertebral fracture or dislocation and the cervical spondylosis group (n=31) with cervical spondylotic myelopathy. End-plate chondrocytes were isolated via enzyme digestion and then cultured in vitro. The cells were stained with toluidine blue and hematoxylin-eosin (H&E). A laser scanning confocal microscope and monodansylcadaverine (MDC) were used to reveal autophagy in the end-plate chondrocytes. Reverse transcription polymerase chain reaction (RT-PCR) was used to detect mRNA expression of type II collagen and aggrecan. Western blotting was conducted to detect LC3 proteins. The chondrocytes isolated from the degenerative human cervical end-plates were cultured successfully in vitro. The morphology of the cells from the cervical spondylosis group tended to exhibit changes in spindle morphology compared with the control group. Autophagic bodies were stained with MDC. LC3 proteins were visible in the intracellular and perinuclear regions under the laser scanning confocal microscope. The mRNA expression levels (relative to those of β-actin) of aggrecan (0.715±0.194) and type II collagen (0.628±0.254) in the cervical spondylosis group were markedly decreased compared with those in the control group (0.913±0.254 and 0.845±0.186, respectively; both P<0.05). The LC3-II/LC3-I ratio was observed to be significantly reduced in the cervical spondylosis group by Western blot analysis. Autophagy has an important role in human cervical disc degeneration. The regulation of autophagy may prevent disc degeneration in cartilage end-plate cells. PMID

  9. Extravehicular activity welding experiment

    NASA Technical Reports Server (NTRS)

    Watson, J. Kevin

    1989-01-01

    The In-Space Technology Experiments Program (INSTEP) provides an opportunity to explore the many critical questions which can only be answered by experimentation in space. The objective of the Extravehicular Activity Welding Experiment definition project was to define the requirements for a spaceflight experiment to evaluate the feasibility of performing manual welding tasks during EVA. Consideration was given to experiment design, work station design, welding hardware design, payload integration requirements, and human factors (including safety). The results of this effort are presented. Included are the specific objectives of the flight test, details of the tasks which will generate the required data, and a description of the equipment which will be needed to support the tasks. Work station requirements are addressed as are human factors, STS integration procedures and, most importantly, safety considerations. A preliminary estimate of the cost and the schedule for completion of the experiment through flight and postflight analysis are given.

  10. Laser welding of micro plastic parts

    NASA Astrophysics Data System (ADS)

    Haberstroh, E.; Hoffmann, W.-M.

    2007-02-01

    Most welding processes for plastics do not meet the demands of micro technology and thus cannot be applied in this innovative industrial sector. One of the few techniques which are applicable in this sector is the laser transmission welding, which has distinctive advantages like low mechanical and thermal load of the joining parts. This makes the laser particularly suitable for the welding of micro plastics parts. Thereby, contour welding is a process variant of laser transmission welding enabling the welding of complex and even three-dimensional weld contours. But so far it has not yet been applied for welding plastics parts of micro scale in the industrial practice. Recent research at the Institute of Plastics Processing (IKV) at the RWTH Aachen University shows the feasibility of this process to weld small and complex micro parts. Good mechanical properties can be achieved. However, it is necessary to apply measures to reduce the formation of flash. Moreover, it can be shown that there is a strong influence of some material parameters on the laser welding process so that some plastics are more suitable than others for the contour welding in micro technology.

  11. Biomechanical Analysis of a Novel Prosthesis Based on the Physiological Curvature of Endplate for Cervical Disc Replacement

    PubMed Central

    Yu, Cheng-Cheng; Hao, Ding-Jun; Huang, Da-Geng; Qian, Li-Xiong; Feng, Hang; Li, Hou-Kun; Zhao, Song-Chuan

    2016-01-01

    Study Design Biomechanical analysis of a novel prosthesis based on the physiological curvature of endplate was performed. Objective To compare the biomechanical differences between a novel prosthesis based on the physiological curvature of the endplate and the Prestige LP prosthesis after cervical disc replacement (CDR). Summary of Background Data Artificial disc prostheses have been widely used to preserve the physiological function of treated and adjacent motion segments in CDR, while most of those present a flat surface instead of an arcuate surface which approximately similar to anatomic structures in vivo. We first reported a well-designed artificial disc prosthesis based on the physiological curvature of the endplate. Methods Three motion segments of 24 ovine cervical spines (C2-5) were evaluated in a robotic spine system with axial compressive loads of 50N. Testing conditions were as follows: 1) intact, 2) C3–4 CDR with artificial disc prosthesis based on the physiological curvature of the endplate, and 3) C3–4 CDR with the Prestige LP prosthesis. The range of motion (ROM) and the pressures on the inferior surface of the two prostheses were recorded and analyzed. Results As compared to the intact state, the ROM of all three segments had no significant difference in the replacement group. Additionally, there was no significant difference in ROM between the two prostheses. The mean pressure on the novel prosthesis was significantly less than the Prestige LP prosthesis. Conclusion ROM in 3 groups (intact group, CDR group with novel prosthesis and CDR group with Prestige LP) showed no significant difference. The mean pressure on the inferior surface of the novel prosthesis was significantly lower than the Prestige LP prosthesis. Therefore, the novel artificial disc prosthesis is feasible and effective, and can reduce the implant-bone interface pressure on the endplate, which may be one possible reason of prosthesis subsidence. PMID:27355319

  12. Adaptation of quantal content to decreased postsynaptic sensitivity at single endplates in alpha-bungarotoxin-treated rats.

    PubMed Central

    Plomp, J J; van Kempen, G T; Molenaar, P C

    1992-01-01

    1. Rats were injected once every 48 h with alpha-bungarotoxin (alpha BTX) for periods up to 6 weeks. Injections caused weakness of facial muscles which lasted about 8 h. Hemidiaphragms were dissected for biochemical and electrophysiological measurements. 2. In muscles from animals treated for 2-3 weeks with toxin, the binding of 125I-alpha BTX was reduced to 58%, and the ACh content to 81% of control values. Choline acetyltransferase activity was unchanged. ACh release evoked by 3 Hz nerve stimulation was increased to 175% of control values. 3. The use of mu-conotoxin, which specifically blocks muscle action potentials, enabled the recording of full-sized endplate potentials (EPPs) and miniature endplate potentials (MEPPs) at normal muscle membrane potentials (-70 to -80 mV). The amplitude of MEPPs was decreased to 57% in muscles from animals treated for 3 weeks with alpha BTX. The mean of the quantal contents, calculated from the ratio of the corrected EPPs and the MEPPs, was increased to 154%. 4. Within individual muscles of both alpha BTX-treated and control rats, there was an inverse relationship between the quantal content of an endplate and its MEPP amplitude. 5. The MEPP frequency of endplates from control muscles was positively correlated with the quantal content. However, this correlation was not found in alpha BTX-affected muscles. 6. Three hours after a single injection of alpha BTX the amplitude of the MEPPs was reduced to about 60% of control values but no increase of the quantal content was found. During the first few days of alpha BTX treatment the quantal content gradually increased; it reached a plateau between 20 and 30 days. 7. The results suggest the existence of an adaptive mechanism, operating at individual endplates, in which retrograde signals at the motor nerve terminals modulate ACh release when neuromuscular transmission is endangered by block of acetylcholine receptors. PMID:1302275

  13. Tomosyn-2 is required for normal motor performance in mice and sustains neurotransmission at motor endplates.

    PubMed

    Geerts, Cornelia J; Plomp, Jaap J; Koopmans, Bastijn; Loos, Maarten; van der Pijl, Elizabeth M; van der Valk, Martin A; Verhage, Matthijs; Groffen, Alexander J A

    2015-07-01

    Tomosyn-1 (STXBP5) is a soluble NSF attachment protein receptor complex-binding protein that inhibits vesicle fusion, but the role of tomosyn-2 (STXBP5L) in the mammalian nervous system is still unclear. Here we generated tomosyn-2 null (Tom2(KO/KO)) mice, which showed impaired motor performance. This was accompanied by synaptic changes at the neuromuscular junction, including enhanced spontaneous acetylcholine release frequency and faster depression of muscle motor endplate potentials during repetitive stimulation. The postsynaptic geometric arrangement and function of acetylcholine receptors were normal. We conclude that tomosyn-2 supports motor performance by regulation of transmitter release willingness to sustain synaptic strength during high-frequency transmission, which makes this gene a candidate for involvement in neuromuscular disorders. PMID:24744148

  14. Thermal behaviour of beams with slant end-plate connection subjected to nonsymmetric gravity load.

    PubMed

    Zahmatkesh, Farshad; Osman, Mohd Hanim; Talebi, Elnaz

    2014-01-01

    Research on the steel structures with confining of axial expansion in fixed beams has been quite intensive in the past decade. It is well established that the thermal behaviour has a key influence on steel structural behaviours. This paper describes mechanical behaviour of beams with bolted slant end-plate connection with nonsymmetric gravity load, subjected to temperature increase. Furthermore, the performance of slant connections of beams in steel moment frame structures in the elastic field is investigated. The proposed model proved that this flexible connection system could successfully decrease the extra thermal induced axial force by both of the friction force dissipation among two faces of slant connection and a small upward movement on the slant plane. The applicability of primary assumption is illustrated. The results from the proposed model are examined within various slant angles, thermal and friction factors. It can be concluded that higher thermal conditions are tolerable when slanting connection is used. PMID:24587720

  15. Thermal Behaviour of Beams with Slant End-Plate Connection Subjected to Nonsymmetric Gravity Load

    PubMed Central

    Osman, Mohd Hanim; Talebi, Elnaz

    2014-01-01

    Research on the steel structures with confining of axial expansion in fixed beams has been quite intensive in the past decade. It is well established that the thermal behaviour has a key influence on steel structural behaviours. This paper describes mechanical behaviour of beams with bolted slant end-plate connection with nonsymmetric gravity load, subjected to temperature increase. Furthermore, the performance of slant connections of beams in steel moment frame structures in the elastic field is investigated. The proposed model proved that this flexible connection system could successfully decrease the extra thermal induced axial force by both of the friction force dissipation among two faces of slant connection and a small upward movement on the slant plane. The applicability of primary assumption is illustrated. The results from the proposed model are examined within various slant angles, thermal and friction factors. It can be concluded that higher thermal conditions are tolerable when slanting connection is used. PMID:24587720

  16. Effect of friction stir welding parameters on defect formation

    NASA Astrophysics Data System (ADS)

    Tarasov, S. Yu.; Rubtsov, V. E.; Eliseev, A. A.; Kolubaev, E. A.; Filippov, A. V.; Ivanov, A. N.

    2015-10-01

    Friction stir welding is a perspective method for manufacturing automotive parts, aviation and space technology. One of the major problems is the formation of welding defects and weld around the welding zone. The formation of defect is the main reason failure of the joint. A possible way to obtain defect-free welded joints is the selection of the correct welding parameters. Experimental results describing the effect of friction stir welding process parameters on the defects of welded joints on aluminum alloy AMg5M have been shown. The weld joint defects have been characterized using the non-destructive radioscopic and ultrasound phase array methods. It was shown how the type and size of defects determine the welded joint strength.

  17. The region-dependent biomechanical and biochemical properties of bovine cartilaginous endplate.

    PubMed

    Wu, Yongren; Cisewski, Sarah E; Sachs, Barton L; Pellegrini, Vincent D; Kern, Michael J; Slate, Elizabeth H; Yao, Hai

    2015-09-18

    Regional biomechanical and biochemical properties of bovine cartilaginous endplate (CEP) and its role in disc mechanics and nutrition were determined. The equilibrium aggregate modulus and hydraulic permeability between the central and lateral regions were examined by confined compression testing. Biochemical assays were conducted to quantify the amount of water, collagen, and glycosaminoglycan (GAG). The equilibrium aggregate modulus of the CEP in the central region (0.23 ± 0.15 MPa) was significantly lower than for the lateral region (0.83 ± 0. 26 MPa). No significant regional difference was found for the permeability of the CEP (central region: 0.13 ± 0.07×10(-15)m(4)/Ns and lateral region: 0.09 ± 0.03 × 10(-15)m(4)/Ns). CEPs were an average of 75.6% water by wet weight, 41.1% collagen, and 20.4% GAG by dry weight in the central region, as well as an average of 70.2% water by wet weight, 73.8% collagen, and 11.7% GAG by dry weight in the lateral region. Regional differences observed for the equilibrium aggregate modulus were likely due to the regional variation in biochemical composition. The lateral bovine endplate is much stiffer and may share a greater portion of the load. Compared with the nucleus pulposus (NP) and annulus fibrosus (AF), a smaller hydraulic permeability was found for the CEP in both the central and lateral regions, which could be due to its lower water content and higher collagen content. Our results suggest that the CEP may block rapid fluid exchange and solute convection, allow pressurization of the interstitial fluid, and play a significant role in nutrient supply in response to loading. PMID:26209084

  18. Correlations between effective permeability and marrow contact channels surface of vertebral endplates.

    PubMed

    Laffosse, Jean-Michel; Accadbled, Franck; Molinier, François; Bonnevialle, Nicolas; de Gauzy, Jérôme Sales; Swider, Pascal

    2010-09-01

    Homeostasis of the intervertebral disc relies on nutrient supply and waste clearance through the dense capillary network that is in contact with the cartilage endplate (CEP). We developed a micro-computerized tomography (micro-CT) method to quantify the marrow contact channel surface (MCCS) with the CEP and to validate the hypothesis according to which MCCS was correlated to the effective permeability of the vertebral endplate (VEP) and influenced by the mechanical stimuli. The influence of compression loading on local vascularization was investigated. Six 4-week-old skeletally immature pigs were instrumented with left pedicle screws and rod at both T5-T6 and L1-L2 levels to create asymmetrical spine tethers. After 3 months of growth, three cylindrical specimens of the VEP (one central and two lateral right and left) were obtained from both the instrumented and the control levels. We used a previously validated method for measuring permeability. Micro-CT analysis (resolution 12 microm) yielded a gray-scale 2D-image of the discal end of each specimen converted into a binary 2D-image to derive the MCCS. Correlations between MCCS and effective permeability were assessed. Effective permeability and MCCS were significantly decreased compared to the control group especially on the tethered side (-41.5%, p = 0.004 and -52.5%, p = 0.0009, respectively). Correlations were significant and showed maximal value (r(2) = 0.430, p < 0.0001) on the tethered side involving maximal compressive loadings. Mechanical stimuli, due to unbalanced growth, altered the vascularization and the convective properties of the CEP. The cascade of mechanobiological events should offer perspectives for research on disc degeneration and attempted treatment. PMID:20225324

  19. Forming Completely Penetrated Welded T-joints when Pulsed Arc Welding

    NASA Astrophysics Data System (ADS)

    Krampit, N. Yu; Krampit, M. A.; Sapozhkov, A. S.

    2016-04-01

    The paper is focused on revealing the influence of welding parameters on weld formation when pulsed arc welding. As an experimental sample a T-joint over 10 mm was selected. Welding was carried out in flat position, which required no edge preparation but provided mono-directional guaranteed root penetration. The following parameters of welding were subjected to investigation: gap in the joint, wire feed rate and incline angles of the torch along and across the weld axis. Technological recommendations have been made with respect to pulsed arc welding; the cost price of product manufacturing can be reduced on their basis due to reduction of labor input required by machining, lowering consumption of welding materials and electric power.

  20. Automatic orbital GTAW welding: Highest quality welds for tomorrow's high-performance systems

    NASA Technical Reports Server (NTRS)

    Henon, B. K.

    1985-01-01

    Automatic orbital gas tungsten arc welding (GTAW) or TIG welding is certain to play an increasingly prominent role in tomorrow's technology. The welds are of the highest quality and the repeatability of automatic weldings is vastly superior to that of manual welding. Since less heat is applied to the weld during automatic welding than manual welding, there is less change in the metallurgical properties of the parent material. The possibility of accurate control and the cleanliness of the automatic GTAW welding process make it highly suitable to the welding of the more exotic and expensive materials which are now widely used in the aerospace and hydrospace industries. Titanium, stainless steel, Inconel, and Incoloy, as well as, aluminum can all be welded to the highest quality specifications automatically. Automatic orbital GTAW equipment is available for the fusion butt welding of tube-to-tube, as well as, tube to autobuttweld fittings. The same equipment can also be used for the fusion butt welding of up to 6 inch pipe with a wall thickness of up to 0.154 inches.

  1. Enabling high speed friction stir welding of aluminum tailor welded blanks

    NASA Astrophysics Data System (ADS)

    Hovanski, Yuri

    Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high-volumes. While friction stir welding (FSW) has traditionally been applied at linear velocities less than one meter per minute, high volume production applications demand the process be extended to higher velocities more amenable to cost sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low to moderate welding velocities do not directly translate to high speed linear friction stir welding. Therefore, in order to facilitate production of high volume aluminum FSW components, parameters were developed with a minimum welding velocity of three meters per minute. With an emphasis on weld quality, welded blanks were evaluated for post-weld formability using a combination of numerical and experimental methods. Evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum tailor-welded blanks, which provided validation of the numerical and experimental analysis of laboratory scale tests.

  2. Butt weld inspection and weld machine diagnostic system for continuous coil processing lines

    SciTech Connect

    Lang, D.D.; Geier, D.; Shultz, B.L.

    1995-07-01

    Weld breaks of steel coil during cold rolling and continuous pickling operations are a significant source of lost productivity and product yield. Babcock and Wilcox Innerspec Technologies has developed and installed a weld process control system which monitors the key variables of the welding process and determines the quality of welds generated by flash-butt welding equipment. The TEMATE 2000 System utilizes Electro-Magnetic Acoustic Transducer (EMAT) technology as the basis for performing on-line, real-time, nondestructive weld quality evaluation. This technique accurately detects voids, laps, misalignment and over/under trim conditions in the weld. Results of the EMAT weld inspection are immediately presented to the weld machine operator for disposition. All weld quality and process parameter data are stored, traceable to each unique weld, and available for post process evaluation. Installation of the TEMATE 2000 system in a major flat rolled steel mill has contributed to near elimination of weld breakage and increased productivity at this facility.

  3. Novel Process Revolutionizes Welding Industry

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Glenn Research Center, Delphi Corporation, and the Michigan Research Institute entered into a research project to study the use of Deformation Resistance Welding (DRW) in the construction and repair of stationary structures with multiple geometries and dissimilar materials, such as those NASA might use on the Moon or Mars. Traditional welding technologies are burdened by significant business and engineering challenges, including high costs of equipment and labor, heat-affected zones, limited automation, and inconsistent quality. DRW addresses each of those issues, while drastically reducing welding, manufacturing, and maintenance costs.

  4. AISI/DOE Technology Roadmap Program: Development of Appropriate Resistance Spot Welding Practice for Transformation-Hardened Steels

    SciTech Connect

    Wayne Chuko; Jerry Gould

    2002-07-08

    This report describes work accomplished in the project, titled ''Development of Appropriate Resistance Spot Welding Practice for Transformation-Hardened Steels.'' The Phase 1 of the program involved development of in-situ temper diagrams for two gauges of representative dual-phase and martensitic grades of steels. The results showed that tempering is an effective way of reducing hold-time sensitivity (HTS) in hardenable high-strength sheet steels. In Phase 2, post-weld cooling rate techniques, incorporating tempering, were evaluated to reduce HTS for the same four steels. Three alternative methods, viz., post-heating, downsloping, and spike tempering, for HTS reduction were investigated. Downsloping was selected for detailed additional study, as it appeared to be the most promising of the cooling rate control methods. The downsloping maps for each of the candidate steels were used to locate the conditions necessary for the peak response. Three specific downslope conditions (at a fix ed final current for each material, timed for a zero-, medium-, and full-softening response) were chosen for further metallurgical and mechanical testing. Representative samples, were inspected metallographically, examining both local hardness variations and microstructures. The resulting downslope diagrams were found to consist largely of a C-curve. The softening observed in these curves, however, was not supported by subsequent metallography, which showed that all welds made, regardless of material and downslope condition, were essentially martensitic. CCT/TTT diagrams, generated based on microstructural modeling done at Oak Ridge National Laboratories, showed that minimum downslope times of 2 and 10 s for the martensitic and dual-phase grades of steels, respectively, were required to avoid martensite formation. These times, however, were beyond those examined in this study. These results show that downsloping is not an effective means of reducing HTS for production resistance spot

  5. The use of laser technology for the welding of the automotive tree mechanical clutch subject to the action of residual intrinsic magnetic field

    NASA Astrophysics Data System (ADS)

    Daurelio, G.; Campanile, E.; D'Alonzo, M.; Memola Capece Minutolo, F.; Spera, M.; Lugarà, M.; Ferrandino, V.

    2007-05-01

    The material in issue is a case-hardening steel, type 20MnCr5 (UNI 8550), that has been previously undergone to a softening annealing process conferring therefore to the material one equal Hardness Brinnel 200 to 220 HB. This steel is very difficult to weld as by laser technology as by other welding technologies by fusion. It has been experienced a power at first laser of 1500 W (for requirements begins them of understanding of the process and the relative to you parameters to set up then) and of 3000 W, like previewed. They have been used a covering gas and a laser beam focusing mirror. All the welded tests have been at first subordinates to taken care of a visual examination to eye and then to an Image Acquisition System, computerized and connected to both metallographic and stereo microscope. Then cut to you with metallographic apparatus, workings to the abrasive papers and metallographic cloths, in order to end with a chemical etching of type NITAL. The best ones turn out to you have been then always visualize in shape of macro and micro-graphs, acquired with the same Image Acquisition System of type NIKON - LUCIA 4.82 vers. by LIM, to storage and automatically measure the cross-section area (melted zone) and then to calculate the efficiency level, on each joint and bead on plate, expressed in Dau unit, to verify the laser welding efficiency, correlated to the laser working parameters. To a better characterization of the produced joints many micro-hardness tests and relate family hardness trends and profiles have been carried out. At the end from the comparison of the values of ETE % and MR % (Model of Swift- Hook & Gick) and of the values of WE in Dau (Model DA.LU.), lead on some beads of the 20MnCr5, has turned out an ulterior and substantial validity and goodness (as well as easiness of employment and calculation of WE) of this last Model and Unit of Measure. In fact the values of ETE % and WE (in Dau) are appeared substantially similar, respecting both all

  6. Syllabus in Trade Welding.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany. Bureau of Secondary Curriculum Development.

    The syllabus outlines material for a course two academic years in length (minimum two and one-half hours daily experience) leading to entry-level occupational ability in several welding trade areas. Fourteen units covering are welding, gas welding, oxyacetylene welding, cutting, nonfusion processes, inert gas shielded-arc welding, welding cast…

  7. Investigation of the Application of Process Analytical Technology for a Laser Welding Process in Medical Device Manufacturing

    NASA Astrophysics Data System (ADS)

    Moore, Sean; Conneely, Alan; Stenzel, Eric; Murphy, Eamonn

    In FDA regulated medical device manufacturing, real time inspection of manufactured product is limited by the requirement to destructively test random samples of the product post production. Infra Red thermography offers the ability to non-destructively test, key critical to quality attributes of medical devices during laser welding and facilitates real time statistical process control for enhanced product quality and yield. This paper will present results of research work focused on non-destructive methods using Infra Red Thermography to potentially replace destructive methods of assessment for laser welded joints in stent delivery catheters. The approach utilizes designed experiments in conjunction with IR assessment and also identifies some limitations of the proposed method.

  8. Underwater welding, cutting and inspection

    SciTech Connect

    Tsai, C.L. . Ohio Underwater Welding Center)

    1995-02-01

    Underwater welding, cutting and inspection of offshore, inland waterway and port facilities are becoming a requirement for both military and industrial communities, as maintenance and repair costs continue to escalate, and as many of the facilities are in operation well beyond their intended design life. In nuclear applications, underwater welding, cutting and inspection for repair and modification of irradiated nuclear power plant components are also a requirement. This article summarizes recent developments in this emerging underwater technology.

  9. Improving Fatigue Performance of AHSS Welds

    SciTech Connect

    Feng, Zhili; Yu, Xinghua; Erdman, III, Donald L.; Wang, Yanli; Kelly, Steve; Hou, Wenkao; Yan, Benda; Wang, Zhifeng; Yu, Zhenzhen; Liu, Stephen

    2015-03-01

    Reported herein is technical progress on a U.S. Department of Energy CRADA project with industry cost-share aimed at developing the technical basis and demonstrate the viability of innovative in-situ weld residual stresses mitigation technology that can substantially improve the weld fatigue performance and durability of auto-body structures. The developed technology would be costeffective and practical in high-volume vehicle production environment. Enhancing weld fatigue performance would address a critical technology gap that impedes the widespread use of advanced high-strength steels (AHSS) and other lightweight materials for auto body structure light-weighting. This means that the automotive industry can take full advantage of the AHSS in strength, durability and crashworthiness without the concern of the relatively weak weld fatigue performance. The project comprises both technological innovations in weld residual stress mitigation and due-diligence residual stress measurement and fatigue performance evaluation. Two approaches were investigated. The first one was the use of low temperature phase transformation (LTPT) weld filler wire, and the second focused on novel thermo-mechanical stress management technique. Both technical approaches have resulted in considerable improvement in fatigue lives of welded joints made of high-strength steels. Synchrotron diffraction measurement confirmed the reduction of high tensile weld residual stresses by the two weld residual stress mitigation techniques.

  10. High-Speed Friction-Stir Welding To Enable Aluminum Tailor-Welded Blanks

    SciTech Connect

    Hovanski, Yuri; Upadhyay, Piyush; Carsley, John; Luzanski, Tom; Carlson, Blair; Eisenmenger, Mark; Soulami, Ayoub; Marshall, Dustin; Landino, Brandon; Hartfield-Wunsch, Susan

    2015-05-01

    Current joining technologies for automotive aluminum alloys are utilized in low-volume and niche applications, and have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high-volumes. While friction stir welding has been traditionally applied at linear velocities less than one meter per minute, high volume production applications demand the process be extended to higher velocities more amenable to cost sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low to moderate welding velocities do not directly translate to high speed linear friction stir welding. Therefore, in order to facilitate production of high volume aluminum welded components, parameters were developed with a minimum welding velocity of three meters per minute. With an emphasis on weld quality, welded blanks were evaluated for post-weld formability utilizing a combination of numerical and experimental methods. Evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum tailor-welded blanks, which provided validation of the numerical and experimental analysis of laboratory scale tests.

  11. Pressure distributions induced by elevon deflections on swept wings and adjacent end-plate surfaces at Mach 6

    NASA Technical Reports Server (NTRS)

    Kaufman, L. G., II; Johnson, C. B.

    1977-01-01

    Surface pressure distributions are presented for regions where three-dimensional separated flow effects are prominent on swept-wing-elevon-end-plate models of 0 degree, 50 degree, and 70 degree sweepback, and with 0 degree, 10 degree, 20 degree, and 30 degree elevon deflections. Surface-oil-flow photographs and pressure distributions on the flat-plate wing, elevon, and end-plate surfaces are presented for numerous geometric variations, including various spacings between the elevon and the end plate, with and without a tip fin. The data, for a free-stream Mach number of 6 and a wing-root-chord Reynolds number of 20 x 10 to the sixth power, reveal considerably larger regions of elevon induced loads on the adjacent end-plate surface than would be anticipated by using inviscid flow analyses.

  12. Transmitter-mediated local contracture of the endplate region of the focally innervated mouse diaphragm treated with anticholinesterase.

    PubMed Central

    Hong, S. J.; Chang, C. C.

    1993-01-01

    1. Local contraction of the endplate region in response to nerve stimulation was studied in isolated mouse diaphragms. In normal preparations, muscle contractions involved the whole length of the muscle fibre with rise and decay times in the order of tens of ms whether evoked with a single or train of pulses. 2. When acetylcholinesterase was inhibited with neostigmine, tetanic stimulation produced a twitch-like phasic contraction and a delayed tonic contracture. A brief train of pulse (10 ms, 300 Hz) was enough to trigger a full size tonic contracture which reached an amplitude about one tenth that of control tetanus and had a duration of about 4 s. 3. Tetanic stimulation evoked a non-propagating prolonged depolarization at the endplate region lasting for about 1 s following a few muscle action potentials. 4. mu-Conotoxin, a specific inhibitor of muscle Na+ channel, selectively abolished the phasic contraction and the muscle action potentials leaving the tonic contracture and the prolonged depolarization unaffected. 5. Both the tonic contracture and the prolonged depolarization were highly sensitive to blockade by tubocurarine (IC50 0.05-0.1 microM) and vesamicol (1 microM, an inhibitor of packaging acetylcholine into synaptic vesicles), were attenuated by increasing Ca2+ concentration and were prolonged by decreasing Ca2+. 6. The results suggest that prolonged activation of endplate nicotinic receptors by endogenously released transmitter can produce substantial contractions of the endplate region when acetylcholinesterase are inhibited. The source of Ca2+ for the contraction seems to come mainly from intracellular stores. PMID:8104646

  13. The Impact of Teaching Oxy-Fuel Welding on Gas Metal Arc Welding Skills

    ERIC Educational Resources Information Center

    Sgro, Sergio D.; Field, Dennis W.; Freeman, Steven A.

    2008-01-01

    Industrial technology programs around the country must be sensitive to the demands of manufacturing and industry as they continue to replace "vocational" curriculum with high-tech alternatives. This article examines whether or not teaching oxyacetylene welding in the industrial technology classroom is required to learn arc welding processes. The…

  14. Insertional mutation of the motor endplate disease (med) locus on mouse chromosome 15

    SciTech Connect

    Kohrman, D.C.; Plummer, N.W.; Schuster, T.

    1995-03-20

    Homozygous transgenic mice from line A4 have an early-onset progressive neuromuscular disorder characterized by paralysis of the rear limbs, muscle atrophy, and lethality by 4 weeks of age. The transgene insertion site was mapped to distal chromosome 15 close to the locus motor endplate disease (med). The sequence of mouse DNA flanking the insertion site junctions was determined. A small (<20 kb) deletion was detected at the insertion site, with no evidence of additional rearrangement of the chromosomal DNA. Noncomplementation of the transgene-induced mutation and med was demonstrated in a cross with med{sup J}/ + mice. The new allele is designated med{sup TgNA4Bs}(med{sup tg}). The homologous human locus MED was assigned to chromosome 12. Synaptotagmin 1 and contactin 1 were eliminated as candidate genes for the med mutation. The transgene-induced allele provides molecular access to the med gene, whose function is required for synaptic transmission at the neuromuscular junction and long-term survival of cerebellar Purkinje cells. 49 refs., 5 figs., 1 tab.

  15. Human cartilage endplate permeability varies with degeneration and intervertebral disc site.

    PubMed

    DeLucca, John F; Cortes, Daniel H; Jacobs, Nathan T; Vresilovic, Edward J; Duncan, Randall L; Elliott, Dawn M

    2016-02-29

    Despite the critical functions the human cartilage endplate (CEP) plays in the intervertebral disc, little is known about its structural and mechanical properties and their changes with degeneration. Quantifying these changes with degeneration is important for understanding how the CEP contributes to the function and pathology of the disc. Therefore the objectives of this study were to quantify the effect of disc degeneration on human CEP mechanical properties, determine the influence of superior and inferior disc site on mechanics and composition, and simulate the role of collagen fibers in CEP and disc mechanics using a validated finite element model. Confined compression data and biochemical composition data were used in a biphasic-swelling model to calculate compressive extrafibrillar elastic and permeability properties. Tensile properties were obtained by applying published tensile test data to an ellipsoidal fiber distribution. Results showed that with degeneration CEP permeability decreased 50-60% suggesting that transport is inhibited in the degenerate disc. CEP fibers are organized parallel to the vertebrae and nucleus pulposus and may contribute to large shear strains (0.1-0.2) and delamination failure of the CEP commonly seen in herniated disc tissue. Fiber-reinforcement also reduces CEP axial strains thereby enhancing fluid flux by a factor of 1.8. Collectively, these results suggest that the structure and mechanics of the CEP may play critical roles in the solute transport and disc mechanics. PMID:26874969

  16. The giant miniature endplate potentials frequency is increased in aged rats.

    PubMed

    Pousinha, Paula A; Correia, Alexandra M; Sebastião, Ana M; Ribeiro, Joaquim A

    2015-01-01

    At the neuromuscular junction, spontaneous giant events (GMEPPs) are enhanced in different conditions when degenerative and/or remodeling processes take place, but no one investigated their incidence upon aging. In the present work, we evaluated evoked and spontaneous neuromuscular transmission events recorded from single muscle fibers. Phrenic-diaphragm preparations of 3-4, 12-16, 36-40 and 70-80 weeks old rat males were used. We found that the occurrence of GMEPPs significantly increases in aged rats. Moreover, in old rats the neuromuscular transmission was significantly impaired due to a significant decrease in the amplitude and quantal content of evoked endplate potentials. Interestingly, the number of observed EPPs failures were ∼ 3 times lower than the predicted value based on the quantal content. This discrepancy was not observed in infant or adult rats. The coincidence of a high GMEPPs frequency with a lower than expected EPPs failure rate suggests that GMEPPs events are needed to preserve effective neuromuscular transmission in aged animals. PMID:25449868

  17. Detection of micro-weld joint by magneto-optical imaging

    NASA Astrophysics Data System (ADS)

    Gao, Xiangdong; Liu, Yonghua; You, Deyong

    2014-10-01

    It is required that the laser beam focus should be controlled to accurately follow the weld joint center during laser butt joint welding; therefore, the weld joint position must be detected automatically in real-time. An approach for detecting the micro-weld joint (weld gap less than 0.1 mm) based on magneto-optical (MO) imaging is investigated during laser butt-joint welding of low carbon steel. Magneto-optical sensor was used to capture the dynamic images of weld joint. Weld MO image gray distribution features were analyzed to extract the transition zone of weld joint. The influences of a different magnetic field intensity and the welding speed on detecting the weld joint position were mainly studied. Under different welding conditions where welding path, weld gap or welding speed varies, it has been found that using magneto-optic imaging technology could effectively detect the position of the micro-weld joint. Different weld joint positions in MO images have been detected with various magnetic field intensities. Experimental results show that the welding speed has little influence on the detection of weld joint position.

  18. Narrow gap laser welding

    DOEpatents

    Milewski, J.O.; Sklar, E.

    1998-06-02

    A laser welding process including: (a) using optical ray tracing to make a model of a laser beam and the geometry of a joint to be welded; (b) adjusting variables in the model to choose variables for use in making a laser weld; and (c) laser welding the joint to be welded using the chosen variables. 34 figs.

  19. Narrow gap laser welding

    DOEpatents

    Milewski, John O.; Sklar, Edward

    1998-01-01

    A laser welding process including: (a) using optical ray tracing to make a model of a laser beam and the geometry of a joint to be welded; (b) adjusting variables in the model to choose variables for use in making a laser weld; and (c) laser welding the joint to be welded using the chosen variables.

  20. Weld pool oscillation during pulsed GTA welding

    SciTech Connect

    Aendenroomer, A.J.R.; Ouden, G. den

    1996-12-31

    This paper deals with weld pool oscillation during pulsed GTA welding and with the possibility to use this oscillation for in-process control of weld penetration. Welding experiments were carried out under different welding conditions. During welding the weld pool was triggered into oscillation by the normal welding pulses or by extra current pulses. The oscillation frequency was measured both during the pulse time and during the base time by analyzing the arc voltage variation using a Fast Fourier Transformation program. Optimal results are obtained when full penetration occurs during the pulse time and partial penetration during the base time. Under these conditions elliptical overlapping spot welds are formed. In the case of full penetration the weld pool oscillates in a low frequency mode (membrane oscillation), whereas in the case of partial penetration the weld pool oscillates in a high frequency mode (surface oscillation). Deviation from the optimal welding conditions occurs when high frequency oscillation is observed during both pulse time and base time (underpenetration) or when low frequency oscillation is observed during both pulse time and base time (overpenetration). In line with these results a penetration sensing system with feedback control was designed, based on the criterion that optimal weld penetration is achieved when two peaks are observed in the frequency distribution. The feasibility of this sensing system for orbital tube welding was confirmed by the results of experiments carried out under various welding conditions.

  1. Probabilistic secretion of quanta and the synaptosecretosome hypothesis: evoked release at active zones of varicosities, boutons, and endplates.

    PubMed Central

    Bennett, M R; Gibson, W G; Robinson, J

    1997-01-01

    A quantum of transmitter may be released upon the arrival of a nerve impulse if the influx of calcium ions through a nearby voltage-dependent calcium channel is sufficient to activate the vesicle-associated calcium sensor protein that triggers exocytosis. A synaptic vesicle, together with its calcium sensor protein, is often found complexed with the calcium channel in active zones to form what will be called a "synaptosecretosome." In the present work, a stochastic analysis is given of the conditions under which a quantum is released from the synaptosecretosome by a nerve impulse. The theoretical treatment considers the rise of calcium at the synaptosecretosome after the stochastic opening of a calcium channel at some time during the impulse, followed by the stochastic binding of calcium to the vesicle-associated protein and the probability of this leading to exocytosis. This allows determination of the probabilities that an impulse will release 0, 1, 2,... quanta from an active zone, whether this is in a varicosity, a bouton, or a motor endplate. A number of experimental observations of the release of transmitter at the active zones of sympathetic varicosities and boutons as well as somatic motor endplates are described by this analysis. These include the likelihood of the secretion of only one quantum at an active zone of endplates and of more than one quantum at an active zone of a sympathetic varicosity. The fourth-power relationship between the probability of transmitter release at the active zones of sympathetic varicosities and motor endplates and the external calcium concentration is also explained by this approach. So, too, is the fact that the time course of the increased rate of quantal secretion from a somatic active zone after an impulse is invariant with changes in the amount of calcium that enters through its calcium channel, whether due to changes consequent on the actions of autoreceptor agents such as adenosine or to facilitation. The increased

  2. Vaccum Gas Tungsten Arc Welding, phase 1

    NASA Technical Reports Server (NTRS)

    Weeks, J. L.; Krotz, P. D.; Todd, D. T.; Liaw, Y. K.

    1995-01-01

    This two year program will investigate Vacuum Gas Tungsten Arc Welding (VGTAW) as a method to modify or improve the weldability of normally difficult-to-weld materials. VGTAW appears to offer a significant improvement in weldability because of the clean environment and lower heat input needed. The overall objective of the program is to develop the VGTAW technology and implement it into a manufacturing environment that will result in lower cost, better quality and higher reliability aerospace components for the space shuttle and other NASA space systems. Phase 1 of this program was aimed at demonstrating the process's ability to weld normally difficult-to-weld materials. Phase 2 will focus on further evaluation, a hardware demonstration and a plan to implement VGTAW technology into a manufacturing environment. During Phase 1, the following tasks were performed: (1) Task 11000 Facility Modification - an existing vacuum chamber was modified and adapted to a GTAW power supply; (2) Task 12000 Materials Selection - four difficult-to-weld materials typically used in the construction of aerospace hardware were chosen for study; (3) Task 13000 VGTAW Experiments - welding experiments were conducted under vacuum using the hollow tungsten electrode and evaluation. As a result of this effort, two materials, NARloy Z and Incoloy 903, were downselected for further characterization in Phase 2; and (4) Task 13100 Aluminum-Lithium Weld Studies - this task was added to the original work statement to investigate the effects of vacuum welding and weld pool vibration on aluminum-lithium alloys.

  3. Improving fatigue performance of rail thermite welds

    NASA Astrophysics Data System (ADS)

    Jezzini-Aouad, M.; Flahaut, P.; Hariri, S.; Winiar, L.

    2010-06-01

    Rail transport development offers economic and ecological interests. Nevertheless, it requires heavy investments in rolling material and infrastructure. To be competitive, this transportation means must rely on safe and reliable infrastructure, which requires optimization of all implemented techniques and structure. Rail thermite (or aluminothermic) welding is widely used within the railway industry for in-track welding during re-rail and defect replacement. The process provides numerous advantages against other welding technology commonly used. Obviously, future demands on train traffic are heavier axle loads, higher train speeds and increased traffic density. Thus, a new enhanced weld should be developed to prevent accidents due to fracture of welds and to lower maintenance costs. In order to improve such assembly process, a detailed metallurgical study coupled to a thermomechanical modelling of the phenomena involved in the thermite welding process is carried out. Obtained data enables us to develop a new improved thermite weld (type A). This joint is made by modifying the routinely specified procedure (type B) used in a railway rail by a standard gap alumino-thermic weld. Joints of type A and B are tested and compared. Based on experimental temperature measurements, a finite element analysis is used to calculate the thermal residual stresses induced. In the vicinity of the weld, the residual stress patterns depend on the thermal conditions during welding as it also shown by litterature [1, 2]. In parallel, X-Ray diffraction has been used to map the residual stress field that is generated in welded rail of types A and B. Their effect on fatigue crack growth in rail welds is studied. An experimental study based on fatigue tests of rails welded by conventional and improved processes adjudicates on the new advances and results will be shown.

  4. The Structure and Mechanical Properties of Bridge Steel Weldings With Glass-Steel Liners

    NASA Astrophysics Data System (ADS)

    Muzalev, V. N.; Semukhin, B. S.; Danilov, V. I.

    2016-04-01

    A new technology is developed for welding multi-span bridge constructions. The mechanical properties and structure of the low-carbon bridge steel welds have been studied. The welding parameters and application of steel-glass liners provide for long-term service of steel constructions in conformity with the welding industry specifications.

  5. NASA Design Strengthens Welds

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Friction Stir Welding (FSW) is a solid-state joining process-a combination of extruding and forging-ideal for use when the original metal characteristics must remain as unchanged as possible. While exploring methods to improve the use of FSW in manufacturing, engineers at Marshall Space Flight Center created technologies to address the method's shortcomings. MTS Systems Corporation, of Eden Prairie, Minnesota, discovered the NASA-developed technology and then signed a co-exclusive license agreement to commercialize Marshall's design for use in high-strength structural alloys. The resulting process offers the added bonuses of being cost-competitive, efficient, and most importantly, versatile.

  6. Laser tissue welding: a urological surgeon's perspective.

    PubMed

    Poppas, D P; Scherr, D S

    1998-07-01

    Laser tissue welding has proven its efficacy in the laboratory setting when compared with more traditional modalities of tissue reapproximation. In the clinical environment, several areas including urethral reconstructive surgery have shown great promise. Several technological advancements including solder development, chromophore enhancement and temperature control have improved upon the welding process and have added more precision and reproducibility to the technique. The current potential applications for laser welding in urology are numerous. On a molecular level, growth factor supplementation has certain potential in improving upon weld site healing and wound strength. Laparoscopic surgery with its need for less cumbersome modes of tissue closure is a field that will greatly benefit from the technology of laser tissue welding. Surgical specialties outside of urology are also participating in developing the field of laser welding. In particular, cardiothoracic surgery, otolaryngology, plastic surgery, neurosurgery among others, have utilized the concept of laser tissue welding. There are many ares that have potential use for laser welding that have yet to be explored. Further investigation will likely reveal more applications for this valuable technology. PMID:9873775

  7. Electroslag and electrogas welding

    NASA Technical Reports Server (NTRS)

    Campbell, H. C.

    1972-01-01

    These two new joining methods perform welding in the vertical position, and therein lies the secret of their impressive advantages in material handling, in weld preparation, in welding speed, in freedom from distortion, and in weld soundness. Once the work has been set in the proper vertical position for welding, no further plate handling is required. The molten filler metal is held in place by copper shoes or dams, and the weld is completed in one pass.

  8. Laser based spot weld characterization

    NASA Astrophysics Data System (ADS)

    Jonietz, Florian; Myrach, Philipp; Rethmeier, Michael; Suwala, Hubert; Ziegler, Mathias

    2016-02-01

    Spot welding is one of the most important joining technologies, especially in the automotive industry. Hitherto, the quality of spot welded joints is tested mainly by random destructive tests. A nondestructive testing technique offers the benefit of cost reduction of the testing procedure and optimization of the fabrication process, because every joint could be examined. This would lead to a reduced number of spot welded joints, as redundancies could be avoided. In the procedure described here, the spot welded joint between two zinc-coated steel sheets (HX340LAD+Z100MB or HC340LA+ZE 50/50) is heated optically on one side. Laser radiation and flash light are used as heat sources. The melted zone, the so called "weld nugget" provides the mechanical stability of the connection, but also constitutes a thermal bridge between the sheets. Due to the better thermal contact, the spot welded joint reveals a thermal behavior different from the surrounding material, where the heat transfer between the two sheets is much lower. The difference in the transient thermal behavior is measured with time resolved thermography. Hence, the size of the thermal contact between the two sheets is determined, which is directly correlated to the size of the weld nugget, indicating the quality of the spot weld. The method performs well in transmission with laser radiation and flash light. With laser radiation, it works even in reflection geometry, thus offering the possibility of testing with just one-sided accessibility. By using heating with collimated laser radiation, not only contact-free, but also remote testing is feasible. A further convenience compared to similar thermographic approaches is the applicability on bare steel sheets without any optical coating for emissivity correction. For this purpose, a proper way of emissivity correction was established.

  9. Laser Micro Welding for Ribbon Bonding

    NASA Astrophysics Data System (ADS)

    Mehlmann, Benjamin; Gehlen, Elmar; Olowinsky, Alexander; Gillner, Arnold

    Laser ribbon bonding is a new field of application for laser micro welding in the electronics industry especially in the area of power electronics. Traditional ribbon bonding is conducted by using ultrasonic welding to create the bond between the aluminum or copper ribbon and a conductive surface. By adapting an ultrasonic ribbon bonder and equipping it with a fiber laser, a galvanometric scanner and a beam focusing and delivery system, a new technology for ribbon bonding is created. The presented work includes test results of the welding of copper ribbons with a thickness of 300 μm to DCB-substrates and the system design of the "laser bonder". For the laser welding of the ribbons spatial power modulation is being used and the effect of this approach on the welded ribbons is presented. The work concludes with advantages and limits of the technology especially concerning the applications compared to ultrasonic bonding.

  10. Innovative Tools Advance Revolutionary Weld Technique

    NASA Technical Reports Server (NTRS)

    2009-01-01

    The iconic, orange external tank of the space shuttle launch system not only contains the fuel used by the shuttle s main engines during liftoff but also comprises the shuttle s backbone, supporting the space shuttle orbiter and solid rocket boosters. Given the tank s structural importance and the extreme forces (7.8 million pounds of thrust load) and temperatures it encounters during launch, the welds used to construct the tank must be highly reliable. Variable polarity plasma arc welding, developed for manufacturing the external tank and later employed for building the International Space Station, was until 1994 the best process for joining the aluminum alloys used during construction. That year, Marshall Space Flight Center engineers began experimenting with a relatively new welding technique called friction stir welding (FSW), developed in 1991 by The Welding Institute, of Cambridge, England. FSW differs from traditional fusion welding in that it is a solid-state welding technique, using frictional heat and motion to join structural components without actually melting any of the material. The weld is created by a shouldered pin tool that is plunged into the seam of the materials to be joined. The tool traverses the line while rotating at high speeds, generating friction that heats and softens but does not melt the metal. (The heat produced approaches about 80 percent of the metal s melting temperature.) The pin tool s rotation crushes and stirs the plasticized metal, extruding it along the seam as the tool moves forward. The material cools and consolidates, resulting in a weld with superior mechanical properties as compared to those weld properties of fusion welds. The innovative FSW technology promises a number of attractive benefits. Because the welded materials are not melted, many of the undesirables associated with fusion welding porosity, cracking, shrinkage, and distortion of the weld are minimized or avoided. The process is more energy efficient, safe

  11. Reduced endplate currents underlie motor unit dysfunction in canine motor neuron disease.

    PubMed

    Rich, Mark M; Waldeck, Robert F; Cork, Linda C; Balice-Gordon, Rita J; Fyffe, Robert E W; Wang, Xueyong; Cope, Timothy C; Pinter, Martin J

    2002-12-01

    Hereditary canine spinal muscular atrophy (HCSMA) is an autosomal dominant degenerative disorder of motor neurons. In homozygous animals, motor units produce decreased force output and fail during repetitive activity. Previous studies suggest that decreased efficacy of neuromuscular transmission underlies these abnormalities. To examine this, we recorded muscle fiber endplate currents (EPCs) and found reduced amplitudes and increased failures during nerve stimulation in homozygotes compared with wild-type controls. Comparison of EPC amplitudes with muscle fiber current thresholds indicate that many EPCs from homozygotes fall below threshold for activating muscle fibers but can be raised above threshold following potentiation. To determine whether axonal abnormalities might play a role in causing motor unit dysfunction, we examined the postnatal maturation of axonal conduction velocity in relation to the appearance of tetanic failure. We also examined intracellularly labeled motor neurons for evidence of axonal neurofilament accumulations, which are found in many instances of motor neuron disease including HCSMA. Despite the appearance of tetanic failure between 90 and 120 days, average motor axon conduction velocity increased with age in homozygotes and achieved adult levels. Normal correlations between motor neuron properties (including conduction velocity) and motor unit properties were also observed. Labeled proximal motor axons of several motor neurons that supplied failing motor units exhibited little or no evidence of axonal swellings. We conclude that decreased release of transmitter from motor terminals underlies motor unit dysfunction in HCSMA and that the mechanisms determining the maturation of axonal conduction velocity and the pattern of correlation between motor neuron and motor unit properties do not contribute to the appearance or evolution of motor unit dysfunction. PMID:12466447

  12. Modal affinities of endplate acetylcholine receptors caused by loop C mutations

    PubMed Central

    Vij, Ridhima; Purohit, Prasad

    2015-01-01

    The time course of the endplate current is determined by the rate and equilibrium constants for acetylcholine receptor (AChR) activation. We measured these constants in single-channel currents from AChRs with mutations at the neurotransmitter-binding sites, in loop C. The main findings are: (a) Almost all perturbations of loop C generate heterogeneity in the channel open probability (“modes”). (b) Modes are generated by different affinities for ACh that can be either higher or lower than in the wild-type receptors. (c) The modes are stable, in so far as each receptor maintains its affinity for at least several minutes. (d) Different agonists show different degrees of modal activity. With the loop C mutation αP197A, there are four modes with ACh but only two with partial agonists. (e) The affinity variations arise exclusively from the αδ-binding site. (f) Substituting four γ-subunit residues into the δ subunit (three in loop E and one in the β5–β5′ linker) reduces modal activity. (g) At each neurotransmitter-binding site, affinity is determined by a core of five aromatic residues. Modes are eliminated by an alanine mutation at δW57 but not at the other aromatics. (h) Modes are eliminated by a phenylalanine substitution at all core aromatics except αY93. The results suggest that, at the αδ agonist site, loop C and the complementary subunit surface can each adopt alternative conformations and interact with each other to influence the position of δW57 with respect to the aromatic core and, hence, affinity. PMID:26503719

  13. Rapsyn Mutations in Humans Cause Endplate Acetylcholine-Receptor Deficiency and Myasthenic Syndrome

    PubMed Central

    Ohno, Kinji; Engel, Andrew G.; Shen, Xin-Ming; Selcen, Duygu; Brengman, Joan; Harper, C. Michel; Tsujino, Akira; Milone, Margherita

    2002-01-01

    Congenital myasthenic syndromes (CMSs) stem from genetic defects in endplate (EP)-specific presynaptic, synaptic, and postsynaptic proteins. The postsynaptic CMSs identified to date stem from a deficiency or kinetic abnormality of the acetylcholine receptor (AChR). All CMSs with a kinetic abnormality of AChR, as well as many CMSs with a deficiency of AChR, have been traced to mutations in AChR-subunit genes. However, in a subset of patients with EP AChR deficiency, the genetic defect has remained elusive. Rapsyn, a 43-kDa postsynaptic protein, plays an essential role in the clustering of AChR at the EP. Seven tetratricopeptide repeats (TPRs) of rapsyn subserve self-association, a coiled-coil domain binds to AChR, and a RING-H2 domain associates with β-dystroglycan and links rapsyn to the subsynaptic cytoskeleton. Rapsyn self-association precedes recruitment of AChR to rapsyn clusters. In four patients with EP AChR deficiency but with no mutations in AChR subunits, we identify three recessive rapsyn mutations: one patient carries L14P in TPR1 and N88K in TPR3; two are homozygous for N88K; and one carries N88K and 553ins5, which frameshifts in TPR5. EP studies in each case show decreased staining for rapsyn and AChR, as well as impaired postsynaptic morphological development. Expression studies in HEK cells indicate that none of the mutations hinders rapsyn self-association but that all three diminish coclustering of AChR with rapsyn. PMID:11791205

  14. Endplate denervation correlates with Nogo-A muscle expression in amyotrophic lateral sclerosis patients

    PubMed Central

    Bruneteau, Gaëlle; Bauché, Stéphanie; Gonzalez de Aguilar, Jose Luis; Brochier, Guy; Mandjee, Nathalie; Tanguy, Marie-Laure; Hussain, Ghulam; Behin, Anthony; Khiami, Frédéric; Sariali, Elhadi; Hell-Remy, Caroline; Salachas, François; Pradat, Pierre-François; Lacomblez, Lucette; Nicole, Sophie; Fontaine, Bertrand; Fardeau, Michel; Loeffler, Jean-Philippe; Meininger, Vincent; Fournier, Emmanuel; Koenig, Jeanine; Hantaï, Daniel

    2015-01-01

    Objective Data from mouse models of amyotrophic lateral sclerosis (ALS) suggest early morphological changes in neuromuscular junctions (NMJs), with loss of nerve–muscle contact. Overexpression of the neurite outgrowth inhibitor Nogo-A in muscle may play a role in this loss of endplate innervation. Methods We used confocal and electron microscopy to study the structure of the NMJs in muscle samples collected from nine ALS patients (five early-stage patients and four long-term survivors). We correlated the morphological results with clinical and electrophysiological data, and with Nogo-A muscle expression level. Results Surface electromyography assessment of neuromuscular transmission was abnormal in 3/9 ALS patients. The postsynaptic apparatus was morphologically altered for almost all NMJs (n = 430) analyzed using confocal microscopy. 19.7% of the NMJs were completely denervated (fragmented synaptic gutters and absence of nerve terminal profile). The terminal axonal arborization was usually sparsely branched and 56.8% of innervated NMJs showed a typical reinnervation pattern. Terminal Schwann cell (TSC) morphology was altered with extensive cytoplasmic processes. A marked intrusion of TSCs in the synaptic cleft was seen in some cases, strikingly reducing the synaptic surface available for neuromuscular transmission. Finally, high-level expression of Nogo-A in muscle was significantly associated with higher extent of NMJ denervation and negative functional outcome. Interpretation Our results support the hypothesis that morphological alterations of NMJs are present from early-stage disease and may significantly contribute to functional motor impairment in ALS patients. Muscle expression of Nogo-A is associated with NMJ denervation and thus constitutes a therapeutic target to slow disease progression. PMID:25909082

  15. Depression of miniature endplate potential frequency by acetylcholine and its analogues in frog.

    PubMed Central

    Nikolsky, E. E.; Bukharaeva, E. A.; Strunsky, E. G.; Vyskocil, F.

    1991-01-01

    1. Acetylcholine (ACh), 7.5 x 10(-5) M, and carbachol, 5 x 10(-6) M (CCh) depressed the frequency of miniature endplate potentials (m.e.p.ps) in the frog (Rana temporaria) sartorius neuromuscular junction with active acetylcholinesterase to about 50-55% of the controls. 2. A similar depression was produced by the nicotinic agonists, nicotine, suberyldicholine and tetramethylammonium. 3. The muscarinic agonists, oxotremorine, methylfurmethide and methacholine were without effect on m.e.p.p. frequency. The muscarinic antagonist, atropine and the nicotinic antagonist, (+)-tubocurarine, had no effect on the depression of m.e.p.p. frequency evoked by CCh. 4. The ganglionic blockers, benzhexonium and IEM-1119, were also without effect on the CCh-evoked depression of m.e.p.p. frequency. 5. Pretreatment of muscles with anticholinesterases did not prevent the CCh-induced drop in m.e.p.p. frequency. 6. The effect of CCh was proportionally the same as in the controls in preparations where the m.e.p.p. frequency was changed by elevation of K+ and in the presence of theophylline, noradrenaline, dibutyryl adenosine 3':5'-cyclic monophosphate (db cyclic AMP) and db cyclic GMP. 7. An inhibitor of Na+,K(+)-ATPase, ouabain, 5 x 10(-5) mol l-1, prevented or reversed the depression of m.e.p.p. frequency by CCh. However, the depression was present in a nominally K(+)-free medium. Insulin and adrenaline, which are considered to be Na+,K(+)-ATPase activators, were without effect on depression of m.e.p.p. frequency. 8. The depression of m.e.p.p. frequency by 5 x 10(-6) M CCh was the same at temperatures between 5 and 30 degrees C with a Q10 near to 1.0.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1667283

  16. Trans-Endplate Pedicle Pillar System in Unstable Spinal Burst Fractures: Design, Technique, and Mechanical Evaluation

    PubMed Central

    Zhao, Chunfeng; Hongo, Michio; Ilharreborde, Brice; Zhao, Kristin D.; Currier, Bradford L.; An, Kai-Nan

    2015-01-01

    Background Short-segment pedicle screw instrumentation (SSPI) is used for unstable burst fractures to correct deformity and stabilize the spine for fusion. However, pedicle screw loosening, pullout, or breakage often occurs due to the large moment applied during spine motion, leading to poor outcomes. The purpose of this study was to test the ability of a newly designed device, the Trans-Endplate Pedicle Pillar System (TEPPS), to enhance SSPI rigidity and decrease the screw bending moment with a simple posterior approach. Methods Six human cadaveric spines (T11-L3) were harvested. A burst fracture was created at L1, and the SSPI (Moss Miami System) was used for SSPI fixation. Strain gauge sensors were mounted on upper pedicle screws to measure screw load bearing. Segmental motion (T12-L2) was measured under pure moment of 7.5 Nm. The spine was tested sequentially under 4 conditions: intact; first SSPI alone (SSPI-1); SSPI+TEPPS; and second SSPI alone (SSPI-2). Results SSPI+TEPPS increased fixation rigidity by 41% in flexion/extension, 28% in lateral bending, and 37% in axial rotation compared with SSPI-1 (P<0.001), and it performed even better compared to SSPI-2 (P<0.001 for all). Importantly, the bending moment on the pedicle screws for SSPI+TEPPS was significantly decreased 63% during spine flexion and 47% in lateral bending (p<0.001). Conclusion TEPPS provided strong anterior support, enhanced SSPI fixation rigidity, and dramatically decreased the load on the pedicle screws. Its biomechanical benefits could potentially improve fusion rates and decrease SSPI instrumentation failure. PMID:26502352

  17. Lasers for welding and their potential in production at GE

    NASA Astrophysics Data System (ADS)

    Jones, Marshall G.

    2014-02-01

    Laser technology has been used in manufacturing in industry since the late 1960s. Industry and GE businesses have leverage laser welding for productivity gains, cost savings, and quality. The presentation will high light several laser-based welding applications, old and new. Applications will include the welding of refractory materials (e.g. Mo and Nb) for lighting products; 40 foot long fuel rods are welded with 2 kW fiber lasers for the nuclear business; head-liner welding for the diesel engine for locomotives (14 kW fiber laser replaced CO2 laser); and X-ray components are welded in a two-station 11kW fiber laser (EB welding replaced by laser). The three fiber laser applications were all transitioned into GE businesses during 2011 and it demonstrates the emergence of fiber laser welding being used in GE for manufacturing, processing.

  18. WELDING APPARATUS

    DOEpatents

    Correy, T.B.; DeWitt, D.E.; Nelson, I.V.

    1963-04-23

    This patent covers an arrangement for replacing air in a welding chamber with an inert gas. This operation usually is time-consuming because of the tendency of the inert gas to mix with the air being removed from the welding chamber. The chamber is open at the bottom and has at its top a cover and a porous plate a little below the cover. The inert gas is admitted to the chamber through two screened openings in the cover. On passing through the porous plate, the gas acts as a piston extending across the chamber and moving downwardly to expel the air through the lower open end of the chamber, with a minimum of mixing with the air being expelled. (AEC)

  19. WELDING PROCESS

    DOEpatents

    Zambrow, J.; Hausner, H.

    1957-09-24

    A method of joining metal parts for the preparation of relatively long, thin fuel element cores of uranium or alloys thereof for nuclear reactors is described. The process includes the steps of cleaning the surfaces to be jointed, placing the sunfaces together, and providing between and in contact with them, a layer of a compound in finely divided form that is decomposable to metal by heat. The fuel element members are then heated at the contact zone and maintained under pressure during the heating to decompose the compound to metal and sinter the members and reduced metal together producing a weld. The preferred class of decomposable compounds are the metal hydrides such as uranium hydride, which release hydrogen thus providing a reducing atmosphere in the vicinity of the welding operation.

  20. Development of a comprehensive weld process model

    SciTech Connect

    Radhakrishnan, B.; Zacharia, T.; Paul, A.

    1997-05-01

    This cooperative research and development agreement (CRADA) between Concurrent Technologies Corporation (CTC) and Lockheed Martin Energy Systems (LMES) combines CTC`s expertise in the welding area and that of LMES to develop computer models and simulation software for welding processes. This development is of significant impact to the industry, including materials producers and fabricators. The main thrust of the research effort was to develop a comprehensive welding simulation methodology. A substantial amount of work has been done by several researchers to numerically model several welding processes. The primary drawback of most of the existing models is the lack of sound linkages between the mechanistic aspects (e.g., heat transfer, fluid flow, and residual stress) and the metallurgical aspects (e.g., microstructure development and control). A comprehensive numerical model which can be used to elucidate the effect of welding parameters/conditions on the temperature distribution, weld pool shape and size, solidification behavior, and microstructure development, as well as stresses and distortion, does not exist. It was therefore imperative to develop a comprehensive model which would predict all of the above phenomena during welding. The CRADA built upon an already existing three-dimensional (3-D) welding simulation model which was developed by LMES which is capable of predicting weld pool shape and the temperature history in 3-d single-pass welds. However, the model does not account for multipass welds, microstructural evolution, distortion and residual stresses. Additionally, the model requires large resources of computing time, which limits its use for practical applications. To overcome this, CTC and LMES have developed through this CRADA the comprehensive welding simulation model described above.

  1. Weld pool phenomena

    SciTech Connect

    David, S.A.; Vitek, J.M.; Zacharia, T.; DebRoy, T.

    1994-09-01

    During welding, the composition, structure and properties of the welded structure are affected by the interaction of the heat source with the metal. The interaction affects the fluid flow, heat transfer and mass transfer in the weld pool, and the solidification behavior of the weld metal. In recent years, there has been a growing recognition of the importance of the weld pool transport processes and the solid state transformation reactions in determining the composition, structure and properties of the welded structure. The relation between the weld pool transport processes and the composition and structure is reviewed. Recent applications of various solidification theories to welding are examined to understand the special problems of weld metal solidification. The discussion is focussed on the important problems and issues related to weld pool transport phenomena and solidification. Resolution of these problems would be an important step towards a science based control of composition, structure and properties of the weld metal.

  2. Friction plug welding

    NASA Technical Reports Server (NTRS)

    Takeshita, Riki (Inventor); Hibbard, Terry L. (Inventor)

    2001-01-01

    Friction plug welding (FPW) usage is advantageous for friction stir welding (FSW) hole close-outs and weld repairs in 2195 Al--Cu--Li fusion or friction stir welds. Current fusion welding methods of Al--Cu--Li have produced welds containing varied defects. These areas are found by non-destructive examination both after welding and after proof testing. Current techniques for repairing typically small (<0.25) defects weaken the weldment, rely heavily on welders' skill, and are costly. Friction plug welding repairs increase strength, ductility and resistance to cracking over initial weld quality, without requiring much time or operator skill. Friction plug welding while pulling the plug is advantageous because all hardware for performing the weld can be placed on one side of the workpiece.

  3. Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur C., Jr.

    2008-01-01

    Friction stir welding (FSW) is a solid state welding process invented in 1991 at The Welding Institute in the United Kingdom. A weld is made in the FSW process by translating a rotating pin along a weld seam so as to stir the sides of the seam together. FSW avoids deleterious effects inherent in melting and promises to be an important welding process for any industries where welds of optimal quality are demanded. This article provides an introduction to the FSW process. The chief concern is the physical effect of the tool on the weld metal: how weld seam bonding takes place, what kind of weld structure is generated, potential problems, possible defects for example, and implications for process parameters and tool design. Weld properties are determined by structure, and the structure of friction stir welds is determined by the weld metal flow field in the vicinity of the weld tool. Metal flow in the vicinity of the weld tool is explained through a simple kinematic flow model that decomposes the flow field into three basic component flows: a uniform translation, a rotating solid cylinder, and a ring vortex encircling the tool. The flow components, superposed to construct the flow model, can be related to particular aspects of weld process parameters and tool design; they provide a bridge to an understanding of a complex-at-first-glance weld structure. Torques and forces are also discussed. Some simple mathematical models of structural aspects, torques, and forces are included.

  4. Study on Sensor Design Technique for Real-Time Robotic Welding Tracking System

    NASA Astrophysics Data System (ADS)

    Liu, C. J.; Li, Y. B.; Zhu, J. G.; Ye, S. H.

    2006-10-01

    Based on visual measurement techniques, the real-time robotic welding tracking system achieves real-time adjustment for robotic welding according to the position and shape changes of a workpiece. In system design, the sensor design technique is so important that its performance directly affects the precision and stability of the tracking system. Through initiative visual measurement technology, a camera unit for real-time sampling is built with multiple-strip structured light and a high-performance CMOS image sensor including 1.3 million pixels; to realize real-time data process and transmission, an image process unit is built with FPGA and DSP. Experiments show that the precision of this sensor reaches 0.3mm, and band rate comes up to 10Mbps, which effectively improves robot welding quality.With the development of advanced manufacturing technology, it becomes an inexorable trend to realize the automatic, flexible and intelligent welding product manufacture. With the advantage of interchangeability and reliability, robotic welding can boost productivity, improve work condition, stabilize and guarantee weld quality, and realize welding automation of the short run products [1]. At present, robotic welding has already become the application trend of automatic welding technology. Traditional welding robots are play-back ones, which cannot adapt environment and weld distortion. Especially in the more and more extensive arc-welding course, the deficiency and limitation of play-back welding technology becomes more prominent because of changeable welding condition. It becomes one of the key technology influencing the development of modern robotic welding technology to eliminate or decrease uncertain influence on quality of welding such as changing welding condition etc [2]. Based on visual measuring principle, this text adopts active visual measuring technology, cooperated with high-speed image process and transmission technology to structure a tracking sensor, to realize

  5. Explosion welding and cutting in aerospace engineering

    NASA Astrophysics Data System (ADS)

    Volgin, L. A.; Koroteev, A. Ia.; Malakovich, A. P.; Petushkov, V. G.; Sitalo, V. G.; Novikov, V. K.

    The paper presents the results of works of the E.O. Paton Electric Welding Institute and other Soviet organizations on the development of technology for explosion-welding of multilayer transition pieces and pipes used in the manufacture of aerospace products. Equipment and accessories used for this technology are described; in particular, a powerful explosion chamber of a tubular structure for up to 200 kg of explosives is presented. Information is also given about linear explosion separation devices.

  6. High-Speed Friction-Stir Welding to Enable Aluminum Tailor-Welded Blanks

    NASA Astrophysics Data System (ADS)

    Hovanski, Yuri; Upadhyay, Piyush; Carsley, John; Luzanski, Tom; Carlson, Blair; Eisenmenger, Mark; Soulami, Ayoub; Marshall, Dustin; Landino, Brandon; Hartfield-Wunsch, Susan

    2015-05-01

    Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and they have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high volumes. While friction-stir welding (FSW) has been traditionally applied at linear velocities less than 1 m/min, high-volume production applications demand the process be extended to higher velocities more amenable to cost-sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low-to-moderate welding velocities do not directly translate to high-speed linear FSW. Therefore, to facilitate production of high-volume aluminum FSW components, parameters were developed with a minimum welding velocity of 3 m/min. With an emphasis on weld quality, welded blanks were evaluated for postweld formability using a combination of numerical and experimental methods. An evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum TWBs, which provided validation of the numerical and experimental analysis of laboratory-scale tests.

  7. Weld-Bead Shaver

    NASA Technical Reports Server (NTRS)

    Guirguis, Kamal; Price, Daniel S.

    1990-01-01

    Hand-held power tool shaves excess metal from inside circumference of welded duct. Removes excess metal deposited by penetration of tungsten/inert-gas weld or by spatter from electron-beam weld. Produces smooth transition across joint. Easier to use and not prone to overshaving. Also cuts faster, removing 35 in. (89 cm) of weld bead per hour.

  8. Introduction to Welding.

    ERIC Educational Resources Information Center

    Fortney, Clarence; Gregory, Mike

    This curriculum guide provides six units of instruction on basic welding. Addressed in the individual units of instruction are the following topics: employment opportunities for welders, welding safety and first aid, welding tools and equipment, basic metals and metallurgy, basic math and measuring, and procedures for applying for a welding job.…

  9. Laser welding in space

    NASA Technical Reports Server (NTRS)

    Kaukler, W. F.; Workman, G. L.

    1991-01-01

    Autogenous welds in 304 stainless steel were performed by Nd-YAG laser heating in a simulated space environment. Simulation consists of welding on the NASA KC-135 aircraft to produce the microgravity and by containing the specimen in a vacuum chamber. Experimental results show that the microgravity welds are stronger, harder in the fusion zone, have deeper penetration and have a rougher surface rippling of the weld pool than one-g welds. To perform laser welding in space, a solar-pumped laser concept that significantly increases the laser conversion efficiency and makes welding viable despite the limited power availability of spacecraft is proposed.

  10. [New welding processes and health effects of welding].

    PubMed

    La Vecchia, G Marina; Maestrelli, Piero

    2011-01-01

    This paper describes some of the recent developments in the control technology to enhance capability of Pulse Gas Metal Arc Welding. Friction Stir Welding (FSW) processing has been also considered. FSW is a new solid-state joining technique. Heat generated by friction at the rotating tool softens the material being welded. FSW can be considered a green and energy-efficient technique without deleterious fumes, gas, radiation, and noise. Application of new welding processes is limited and studies on health effects in exposed workers are lacking. Acute and chronic health effects of conventional welding have been described. Metal fume fever and cross-shift decline of lung function are the main acute respiratory effects. Skin and eyes may be affected by heat, electricity and UV radiations. Chronic effects on respiratory system include chronic bronchitis, a benign pneumoconiosis (siderosis), asthma, and a possible increase in the incidence of lung cancer. Pulmonary infections are increased in terms of severity, duration, and frequency among welders. PMID:22073669

  11. Advanced Welding Applications

    NASA Technical Reports Server (NTRS)

    Ding, Robert J.

    2010-01-01

    Some of the applications of advanced welding techniques are shown in this poster presentation. Included are brief explanations of the use on the Ares I and Ares V launch vehicle and on the Space Shuttle Launch vehicle. Also included are microstructural views from four advanced welding techniques: Variable Polarity Plasma Arc (VPPA) weld (fusion), self-reacting friction stir welding (SR-FSW), conventional FSW, and Tube Socket Weld (TSW) on aluminum.

  12. Optical Welding Torch

    NASA Technical Reports Server (NTRS)

    Richardson, R. W.

    1987-01-01

    Gas/tungsten-arc welding torch supports electrode at center while enabling viewing of weld area along torch axis. Gas torch accommodates lens and optical fibers, all part of vision system for welding robot. Welding torch includes spoked structure in central bore of optical body. Structure supports welding electrode, carries electric current to it, and takes heat away from it. Spokes formed by drilling six holes 60 degrees apart around center line of torch.

  13. Characterization of Defocused Electron Beams and Welds in Stainless Steel and Refractory Metals using the Enhanced Modified Faraday Cup Diagnostic

    SciTech Connect

    Elmer, J W

    2009-01-23

    As the first part of a project to compare new generation, continuous wave, laser welding technology to traditional electron beam welding technology, electron beam welds were made on commercially pure vanadium refractory metal and 21-6-9 austenitic stainless steel. The electron beam welds were made while employing EB diagnostics to fully characterize the beams so that direct comparisons could be made between electron beam and laser beams and the welds that each process produces.

  14. Global Gene Expression Profiling and Alternative Splicing Events during the Chondrogenic Differentiation of Human Cartilage Endplate-Derived Stem Cells

    PubMed Central

    Shang, Jin; Fan, Xin; Shangguan, Lei; Liu, Huan; Zhou, Yue

    2015-01-01

    Low back pain (LBP) is a very prevalent disease and degenerative disc diseases (DDDs) usually account for the LBP. However, the pathogenesis of DDDs is complicated and difficult to elucidate. Alternative splicing is a sophisticated regulatory process which greatly increases cellular complexity and phenotypic diversity of eukaryotic organisms. In addition, the cartilage endplate-derived stem cells have been discovered and identified by our research group. In this paper, we continue to investigate gene expression profiling and alternative splicing events during chondrogenic differentiation of cartilage endplate-derived stem cells. We adopted Affymetrix Human Transcriptome Array 2.0 (HTA 2.0) to compare the transcriptional and splicing changes between the control and differentiated samples. RT-PCR and quantitative PCR are used to validate the microarray results. The GO and KEGG pathway analysis was also performed. After bioinformatics analysis of the data, we detected 1953 differentially expressed genes. In terms of alternative splicing, the Splicing Index algorithm was used to select alternatively spliced genes. We detected 4411 alternatively spliced genes. GO and KEGG pathway analysis also revealed several functionally involved biological processes and signaling pathways. To our knowledge, this is the first study to investigate the alternative splicing mechanisms in chondrogenic differentiation of stem cells on a genome-wide scale. PMID:26649308

  15. Effects of calcium and magnesium on the frequency of miniature end-plate potentials during prolonged tetanization

    PubMed Central

    Hurlbut, W. P.; Longenecker, H. B.; Mauro, Alexander

    1971-01-01

    1. End-plate potentials (e.p.p.s) and miniature end-plate potentials (min.e.p.p.s) were recorded intracellularly from the cutaneous pectoris nerve-muscle preparation of the frog during prolonged stimulation at low frequencies (5/sec—50/sec). 2. When Ca was present in the bathing solution, the quantum content of the e.p.p. and the frequency of occurrence of the min.e.p.p.s gradually increased during the period of stimulation. During the first few minutes of stimulation, the min.e.p.p. frequency increased linearly with time, and the rate of increase was dependent on the Ca concentration of the bathing solution. However, Mg had no effect on this Ca-dependent increase in min.e.p.p. frequency. 3. A large maintained increase in min.e.p.p. frequency also occurred during prolonged stimulation in solutions that contained no added Ca and 1-2 mM-EGTA. Under these conditions the increase in min.e.p.p. frequency was dependent on the Mg concentration of the bathing solution and was exponential in time. 4. It is suggested that the rise in min.e.p.p. frequency is caused by an accumulation of Ca or Mg ions in the nerve terminal, and it is suggested that these ions enter the terminal at relatively non-specific sites distinct from the Ca-specific sites that trigger the `phasic' release of transmitter. PMID:5316661

  16. Friction Stir Welding and Processing

    SciTech Connect

    Hovanski, Yuri; Carsley, John; Clarke, Kester D.; Krajewski, Paul E.

    2015-05-01

    With nearly twenty years of international research and collaboration in friction stir welding (FSW) and processing industrial applications have spread into nearly every feasible market. Currently applications exist in aerospace, railway, automotive, personal computers, technology, marine, cutlery, construction, as well as several other markets. Implementation of FSW has demonstrated diverse opportunities ranging from enabling new materials to reducing the production costs of current welding technologies by enabling condensed packaging solutions for traditional fabrication and assembly. TMS has sponsored focused instruction and communication in this technology area for more than fifteen years, with leadership from the Shaping and Forming Committee, which organizes a biannual symposium each odd year at the annual meeting. A focused publication produced from each of these symposia now comprises eight volumes detailing the primary research and development activities in this area over the last two decades. The articles assembled herein focus on both recent developments and technology reviews of several key markets from international experts in this area.

  17. The Influence of Friction Stir Weld Tool Form and Welding Parameters on Weld Structure and Properties: Nugget Bulge in Self-Reacting Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Schneider, Judy; Nunes, Arthur C., Jr.; Brendel, Michael S.

    2010-01-01

    Although friction stir welding (FSW) was patented in 1991, process development has been based upon trial and error and the literature still exhibits little understanding of the mechanisms determining weld structure and properties. New concepts emerging from a better understanding of these mechanisms enhance the ability of FSW engineers to think about the FSW process in new ways, inevitably leading to advances in the technology. A kinematic approach in which the FSW flow process is decomposed into several simple flow components has been found to explain the basic structural features of FSW welds and to relate them to tool geometry and process parameters. Using this modelling approach, this study reports on a correlation between the features of the weld nugget, process parameters, weld tool geometry, and weld strength. This correlation presents a way to select process parameters for a given tool geometry so as to optimize weld strength. It also provides clues that may ultimately explain why the weld strength varies within the sample population.

  18. Development of a Comprehensive Weld Process Model

    SciTech Connect

    Radhakrishnan, B.; Zacharia, T.

    1997-05-01

    This cooperative research and development agreement (CRADA) between Concurrent Technologies Corporation (CTC) and Lockheed Martin Energy Systems (LMES) combines CTC's expertise in the welding area and that of LMES to develop computer models and simulation software for welding processes. This development is of significant impact to the industry, including materials producers and fabricators. The main thrust of the research effort was to develop a comprehensive welding simulation methodology. A substantial amount of work has been done by several researchers to numerically model several welding processes. The primary drawback of most of the existing models is the lack of sound linkages between the mechanistic aspects (e.g., heat transfer, fluid flow, and residual stress) and the metallurgical aspects (e.g., microstructure development and control). A comprehensive numerical model which can be used to elucidate the effect of welding parameters/conditions on the temperature distribution, weld pool shape and size, solidification behavior, and microstructure development, as well as stresses and distortion, does not exist. It was therefore imperative to develop a comprehensive model which would predict all of the above phenomena during welding. The CRADA built upon an already existing three- dimensional (3-D) welding simulation model which was developed by LMES which is capable of predicting weld pool shape and the temperature history in 3-d single-pass welds. However, the model does not account for multipass welds, microstructural evolution, distortion and residual stresses. Additionally, the model requires large resources of computing time, which limits its use for practical applications. To overcome this, CTC and LMES have developed through this CRADA the comprehensive welding simulation model described above. The following technical tasks have been accomplished as part of the CRADA. 1. The LMES welding code has been ported to the Intel Paragon parallel computer at ORNL

  19. Television Monitoring System for Welding

    NASA Technical Reports Server (NTRS)

    Vallow, K.; Gordon, S.

    1986-01-01

    Welding process in visually inaccessible spots viewed and recorded. Television system enables monitoring of welding in visually inaccessible locations. System assists welding operations and provide video record, used for weld analysis and welder training.

  20. Laser weld jig

    DOEpatents

    Van Blarigan, Peter; Haupt, David L.

    1982-01-01

    A system is provided for welding a workpiece (10, FIG. 1) along a predetermined weld line (12) that may be of irregular shape, which includes the step of forming a lip (32) on the workpiece to extend parallel to the weld line, and moving the workpiece by engaging the lip between a pair of rotatable members (34, 36). Rotation of one of the members at a constant speed, causes the workpiece to move so that all points on the weld line sequentially pass a fixed point in space (17) at a constant speed, so that a laser welding beam can be directed at that fixed point to form a weld along the weld line. The workpiece can include a reuseable jig (24) forming the lip, and with the jig constructed to detachably hold parts (22, 20) to be welded at a position wherein the weld line of the parts extends parallel to the lip on the jig.

  1. HEAT INPUT AND POST WELD HEAT TREATMENT EFFECTS ON REDUCED-ACTIVATION FERRITIC/MARTENSITIC STEEL FRICTION STIR WELDS

    SciTech Connect

    Tang, Wei; Chen, Gaoqiang; Chen, Jian; Yu, Xinghua; Frederick, David Alan; Feng, Zhili

    2015-01-01

    Reduced-activation ferritic/martensitic (RAFM) steels are an important class of structural materials for fusion reactor internals developed in recent years because of their improved irradiation resistance. However, they can suffer from welding induced property degradations. In this paper, a solid phase joining technology friction stir welding (FSW) was adopted to join a RAFM steel Eurofer 97 and different FSW parameters/heat input were chosen to produce welds. FSW response parameters, joint microstructures and microhardness were investigated to reveal relationships among welding heat input, weld structure characterization and mechanical properties. In general, FSW heat input results in high hardness inside the stir zone mostly due to a martensitic transformation. It is possible to produce friction stir welds similar to but not with exactly the same base metal hardness when using low power input because of other hardening mechanisms. Further, post weld heat treatment (PWHT) is a very effective way to reduce FSW stir zone hardness values.

  2. Fusion welding process

    DOEpatents

    Thomas, Kenneth C.; Jones, Eric D.; McBride, Marvin A.

    1983-01-01

    A process for the fusion welding of nickel alloy steel members wherein a ferrite containing pellet is inserted into a cavity in one member and melted by a welding torch. The resulting weld nugget, a fusion of the nickel containing alloy from the members to be welded and the pellet, has a composition which is sufficiently low in nickel content such that ferrite phases occur within the weld nugget, resulting in improved weld properties. The steel alloys encompassed also include alloys containing carbon and manganese, considered nickel equivalents.

  3. A study on the influence of ultrasonic processing on microstructure during laser welding phases

    NASA Astrophysics Data System (ADS)

    Liu, H. D.; Hu, F. Y.; Cui, A. Y.; Li, H. B.

    2015-12-01

    This paper proposes new welding technology that combines ultrasonic processing across different phases based on laser welding (UPPLW) and laser processing technology. The welding experiment used a 1.5 mm thick titanium alloy. The specimen was made metallographically prepared and the microstructural grain size of the welded joint was rated by metallurgical processing software, verifying that this new process can refine grains and improve joint properties.

  4. Structural integrity and fatigue crack propagation life assessment of welded and weld-repaired structures

    NASA Astrophysics Data System (ADS)

    Alam, Mohammad Shah

    2005-11-01

    Structural integrity is the science and technology of the margin between safety and disaster. Proper evaluation of the structural integrity and fatigue life of any structure (aircraft, ship, railways, bridges, gas and oil transmission pipelines, etc.) is important to ensure the public safety, environmental protection, and economical consideration. Catastrophic failure of any structure can be avoided if structural integrity is assessed and necessary precaution is taken appropriately. Structural integrity includes tasks in many areas, such as structural analysis, failure analysis, nondestructive testing, corrosion, fatigue and creep analysis, metallurgy and materials, fracture mechanics, fatigue life assessment, welding metallurgy, development of repairing technologies, structural monitoring and instrumentation etc. In this research fatigue life assessment of welded and weld-repaired joints is studied both in numerically and experimentally. A new approach for the simulation of fatigue crack growth in two elastic materials has been developed and specifically, the concept has been applied to butt-welded joint in a straight plate and in tubular joints. In the proposed method, the formation of new surface is represented by an interface element based on the interface potential energy. This method overcomes the limitation of crack growth at an artificial rate of one element length per cycle. In this method the crack propagates only when the applied load reaches the critical bonding strength. The predicted results compares well with experimental results. The Gas Metal Arc welding processes has been simulated to predict post-weld distortion, residual stresses and development of restraining forces in a butt-welded joint. The effect of welding defects and bi-axial interaction of a circular porosity and a solidification crack on fatigue crack propagation life of butt-welded joints has also been investigated. After a weld has been repaired, the specimen was tested in a universal

  5. 2195 Aluminum-Copper-Lithium Friction Plug Welding Development

    NASA Technical Reports Server (NTRS)

    Takeshita, Rike P.; Hartley, Paula J.; Baker, Kent S.

    1997-01-01

    Technology developments and applications of friction plug welding is presented. This friction repair welding technology is being studied for implementation on the Space Transportation System's Super Light Weight External Tank. Single plug repairs will be used on a vast majority of weld defects, however, linear defects of up to several inches can be repaired by overlapping plug welds. Methods and results of tensile, bend, simulated service, surface crack tension and other tests at room and cryogenic temperatures is discussed. Attempts to implement Friction Plug Welding has led to both tool and process changes in an attempt to minimize expansive tooling and lengthy implementation times. Process control equipment and data storage methods intended for large scale production will also be addressed. Benefits include increased strength and toughness, decreased weld repair time, automated and highly reliable process, and a lower probability of having to re-repair defect locations.

  6. Comparison of Tensile Damage Evolution in Ti6A14V Joints Between Laser Beam Welding and Gas Tungsten Arc Welding

    NASA Astrophysics Data System (ADS)

    Gao, Xiao-Long; Zhang, Lin-Jie; Liu, Jing; Zhang, Jian-Xun

    2014-12-01

    The present paper studied the evolution of tensile damage in joints welded using laser beam welding (LBW) and gas tungsten arc welding (TIG) under a uniaxial tensile load. The damage evolution in the LBW joints and TIG-welded joints was studied by using digital image correlation (DIC) technology and monitoring changes in Young's modulus during tensile testing. To study the mechanism of void nucleation and growth in the LBW joints and TIG-welded joints, test specimens with various amounts of plastic deformation were analyzed using a scanning electron microscope (SEM). Compared with TIG-welded joints, LBW-welded joints have a finer microstructure and higher microhardness in the fusion zone. The SEM analysis and DIC test results indicated that the critical strain of void nucleation was greater in the LBW-welded joints than in the TIG-welded joints, while the growth rate of voids was lower in the LBW-welded joints than in the TIG-welded joints. Thus, the damage ratio in the LBW joints was lower than that in the TIG-welded joints during tensile testing. This can be due to the coarser martensitic α' and the application of TC-1 welding rods in the TIG-welded joint.

  7. Comparison of Tensile Damage Evolution in Ti6A14V Joints Between Laser Beam Welding and Gas Tungsten Arc Welding

    NASA Astrophysics Data System (ADS)

    Gao, Xiao-Long; Zhang, Lin-Jie; Liu, Jing; Zhang, Jian-Xun

    2014-09-01

    The present paper studied the evolution of tensile damage in joints welded using laser beam welding (LBW) and gas tungsten arc welding (TIG) under a uniaxial tensile load. The damage evolution in the LBW joints and TIG-welded joints was studied by using digital image correlation (DIC) technology and monitoring changes in Young's modulus during tensile testing. To study the mechanism of void nucleation and growth in the LBW joints and TIG-welded joints, test specimens with various amounts of plastic deformation were analyzed using a scanning electron microscope (SEM). Compared with TIG-welded joints, LBW-welded joints have a finer microstructure and higher microhardness in the fusion zone. The SEM analysis and DIC test results indicated that the critical strain of void nucleation was greater in the LBW-welded joints than in the TIG-welded joints, while the growth rate of voids was lower in the LBW-welded joints than in the TIG-welded joints. Thus, the damage ratio in the LBW joints was lower than that in the TIG-welded joints during tensile testing. This can be due to the coarser martensitic α' and the application of TC-1 welding rods in the TIG-welded joint.

  8. Welding in airplane construction

    NASA Technical Reports Server (NTRS)

    Rechtlich, A; Schrenk, M

    1928-01-01

    The present article attempts to explain the principles for the production of a perfect weld and to throw light on the unexplained problems. Moreover, it is intended to elucidate the possibilities of testing the strength and reliability of welded parts.

  9. Unusual presentation of vertebral endplate Modic changes in congenital scoliosis associated with pain: a report of two cases.

    PubMed

    Siribumrungwong, Koopong; Gupta, Sachin; Gupta, Munish C

    2016-05-01

    Congenital scoliosis is not normally associated with pain in young children. We are presenting two cases of young patients with congenital scoliosis and moderate to severe pain. There were no spinal cord abnormalities found in these patients. The magnetic resonance imaging and CT scan revealed disc degeneration with Modic changes at the apex of the congenital scoliosis. We hypothesized that the mechanical instability resulting from poor spinal element formations associated with congenital scoliosis was responsible for causing the disc degeneration and endplate changes. Modic changes have been reported to be associated with pain in degenerative conditions of the spine. Both patients underwent a posterior spinal fusion and instrumentation, which relieved their pain immediately. PMID:26370390

  10. From Modic 1 vertebral-endplate subchondral bone signal changes detected by MRI to the concept of 'active discopathy'.

    PubMed

    Nguyen, Christelle; Poiraudeau, Serge; Rannou, François

    2015-08-01

    Late-1980s MRI-detected vertebral-endplate subchondral bone signal changes associated with degenerative disc disease as well as recent studies suggest that in some patients, non-specific chronic low back pain (NS cLBP) can be defined by specific clinical, radiological and biological features, for a concept of active discopathy. This concept allows for associating a particular NS cLBP phenotype to a specific anatomical lesion, namely those with Modic 1 signal changes seen on MRI. Local inflammation is thought to play a pivotal role in these changes. Other etiopathogenic processes may include local infection and mechanical or biochemical stress combined with predisposing genetic factors; treatment strategies remain debated. Modic 1 changes detected by MRI can be considered a first biomarker in NS cLBP. Such changes are of high clinical relevance because they are associated with a specific clinical phenotype and can be targeted by specific treatments. PMID:25977562

  11. Welding-Current Indicator

    NASA Technical Reports Server (NTRS)

    Hensley, Milton C.; Huston, Steven W.; Kroy, Ralph E.

    1990-01-01

    Light flashes on to indicate high current. Simple, inexpensive display circuit indicates when 3,000-A welding current flows in welding gun. Onset of welding current induces voltage and current in 1,000-turn, 28-gauge copper-wire coil. Single-transistor amplifier amplifies induced current, energizing light-emitting diode (LED) connected to collector of transistor. Light from LED gives simple, direct indication of welding current.

  12. Infrared Thermography For Welding

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.; Lucky, Brian D.; Spiegel, Lyle B.; Hudyma, Russell M.

    1992-01-01

    Infrared imaging and image-data-processing system shows temperatures of joint during welding and provides data from which rates of heating and cooling determined. Information used to control welding parameters to ensure reliable joints, in materials which microstructures and associated metallurgical and mechanical properties depend strongly on rates of heating and cooling. Applicable to variety of processes, including tungsten/inert-gas welding; plasma, laser, and resistance welding; cutting; and brazing.

  13. Coil Welding Aid

    NASA Technical Reports Server (NTRS)

    Wiesenbach, W. T.; Clark, M. C.

    1983-01-01

    Positioner holds coil inside cylinder during tack welding. Welding aid spaces turns of coil inside cylinder and applies contact pressure while coil is tack-welded to cylinder. Device facilitates fabrication of heat exchangers and other structures by eliminating hand-positioning and clamping of individual coil turns.

  14. Instructional Guidelines. Welding.

    ERIC Educational Resources Information Center

    Fordyce, H. L.; Doshier, Dale

    Using the standards of the American Welding Society and the American Society of Mechanical Engineers, this welding instructional guidelines manual presents a course of study in accordance with the current practices in industry. Intended for use in welding programs now practiced within the Federal Prison System, the phases of the program are…

  15. Welding Course Curriculum.

    ERIC Educational Resources Information Center

    Genits, Joseph C.

    This guide is intended for use in helping students gain a fundamental background on the major aspects of the welding trade. The course emphasis is on mastery of the manipulative skills necessary to develop successful welding techniques and on acquisition of an understanding of the specialized tools and equipment used in welding. The first part…

  16. Penetration in GTA welding

    SciTech Connect

    Heiple, C.R.; Burgardt, P.

    1990-01-01

    The size and shape of the weld bead produced in GTA welding depends on the magnitude and distribution of the energy incident on the workpiece surfaces as well as the dissipation of that energy in the workpiece. The input energy is largely controllable through the welding parameters selected, however the dissipation of that energy in the workpiece is less subject to control. Changes in energy dissipation can produce large changes in weld shape or penetration. Heat transport away from the weld pool is almost entirely by conduction, but heat transport in the weld pool is more complicated. Heat conduction through the liquid is an important component, but heat transport by convection (mass transport) is often the dominant mechanism. Convective heat transport is directional and changes the weld pool shape from that produced by conduction alone. Surface tension gradients are often the dominant forces driving fluid flow in GTA weld pools. These gradients are sensitive functions of weld pool chemistry and the energy input distribution to the weld. Experimental and theoretical work conducted primarily in the past decade has greatly enhanced our understanding of weld pool fluid flow, the forces which drive it, and its effects on weld pool shape. This work is reviewed here. While less common, changes in energy dissipation through the unmelted portion of the workpiece can also affect fusion zone shape or penetration. These effects are also described. 41 refs., 9 figs.

  17. Portable Weld Tester.

    ERIC Educational Resources Information Center

    Eckert, Douglas

    This training manual, which was developed for employees of an automotive plant, is designed to teach trainees to operate a portable weld tester (Miyachi MM-315). In chapter 1, the weld tester's components are illustrated and described, and the procedure for charging its batteries is explained. Chapter 2 illustrates the weld tester's parts,…

  18. Active weld control

    NASA Technical Reports Server (NTRS)

    Powell, Bradley W.; Burroughs, Ivan A.

    1994-01-01

    Through the two phases of this contract, sensors for welding applications and parameter extraction algorithms have been developed. These sensors form the foundation of a weld control system which can provide action weld control through the monitoring of the weld pool and keyhole in a VPPA welding process. Systems of this type offer the potential of quality enhancement and cost reduction (minimization of rework on faulty welds) for high-integrity welding applications. Sensors for preweld and postweld inspection, weld pool monitoring, keyhole/weld wire entry monitoring, and seam tracking were developed. Algorithms for signal extraction were also developed and analyzed to determine their application to an adaptive weld control system. The following sections discuss findings for each of the three sensors developed under this contract: (1) weld profiling sensor; (2) weld pool sensor; and (3) stereo seam tracker/keyhole imaging sensor. Hardened versions of these sensors were designed and built under this contract. A control system, described later, was developed on a multiprocessing/multitasking operating system for maximum power and flexibility. Documentation for sensor mechanical and electrical design is also included as appendices in this report.

  19. Diffusion welding tool

    NASA Technical Reports Server (NTRS)

    Milam, T. B.

    1973-01-01

    Tool allows flat plate diffusion welding to be done in standard brazing furnace. Weld is achieved using high water pressure applied by hand-operated positive-displacement pump. Good welds have been obtained between nickel and nickel-base alloy plates at temperature of 1200 K and water pressure of 13.8 million N/sq m.

  20. Method for welding beryllium

    DOEpatents

    Dixon, Raymond D.; Smith, Frank M.; O'Leary, Richard F.

    1997-01-01

    A method is provided for joining beryllium pieces which comprises: depositing aluminum alloy on at least one beryllium surface; contacting that beryllium surface with at least one other beryllium surface; and welding the aluminum alloy coated beryllium surfaces together. The aluminum alloy may be deposited on the beryllium using gas metal arc welding. The aluminum alloy coated beryllium surfaces may be subjected to elevated temperatures and pressures to reduce porosity before welding the pieces together. The aluminum alloy coated beryllium surfaces may be machined into a desired welding joint configuration before welding. The beryllium may be an alloy of beryllium or a beryllium compound. The aluminum alloy may comprise aluminum and silicon.

  1. Multi-physical Simulation of Laser Welding

    NASA Astrophysics Data System (ADS)

    Vázquez, Rodrigo Gómez; Koch, Holger M.; Otto, Andreas

    Laser welding is a highly demanded technology for manufacturing of body parts in the automotive industry. Application of powerful multi-physical simulation models permits detailed investigation of the laser process avoiding intricate experimental setups and procedures. Features like the degree of power coupling, keyhole evolution or currents inside the melt pool can be analyzed easily. The implementation of complex physical phenomena, like multi-reflection absorption provides insight into process characteristics under selectable conditions and yields essential information concerning the driving mechanisms. The implementation of additional physical models e. g. for diffusion discloses new potential for investigating welding of dissimilar materials. In this paper we present a computational study of laser welding for different conditions. Applied to a real case model predictions show good agreement with experimental results. Initial tests including species diffusion during welding of dissimilar materials are also presented.

  2. Physical processes involved in strip electrode welding using the method of slatted splicing

    SciTech Connect

    Bushma, V. O.

    2010-12-15

    Physical processes that take place in a strip electrode during welding using the slatted splicing technique are considered. Flowing of the welding current in the electrode is shown to be the key process which determines electrode heating and melting. Technological receipts are proposed that allow obtaining high-quality welds by the method of slatted splicing.

  3. Optically controlled welding system

    NASA Technical Reports Server (NTRS)

    Gordon, Stephen S. (Inventor)

    1989-01-01

    An optically controlled welding system (10) wherein a welding torch (12) having through-the-torch viewing capabilities is provided with an optical beam splitter (56) to create a transmitted view and a reflective view of a welding operation. These views are converted to digital signals which are then processed and utilized by a computerized robotic welder (15) to make the welding torch responsive thereto. Other features includes an actively cooled electrode holder (26) which minimizes a blocked portion of the view by virtue of being constructed of a single spoke or arm (28) and a weld pool contour detector (14) comprising a laser beam directed onto the weld pool with the position of specular radiation reflected therefrom being characteristic of a penetrated or unpenetrated condition of the weld pool.

  4. Optically controlled welding system

    NASA Technical Reports Server (NTRS)

    Gordon, Stephen S. (Inventor)

    1988-01-01

    An optically controlled welding system wherein a welding torch having through-the-torch viewing capabilities is provided with an optical beam splitter to create a transmitted view and a reflective view of a welding operation. These views are converted to digital signals which are then processed and utilized by a computerized robotic welder to make the welding torch responsive thereto. Other features include an actively cooled electrode holder which minimizes a blocked portion of the view by virtue of being constructed of a single spoke or arm, and a weld pool contour detector comprising a laser beam directed onto the weld pool with the position of specular radiation reflected therefrom, being characteristic of a penetrated or unpenetrated condition of the weld pool.

  5. Robotic Welding Of Injector Manifold

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.; Shelley, D. Mark

    1992-01-01

    Brief report presents history, up through October 1990, of continuing efforts to convert from manual to robotic gas/tungsten arc welding in fabrication of main injector inlet manifold of main engine of Space Shuttle. Includes photographs of welding machinery, welds, and weld preparations. Of interest to engineers considering establishment of robotic-welding facilities.

  6. Dual wire weld feed proportioner

    NASA Technical Reports Server (NTRS)

    Nugent, R. E.

    1968-01-01

    Dual feed mechanism enables proportioning of two different weld feed wires during automated TIG welding to produce a weld alloy deposit of the desired composition. The wires are fed into the weld simultaneously. The relative feed rates of the wires and the wire diameters determine the weld deposit composition.

  7. In vitro RPM fibrogenic potential assay of welding fumes.

    PubMed Central

    Stern, R M; Pigott, G H

    1983-01-01

    The fibrogenic potential of 11 different welding fumes and metallic aerosols, considered to be reference standard surrogates for the commonly used welding technologies and applications responsible for 70% of welders exposure, is screened by using the rat peritoneal macrophage (RPM) in vitro bioassay. Only one class of fumes, that from the manual metal are welding of stainless steel, shows distinct fibrogenic potential. This fume, however, is not common to more than four or five of the heretofore 90 cases of pulmonary fibrosis reported among welders. Thus, although insoluble Cr(VI) is probably the active fibrogen in stainless steel fumes, an etiological factor common to all fibrogenic welding exposures must be sought; it is tentatively proposed to be NO chi, a potent experimental in vivo fibrogen copiously produced by certain welding processes and ubiquitous at low concentrations in the welding environment. PMID:6641657

  8. Defect Detectability Improvement for Conventional Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Hill, Chris

    2013-01-01

    This research was conducted to evaluate the effects of defect detectability via phased array ultrasound technology in conventional friction stir welds by comparing conventionally prepped post weld surfaces to a machined surface finish. A machined surface is hypothesized to improve defect detectability and increase material strength.

  9. Studies on A-TIG welding of Low Activation Ferritic/Martensitic (LAFM) steel

    NASA Astrophysics Data System (ADS)

    Vasantharaja, P.; Vasudevan, M.

    2012-02-01

    Low Activation Ferritic-Martensitic steels (LAFM) are chosen as the candidate material for structural components in fusion reactors. The structural components are generally fabricated by welding processes. Activated Tungsten Inert Gas (A-TIG) welding is an emerging process for welding of thicker components. In the present work, attempt was made to develop A-TIG welding technology for LAFM steel plates of 10 mm thick. Activated flux was developed for LAFM steel by carrying out various bead-on-plate TIG welds without flux and with flux. The optimum flux was identified as one which gave maximum depth of penetration at minimum heat input values. With the optimized flux composition, LAFM steel plate of 10 mm thickness was welded in square butt weld joint configuration using double side welding technique. Optical and Scanning Electron Microscopy was used for characterizing the microstructures. Microhardness measurements were made across the weld cross section for as welded and post weld heat treated samples. Tensile and impact toughness properties were determined. The mechanical properties values obtained in A-TIG weld joint were comparable to that obtained in weld joints of LAFM steel made by Electron beam welding process.

  10. Retractable Pin Tools for the Friction Stir Welding Process

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Two companies have successfully commercialized a specialized welding tool developed at the Marshall Space Flight Center (MSFC). Friction stir welding uses the high rotational speed of a tool and the resulting frictional heat created from contact to crush, 'stir' together, and forge a bond between two metal alloys. It has had a major drawback, reliance on a single-piece pin tool. The pin is slowly plunged into the joint between two materials to be welded and rotated as high speed. At the end of the weld, the single-piece pin tool is retracted and leaves a 'keyhole,' something which is unacceptable when welding cylindrical objects such as drums, pipes and storage tanks. Another drawback is the requirement for different-length pin tools when welding materials of varying thickness. An engineer at the MSFC helped design an automatic retractable pin tool that uses a computer-controlled motor to automatically retract the pin into the shoulder of the tool at the end of the weld, preventing keyholes. This design allows the pin angle and length to be adjusted for changes in material thickness and results in a smooth hole closure at the end of the weld. Benefits of friction stir welding, using the MSFC retractable pin tool technology, include the following: The ability to weld a wide range of alloys, including previously unweldable and composite materials; provision of twice the fatigue resistance of fusion welds and no keyholes; minimization of material distortion; no creation of hazards such as welding fumes, radiation, high voltage, liquid metals, or arcing; automatic retraction of the pin at the end of the weld; and maintaining full penetration of the pin.

  11. Improving Processes of Mechanized Pulsed Arc Welding of Low-Frequency Range Variation of Mode Parameters

    NASA Astrophysics Data System (ADS)

    Saraev, Yu N.; Solodskiy, S. A.; Ulyanova, O. V.

    2016-04-01

    A new technology of low-frequency modulation of the arc current in MAG and MIG welding is presented. The technology provides control of thermal and crystallization processes, stabilizes the time of formation and crystallization of the weld pool. Conducting theoretical studies allowed formulating the basic criteria for obtaining strong permanent joints for high-duty structures, providing conditions for more equilibrium structure of the deposited metal and the smaller width of the HAZ. The stabilization of time of the formation and crystallization of the weld pool improves the formation of the weld and increases productivity in welding thin sheet metal.

  12. VPPA weld model evaluation

    NASA Technical Reports Server (NTRS)

    Mccutcheon, Kimble D.; Gordon, Stephen S.; Thompson, Paul A.

    1992-01-01

    NASA uses the Variable Polarity Plasma Arc Welding (VPPAW) process extensively for fabrication of Space Shuttle External Tanks. This welding process has been in use at NASA since the late 1970's but the physics of the process have never been satisfactorily modeled and understood. In an attempt to advance the level of understanding of VPPAW, Dr. Arthur C. Nunes, Jr., (NASA) has developed a mathematical model of the process. The work described in this report evaluated and used two versions (level-0 and level-1) of Dr. Nunes' model, and a model derived by the University of Alabama at Huntsville (UAH) from Dr. Nunes' level-1 model. Two series of VPPAW experiments were done, using over 400 different combinations of welding parameters. Observations were made of VPPAW process behavior as a function of specific welding parameter changes. Data from these weld experiments was used to evaluate and suggest improvements to Dr. Nunes' model. Experimental data and correlations with the model were used to develop a multi-variable control algorithm for use with a future VPPAW controller. This algorithm is designed to control weld widths (both on the crown and root of the weld) based upon the weld parameters, base metal properties, and real-time observation of the crown width. The algorithm exhibited accuracy comparable to that of the weld width measurements for both aluminum and mild steel welds.

  13. Weld electrode cooling study

    NASA Astrophysics Data System (ADS)

    Masters, Robert C.; Simon, Daniel L.

    1999-03-01

    The U.S. auto/truck industry has been mandated by the Federal government to continuously improve their fleet average gas mileage, measured in miles per gallon. Several techniques are typically used to meet these mandates, one of which is to reduce the overall mass of cars and trucks. To help accomplish this goal, lighter weight sheet metal parts, with smaller weld flanges, have been designed and fabricated. This paper will examine the cooling characteristics of various water cooled weld electrodes and shanks used in resistance spot welding applications. The smaller weld flanges utilized in modern vehicle sheet metal fabrications have increased industry's interest in using one size of weld electrode (1/2 inch diameter) for certain spot welding operations. The welding community wants more data about the cooling characteristics of these 1/2 inch weld electrodes. To hep define the cooling characteristics, an infrared radiometer thermal vision system (TVS) was used to capture images (thermograms) of the heating and cooling cycles of several size combinations of weld electrodes under typical production conditions. Tests results will show why the open ended shanks are more suitable for cooling the weld electrode assembly then closed ended shanks.

  14. Superplastic Forming of Aluminum Multisheet Structures Fabricated Using Friction Stir Welding and Refill Friction Stir Spot Welding

    SciTech Connect

    Grant, Glenn J.; Herling, Darrell R.; Arbegast, William J.; Allen, Casey D.; Degen, Cassandra M.

    2006-12-20

    Superplastically-formed structural panels are growing in their applications in aerospace, aircraft, automotive, and other industries. Generally, monolithic sheets are employed, limiting the size and complexity of the final part. However, more complex and larger final geometries are possible if individual sheet materials can be joined together through an appropriate joining technology, then SPF formed to final shape. The primary challenge in this type of SPF fabrication has been making a joint between the sheets that will survive the SPF forming event and display the correct amount of elongation in the joint relative to the base materials being formed. Friction Stir Welding is an ideal joining technology for SPF applications because the forming response of the weld metal at SPF conditions is adjustable by selecting different weld process parameters during initial joining. This allows the SPF deformation in the weld metal to be “tuned” to the deformation of the parent sheet to prevent early failure from occurring in either the weld metal or the parent sheet due to mismatched SPF flow stresses. Industrial application of the concept of matching flow stresses is currently being pursued on a program at the Pacific Northwest National Laboratory on room temperature formed friction stir welded tailor welded blanks for heavy truck applications. Flow stress matching and process parameter “tuning” is also important in the fabrication of SPF multisheet structural panels. These panels are fabricated by joining three sheets together with alternating welds top and bottom, so that each weld penetrates only two of the three sheets. This sheet pack is then sealed with a weld seam around the outside and hot gas is introduced between the sheets through a welded tube. Under SPF conditions the sheet pack inflates to produce an internally supported structure. In this paper we presents results on an investigation into using FSW and Refill Friction Stir Spot Welding to fabricated

  15. Cleaning Internal-Weld Splatter

    NASA Technical Reports Server (NTRS)

    Snodgrass, R.

    1982-01-01

    Splattered metal produced by welding can be easily removed from inaccessible areas by method resembling ball milling. Hard steel balls are vibrated inside welded unit so that they "scrub away" excess metal on interior side of weld joint.

  16. EVALUATION OF CONSTANT CURRENT WELD CONTROL FOR PINCH WELDING

    SciTech Connect

    Korinko, P; STANLEY, S; HOWARD, H

    2005-10-11

    Modern weld controllers typically use current to control the weld process. SRS uses a legacy voltage control method. This task was undertaken to determine if the improvements in the weld control equipment could be implemented to provide improvements to the process control. The constant current mode of operation will reduce weld variability by about a factor of 4. The constant voltage welds were slightly hotter than the constant current welds of the same nominal current. The control mode did not appear to adversely affect the weld quality, but appropriate current ranges need to be established and a qualification methodology for both welding and shunt calibrations needs to be developed and documented.

  17. Computerized adaptive control weld skate with CCTV weld guidance project

    NASA Technical Reports Server (NTRS)

    Wall, W. A.

    1976-01-01

    This report summarizes progress of the automatic computerized weld skate development portion of the Computerized Weld Skate with Closed Circuit Television (CCTV) Arc Guidance Project. The main goal of the project is to develop an automatic welding skate demonstration model equipped with CCTV weld guidance. The three main goals of the overall project are to: (1) develop a demonstration model computerized weld skate system, (2) develop a demonstration model automatic CCTV guidance system, and (3) integrate the two systems into a demonstration model of computerized weld skate with CCTV weld guidance for welding contoured parts.

  18. Ultrasonic Stir Welding

    NASA Technical Reports Server (NTRS)

    Nabors, Sammy

    2015-01-01

    NASA Marshall Space Flight Center (MSFC) developed Ultrasonic Stir Welding (USW) to join large pieces of very high-strength metals such as titanium and Inconel. USW, a solid-state weld process, improves current thermal stir welding processes by adding high-power ultrasonic (HPU) energy at 20 kHz frequency. The addition of ultrasonic energy significantly reduces axial, frictional, and shear forces; increases travel rates; and reduces wear on the stir rod, which results in extended stir rod life. The USW process decouples the heating, stirring, and forging elements found in the friction stir welding process allowing for independent control of each process element and, ultimately, greater process control and repeatability. Because of the independent control of USW process elements, closed-loop temperature control can be integrated into the system so that a constant weld nugget temperature can be maintained during welding.

  19. Welding in Space Workshop

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.

    1990-01-01

    The potential was discussed for welding in space, its advantages and disadvantages, and what type of programs can benefit from the capability. Review of the various presentations and comments made in the course of the workshop suggests several routes to obtaining a better understanding of how welding processes can be used in NASA's initiatives in space. They are as follows: (1) development of a document identifying well processes and equipment requirements applicable to space and lunar environments; (2) more demonstrations of welding particular hardware which are to be used in the above environments, especially for space repair operations; (3) increased awareness among contractors responsible for building space equipment as to the potential for welding operations in space and on other planetary bodies; and (4) continuation of space welding research projects is important to maintain awareness within NASA that welding in space is viable and beneficial.

  20. WELDED JACKETED URANIUM BODY

    DOEpatents

    Gurinsky, D.H.

    1958-08-26

    A fuel element is presented for a neutronic reactor and is comprised of a uranium body, a non-fissionable jacket surrounding sald body, thu jacket including a portion sealed by a weld, and an inclusion in said sealed jacket at said weld of a fiux having a low neutron capture cross-section. The flux is provided by combining chlorine gas and hydrogen in the intense heat of-the arc, in a "Heliarc" welding muthod, to form dry hydrochloric acid gas.

  1. Dual wire welding torch and method

    DOEpatents

    Diez, Fernando Martinez; Stump, Kevin S.; Ludewig, Howard W.; Kilty, Alan L.; Robinson, Matthew M.; Egland, Keith M.

    2009-04-28

    A welding torch includes a nozzle with a first welding wire guide configured to orient a first welding wire in a first welding wire orientation, and a second welding wire guide configured to orient a second welding wire in a second welding wire orientation that is non-coplanar and divergent with respect to the first welding wire orientation. A method of welding includes moving a welding torch with respect to a workpiece joint to be welded. During moving the welding torch, a first welding wire is fed through a first welding wire guide defining a first welding wire orientation and a second welding wire is fed through a second welding wire guide defining a second welding wire orientation that is divergent and non-coplanar with respect to the first welding wire orientation.

  2. Bond formation in ultrasonically welded aluminum sheet metal

    NASA Astrophysics Data System (ADS)

    Wilkosz, Daniel Edward

    Ultrasonic welding (USW), a solid state joining technology, has been used to bond aluminum alloys commonly used in the automotive industry. Bonding occurs due to USW's high frequency (˜20 kHz) in-plane vibration of sample interfaces while being held under moderate clamp pressure normal to the plane of vibration. Vibration and clamp pressure are transmitted into bond formation via contact with a weld-tip. To better understand how weld-tip geometry affected bond formation, experiments were conducted to quantify how tip geometry influenced plastic deformation characteristics between fully welded coupons of 0.9mm thick AA6111-T4 aluminum alloy. Weld-interface microstructure features were documented by optical microscopy and features quantified in a 19 point matrix. Correlation between microstructure features, such as rolling-wakes, and resulting weld bond strengths of more than 3.0kN is made. Weld zone microstructure features appear to result from deformation at and severe migration of the original weld interface during USW. To confirm this hypothesis, intrinsic and extrinsic markers were employed to monitor weld interface deformation characteristics. Various physical and analytical techniques were used in conjunction with these markers to show that joining of "like" and "dislike" aluminum samples is achieved through mechanical mixing of mating interfaces and not by elemental diffusion. It is also hypothesized that severe deformation of the original interface would result in areas of high residual strain within a formed weld zone. To investigate this and the influence that tip geometry may have on residual strain, fully welded samples were annealed at 500°C for a controlled period of time and recovery, recrystallization and grain growth characteristics were monitored. In all welds, initial recrystallization and grain growth occurred at the outer ends of weld zones and along weld interfaces where the most turbulent mixing and grain size reduction was observed

  3. IR Spot Weld Inspect

    SciTech Connect

    Chen, Jian; Feng, Zhili

    2014-01-01

    In automotive industry, destructive inspection of spot welds is still the mandatory quality assurance method due to the lack of efficient non-destructive evaluation (NDE) tools. However, it is costly and time-consuming. Recently at ORNL, a new NDE prototype system for spot weld inspection using infrared (IR) thermography has been developed to address this problem. This software contains all the key functions that ensure the NDE system to work properly: system input/output control, image acquisition, data analysis, weld quality database generation and weld quality prediction, etc.

  4. Robot welding process control

    NASA Technical Reports Server (NTRS)

    Romine, Peter L.

    1991-01-01

    This final report documents the development and installation of software and hardware for Robotic Welding Process Control. Primary emphasis is on serial communications between the CYRO 750 robotic welder, Heurikon minicomputer running Hunter & Ready VRTX, and an IBM PC/AT, for offline programming and control and closed-loop welding control. The requirements for completion of the implementation of the Rocketdyne weld tracking control are discussed. The procedure for downloading programs from the Intergraph, over the network, is discussed. Conclusions are made on the results of this task, and recommendations are made for efficient implementation of communications, weld process control development, and advanced process control procedures using the Heurikon.

  5. IR Spot Weld Inspect

    Energy Science and Technology Software Center (ESTSC)

    2014-01-01

    In automotive industry, destructive inspection of spot welds is still the mandatory quality assurance method due to the lack of efficient non-destructive evaluation (NDE) tools. However, it is costly and time-consuming. Recently at ORNL, a new NDE prototype system for spot weld inspection using infrared (IR) thermography has been developed to address this problem. This software contains all the key functions that ensure the NDE system to work properly: system input/output control, image acquisition, datamore » analysis, weld quality database generation and weld quality prediction, etc.« less

  6. Electric arc welding gun

    DOEpatents

    Luttrell, Edward; Turner, Paul W.

    1978-01-01

    This invention relates to improved apparatus for arc welding an interior joint formed by intersecting tubular members. As an example, the invention is well suited for applications where many similar small-diameter vertical lines are to be welded to a long horizontal header. The improved apparatus includes an arc welding gun having a specially designed welding head which is not only very compact but also produces welds that are essentially free from rolled-over solidified metal. The welding head consists of the upper end of the barrel and a reversely extending electrode holder, or tip, which defines an acute angle with the barrel. As used in the above-mentioned example, the gun is positioned to extend upwardly through the vertical member and the joint to be welded, with its welding head disposed within the horizontal header. Depending on the design of the welding head, the barrel then is either rotated or revolved about the axis of the vertical member to cause the electrode to track the joint.

  7. Physics of Fusion Welding

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.

    1986-01-01

    Applicabilities and limitations of three techniques analyzed. NASA technical memorandum discusses physics of electron-beam, gas/ tungsten-arc, and laser-beam welding. From comparison of capabilities and limitations of each technique with regard to various welding conditions and materials, possible to develop criteria for selecting best welding technique in specific application. All three techniques classified as fusion welding; small volume of workpiece melted by intense heat source. Heat source moved along seam, leaving in wake solid metal that joins seam edges together.

  8. Neuromuscular organization of the superior longitudinalis muscle in the human tongue. 1. Motor endplate morphology and muscle fiber architecture.

    PubMed

    Slaughter, Katrina; Li, Haiyan; Sokoloff, Alan J

    2005-01-01

    Proper tongue function is essential for respiration and mastication, yet we lack basic information on the anatomical organization underlying human tongue movement. Here we use microdissection, acetylcholinesterase histochemistry, silver staining of nerves, alpha bungarotoxin binding and immunohistochemistry to describe muscle fiber architecture and motor endplate (MEP) distribution of the human superior longitudinalis muscle (SL). The human SL extends from tongue base to tongue tip and is composed of fiber bundles that range from 2.8 to 15.7 mm in length. Individual muscle fibers of the SL range from 1.2 to 17.3 mm in length (1.3-18.2% of muscle length). Seventy-one percent of SL fibers have blunt-blunt terminations; the remainder have blunt-taper terminations. Multiple MEPs are present along SL length and dual MEPs are present on some muscle fibers. These data demonstrate that the human SL is a muscle of "in-series" design. We suggest that SL motor units are organized to innervate specific regions of the tongue body and that activation of SL motor units according to anteroposterior location is one strategy employed by the nervous system to control tongue shape and tongue movement. PMID:16439818

  9. Matrix stiffness promotes cartilage endplate chondrocyte calcification in disc degeneration via miR-20a targeting ANKH expression

    PubMed Central

    Liu, Ming-Han; Sun, Chao; Yao, Yuan; Fan, Xin; Liu, Huan; Cui, You-Hong; Bian, Xiu-Wu; Huang, Bo; Zhou, Yue

    2016-01-01

    The mechanical environment is crucial for intervertebral disc degeneration (IDD). However, the mechanisms underlying the regulation of cartilage endplate (CEP) calcification by altered matrix stiffness remain unclear. In this study, we found that matrix stiffness of CEP was positively correlated with the degree of IDD, and stiff matrix, which mimicked the severe degeneration of CEP, promoted inorganic phosphate-induced calcification in CEP chondrocytes. Co-expression analysis of the miRNA and mRNA profiles showed that increasing stiffness resulted in up-regulation of miR-20a and down-regulation of decreased ankylosis protein homolog (ANKH) during inorganic phosphate-induced calcification in CEP chondrocytes. Through a dual luciferase reporter assay, we confirmed that miR-20a directly targets 3′-untranslated regions of ANKH. The inhibition of miR-20a attenuated the calcium deposition and calcification-related gene expression, whereas the overexpression of miR-20a enhanced calcification in CEP chondrocytes on stiff matrix. The rescue of ANKH expression restored the decreased pyrophosphate efflux and inhibited calcification. In clinical samples, the levels of ANKH expression were inversely associated with the degeneration degree of CEP. Thus, our findings demonstrate that the miR-20a/ANKH axis mediates the stiff matrix- promoted CEP calcification, suggesting that miR-20a and ANKH are potential targets in restraining the progression of IDD. PMID:27142968

  10. Development of sensor augmented robotic weld systems for aerospace propulsion system fabrication

    NASA Technical Reports Server (NTRS)

    Jones, C. S.; Gangl, K. J.

    1986-01-01

    In order to meet stringent performance goals for power and reuseability, the Space Shuttle Main Engine was designed with many complex, difficult welded joints that provide maximum strength and minimum weight. To this end, the SSME requires 370 meters of welded joints. Automation of some welds has improved welding productivity significantly over manual welding. Application has previously been limited by accessibility constraints, requirements for complex process control, low production volumes, high part variability, and stringent quality requirements. Development of robots for welding in this application requires that a unique set of constraints be addressed. This paper shows how robotic welding can enhance production of aerospace components by addressing their specific requirements. A development program at the Marshall Space Flight Center combining industrial robots with state-of-the-art sensor systems and computer simulation is providing technology for the automation of welds in Space Shuttle Main Engine production.