Aircraft gas-turbine engines: Noise reduction and vibration control. (Latest citations from Information Services in Mechanical Engineering data base). Published Search

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

Not Available

1992-06-01

The bibliography contains citations concerning the design and analysis of aircraft gas turbine engines with respect to noise and vibration control. Included are studies regarding the measurement and reduction of noise at its source, within the aircraft, and on the ground. Inlet, nozzle and core aerodynamic studies are cited. Propfan, turbofan, turboprop engines, and applications in short take-off and landing (STOL) aircraft are included. (Contains a minimum of 202 citations and includes a subject term index and title list.)

In Operation Detection and Correction of Rotor Imbalance in Jet Engines Using Active Vibration Control

NASA Technical Reports Server (NTRS)

Manchala, Daniel W.; Palazzolo, Alan B.; Kascak, Albert F.; Montague, Gerald T.; Brown, Gerald V.; Lawrence, Charles; Klusman, Steve

1994-01-01

Jet Engines may experience severe vibration due to the sudden imbalance caused by blade failure. This research investigates employment of on board magnetic bearings or piezoelectric actuators to cancel these forces in flight. This operation requires identification of the source of the vibrations via an expert system, determination of the required phase angles and amplitudes for the correction forces, and application of the desired control signals to the magnetic bearings or piezo electric actuators. This paper will show the architecture of the software system, details of the control algorithm used for the sudden imbalance correction project described above, and the laboratory test results.

Vibration measurements of automobile catalyst

NASA Astrophysics Data System (ADS)

Aatola, Seppo

1994-09-01

Vibration of catalyst cell, which is inside the casing of the catalyst, is difficult to measure with usual measuring instrumentation. When catalyst is in use, there is hot exhaust gas flow though the catalyst cell and temperature of the cell is approximately +900 degree(s)C. Therefore non-contact Laser- Doppler-Vibrometer was used to measure vibration velocity of the catalyst cell. The laser beam was directed towards the cell through pipe which was put through and welded to the casing of the catalyst. The outer end of the pipe was screw down with a tempered class to prevent exhaust gas flow from the pipe. The inner end of the pipe was open and few millimeters away from the measuring point. Catalyst was attached to the engine with two ways, rigidly close to the engine and flexible under the engine. The engine was running in test bench under controlled conditions. Vibration measurements were carried out during constant running speeds of the engine. Vibration signals were captured and analyzed with FFT-analyzer. Vibration of catalyst cell was strongest at running speed of 5000 rpm, from 10 to 20 g (1 g equals 9.81 ms-2), when catalyst was attached rigidly close to the engine. At running speed of 3000 rpm, vibration of catalyst cell was from 2 to 3 g in most cases, when catalyst was attached either rigidly or flexible to the engine. It is estimated that in real life, i.e. when catalyst is attached to car with same engine, vibration of catalyst cell at running speed of 5000 rpm is somewhere between 1 and 10 g. At running speed of 3000 rpm, which may be more often used when driving car (car speed approximately 100 kmh-1), vibration of catalyst cell is probably few g's.

Advanced Health Management System for the Space Shuttle Main Engine

NASA Technical Reports Server (NTRS)

Davidson, Matt; Stephens, John; Rodela, Chris

2006-01-01

Pratt & Whitney Rocketdyne, Inc., in cooperation with NASA-Marshall Space Flight Center (MSFC), has developed a new Advanced Health Management System (AHMS) controller for the Space Shuttle Main Engine (SSME) that will increase the probability of successfully placing the shuttle into the intended orbit and increase the safety of the Space Transportation System (STS) launches. The AHMS is an upgrade o the current Block II engine controller whose primary component is an improved vibration monitoring system called the Real-Time Vibration Monitoring System (RTVMS) that can effectively and reliably monitor the state of the high pressure turbomachinery and provide engine protection through a new synchronous vibration redline which enables engine shutdown if the vibration exceeds predetermined thresholds. The introduction of this system required improvements and modification to the Block II controller such as redesigning the Digital Computer Unit (DCU) memory and the Flight Accelerometer Safety Cut-Off System (FASCOS) circuitry, eliminating the existing memory retention batteries, installation of the Digital Signal Processor (DSP) technology, and installation of a High Speed Serial Interface (HSSI) with accompanying outside world connectors. Test stand hot-fire testing along with lab testing have verified successful implementation and is expected to reduce the probability of catastrophic engine failures during the shuttle ascent phase and improve safely by about 23% according to the Quantitative Risk Assessment System (QRAS), leading to a safer and more reliable SSME.

A study of the durability of beryllium rocket engines. [space shuttle reaction control system

NASA Technical Reports Server (NTRS)

Paster, R. D.; French, G. C.

1974-01-01

An experimental test program was performed to demonstrate the durability of a beryllium INTEREGEN rocket engine when operating under conditions simulating the space shuttle reaction control system. A vibration simulator was exposed to the equivalent of 100 missions of X, Y, and Z axes random vibration to demonstrate the integrity of the recently developed injector-to-chamber braze joint. An off-limits engine was hot fired under extreme conditions of mixture ratio, chamber pressure, and orifice plugging. A durability engine was exposed to six environmental cycles interspersed with hot-fire tests without intermediate cleaning, service, or maintenance. Results from this program indicate the ability of the beryllium INTEREGEN engine concept to meet the operational requirements of the space shuttle reaction control system.

Piezoelectric Vibration Damping Study for Rotating Composite Fan Blades

NASA Technical Reports Server (NTRS)

Min, James B.; Duffy, Kirsten P.; Choi, Benjamin B.; Provenza, Andrew J.; Kray, Nicholas

2012-01-01

Resonant vibrations of aircraft engine blades cause blade fatigue problems in engines, which can lead to thicker and aerodynamically lower performing blade designs, increasing engine weight, fuel burn, and maintenance costs. In order to mitigate undesirable blade vibration levels, active piezoelectric vibration control has been investigated, potentially enabling thinner blade designs for higher performing blades and minimizing blade fatigue problems. While the piezoelectric damping idea has been investigated by other researchers over the years, very little study has been done including rotational effects. The present study attempts to fill this void. The particular objectives of this study were: (a) to develop and analyze a multiphysics piezoelectric finite element composite blade model for harmonic forced vibration response analysis coupled with a tuned RLC circuit for rotating engine blade conditions, (b) to validate a numerical model with experimental test data, and (c) to achieve a cost-effective numerical modeling capability which enables simulation of rotating blades within the NASA Glenn Research Center (GRC) Dynamic Spin Rig Facility. A numerical and experimental study for rotating piezoelectric composite subscale fan blades was performed. It was also proved that the proposed numerical method is feasible and effective when applied to the rotating blade base excitation model. The experimental test and multiphysics finite element modeling technique described in this paper show that piezoelectric vibration damping can significantly reduce vibrations of aircraft engine composite fan blades.

Simultaneous vibration control and energy harvesting using actor-critic based reinforcement learning

NASA Astrophysics Data System (ADS)

Loong, Cheng Ning; Chang, C. C.; Dimitrakopoulos, Elias G.

2018-03-01

Mitigating excessive vibration of civil engineering structures using various types of devices has been a conspicuous research topic in the past few decades. Some devices, such as electromagnetic transducers, which have a capability of exerting control forces while simultaneously harvesting energy, have been proposed recently. These devices make possible a self-regenerative system that can semi-actively mitigate structural vibration without the need of external energy. Integrating mechanical, electrical components, and control algorithms, these devices open up a new research domain that needs to be addressed. In this study, the feasibility of using an actor-critic based reinforcement learning control algorithm for simultaneous vibration control and energy harvesting for a civil engineering structure is investigated. The actor-critic based reinforcement learning control algorithm is a real-time, model-free adaptive technique that can adjust the controller parameters based on observations and reward signals without knowing the system characteristics. It is suitable for the control of a partially known nonlinear system with uncertain parameters. The feasibility of implementing this algorithm on a building structure equipped with an electromagnetic damper will be investigated in this study. Issues related to the modelling of learning algorithm, initialization and convergence will be presented and discussed.

Active vibration control of structures undergoing bending vibrations

NASA Technical Reports Server (NTRS)

Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor)

1995-01-01

An active vibration control subassembly for a structure (such as a jet engine duct or a washing machine panel) undergoing bending vibrations caused by a source (such as the clothes agitator of the washing machine) independent of the subassembly. A piezoceramic actuator plate is vibratable by an applied electric AC signal. The plate is connected to the structure such that vibrations in the plate induced by the AC signal cause canceling bending vibrations in the structure and such that the plate is compressively pre-stressed along the structure when the structure is free of any bending vibrations. The compressive prestressing increases the amplitude of the canceling bending vibrations before the critical tensile stress level of the plate is reached. Preferably, a positive electric DC bias is also applied to the plate in its poling direction.

Disk Crack Detection for Seeded Fault Engine Test

NASA Technical Reports Server (NTRS)

Luo, Huageng; Rodriguez, Hector; Hallman, Darren; Corbly, Dennis; Lewicki, David G. (Technical Monitor)

2004-01-01

Work was performed to develop and demonstrate vibration diagnostic techniques for the on-line detection of engine rotor disk cracks and other anomalies through a real engine test. An existing single-degree-of-freedom non-resonance-based vibration algorithm was extended to a multi-degree-of-freedom model. In addition, a resonance-based algorithm was also proposed for the case of one or more resonances. The algorithms were integrated into a diagnostic system using state-of-the- art commercial analysis equipment. The system required only non-rotating vibration signals, such as accelerometers and proximity probes, and the rotor shaft 1/rev signal to conduct the health monitoring. Before the engine test, the integrated system was tested in the laboratory by using a small rotor with controlled mass unbalances. The laboratory tests verified the system integration and both the non-resonance and the resonance-based algorithm implementations. In the engine test, the system concluded that after two weeks of cycling, the seeded fan disk flaw did not propagate to a large enough size to be detected by changes in the synchronous vibration. The unbalance induced by mass shifting during the start up and coast down was still the dominant response in the synchronous vibration.

Magnetic Fields Can Control Heat and Sound

DTIC Science & Technology

2015-03-23

solids. When we talk to each other, the vocal chords of the speaker vibrate , causing the air coming from his lungs to vibrate as well. This creates...Physics, and Materials Science & Engineering at The Ohio State University Sound is carried by periodic vibrations of atoms in gases, liquids and...sound waves, which then propagate through the air until they hit a listener’s eardrums and make them vibrate as well. From these vibrations , the listener

Adaptive-passive vibration control systems for industrial applications

NASA Astrophysics Data System (ADS)

Mayer, D.; Pfeiffer, T.; Vrbata, J.; Melz, T.

2015-04-01

Tuned vibration absorbers have become common for passive vibration reduction in many industrial applications. Lightly damped absorbers (also called neutralizers) can be used to suppress narrowband disturbances by tuning them to the excitation frequency. If the resonance is adapted in-operation, the performance of those devices can be significantly enhanced, or inertial mass can be decreased. However, the integration of actuators, sensors and control electronics into the system raises new design challenges. In this work, the development of adaptive-passive systems for vibration reduction at an industrial scale is presented. As an example, vibration reduction of a ship engine was studied in a full scale test. Simulations were used to study the feasibility and evaluate the system concept at an early stage. Several ways to adjust the resonance of the neutralizer were evaluated, including piezoelectric actuation and common mechatronic drives. Prototypes were implemented and tested. Since vibration absorbers suffer from high dynamic loads, reliability tests were used to assess the long-term behavior under operational conditions and to improve the components. It was proved that the adaptive systems are capable to withstand the mechanical loads in an industrial application. Also a control strategy had to be implemented in order to track the excitation frequency. The most mature concepts were integrated into the full scale test. An imbalance exciter was used to simulate the engine vibrations at a realistic level experimentally. The neutralizers were tested at varying excitation frequencies to evaluate the tracking capabilities of the control system. It was proved that a significant vibration reduction is possible.

46 CFR 182.415 - Carburetors.

Code of Federal Regulations, 2010 CFR

2010-10-01

... acceptable means of backfire flame control. Installation of backfire flame arresters bearing basic Approval... acceptable means of backfire flame control for gasoline engines: (1) A backfire flame arrester complying with... and firmly secured to withstand vibration, shock, and engine backfire. Such installations do not...

46 CFR 182.415 - Carburetors.

Code of Federal Regulations, 2012 CFR

2012-10-01

... acceptable means of backfire flame control. Installation of backfire flame arresters bearing basic Approval... acceptable means of backfire flame control for gasoline engines: (1) A backfire flame arrester complying with... and firmly secured to withstand vibration, shock, and engine backfire. Such installations do not...

46 CFR 182.415 - Carburetors.

Code of Federal Regulations, 2011 CFR

2011-10-01

... acceptable means of backfire flame control. Installation of backfire flame arresters bearing basic Approval... acceptable means of backfire flame control for gasoline engines: (1) A backfire flame arrester complying with... and firmly secured to withstand vibration, shock, and engine backfire. Such installations do not...

46 CFR 182.415 - Carburetors.

Code of Federal Regulations, 2013 CFR

2013-10-01

... acceptable means of backfire flame control. Installation of backfire flame arresters bearing basic Approval... acceptable means of backfire flame control for gasoline engines: (1) A backfire flame arrester complying with... and firmly secured to withstand vibration, shock, and engine backfire. Such installations do not...

46 CFR 182.415 - Carburetors.

Code of Federal Regulations, 2014 CFR

2014-10-01

... acceptable means of backfire flame control. Installation of backfire flame arresters bearing basic Approval... acceptable means of backfire flame control for gasoline engines: (1) A backfire flame arrester complying with... and firmly secured to withstand vibration, shock, and engine backfire. Such installations do not...

Turbine gas temperature measurement and control system

NASA Technical Reports Server (NTRS)

Webb, W. L.

1973-01-01

A fluidic Turbine Inlet Gas Temperature (TIGIT) Measurement and Control System was developed for use on a Pratt and Whitney Aircraft J58 engine. Based on engine operating requirements, criteria for high temperature materials selection, system design, and system performance were established. To minimize development and operational risk, the TIGT control system was designed to interface with an existing Exhaust Gas Temperature (EGT) Trim System and thereby modulate steady-state fuel flow to maintain a desired TIGT level. Extensive component and system testing was conducted including heated (2300F) vibration tests for the fluidic sensor and gas sampling probe, temperature and vibration tests on the system electronics, burner rig testing of the TIGT measurement system, and in excess of 100 hours of system testing on a J58 engine. (Modified author abstract)

Active Engine Mount Technology for Automobiles

NASA Technical Reports Server (NTRS)

Rahman, Z.; Spanos, J.

1996-01-01

We present a narrow-band tracking control using a variant of the Least Mean Square (LMS) algorithm [1,2,3] for supressing automobile engine/drive-train vibration disturbances. The algorithm presented here has a simple structure and may be implemented in a low cost micro controller.

14 CFR 29.907 - Engine vibration.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine vibration. 29.907 Section 29.907... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant General § 29.907 Engine vibration. (a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft. (b) The...

14 CFR 29.907 - Engine vibration.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Engine vibration. 29.907 Section 29.907... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant General § 29.907 Engine vibration. (a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft. (b) The...

14 CFR 29.907 - Engine vibration.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Engine vibration. 29.907 Section 29.907... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant General § 29.907 Engine vibration. (a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft. (b) The...

14 CFR 29.907 - Engine vibration.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Engine vibration. 29.907 Section 29.907... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant General § 29.907 Engine vibration. (a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft. (b) The...

14 CFR 29.907 - Engine vibration.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Engine vibration. 29.907 Section 29.907... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant General § 29.907 Engine vibration. (a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft. (b) The...

Semi-active control of a sandwich beam partially filled with magnetorheological elastomer

NASA Astrophysics Data System (ADS)

Dyniewicz, Bartłomiej; Bajkowski, Jacek M.; Bajer, Czesław I.

2015-08-01

The paper deals with the semi-active control of vibrations of structural elements. Elastomer composites with ferromagnetic particles that act as magnetorheological fluids are used. The damping coefficient and the shear modulus of the elastomer increases when it is exposed to an electro-magnetic field. The control of this process in time allows us to reduce vibrations more effectively than if the elastomer is permanently exposed to a magnetic field. First the analytical solution for the vibrations of a sandwich beam filled with an elastomer is given. Then the control problem is defined and applied to the analytical formula. The numerical solution of the minimization problem results in a periodic, perfectly rectangular control function if free vibrations are considered. Such a temporarily acting magnetic field is more efficient than a constantly acting one. The surplus reaches 20-50% or more, depending on the filling ratio of the elastomer. The resulting control was verified experimentally in the vibrations of a cantilever sandwich beam. The proposed semi-active control can be directly applied to engineering vibrating structural elements, for example helicopter rotors, aircraft wings, pads under machines, and vehicles.

A novel simplified model for torsional vibration analysis of a series-parallel hybrid electric vehicle

NASA Astrophysics Data System (ADS)

Tang, Xiaolin; Yang, Wei; Hu, Xiaosong; Zhang, Dejiu

2017-02-01

In this study, based on our previous work, a novel simplified torsional vibration dynamic model is established to study the torsional vibration characteristics of a compound planetary hybrid propulsion system. The main frequencies of the hybrid driveline are determined. In contrast to vibration characteristics of the previous 16-degree of freedom model, the simplified model can be used to accurately describe the low-frequency vibration property of this hybrid powertrain. This study provides a basis for further vibration control of the hybrid powertrain during the process of engine start/stop.

An improved design method of a tuned mass damper for an in-service footbridge

NASA Astrophysics Data System (ADS)

Shi, Weixing; Wang, Liangkun; Lu, Zheng

2018-03-01

Tuned mass damper (TMD) has a wide range of applications in the vibration control of footbridges. However, the traditional engineering design method may lead to a mistuned TMD. In this paper, an improved TMD design method based on the model updating is proposed. Firstly, the original finite element model (FEM) is studied and the natural characteristics of the in-service or newly built footbridge is identified by field test, and then the original FEM is updated. TMD is designed according to the new updated FEM, and it is optimized according to the simulation on vibration control effects. Finally, the installation and field measurement of TMD are carried out. The improved design method can be applied to both in-service and newly built footbridges. This paper illustrates the improved design method with an engineering example. The frequency identification results of field test and original FEM show that there is a relatively large difference between them. The TMD designed according to the updated FEM has better vibration control effect than the TMD designed according to the original FEM. The site test results show that TMD has good effect on controlling human-induced vibrations.

Wireless Inductive Power Device Suppresses Blade Vibrations

NASA Technical Reports Server (NTRS)

Morrison, Carlos R.; Provenza, Andrew J.; Choi, Benjamin B.; Bakhle, Milind A.; Min, James B.; Stefko, George L.; Duffy, Kirsten P.; Fougers, Alan J.

2011-01-01

Vibration in turbomachinery can cause blade failures and leads to the use of heavier, thicker blades that result in lower aerodynamic efficiency and increased noise. Metal and/or composite fatigue in the blades of jet engines has resulted in blade destruction and loss of lives. Techniques for suppressing low-frequency blade vibration, such as gtuned circuit resistive dissipation of vibratory energy, h or simply "passive damping," can require electronics incorporating coils of unwieldy dimensions and adding unwanted weight to the rotor. Other approaches, using vibration-dampening devices or damping material, could add undesirable weight to the blades or hub, making them less efficient. A wireless inductive power device (WIPD) was designed, fabricated, and developed for use in the NASA Glenn's "Dynamic Spin Rig" (DSR) facility. The DSR is used to simulate the functionality of turbomachinery. The relatively small and lightweight device [10 lb (approx.=4.5 kg)] replaces the existing venerable and bulky slip-ring. The goal is the eventual integration of this technology into actual turbomachinery such as jet engines or electric power generators, wherein the device will facilitate the suppression of potentially destructive vibrations in fan blades. This technology obviates slip rings, which require cooling and can prove unreliable or be problematic over time. The WIPD consists of two parts: a remote element, which is positioned on the rotor and provides up to 100 W of electrical power to thin, lightweight piezoelectric patches strategically placed on/in fan blades; and a stationary base unit that wirelessly communicates with the remote unit. The base unit supplies inductive power, and also acts as an input and output corridor for wireless measurement, and active control command to the remote unit. Efficient engine operation necessitates minimal disturbance to the gas flow across the turbine blades in any effort to moderate blade vibration. This innovation makes it possible to moderate vibration on or in turbomachinery blades by providing 100 W of wireless electrical power and actuation control to thin, lightweight vibration-suppressing piezoelectric patches (eight actuation and eight sensor patches in this prototype, for a total of 16 channels) positioned strategically on the surface of, or within, titanium fan blades, or embedded in composite fan blades. This approach moves significantly closer to the ultimate integration of "active" vibration suppression technology into jet engines and other turbomachinery devices such as turbine electrical generators used in the power industry. The novel feature of this device is in its utilization of wireless technology to simultaneously sense and actively control vibration in rotating or stationary turbomachinery blades using piezoelectric patches. In the past, wireless technology was used solely for sensing and diagnostics. This technology, however, will accomplish much more, in terms of simultaneously sensing, suppressing blade vibration, and making it possible for detailed study of vibration impact in turbomachinery blades.

14 CFR 33.83 - Vibration test.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Vibration test. 33.83 Section 33.83... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.83 Vibration test. (a) Each engine must undergo vibration surveys to establish that the vibration characteristics of those components that...

Occupational and genetic risk factors associated with intervertebral disc disease.

PubMed

Virtanen, Iita M; Karppinen, Jaro; Taimela, Simo; Ott, Jürg; Barral, Sandra; Kaikkonen, Kaisu; Heikkilä, Olli; Mutanen, Pertti; Noponen, Noora; Männikkö, Minna; Tervonen, Osmo; Natri, Antero; Ala-Kokko, Leena

2007-05-01

Cross-sectional epidemiologic study. To evaluate the interaction between known genetic risk factors and whole-body vibration for symptomatic intervertebral disc disease (IDD) in an occupational sample. Risk factors of IDD include, among others, whole-body vibration and heredity. In this study, the importance of a set of known genetic risk factors and whole-body vibration was evaluated in an occupational sample of train engineers and sedentary controls. Eleven variations in 8 genes (COL9A2, COL9A3, COL11A2, IL1A, IL1B, IL6, MMP-3, and VDR) were genotyped in 150 male train engineers with an average of 21-year exposure to whole-body vibration and 61 male paper mill workers with no exposure to vibration. Subjects were classified into IDD-phenotype and asymptomatic groups, based on the latent class analysis. The number of individuals belonging to the IDD-phenotype was significantly higher among train engineers (42% of train engineers vs. 17.5% of sedentary workers; P = 0.005). IL1A -889T allele represented a significant risk factor for the IDD-phenotype both in the single marker allelic association test (P = 0.043) and in the logistic regression analysis (P = 0.01). None of the other allele markers was significantly associated with symptoms when analyzed independently. However, for all the SNP markers considered, whole-body vibration represents a nominally significant risk factor. The results suggest that whole-body vibration is a risk factor for symptomatic IDD. Moreover, whole-body vibration had an additive effect with genetic risk factors increasing the likelihood of belonging to the IDD-phenotype group. Of the independent genetic markers, IL1A -889T allele had strongest association with IDD-phenotype.

An approach to optimal semi-active control of vibration energy harvesting based on MEMS

NASA Astrophysics Data System (ADS)

Rojas, Rafael A.; Carcaterra, Antonio

2018-07-01

In this paper the energy harvesting problem involving typical MEMS technology is reduced to an optimal control problem, where the objective function is the absorption of the maximum amount of energy in a given time interval from a vibrating environment. The interest here is to identify a physical upper bound for this energy storage. The mathematical tool is a new optimal control called Krotov's method, that has not yet been applied to engineering problems, except in quantum dynamics. This approach leads to identify new maximum bounds to the energy harvesting performance. Novel MEMS-based device control configurations for vibration energy harvesting are proposed with particular emphasis to piezoelectric, electromagnetic and capacitive circuits.

Vibration syndrome in chipping and grinding workers.

PubMed

1984-10-01

A clear conclusion from these studies is that vibration syndrome occurs in chipping and grinding workers in this country and that earlier reports that it may not exist were probably inaccurate. The careful selection of exposed and control groups for analysis strengthens the observed association between vibration syndrome and the occupational use of pneumatic chipping hammers and grinding tools. In the foundry populations studied the vibration syndrome was severe, with short latencies and high prevalences of the advanced stages. The shipyard population did not display this pattern. This difference can be attributed to variations in work practices but the more important factor seems to be the effect of incentive work schedules. Comparisons of groups of hourly and incentive workers from the shipyard and within foundry populations consistently demonstrated that incentive work was associated with increased severity of vibration syndrome. Excessive vibration levels were measured on chipping and grinding tools. Of the factors studied, reduction of throttle level decreased the vibration levels measured on chipping hammers. For grinders, the working condition of the tool affected the measured vibration acceleration levels. Grinders receiving average to poor maintenance showed higher vibration levels. The results of objective clinical testing did not yield tests with diagnostic properties. To date, the clinical judgment of the physician remains the primary focus of the diagnosis of vibration syndrome. A number of actions can be taken to prevent vibration syndrome. Preplacement medical examinations can identify workers predisposed to or experiencing Raynaud's phenomenon or disease. Informing employees and employers about the signs, symptoms, and consequences of vibration syndrome can encourage workers to report the condition to their physicians promptly. Engineering approaches to preventing vibration syndrome include increased quality control on castings to reduce finishing time and automation of the finishing process. Tool manufacturers can contribute by modifying or redesigning tools to reduce vibration. The technology to reduce vibration from hand tools exists but the engineering application is difficult. Vibration from chain saws has been reduced through changes in design and some companies have begun to redesign jackhammers, scalers, grinders, and chipping hammers. As these become available, purchasers can encourage manufacturers by selecting tools with antivibration characteristics. Vibration from tools currently in use can be controlled by periodically scheduled inspection and maintenance programs for vibrating tools.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparison of spectral analysis of vibration using commercial knock sensor and 3-axis acceleration sensor

NASA Astrophysics Data System (ADS)

Zieliński, Ł.; Walczak, D.; Szczurowski, K.; Radkowski, S.

2016-09-01

With the development of internal combustion engines, engineers attempt to reduce the noise and vibration generated. Due to the high cost of fuel, are increasingly looking for new sources of power in order to reduce costs. In diesel engines, an increasingly popular method is the admixture of propane-butane. This follows because of the price of the fuel as well as to improve the efficiency of combustion. With the development of this type of dual fuel power seems to be a reasonable study of the effects of LPG to generate noise and vibration, as well as an attempt to evaluate the combustion process. Unfortunately, too much addition of LPG causes a phenomenon called knock consisting in abnormal, uneven, explosive combustion of fuels in reciprocating engines. This phenomenon may lead to a reduction in engine performance and permanent damage. Control of the knock detection uses vibration acceleration sensors recording the high frequency ranges. Within the framework of the research conducted by the team of authors, an attempt was made to compare the vibroacoustic signals originating from the commercial knocking sensor with a three-axis acceleration sensor. These signals were subject to a quick Fourier transform in the purpose of analysing the amplitude spectra.

NASA GSFC Mechanical Engineering Latest Inputs for Verification Standards (GEVS) Updates

NASA Technical Reports Server (NTRS)

Kaufman, Daniel

2003-01-01

This viewgraph presentation provides information on quality control standards in mechanical engineering. The presentation addresses safety, structural loads, nonmetallic composite structural elements, bonded structural joints, externally induced shock, random vibration, acoustic tests, and mechanical function.

Incorporating a disturbance observer with direct velocity feedback for control of human-induced vibrations

NASA Astrophysics Data System (ADS)

Nyawako, Donald; Reynolds, Paul; Hudson, Emma

2016-04-01

Feedback control strategies are desirable for disturbance rejection of human-induced vibrations in civil engineering structures as human walking forces cannot easily be measured. In relation to human-induced vibration control studies, most past researches have focused on floors and footbridges and the widely used linear controller implemented in the trials has been the direct velocity feedback (DVF) scheme. With appropriate compensation to enhance its robustness, it has been shown to be effective at damping out the problematic modes of vibration of the structures in which the active vibration control systems have been implemented. The work presented here introduces a disturbance observer (DOB) that is used with an outer-loop DVF controller. Results of analytical studies presented in this work based on the dynamic properties of a walkway bridge structure demonstrate the potential of this approach for enhancing the vibration mitigation performance offered by a purely DVF controller. For example, estimates of controlled frequency response functions indicate improved attenuation of vibration around the dominant frequency of the walkway bridge structure as well as at higher resonant frequencies. Controlled responses from three synthesized walking excitation forces on a walkway bridge structure model show that the inclusion of the disturbance observer with an outer loop DVF has potential to improve on the vibration mitigation performance by about 3.5% at resonance and 6-10% off-resonance. These are realised with hard constraints being imposed on the low frequency actuator displacements.

Effects of unbalance location on dynamic characteristics of high-speed gasoline engine turbocharger with floating ring bearings

NASA Astrophysics Data System (ADS)

Wang, Longkai; Bin, Guangfu; Li, Xuejun; Liu, Dingqu

2016-03-01

For the high-speed gasoline engine turbocharger rotor, due to the heterogeneity of multiple parts material, manufacturing and assembly errors, running wear in impeller and uneven carbon of turbine, the random unbalance usually can be developed which will induce excessive rotor vibration, and even lead to nonlinear vibration accidents. However, the investigation of unbalance location on the nonlinear high-speed turbocharger rotordynamic characteristics is less. In order to discuss the rotor unbalance location effects of turbocharger with nonlinear floating ring bearings(FRBs), the realistic turbocharger of gasoline engine is taken as a research object. The rotordynamic equations of motion under the condition of unbalance are derived by applied unbalance force and nonlinear oil film force of FRBs. The FE model of turbocharger rotor-bearing system is modeled which includes the unbalance excitation and nonlinear FRBs. Under the conditions of four different applied locations of unbalance, the nonlinear transient analyses are performed based on the rotor FEM. The differences of dynamic behavior are obvious to the turbocharger rotor systems for four conditions, and the bifurcation phenomena are different. From the results of waterfall and transient response analysis, the speed for the appearance of fractional frequency is not identical and the amplitude magnitude is different from the different unbalance locations, and the non-synchronous vibration does not occur in the turbocharger and the amplitude is relative stable and minimum under the condition 4. The turbocharger vibration and non-synchronous components could be reduced or suppressed by controlling the applied location of unbalance, which is helpful for the dynamic design, fault diagnosis and vibration control of the high-speed gasoline engine turbochargers.

Design and initial validation of a wireless control system based on WSN

NASA Astrophysics Data System (ADS)

Yu, Yan; Li, Luyu; Li, Peng; Wang, Xu; Liu, Hang; Ou, Jinping

2013-04-01

At present, cantilever structure used widely in civil structures will generate continuous vibration by external force due to their low damping characteristic, which leads to a serious impact on the working performance and service time. Therefore, it is very important to control the vibration of these structures. The active vibration control is the primary means of controlling the vibration with high precision and strong adaptive ability. Nowadays, there are many researches using piezoelectric materials in the structural vibration control. Piezoelectric materials are cheap, reliable and they can provide braking and sensing method harmless to the structure, therefore they have broad usage. They are used for structural vibration control in a lot of civil engineering research currently. In traditional sensor applications, information exchanges with the monitoring center or a computer system through wires. If wireless sensor networks(WSN) technology is used, cabling links is not needed, thus the cost of the whole system is greatly reduced. Based on the above advantages, a wireless control system is designed and validated through preliminary tests. The system consists of a cantilever, PVDF as sensor, signal conditioning circuit(SCM), A/D acquisition board, control arithmetic unit, D/A output board, power amplifier, piezoelectric bimorph as actuator. DSP chip is used as the control arithmetic unit and PD control algorithm is embedded in it. PVDF collects the parameters of vibration, sends them to the SCM after A/D conversion. SCM passes the data to the DSP through wireless technology, and DSP calculates and outputs the control values according to the control algorithm. The output signal is amplified by the power amplifier to drive the piezoelectric bimorph for vibration control. The structural vibration duration reduces to 1/4 of the uncontrolled case, which verifies the feasibility of the system.

T55 power turbine rotor multiplane-multispeed balancing study

NASA Technical Reports Server (NTRS)

Martin, M. R.

1982-01-01

A rotordynamic analysis of the T55-L-11C engine was used to evaluate the balancing needs of the power turbine and to optimize the balancing procedure. As a result, recommendations were made for implementation of a multiplane-multispeed balancing plan. Precision collars for the attachment of trial weights to a slender rotor were designed enabling demonstration balancing on production hardware. The quality of the balance was then evaluated by installing a high speed balanced power turbine in an engine and running in a test cell at the Corpus Christi Army depot. The engine used had been tested prior to the turbine changeout and showed acceptable overall vibration levels for the engine were significantly reduced, demonstrating the ability of multiplane-multispeed balancing to control engine vibration.

A new compound control method for sine-on-random mixed vibration test

NASA Astrophysics Data System (ADS)

Zhang, Buyun; Wang, Ruochen; Zeng, Falin

2017-09-01

Vibration environmental test (VET) is one of the important and effective methods to provide supports for the strength design, reliability and durability test of mechanical products. A new separation control strategy was proposed to apply in multiple-input multiple-output (MIMO) sine on random (SOR) mixed mode vibration test, which is the advanced and intensive test type of VET. As the key problem of the strategy, correlation integral method was applied to separate the mixed signals which included random and sinusoidal components. The feedback control formula of MIMO linear random vibration system was systematically deduced in frequency domain, and Jacobi control algorithm was proposed in view of the elements, such as self-spectrum, coherence, and phase of power spectral density (PSD) matrix. Based on the excessive correction of excitation in sine vibration test, compression factor was introduced to reduce the excitation correction, avoiding the destruction to vibration table or other devices. The two methods were synthesized to be applied in MIMO SOR vibration test system. In the final, verification test system with the vibration of a cantilever beam as the control object was established to verify the reliability and effectiveness of the methods proposed in the paper. The test results show that the exceeding values can be controlled in the tolerance range of references accurately, and the method can supply theory and application supports for mechanical engineering.

Motor vehicle technology:Mobility for prosperity

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

Not Available

1985-01-01

This book presents the papers given at a conference on internal combustion engines for vehicles. Topics considered at the conference included combustion chambers, the lubrication of turbocharged engines, oil filters, fuel consumption, traffic control, crashworthiness, brakes, acceleration, unleaded gasoline, methanol fuels, pressure drop, safety regulations, tire vibration, detergents, fuel economy, ceramics in engines, steels, catalytic converters, fuel additives, heat exchangers, pump systems, emissions control, fuel injection systems, noise pollution control, natural gas fuels, assembly plant productivity, aerodynamics, torsion, electronics, and automatic transmissions.

77 FR 58301 - Technical Amendment; Airworthiness Standards: Aircraft Engines; Correction

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-20

... technical amendment, the FAA clarified aircraft engine vibration test requirements in the airworthiness... amendment, the FAA intended to clarify vibration test requirements in Sec. 33.83 of 14 Code of Federal... read as follows: Sec. 33.83 Vibration test. (a) Each engine must undergo vibration surveys to establish...

Journal of Engineering Thermophysics (Selected Articles),

DTIC Science & Technology

1983-05-13

compressor, prediction of unsteady vibration , and prevention of unsteady vibration . This test was undergone on a turbojet engine. The paper stresses the...induce unsteady engine vibration . While studying the effect of inlet anomaly and variation of the first stage nozzle area of the turbine, the engine...constant revolution speed curve until unsteady vibration or stall appeared. In studying the influence of the starting sequence, starting was

Analysis of automobile engine cylinder pressure and rotation speed from engine body vibration signal

NASA Astrophysics Data System (ADS)

Wang, Yuhua; Cheng, Xiang; Tan, Haishu

2016-01-01

In order to improve the engine vibration signal process method for the engine cylinder pressure and engine revolution speed measurement instrument, the engine cylinder pressure varying with the engine working cycle process has been regarded as the main exciting force for the engine block forced vibration. The forced vibration caused by the engine cylinder pressure presents as a low frequency waveform which varies with the cylinder pressure synchronously and steadily in time domain and presents as low frequency high energy discrete humorous spectrum lines in frequency domain. The engine cylinder pressure and the rotation speed can been extract form the measured engine block vibration signal by low-pass filtering analysis in time domain or by FFT analysis in frequency domain, the low-pass filtering analysis in time domain is not only suitable for the engine in uniform revolution condition but also suitable for the engine in uneven revolution condition. That provides a practical and convenient way to design motor revolution rate and cylinder pressure measurement instrument.

77 FR 4650 - Airworthiness Directives; General Electric Company Turbofan Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-31

... blade borescope inspection (BSI) or a failed engine core vibration survey, establishes a new lower life... LPT rotor stage 3 disk removal after a failed HPT blade BSI or a failed engine core vibration survey... engine test cell as part of an engine manual performance run fulfill the vibration survey requirements of...

Recent advances in micro-vibration isolation

NASA Astrophysics Data System (ADS)

Liu, Chunchuan; Jing, Xingjian; Daley, Steve; Li, Fengming

2015-05-01

Micro-vibration caused by disturbance sources onboard spacecraft can severely degrade the working environment of sensitive payloads. Some notable vibration control methods have been developed particularly for the suppression or isolation of micro-vibration over recent decades. Usually, passive isolation techniques are deployed in aerospace engineering. Active isolators, however, are often proposed to deal with the low frequency vibration that is common in spacecraft. Active/passive hybrid isolation has also been effectively used in some spacecraft structures for a number of years. In semi-active isolation systems, the inherent structural performance can be adjusted to deal with variation in the aerospace environment. This latter approach is potentially one of the most practical isolation techniques for micro-vibration isolation tasks. Some emerging advanced vibration isolation methods that exploit the benefits of nonlinearity have also been reported in the literature. This represents an interesting and highly promising approach for solving some challenging problems in the area. This paper serves as a state-of-the-art review of the vibration isolation theory and/or methods which were developed, mainly over the last decade, specifically for or potentially could be used for, micro-vibration control.

Functionally Graded Shape Memory Alloy Composites Optimized for Passive Vibration Control

DTIC Science & Technology

2006-11-20

Nitinol , it is anticipated that the wire can only experience an incomplete hysteresis. 2.1. SMA wires in sleeves continuously bonded to the plate...Gilheany, J. 1995. Control of the natural frequencies of nitinol -reinforced composite beams, Journal of Sound and Vibrations, Vol. 185, 171-185. 3 Ro...J., and Baz, A., 1995. Nitinol -reinforced plates: Part III, Dynamic characteristics, Composites Engineering, Vol. 5, 91-106. 4 Epps, J and Chandra

77 FR 28569 - Foreign-Trade Zone 92-Gulfport, MS Notification of Proposed Production Activity; Gulf Ship, LLC...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-15

... engines, winches, steering gears, electric motors, generators, raceways, doors, tefrotex, floor coatings..., vibration control dampeners, oil booms, lighting equipment, controllers, electrical cabinets, bearings...

14 CFR 27.907 - Engine vibration.

Code of Federal Regulations, 2010 CFR

2010-01-01

... engine to excessive vibration stresses. This must be shown by a vibration investigation. (c) No part of the rotor drive system may be subjected to excessive vibration stresses. Rotor Drive System ...

14 CFR 27.907 - Engine vibration.

Code of Federal Regulations, 2012 CFR

2012-01-01

... engine to excessive vibration stresses. This must be shown by a vibration investigation. (c) No part of the rotor drive system may be subjected to excessive vibration stresses. Rotor Drive System ...

14 CFR 27.907 - Engine vibration.

Code of Federal Regulations, 2014 CFR

2014-01-01

... engine to excessive vibration stresses. This must be shown by a vibration investigation. (c) No part of the rotor drive system may be subjected to excessive vibration stresses. Rotor Drive System ...

14 CFR 27.907 - Engine vibration.

Code of Federal Regulations, 2013 CFR

2013-01-01

... engine to excessive vibration stresses. This must be shown by a vibration investigation. (c) No part of the rotor drive system may be subjected to excessive vibration stresses. Rotor Drive System ...

14 CFR 27.907 - Engine vibration.

Code of Federal Regulations, 2011 CFR

2011-01-01

... engine to excessive vibration stresses. This must be shown by a vibration investigation. (c) No part of the rotor drive system may be subjected to excessive vibration stresses. Rotor Drive System ...

Technical preventive measures in Japan.

PubMed

Yonekawa, Y

1994-05-01

Technical preventive measures against vibration syndrome in the field of industrial health are reviewed in the present paper. The first technical prevention measure is to reduce vibration transmission from the tools to the operators. This measure employs vibration isolators between the handles and vibration sources of machine tools. Handles of tools using Neidhalt dampers, shear type rubber mounts and springs have reduced frequency-weighted acceleration levels (Lh,w) from 2 dB to 10 dB (Lh,w (dB) = 20 log a/ao; a: frequency-weighted acceleration (rms), ao = 10(-5) m/s2) in Z direction, while no reduction was found in X, Y directions. The second measure is to reduce vibration at the source; New chain saws have been developed to reduce vibration with twin cylinder instead of a single cylinder engines. This cancels unbalanced movements inside the internal combustion engine. Such chain saws reduced Lh,w values more than 10 dB in both front and rear handles except in Z direction of the front handle. A new type of impact wrench has been devised with an oil pulse device to avoid direct metal contact inside the power source. This new impact wrench lowered Lh,w values more than 10 dB in three directions. The third measure is to use a remote control system or to substitute another machine generating less vibration. Vibration reduction at the handle lever of the remote control chain saw was more than 20 dB. A more effective means is to substitute other machines for conventional tools: a hydraulic wheel jumbo instead of a leg-type rock drill; a hydraulic breaker instead of a hand-held breaker. However, these heavy machines produce whole-body vibration which might give rise to other problems such as back pain.

Model identification of terfenol-D magnetostrictive actuator for precise positioning control

NASA Astrophysics Data System (ADS)

Saleem, Ashraf; Ghodsi, Mojtaba; Mesbah, Mostefa; Ozer, Abdullah

2016-04-01

Feedback control strategies are desirable for disturbance rejection of human-induced vibrations in civil engineering structures as human walking forces cannot easily be measured. In relation to human-induced vibration control studies, most past researches have focused on floors and footbridges and the widely used linear controller implemented in the trials has been the direct velocity feedback (DVF) scheme. With appropriate compensation to enhance its robustness, it has been shown to be effective at damping out the problematic modes of vibration of the structures in which the active vibration control systems have been implemented. The work presented here introduces a disturbance observer (DOB) that is used with an outer-loop DVF controller. Results of analytical studies presented in this work based on the dynamic properties of a walkway bridge structure demonstrate the potential of this approach for enhancing the vibration mitigation performance offered by a purely DVF controller. For example, estimates of controlled frequency response functions indicate improved attenuation of vibration around the dominant frequency of the walkway bridge structure as well as at higher resonant frequencies. Controlled responses from three synthesized walking excitation forces on a walkway bridge structure model show that the inclusion of the disturbance observer with an outer loop DVF has potential to improve on the vibration mitigation performance by about 3.5% at resonance and 6-10% off-resonance. These are realised with hard constraints being imposed on the low frequency actuator displacements.

Design and test of aircraft engine isolators for reduced interior noise

NASA Technical Reports Server (NTRS)

Unruh, J. F.; Scheidt, D. C.

1982-01-01

Improved engine vibration isolation was proposed to be the most weight and cost efficient retrofit structure-borne noise control measure for single engine general aviation aircraft. A study was carried out the objectives: (1) to develop an engine isolator design specification for reduced interior noise transmission, (2) select/design candidate isolators to meet a 15 dB noise reduction design goal, and (3) carry out a proof of concept evaluation test. Analytical model of the engine, vibration isolators and engine mount structure were coupled to an empirical model of the fuselage for noise transmission evaluation. The model was used to develop engine isolator dynamic properties design specification for reduced noise transmission. Candidate isolators ere chosen from available product literature and retrofit to a test aircraft. A laboratory based test procedure was then developed to simulate engine induced noise transmission in the aircraft for a proof of concept evaluation test. Three candidate isolator configurations were evaluated for reduced structure-borne noise transmission relative to the original equipment isolators.

Non-Synchronous Vibration of Turbomachinery Airfoils

DTIC Science & Technology

2006-03-01

study and prevention of non-synchronous vibrations. Non-synchronous vibrations in turbine engine blades are the result of the interaction of an...was a modern fan vane blade known as the H2 case. This blade encountered NSV in experimental rig testing. An analysis was performed with TURBO ...design stage for flow over turbine engine blades . REFERENCES Anagnostopoulos, P., ed. Flow-Induced Vibrations in Engineering

Space Shuttle Main Engine: Advanced Health Monitoring System

NASA Technical Reports Server (NTRS)

Singer, Chirs

1999-01-01

The main gola of the Space Shuttle Main Engine (SSME) Advanced Health Management system is to improve flight safety. To this end the new SSME has robust new components to improve the operating margen and operability. The features of the current SSME health monitoring system, include automated checkouts, closed loop redundant control system, catastropic failure mitigation, fail operational/ fail-safe algorithms, and post flight data and inspection trend analysis. The features of the advanced health monitoring system include: a real time vibration monitor system, a linear engine model, and an optical plume anomaly detection system. Since vibration is a fundamental measure of SSME turbopump health, it stands to reason that monitoring the vibration, will give some idea of the health of the turbopumps. However, how is it possible to avoid shutdown, when it is not necessary. A sensor algorithm has been developed which has been exposed to over 400 test cases in order to evaluate the logic. The optical plume anomaly detection (OPAD) has been developed to be a sensitive monitor of engine wear, erosion, and breakage.

Novel design of a self powered and self sensing magneto-rheological damper

NASA Astrophysics Data System (ADS)

Meftahul Ferdaus, Mohammad; Rashid, M. M.; Bhuiyan, M. M. I.; Muthalif, Asan Gani Bin Abdul; Hasan, M. R.

2013-12-01

Magneto-rheological (MR) dampers are semi-active control devices and use MR fluids. Magneto-rheological dampers have successful applications in mechatronics engineering, civil engineering and numerous areas of engineering. At present, traditional MR damper systems, require a isolated power supply and dynamic sensor. This paper presents the achievability and accuracy of a self- powered and self-sensing magneto-rheological damper using harvested energy from the vibration and shock environment in which it is deployed and another important part of this paper is the increased yield stress of the Magneto rheological Fluids. Magneto rheological fluids using replacement of glass beads for Magnetic Particles to surge yield stress is implemented here. Clearly this shows better result on yield stress, viscosity, and settling rate. Also permanent magnet generator (PMG) is designed and attached to a MR damper. For evaluating the self-powered MR damper's vibration mitigating capacity, an Engine Mount System using the MR damper is simulated. The ideal stiffness of the PMG for the Engine Mount System (EMS) is calculated by numerical study. The vibration mitigating performance of the EMS employing the self-powered & self sensing MR damper is theoretically calculated and evaluated in the frequency domain.

Propulsion Health Monitoring for Enhanced Safety

NASA Technical Reports Server (NTRS)

Butz, Mark G.; Rodriguez, Hector M.

2003-01-01

This report presents the results of the NASA contract Propulsion System Health Management for Enhanced Safety performed by General Electric Aircraft Engines (GE AE), General Electric Global Research (GE GR), and Pennsylvania State University Applied Research Laboratory (PSU ARL) under the NASA Aviation Safety Program. This activity supports the overall goal of enhanced civil aviation safety through a reduction in the occurrence of safety-significant propulsion system malfunctions. Specific objectives are to develop and demonstrate vibration diagnostics techniques for the on-line detection of turbine rotor disk cracks, and model-based fault tolerant control techniques for the prevention and mitigation of in-flight engine shutdown, surge/stall, and flameout events. The disk crack detection work was performed by GE GR which focused on a radial-mode vibration monitoring technique, and PSU ARL which focused on a torsional-mode vibration monitoring technique. GE AE performed the Model-Based Fault Tolerant Control work which focused on the development of analytical techniques for detecting, isolating, and accommodating gas-path faults.

Active Blade Vibration Control Being Developed and Tested

NASA Technical Reports Server (NTRS)

Johnson, Dexter

2003-01-01

Gas turbine engines are currently being designed to have increased performance, lower weight and manufacturing costs, and higher reliability. Consequently, turbomachinery components, such as turbine and compressor blades, have designs that are susceptible to new vibration problems and eventual in-service failure due to high-cycle fatigue. To address this problem, researchers at the NASA Glenn Research Center are developing and testing innovative active blade vibration control concepts. Preliminary results of using an active blade vibration control system, involving a rotor supported by an active magnetic bearing in Glenn's Dynamic Spin Rig, indicate promising results (see the photograph). Active blade vibration control was achieved using feedback of blade strain gauge signals within the magnetic bearing control loop. The vibration amplitude was reduced substantially (see the graphs). Also, vibration amplitude amplification was demonstrated; this could be used to enhance structural mode identification, if desired. These results were for a nonrotating two-bladed disk. Tests for rotating blades are planned. Current and future active blade vibration control research is planned to use a fully magnetically suspended rotor and smart materials. For the fully magnetically suspended rotor work, three magnetic bearings (two radial and one axial) will be used as actuators instead of one magnetic bearing. This will allow additional degrees of freedom to be used for control. For the smart materials work, control effectors located on and off the blade will be considered. Piezoelectric materials will be considered for on-the-blade actuation, and actuator placement on a stator vane, or other nearby structure, will be investigated for off-the-blade actuation. Initial work will focus on determining the feasibility of these methods by performing basic analysis and simple experiments involving feedback control.

An innovative and multi-functional smart vibration platform

NASA Astrophysics Data System (ADS)

Olmi, C.; Song, G.; Mo, Y. L.

2007-08-01

Recently, there has been increasing efforts to incorporate vibration damping or energy dissipation mechanisms into civil structures, particularly by using smart materials technologies. Although papers about structural vibration control using smart materials have been published for more than two decades, there has been little research in developing teaching equipment to introduce smart materials to students via in-classroom demonstration or hands-on experiments. In this paper, an innovative and multi-functional smart vibration platform (SVP) has been developed by the Smart Materials and Structures Laboratory at the University of Houston to demonstrate vibration control techniques using multiple smart materials for educational and research purposes. The vibration is generated by a motor with a mass imbalance mounted on top of the frame. Shape memory alloys (SMA) and magneto-rheological (MR) fluid are used to increase the stiffness and damping ratio, respectively, while a piezoceramic sensor (lead zirconate titanate, or PZT) is used as a vibration sensing device. An electrical circuit has been designed to control the platform in computer-control or manual mode through the use of knobs. The former mode allows for an automated demonstration, while the latter requires the user to manually adjust the stiffness and damping ratio of the frame. In addition, the system accepts network connections and can be used in a remote experiment via the internet. This platform has great potential to become an effective tool for teaching vibration control and smart materials technologies to students in civil, mechanical and electrical engineering for both education and research purposes.

Advanced Engine Health Management Applications of the SSME Real-Time Vibration Monitoring System

NASA Technical Reports Server (NTRS)

Fiorucci, Tony R.; Lakin, David R., II; Reynolds, Tracy D.; Turner, James E. (Technical Monitor)

2000-01-01

The Real Time Vibration Monitoring System (RTVMS) is a 32-channel high speed vibration data acquisition and processing system developed at Marshall Space Flight Center (MSFC). It Delivers sample rates as high as 51,200 samples/second per channel and performs Fast Fourier Transform (FFT) processing via on-board digital signal processing (DSP) chips in a real-time format. Advanced engine health assessment is achieved by utilizing the vibration spectra to provide accurate sensor validation and enhanced engine vibration redlines. Discrete spectral signatures (such as synchronous) that are indicators of imminent failure can be assessed and utilized to mitigate catastrophic engine failures- a first in rocket engine health assessment. This paper is presented in viewgraph form.

Nonlinear dissipative devices in structural vibration control: A review

NASA Astrophysics Data System (ADS)

Lu, Zheng; Wang, Zixin; Zhou, Ying; Lu, Xilin

2018-06-01

Structural vibration is a common phenomenon existing in various engineering fields such as machinery, aerospace, and civil engineering. It should be noted that the effective suppression of structural vibration is conducive to enhancing machine performance, prolonging the service life of devices, and promoting the safety and comfort of structures. Conventional linear energy dissipative devices (linear dampers) are largely restricted for wider application owing to their low performance under certain conditions, such as the detuning effect of tuned mass dampers subjected to nonstationary excitations and the excessively large forces generated in linear viscous dampers at high velocities. Recently, nonlinear energy dissipative devices (nonlinear dampers) with broadband response and high robustness are being increasingly used in practical engineering. At the present stage, nonlinear dampers can be classified into three groups, namely nonlinear stiffness dampers, nonlinear-stiffness nonlinear-damping dampers, and nonlinear damping dampers. Corresponding to each nonlinear group, three types of nonlinear dampers that are widely utilized in practical engineering are reviewed in this paper: the nonlinear energy sink (NES), particle impact damper (PID), and nonlinear viscous damper (NVD), respectively. The basic concepts, research status, engineering applications, and design approaches of these three types of nonlinear dampers are summarized. A comparison between their advantages and disadvantages in practical engineering applications is also conducted, to provide a reference source for practical applications and new research.

KENNEDY SPACE CENTER, FLA. - As the crawler transporter slowly moves the Mobile Launcher Platform (MLP) out of the Vehicle Assembly Building, the driver of the front control cab can be seen. The MLP is carrying two solid rocket boosters for engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-17

KENNEDY SPACE CENTER, FLA. - As the crawler transporter slowly moves the Mobile Launcher Platform (MLP) out of the Vehicle Assembly Building, the driver of the front control cab can be seen. The MLP is carrying two solid rocket boosters for engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

Evaluation of commercially available seat suspensions to reduce whole body vibration exposures in mining heavy equipment vehicle operators.

PubMed

Kim, Jeong Ho; Marin, Luz S; Dennerlein, Jack T

2018-09-01

As mining vehicle operators are exposed to high level of Whole body vibration (WBV) for prolonged periods of time, approaches to reduce this exposure are needed for the specific types of exposures in mining. Although various engineering controls (i.e. seat suspension systems) have been developed to address WBV, there has been lack of research to systematically evaluate these systems in reducing WBV exposures in mining heavy equipment vehicle settings. Therefore, this laboratory-based study evaluated the efficacy of different combinations of fore-aft (x-axis), lateral (y-axis), and vertical (z-axis) suspensions in reducing WBV exposures. The results showed that the active vertical suspension more effectively reduced the vertical vibration (∼50%; p's < 0.0001) as compared to the passive vertical suspension (10%; p's < 0.11). The passive fore-aft (x-axis) and lateral (y-axis) suspension systems did not attenuate the corresponding axis vibration (p's > 0.06) and sometimes amplified the floor vibration, especially when the non-vertical vibration was predominant (p's < 0.02). These results indicate that there is a critical need to develop more effective engineering controls including better seat suspensions to address non-vertical WBV exposures, especially because these non-vertical WBV exposures can increase risks for adverse health effects including musculoskeletal loading, discomfort, and impaired visual acuity. Copyright © 2018 Elsevier Ltd. All rights reserved.

14 CFR 33.83 - Vibration test.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Vibration test. 33.83 Section 33.83 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.83 Vibration test. (a) Each engine...

Measurements and analyses of principal dynamic parameters of building structures as a function of type of vibration excitation

NASA Astrophysics Data System (ADS)

Bartmański, Cezary; Bochenek, Wojciech; Passia, Henryk; Szade, Adam

2006-06-01

The methods of direct measurement and analysis of the dynamic response of a building structure through real-time recording of the amplitude of low-frequency vibration (tilt) have been presented. Subject to analyses was the reaction induced either by kinematic excitation (road traffic and mining-induced vibration) or controlled action of solid-fuel rocket micro-engines installed on the building. The forces were analysed by means of a set of transducers installed both in the ground and on the structure. After the action of excitation forces has been stopped, the system (structure) makes damped vibration around the static equilibrium position. It has been shown that the type of excitation affects the accuracy of evaluation of principal dynamic parameters of the structure. In the authors opinion these are the decrement of damping and natural vibration frequency. Positive results of tests with the use of excitation by means of short-action (0.6 second) rocket micro-engines give a chance to develop a reliable method for periodical assessment of acceptable loss of usability characteristics of building structures heavily influenced by environmental effects.

14 CFR 33.43 - Vibration test.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Vibration test. 33.43 Section 33.43... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.43 Vibration test. (a) Each... configuration of the propeller type which is used for the endurance test, and using, for other engines, the same...

14 CFR 33.83 - Vibration test.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration test. 33.83 Section 33.83... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.83 Vibration test. (a) Each engine... experience, analysis, and component test and shall address, as a minimum, blades, vanes, rotor discs, spacers...

14 CFR 33.83 - Vibration test.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Vibration test. 33.83 Section 33.83... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.83 Vibration test. (a) Each engine... experience, analysis, and component test and shall address, as a minimum, blades, vanes, rotor discs, spacers...

14 CFR 33.43 - Vibration test.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration test. 33.43 Section 33.43... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.43 Vibration test. (a) Each... configuration of the propeller type which is used for the endurance test, and using, for other engines, the same...

14 CFR 33.83 - Vibration test.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Vibration test. 33.83 Section 33.83... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.83 Vibration test. (a) Each engine... experience, analysis, and component test and shall address, as a minimum, blades, vanes, rotor discs, spacers...

14 CFR 33.43 - Vibration test.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Vibration test. 33.43 Section 33.43... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.43 Vibration test. (a) Each... configuration of the propeller type which is used for the endurance test, and using, for other engines, the same...

UHB demonstrator interior noise control flight tests and analysis

NASA Astrophysics Data System (ADS)

Simpson, M. A.; Druez, P. M.; Kimbrough, A. J.; Brock, M. P.; Burge, P. L.; Mathur, G. P.; Cannon, M. R.; Tran, B. N.

1989-10-01

The measurement and analysis of MD-UHB (McDonnell Douglas Ultra High Bypass) Demonstrator noise and vibration flight test data are described as they relate to passenger cabin noise. The analyses were done to investigate the interior noise characteristics of advanced turboprop aircraft with aft-mounted engines, and to study the effectiveness of selected noise control treatments in reducing passenger cabin noise. The UHB Demonstrator is an MD-80 test aircraft with the left JT8D engine replaced with a prototype UHB engine. For these tests, the UHB engine was a General Electric Unducted Fan, with either 8x8 or 10x8 counter-rotating propeller configurations. Interior noise level characteristics were studied for several altitudes and speeds, with emphasis on high altitude (35,000 ft), high speed (0.75 Mach) cruise conditions. The effectiveness of several noise control treatments was evaluated based on cabin noise measurements. The important airborne and structureborne transmission paths were identified for both tonal and broadband sources using the results of a sound intensity survey, exterior and interior noise and vibration data, and partial coherence analysis techniques. Estimates of the turbulent boundary layer pressure wavenumber-frequency spectrum were made, based on measured fuselage noise levels.

UHB demonstrator interior noise control flight tests and analysis

NASA Technical Reports Server (NTRS)

Simpson, M. A.; Druez, P. M.; Kimbrough, A. J.; Brock, M. P.; Burge, P. L.; Mathur, G. P.; Cannon, M. R.; Tran, B. N.

1989-01-01

The measurement and analysis of MD-UHB (McDonnell Douglas Ultra High Bypass) Demonstrator noise and vibration flight test data are described as they relate to passenger cabin noise. The analyses were done to investigate the interior noise characteristics of advanced turboprop aircraft with aft-mounted engines, and to study the effectiveness of selected noise control treatments in reducing passenger cabin noise. The UHB Demonstrator is an MD-80 test aircraft with the left JT8D engine replaced with a prototype UHB engine. For these tests, the UHB engine was a General Electric Unducted Fan, with either 8x8 or 10x8 counter-rotating propeller configurations. Interior noise level characteristics were studied for several altitudes and speeds, with emphasis on high altitude (35,000 ft), high speed (0.75 Mach) cruise conditions. The effectiveness of several noise control treatments was evaluated based on cabin noise measurements. The important airborne and structureborne transmission paths were identified for both tonal and broadband sources using the results of a sound intensity survey, exterior and interior noise and vibration data, and partial coherence analysis techniques. Estimates of the turbulent boundary layer pressure wavenumber-frequency spectrum were made, based on measured fuselage noise levels.

Real time identification of the internal combustion engine combustion parameters based on the vibration velocity signal

NASA Astrophysics Data System (ADS)

Zhao, Xiuliang; Cheng, Yong; Wang, Limei; Ji, Shaobo

2017-03-01

Accurate combustion parameters are the foundations of effective closed-loop control of engine combustion process. Some combustion parameters, including the start of combustion, the location of peak pressure, the maximum pressure rise rate and its location, can be identified from the engine block vibration signals. These signals often include non-combustion related contributions, which limit the prompt acquisition of the combustion parameters computationally. The main component in these non-combustion related contributions is considered to be caused by the reciprocating inertia force excitation (RIFE) of engine crank train. A mathematical model is established to describe the response of the RIFE. The parameters of the model are recognized with a pattern recognition algorithm, and the response of the RIFE is predicted and then the related contributions are removed from the measured vibration velocity signals. The combustion parameters are extracted from the feature points of the renovated vibration velocity signals. There are angle deviations between the feature points in the vibration velocity signals and those in the cylinder pressure signals. For the start of combustion, a system bias is adopted to correct the deviation and the error bound of the predicted parameters is within 1.1°. To predict the location of the maximum pressure rise rate and the location of the peak pressure, algorithms based on the proportion of high frequency components in the vibration velocity signals are introduced. Tests results show that the two parameters are able to be predicted within 0.7° and 0.8° error bound respectively. The increase from the knee point preceding the peak value point to the peak value in the vibration velocity signals is used to predict the value of the maximum pressure rise rate. Finally, a monitoring frame work is inferred to realize the combustion parameters prediction. Satisfactory prediction for combustion parameters in successive cycles is achieved, which validates the proposed methods.

Monitoring Engine Vibrations And Spectrum Of Exhaust

NASA Technical Reports Server (NTRS)

Martinez, Carol L.; Randall, Michael R.; Reinert, John W.

1991-01-01

Real-time computation of intensities of peaks in visible-light emission spectrum of exhaust combined with real-time spectrum analysis of vibrations into developmental monitoring technique providing up-to-the-second information on conditions of critical bearings in engine. Conceived to monitor conditions of bearings in turbopump suppling oxygen to Space Shuttle main engine, based on observations that both vibrations in bearings and intensities of visible light emitted at specific wavelengths by exhaust plume of engine indicate wear and incipient failure of bearings. Applicable to monitoring "health" of other machinery via spectra of vibrations and electromagnetic emissions from exhausts. Concept related to one described in "Monitoring Bearing Vibrations For Signs Of Damage", (MFS-29734).

Designing and Building to ``Impossible'' Tolerances for Vibration Sensitive Equipment

NASA Astrophysics Data System (ADS)

Hertlein, Bernard H.

2003-03-01

As the precision and production capabilities of modern machines and factories increase, our expectations of them rise commensurately. Facility designers and engineers find themselves increasingly involved with measurement needs and design tolerances that were almost unthinkable a few years ago. An area of expertise that demonstrates this very clearly is the field of vibration measurement and control. Magnetic Resonance Imaging, Semiconductor manufacturing, micro-machining, surgical microscopes — These are just a few examples of equipment or techniques that need an extremely stable vibration environment. The challenge to architects, engineers and contractors is to provide that level of stability without undue cost or sacrificing the aesthetics and practicality of a structure. In addition, many facilities have run out of expansion room, so the design is often hampered by the need to reuse all or part of an existing structure, or to site vibration-sensitive equipment close to an existing vibration source. High resolution measurements and nondestructive testing techniques have proven to be invaluable additions to the engineer's toolbox in meeting these challenges. The author summarizes developments in this field over the last fifteen years or so, and lists some common errors of design and construction that can cost a lot of money in retrofit if missed, but can easily be avoided with a little foresight, an appropriate testing program and a carefully thought out checklist.

Active and passive vibration suppression for space structures

NASA Technical Reports Server (NTRS)

Hyland, David C.

1991-01-01

The relative benefits of passive and active vibration suppression for large space structures (LSS) are discussed. The intent is to sketch the true ranges of applicability of these approaches using previously published technical results. It was found that the distinction between active and passive vibration suppression approaches is not as sharp as might be thought at first. The relative simplicity, reliability, and cost effectiveness touted for passive measures are vitiated by 'hidden costs' bound up with detailed engineering implementation issues and inherent performance limitations. At the same time, reliability and robustness issues are often cited against active control. It is argued that a continuum of vibration suppression measures offering mutually supporting capabilities is needed. The challenge is to properly orchestrate a spectrum of methods to reap the synergistic benefits of combined advanced materials, passive damping, and active control.

Modular Wideband Active Vibration Absorber

NASA Technical Reports Server (NTRS)

Zewari, Wahid; Lee, Kenneth Y.; Smith, David R.

1999-01-01

A comparison of space experiments with previous missions shows a common theme. Some of the recent experiments are based on the scientific fundamentals of instruments of prior years. However, the main distinguishing characteristic is the embodiment of advances in engineering and manufacturing in order to extract clearer and sharper images and extend the limits of measurement. One area of importance to future missions is providing vibration free observation platforms at acceptable costs. It has been shown by researchers that vibration problems cannot be eliminated by passive isolation techniques alone. Therefore, various organizations have conducted research in the area of combining active and passive vibration control techniques. The essence of this paper is to present progress in what is believed to be a new concept in this arena. It is based on the notion that if one active element in a vibration transmission path can provide a reasonable vibration attenuation, two active elements in series may provide more control options and better results. The paper presents the functions of a modular split shaft linear actuator developed by NASA's Goddard Space Flight Center and University of Massachusetts Lowell. It discusses some of the control possibilities facilitated by the device. Some preliminary findings and problems are also discussed.

Test and theory for piezoelectric actuator-active vibration control of rotating machinery

NASA Technical Reports Server (NTRS)

Palazzolo, A. B.; Lin, R. R.; Alexander, R. M.; Kascak, A. F.; Montague, J.

1989-01-01

The application of piezoelectric actuators for active vibration control (AVC) of rotating machinery is examined. Theory is derived and the resulting predictions are shown to agree closely with results of tests performed on an air turbine driven-overhung rotor. The test results show significant reduction in unbalance, transient and sub-synchronous responses. Results from a 30-hour endurance test support the AVD system reliability. Various aspects of the electro-mechanical stability of the control system are also discussed and illustrated. Finally, application of the AVC system to an actual jet engine is discussed.

Developing a Dynamics and Vibrations Course for Civil Engineering Students Based on Fundamental-Principles

ERIC Educational Resources Information Center

Barroso, Luciana R.; Morgan, James R.

2012-01-01

This paper describes the creation and evolution of an undergraduate dynamics and vibrations course for civil engineering students. Incorporating vibrations into the course allows students to see and study "real" civil engineering applications of the course content. This connection of academic principles to real life situations is in…

Shunted Piezoelectric Vibration Damping Analysis Including Centrifugal Loading Effects

NASA Technical Reports Server (NTRS)

Min, James B.; Duffy, Kirsten P.; Provenza, Andrew J.

2011-01-01

Excessive vibration of turbomachinery blades causes high cycle fatigue problems which require damping treatments to mitigate vibration levels. One method is the use of piezoelectric materials as passive or active dampers. Based on the technical challenges and requirements learned from previous turbomachinery rotor blades research, an effort has been made to investigate the effectiveness of a shunted piezoelectric for the turbomachinery rotor blades vibration control, specifically for a condition with centrifugal rotation. While ample research has been performed on the use of a piezoelectric material with electric circuits to attempt to control the structural vibration damping, very little study has been done regarding rotational effects. The present study attempts to fill this void. Specifically, the objectives of this study are: (a) to create and analyze finite element models for harmonic forced response vibration analysis coupled with shunted piezoelectric circuits for engine blade operational conditions, (b) to validate the experimental test approaches with numerical results and vice versa, and (c) to establish a numerical modeling capability for vibration control using shunted piezoelectric circuits under rotation. Study has focused on a resonant damping control using shunted piezoelectric patches on plate specimens. Tests and analyses were performed for both non-spinning and spinning conditions. The finite element (FE) shunted piezoelectric circuit damping simulations were performed using the ANSYS Multiphysics code for the resistive and inductive circuit piezoelectric simulations of both conditions. The FE results showed a good correlation with experimental test results. Tests and analyses of shunted piezoelectric damping control, demonstrating with plate specimens, show a great potential to reduce blade vibrations under centrifugal loading.

Detection on vehicle vibration induced by the engine shaking based on the laser triangulation

NASA Astrophysics Data System (ADS)

Chen, Wenxue; Yang, Biwu; Ni, Zhibin; Hu, Xinhan; Han, Tieqiang; Hu, Yaocheng; Zhang, Wu; Wang, Yunfeng

2017-10-01

The magnitude of engine shaking is chosen to evaluate the vehicle performance. The engine shaking is evaluated by the vehicle vibration. Based on the laser triangulation, the vehicle vibration is measured by detecting the distance variation between the bodywork and road surface. The results represent the magnitude of engine shaking. The principle and configuration of the laser triangulation is also introduced in this paper.

Torsional vibration of aircraft engines

NASA Technical Reports Server (NTRS)

Lurenbaum, Karl

1932-01-01

Exhaustive torsional-vibration investigations are required to determine the reliability of aircraft engines. A general outline of the methods used for such investigations and of the theoretical and mechanical means now available for this purpose is given, illustrated by example. True vibration diagrams are usually obtained from vibration measurements on the completed engine. Two devices for this purpose and supplementing each other, the D.V.L. torsiograph and the D.V.L. torsion recorder, are described in this report.

14 CFR 33.63 - Vibration.

Code of Federal Regulations, 2011 CFR

2011-01-01

... and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.63 Vibration. Each engine... range of rotational speeds and power/thrust, without inducing excessive stress in any engine part...

14 CFR 33.63 - Vibration.

Code of Federal Regulations, 2010 CFR

2010-01-01

... and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.63 Vibration. Each engine... range of rotational speeds and power/thrust, without inducing excessive stress in any engine part...

Embedded expert system for space shuttle main engine maintenance

NASA Technical Reports Server (NTRS)

Pooley, J.; Thompson, W.; Homsley, T.; Teoh, W.; Jones, J.; Lewallen, P.

1987-01-01

The SPARTA Embedded Expert System (SEES) is an intelligent health monitoring system that directs analysis by placing confidence factors on possible engine status and then recommends a course of action to an engineer or engine controller. The technique can prevent catastropic failures or costly rocket engine down time because of false alarms. Further, the SEES has potential as an on-board flight monitor for reusable rocket engine systems. The SEES methodology synergistically integrates vibration analysis, pattern recognition and communications theory techniques with an artificial intelligence technique - the Embedded Expert System (EES).

Detection of cylinder unbalance from Bayesian inference combining cylinder pressure and vibration block measurement in a Diesel engine

NASA Astrophysics Data System (ADS)

Nguyen, Emmanuel; Antoni, Jerome; Grondin, Olivier

2009-12-01

In the automotive industry, the necessary reduction of pollutant emission for new Diesel engines requires the control of combustion events. This control is efficient provided combustion parameters such as combustion occurrence and combustion energy are relevant. Combustion parameters are traditionally measured from cylinder pressure sensors. However this kind of sensor is expensive and has a limited lifetime. Thus this paper proposes to use only one cylinder pressure on a multi-cylinder engine and to extract combustion parameters from the other cylinders with low cost knock sensors. Knock sensors measure the vibration circulating on the engine block, hence they do not all contain the information on the combustion processes, but they are also contaminated by other mechanical noises that disorder the signal. The question is how to combine the information coming from one cylinder pressure and knock sensors to obtain the most relevant combustion parameters in all engine cylinders. In this paper, the issue is addressed trough the Bayesian inference formalism. In that cylinder where a cylinder pressure sensor is mounted, combustion parameters will be measured directly. In the other cylinders, they will be measured indirectly from Bayesian inference. Experimental results obtained on a four cylinder Diesel engine demonstrate the effectiveness of the proposed algorithm toward that purpose.

Technology for the Sound of Music

NASA Technical Reports Server (NTRS)

1994-01-01

In the early 1960s during an industry recession, Kaman Aircraft lost several defense contracts. Forced to diversify, the helicopter manufacturer began to manufacture acoustic guitars. Kaman's engineers used special vibration analysis equipment based on aerospace technology. While a helicopter's rotor system is highly susceptible to vibration, which must be reduced or "dampened," vibration enhances a guitar's sound. After two years of vibration analysis Kaman produced an instrument, which is very successful. The Ovation guitar is made of fiberglass. It is stronger than the traditional rosewood and manufactured with adapted aircraft techniques such as jigs and fixtures, reducing labor and assuring quality and cost control. Kaman Music Corporation now has annual sales of $100 million.

Control of Torsional Vibrations by Pendulum Masses

NASA Technical Reports Server (NTRS)

Stieglitz, Albert

1942-01-01

Various versions of pendulum masses have been developed abroad within the past few years by means of which resonant vibrations of rotating shafts can be eliminated at a given tuning. They are already successfully employed on radial engines in the form of pendulous counterweights. Compared with the commonly known torsional vibration dampers, the pendulum masses have the advantage of being structurally very simple, requiring no internal damping and being capable of completely eliminating certain vibrations. Unexplained, so far, remains the problem of behavior of pendulum masses in other critical zones to which they are not tuned, their dynamic behavior at some tuning other than in resonance, and their effect within a compound vibration system and at simultaneous application of several differently tuned pendulous masses. These problems are analyzed in the present report. The results constitute an enlargement of the scope of application of pendulum masses, especially for in-line engines. Among other things it is found that the natural frequency of a system can be raised by means of a correspondingly tuned pendulum mass. The formulas necessary for the design of any practical version are developed, and a pendulum mass having two different natural frequencies simultaneously is described.

Using Long-Short-Term-Memory Recurrent Neural Networks to Predict Aviation Engine Vibrations

NASA Astrophysics Data System (ADS)

ElSaid, AbdElRahman Ahmed

This thesis examines building viable Recurrent Neural Networks (RNN) using Long Short Term Memory (LSTM) neurons to predict aircraft engine vibrations. The different networks are trained on a large database of flight data records obtained from an airline containing flights that suffered from excessive vibration. RNNs can provide a more generalizable and robust method for prediction over analytical calculations of engine vibration, as analytical calculations must be solved iteratively based on specific empirical engine parameters, and this database contains multiple types of engines. Further, LSTM RNNs provide a "memory" of the contribution of previous time series data which can further improve predictions of future vibration values. LSTM RNNs were used over traditional RNNs, as those suffer from vanishing/exploding gradients when trained with back propagation. The study managed to predict vibration values for 1, 5, 10, and 20 seconds in the future, with 2.84% 3.3%, 5.51% and 10.19% mean absolute error, respectively. These neural networks provide a promising means for the future development of warning systems so that suitable actions can be taken before the occurrence of excess vibration to avoid unfavorable situations during flight.

Development of a measuring system for the analysis of vibrations sent from engine to passenger seat

NASA Astrophysics Data System (ADS)

Voicu, D.; Truta, M.; Barothi, L.; Stoica, R.; Dorobantu, G. I.

2017-10-01

The present paper aims at developing a measuring system for vibrations analysis of engine cylinder cover and passenger seat fixing device. Such a system is useful for analyzing the correlation, if any, between the vibrations generated by internal combustion engine and those felt by the passenger (which create a certain degree of discomfort).

Active Control Of Structure-Borne Noise

NASA Astrophysics Data System (ADS)

Elliott, S. J.

1994-11-01

The successful practical application of active noise control requires an understanding of both its acoustic limitations and the limitations of the electrical control strategy used. This paper is concerned with the active control of sound in enclosures. First, a review is presented of the fundamental physical limitations of using loudspeakers to achieve either global or local control. Both approaches are seen to have a high frequency limit, due to either the acoustic modal overlap, or the spatial correlation function of the pressure field. These physical performance limits could, in principle, be achieved with either a feedback or a feedforward control strategy. These strategies are reviewed and the use of adaptive digital filters is discussed for both approaches. The application of adaptive feedforward control in the control of engine and road noise in cars is described. Finally, an indirect approach to the active control of sound is discussed, in which the vibration is suppressed in the structural paths connecting the source of vibration to the enclosure. Two specific examples of this strategy are described, using an active automotive engine mount and the incorporation of actuators into helicopter struts to control gear-meshing tones. In both cases good passive design can minimize the complexity of the active controller.

Intelligent Control and Health Monitoring. Chapter 3

NASA Technical Reports Server (NTRS)

Garg, Sanjay; Kumar, Aditya; Mathews, H. Kirk; Rosenfeld, Taylor; Rybarik, Pavol; Viassolo, Daniel E.

2009-01-01

Advanced model-based control architecture overcomes the limitations state-of-the-art engine control and provides the potential of virtual sensors, for example for thrust and stall margin. "Tracking filters" are used to adapt the control parameters to actual conditions and to individual engines. For health monitoring standalone monitoring units will be used for on-board analysis to determine the general engine health and detect and isolate sudden faults. Adaptive models open up the possibility of adapting the control logic to maintain desired performance in the presence of engine degradation or to accommodate any faults. Improved and new sensors are required to allow sensing at stations within the engine gas path that are currently not instrumented due in part to the harsh conditions including high operating temperatures and to allow additional monitoring of vibration, mass flows and energy properties, exhaust gas composition, and gas path debris. The environmental and performance requirements for these sensors are summarized.

Application of Time-Delay Absorber to Suppress Vibration of a Dynamical System to Tuned Excitation.

PubMed

El-Ganaini, W A A; El-Gohary, H A

2014-08-01

In this work, we present a comprehensive investigation of the time delay absorber effects on the control of a dynamical system represented by a cantilever beam subjected to tuned excitation forces. Cantilever beam is one of the most widely used system in too many engineering applications, such as mechanical and civil engineering. The main aim of this work is to control the vibration of the beam at simultaneous internal and combined resonance condition, as it is the worst resonance case. Control is conducted via time delay absorber to suppress chaotic vibrations. Time delays often appear in many control systems in the state, in the control input, or in the measurements. Time delay commonly exists in various engineering, biological, and economical systems because of the finite speed of the information processing. It is a source of performance degradation and instability. Multiple time scale perturbation method is applied to obtain a first order approximation for the nonlinear differential equations describing the system behavior. The different resonance cases are reported and studied numerically. The stability of the steady-state solution at the selected worst resonance case is investigated applying Runge-Kutta fourth order method and frequency response equations via Matlab 7.0 and Maple11. Time delay absorber is effective, but within a specified range of time delay. It is the critical factor in selecting such absorber. Time delay absorber is better than the ordinary one as from the effectiveness point of view. The effects of the different absorber parameters on the system behavior and stability are studied numerically. A comparison with the available published work showed a close agreement with some previously published work.

Vibration control in smart coupled beams subjected to pulse excitations

NASA Astrophysics Data System (ADS)

Pisarski, Dominik; Bajer, Czesław I.; Dyniewicz, Bartłomiej; Bajkowski, Jacek M.

2016-10-01

In this paper, a control method to stabilize the vibration of adjacent structures is presented. The control is realized by changes of the stiffness parameters of the structure's couplers. A pulse excitation applied to the coupled adjacent beams is imposed as the kinematic excitation. For such a representation, the designed control law provides the best rate of energy dissipation. By means of a stability analysis, the performance in different structural settings is studied. The efficiency of the proposed strategy is examined via numerical simulations. In terms of the assumed energy metric, the controlled structure outperforms its passively damped equivalent by over 50 percent. The functionality of the proposed control strategy should attract the attention of practising engineers who seek solutions to upgrade existing damping systems.

Method of vibration isolating an aircraft engine

NASA Technical Reports Server (NTRS)

Bender, Stanley I. (Inventor); Butler, Lawrence (Inventor); Dawes, Peter W. (Inventor)

1991-01-01

A method for coupling an engine to a support frame for mounting to a fuselage of an aircraft using a three point vibration isolating mounting system in which the load reactive forces at each mounting point are statically and dynamically determined. A first vibration isolating mount pivotably couples a first end of an elongated support beam to a stator portion of an engine with the pivoting action of the vibration mount being oriented such that it is pivotable about a line parallel to a center line of the engine. An aft end of the supporting frame is coupled to the engine through an additional pair of vibration isolating mounts with the mounts being oriented such that they are pivotable about a circumference of the engine. The aft mounts are symmetrically spaced to each side of the supporting frame by 45 degrees. The relative orientation between the front mount and the pair of rear mounts is such that only the rear mounts provide load reactive forces parallel to the engine center line, in support of the engine to the aircraft against thrust forces. The forward mount is oriented so as to provide only radial forces to the engine and some lifting forces to maintain the engine in position adjacent a fuselage. Since each mount is connected to provide specific forces to support the engine, forces required of each mount are statically and dynamically determinable.

Engine classification using vibrations measured by Laser Doppler Vibrometer on different surfaces

NASA Astrophysics Data System (ADS)

Wei, J.; Liu, Chi-Him; Zhu, Zhigang; Vongsy, Karmon; Mendoza-Schrock, Olga

2015-05-01

In our previous studies, vehicle surfaces' vibrations caused by operating engines measured by Laser Doppler Vibrometer (LDV) have been effectively exploited in order to classify vehicles of different types, e.g., vans, 2-door sedans, 4-door sedans, trucks, and buses, as well as different types of engines, such as Inline-four engines, V-6 engines, 1-axle diesel engines, and 2-axle diesel engines. The results are achieved by employing methods based on an array of machine learning classifiers such as AdaBoost, random forests, neural network, and support vector machines. To achieve effective classification performance, we seek to find a more reliable approach to pick authentic vibrations of vehicle engines from a trustworthy surface. Compared with vibrations directly taken from the uncooperative vehicle surfaces that are rigidly connected to the engines, these vibrations are much weaker in magnitudes. In this work we conducted a systematic study on different types of objects. We tested different types of engines ranging from electric shavers, electric fans, and coffee machines among different surfaces such as a white board, cement wall, and steel case to investigate the characteristics of the LDV signals of these surfaces, in both the time and spectral domains. Preliminary results in engine classification using several machine learning algorithms point to the right direction on the choice of type of object surfaces to be planted for LDV measurements.

Analytical and experimental investigation on a multiple-mass-element pendulum impact damper for vibration mitigation

NASA Astrophysics Data System (ADS)

Egger, Philipp; Caracoglia, Luca

2015-09-01

Impact dampers are often used in the field of civil, mechanical and aerospace engineering for reducing structural vibrations. The behavior of this type of passive control device has been investigated for several decades. In this research a distributed-mass impact damper, similar to the "chain damper" used in wind engineering, has been examined and applied to the vibration reduction on a slender line-like structural element (stay-cable). This study is motivated by a practical problem and describes the derivation of a reduced-order model for explaining the behavior, observed during a field experiment on a prototype system. In its simplest form, the dynamics of the apparatus is modeled as a "resilient damper", composed of mass-spring-dashpot secondary elements, attached to the primary structure. Various sources of excitation are analyzed: free vibration, external harmonic force and random excitation. The proposed model is general and potentially applicable to the analysis of several structural systems. The study also shows that the model can adequately describe and explain the experimentally observed behavior.

Role of structural noise in aircraft pressure cockpit from vibration action of new-generation engines

NASA Astrophysics Data System (ADS)

Baklanov, V. S.

2016-07-01

The evolution of new-generation aircraft engines is transitioning from a bypass ratio of 4-6 to an increased ratio of 8-12. This is leading to substantial broadening of the vibration spectrum of engines with a shift to the low-frequency range due to decreased rotation speed of the fan rotor, in turn requiring new solutions to decrease structural noise from engine vibrations to ensure comfort in the cockpits and cabins of aircraft.

Data on the noise vibrations of modern traction locomotives. [auditory effects on diesel engine operators

NASA Technical Reports Server (NTRS)

Paslaru, V.; Popescu, A.; Vrasti, R.

1974-01-01

A survey is presented of data on noise and vibration sources in modern locomotives and their influence on engine drivers. An attempt is made hierarchize noise and vibration sources in terms of importance and to correlate the noise level with the influence of noise on the engine drivers' organ of hearing. Some possible recommendations are outlined for reducing the level of these noxae in order to improve the acoustic comfort of engine drivers.

Wireless alerting system using vibration for vehicles dashboard

NASA Astrophysics Data System (ADS)

Raj, Sweta; Rai, Shweta; Magaramagara, Wilbert; Sivacoumar, R.

2017-11-01

This paper aims at improving the engine life of any vehicle through a continuous measurement and monitoring of vital engine operational parameters and providing an effective alerting to drivers for any abnormality. Vehicles currently are using audio and visible alerting signals through alarms and light as a warning to the driver but these are not effective in noisy environments and during daylight. Through the use of the sense of feeling a driver can be alerted effectively. The need to no other vehicle parameter needs to be aided through the mobile display (phone).Thus a system is designed and implements to measure engine temperature, RPM, Oil level and Coolant level using appropriate sensors and a wireless communication (Bluetooth) is established to actuate a portable vibration control device and to read the different vehicle sensor readings through an android application for display and diagnosis.

Modelling and study of active vibration control for off-road vehicle

NASA Astrophysics Data System (ADS)

Zhang, Junwei; Chen, Sizhong

2014-05-01

In view of special working characteristics and structure, engineering machineries do not have conventional suspension system typically. Consequently, operators have to endure severe vibrations which are detrimental both to their health and to the productivity of the loader. Based on displacement control, a kind of active damping method is developed for a skid-steer loader. In this paper, the whole hydraulic system for active damping method is modelled which include swash plate dynamics model, proportional valve model, piston accumulator model, pilot-operated check valve model, relief valve model, pump loss model, and cylinder model. A new road excitation model is developed for the skid-steer loader specially. The response of chassis vibration acceleration to road excitation is verified through simulation. The simulation result of passive accumulator damping is compared with measurements and the comparison shows that they are close. Based on this, parallel PID controller and track PID controller with acceleration feedback are brought into the simulation model, and the simulation results are compared with passive accumulator damping. It shows that the active damping methods with PID controllers are better in reducing chassis vibration acceleration and pitch movement. In the end, the test work for active damping method is proposed for the future work.

Nonlinear Dynamics and Control of Flexible Structures

DTIC Science & Technology

1991-03-01

of which might be used for space applications. This project was a collaborative one involving structural, electrical and mechanical engineers and...methods for vibration analysis and new models to analyze chaotic dynamics in nonlinear structures with large deformations and friction forces. Finally... electrical and mechanical engineers and resulted in nine doctoral dissertations and two masters theses wholly or partially supported by this grant

Least Squares Computations in Science and Engineering

DTIC Science & Technology

1994-02-01

iterative least squares deblurring procedure. Because of the ill-posed characteristics of the deconvolution problem, in the presence of noise , direct...optimization methods. Generally, the problems are accompanied by constraints, such as bound constraints, and the observations are corrupted by noise . The...engineering. This effort has involved interaction with researchers in closed-loop active noise (vibration) control at Phillips Air Force Laboratory

An evaluation of the accuracy of the Federal Transit Administration approved, groundborne noise and vibration prediction model for rail transit systems; a case study for a new subway line using post construction, transit operation measurements

NASA Astrophysics Data System (ADS)

Carman, Richard A.; Reyes, Carlos H.

2005-09-01

The groundborne noise and vibration model developed by Nelson and Saurenman in 1984, now recognized by the Federal Transit Administration as the approved model for new transit system facilities, is entering its third decade of use by engineers and consultants in the transit industry. The accuracy of the model has been explored in the past (e.g., Carman and Wolfe). New data obtained for a recently completed extension to a major heavy rail transit system provides an opportunity to evaluate the accuracy of the model once more. During the engineering design phase of the project, noise and vibration predictions were performed for numerous buildings adjacent to the new subway line. The values predicted by the model were used to determine the need for and type of noise and/or vibration control measures. After the start of transit operations on the new line, noise and vibration measurements were made inside several of the buildings to determine whether the criteria were in fact achieved. The measurement results are compared with the values predicted by the model. The predicted and measured, overall noise and vibration levels show very good agreement, whereas the spectral comparisons indicate some differences. Possible reasons for these differences are offered.

Inter-noise 89 - Engineering for environmental noise control; Proceedings of the International Conference on Noise Control Engineering, Newport Beach, CA, Dec. 4-6, 1989. Vols. 1 & 2

NASA Astrophysics Data System (ADS)

Maling, George C., Jr.

Recent advances in noise analysis and control theory and technology are discussed in reviews and reports. Topics addressed include noise generation; sound-wave propagation; noise control by external treatments; vibration and shock generation, transmission, isolation, and reduction; multiple sources and paths of environmental noise; noise perception and the physiological and psychological effects of noise; instrumentation, signal processing, and analysis techniques; and noise standards and legal aspects. Diagrams, drawings, graphs, photographs, and tables of numerical data are provided.

The performance of a piezoelectric-sensor-based SHM system under a combined cryogenic temperature and vibration environment

NASA Astrophysics Data System (ADS)

Qing, Xinlin P.; Beard, Shawn J.; Kumar, Amrita; Sullivan, Kevin; Aguilar, Robert; Merchant, Munir; Taniguchi, Mike

2008-10-01

A series of tests have been conducted to determine the survivability and functionality of a piezoelectric-sensor-based active structural health monitoring (SHM) SMART Tape system under the operating conditions of typical liquid rocket engines such as cryogenic temperature and vibration loads. The performance of different piezoelectric sensors and a low temperature adhesive under cryogenic temperature was first investigated. The active SHM system for liquid rocket engines was exposed to flight vibration and shock environments on a simulated large booster LOX-H2 engine propellant duct conditioned to cryogenic temperatures to evaluate the physical robustness of the built-in sensor network as well as operational survivability and functionality. Test results demonstrated that the developed SMART Tape system can withstand operational levels of vibration and shock energy on a representative rocket engine duct assembly, and is functional under the combined cryogenic temperature and vibration environment.

Novel magnetically induced membrane vibration (MMV) for fouling control in membrane bioreactors.

PubMed

Bilad, Muhammad R; Mezohegyi, Gergo; Declerck, Priscilla; Vankelecom, Ivo F J

2012-01-01

Conventional submerged membrane bioreactors (MBRs) rely on the coarse bubbles aeration to generate shear at the liquid-membrane interface to limit membrane fouling. Unfortunately, it is a very energy consuming method, still often resulting in a rapid decrease of membrane permeability and consequently in higher expenses. In this paper, the feasibility of a novel magnetically induced membrane vibration (MMV) system was studied in a lab-scale MBR treating synthetic wastewater. The effects on membrane fouling of applied electrical power of different operation strategies, of membrane flux and of the presence of multiple membranes on one vibrating engine on membrane fouling were investigated. The filtration performance was evaluated by determining the filtration resistance profiles and critical flux. The results showed clear advantages of the vibrating system over conventional MBR processes by ensuring higher fluxes at lower fouling rates. Intermittent vibration was found a promising strategy for both efficient fouling control and significant energy saving. The optimised MMV system is presumed to lead to significant energy and cost reduction in up-scaled MBR operations. Copyright © 2011 Elsevier Ltd. All rights reserved.

Progress in industrial holography in France

NASA Astrophysics Data System (ADS)

Smigielski, Paul

1992-01-01

Industrial applications of holography in France are briefly reviewed. Particular attention is given to nondestructive testing of helicopter blades at Aerospatiale Central Laboratory, the use of holography at Renault for car-engine vibration study, vibration characterization of turbo-jet engine components at SNECMA, and vibration analysis of plates in an industrial hemodynamic tunnel.

Rocket Engine Nozzle Side Load Transient Analysis Methodology: A Practical Approach

NASA Technical Reports Server (NTRS)

Shi, John J.

2005-01-01

During the development stage, in order to design/to size the rocket engine components and to reduce the risks, the local dynamic environments as well as dynamic interface loads must be defined. There are two kinds of dynamic environment, i.e. shock transients and steady-state random and sinusoidal vibration environments. Usually, the steady-state random and sinusoidal vibration environments are scalable, but the shock environments are not scalable. In other words, based on similarities only random vibration environments can be defined for a new engine. The methodology covered in this paper provides a way to predict the shock environments and the dynamic loads for new engine systems and new engine components in the early stage of new engine development or engine nozzle modifications.

Max Launch Abort System (MLAS) Pad Abort Test Vehicle (PATV) II Attitude Control System (ACS) Integration and Pressurization Subsystem Dynamic Random Vibration Analysis

NASA Technical Reports Server (NTRS)

Ekrami, Yasamin; Cook, Joseph S.

2011-01-01

In order to mitigate catastrophic failures on future generation space vehicles, engineers at the National Aeronautics and Space Administration have begun to integrate a novel crew abort systems that could pull a crew module away in case of an emergency at the launch pad or during ascent. The Max Launch Abort System (MLAS) is a recent test vehicle that was designed as an alternative to the baseline Orion Launch Abort System (LAS) to demonstrate the performance of a "tower-less" LAS configuration under abort conditions. The MLAS II test vehicle will execute a propulsive coast stabilization maneuver during abort to control the vehicles trajectory and thrust. To accomplish this, the spacecraft will integrate an Attitude Control System (ACS) with eight hypergolic monomethyl hydrazine liquid propulsion engines that are capable of operating in a quick pulsing mode. Two main elements of the ACS include a propellant distribution subsystem and a pressurization subsystem to regulate the flow of pressurized gas to the propellant tanks and the engines. The CAD assembly of the Attitude Control System (ACS) was configured and integrated into the Launch Abort Vehicle (LAV) design. A dynamic random vibration analysis was conducted on the Main Propulsion System (MPS) helium pressurization panels to assess the response of the panel and its components under increased gravitational acceleration loads during flight. The results indicated that the panels fundamental and natural frequencies were farther from the maximum Acceleration Spectral Density (ASD) vibrations which were in the range of 150-300 Hz. These values will direct how the components will be packaged in the vehicle to reduce the effects high gravitational loads.

Laser vibrometry exploitation for vehicle identification

NASA Astrophysics Data System (ADS)

Nolan, Adam; Lingg, Andrew; Goley, Steve; Sigmund, Kevin; Kangas, Scott

2014-06-01

Vibration signatures sensed from distant vehicles using laser vibrometry systems provide valuable information that may be used to help identify key vehicle features such as engine type, engine speed, and number of cylinders. Through the use of physics models of the vibration phenomenology, features are chosen to support classification algorithms. Various individual exploitation algorithms were developed using these models to classify vibration signatures into engine type (piston vs. turbine), engine configuration (Inline 4 vs. Inline 6 vs. V6 vs. V8 vs. V12) and vehicle type. The results of these algorithms will be presented for an 8 class problem. Finally, the benefits of using a factor graph representation to link these independent algorithms together will be presented which constructs a classification hierarchy for the vibration exploitation problem.

Engine-Vibration Analyzer

NASA Technical Reports Server (NTRS)

Tolmei, V. R.

1982-01-01

Proposed circuit would monitor vibration spectrum of engines under test or in service. It could detect subtle out-of-specification conditions and could be programed to shut down engine if an out-of-limits condition develops. Possible uses of monitor are in bench testing automobiles and outboard motors and as a safety device in very critical engine applications.

Diesel Engine Valve Clearance Fault Diagnosis Based on Features Extraction Techniques and FastICA-SVM

NASA Astrophysics Data System (ADS)

Jing, Ya-Bing; Liu, Chang-Wen; Bi, Feng-Rong; Bi, Xiao-Yang; Wang, Xia; Shao, Kang

2017-07-01

Numerous vibration-based techniques are rarely used in diesel engines fault diagnosis in a direct way, due to the surface vibration signals of diesel engines with the complex non-stationary and nonlinear time-varying features. To investigate the fault diagnosis of diesel engines, fractal correlation dimension, wavelet energy and entropy as features reflecting the diesel engine fault fractal and energy characteristics are extracted from the decomposed signals through analyzing vibration acceleration signals derived from the cylinder head in seven different states of valve train. An intelligent fault detector FastICA-SVM is applied for diesel engine fault diagnosis and classification. The results demonstrate that FastICA-SVM achieves higher classification accuracy and makes better generalization performance in small samples recognition. Besides, the fractal correlation dimension and wavelet energy and entropy as the special features of diesel engine vibration signal are considered as input vectors of classifier FastICA-SVM and could produce the excellent classification results. The proposed methodology improves the accuracy of feature extraction and the fault diagnosis of diesel engines.

Viking 1975 Orbiter Development Test Model/Lander Dynamic Test Model dynamic environmental testing - An overview

NASA Technical Reports Server (NTRS)

Milder, G.

1975-01-01

The current work presents an overview of the Viking 1975 environmental testing from an engineering standpoint. An extremely large vibration test fixture had to be designed, analyzed, and integrated into a test setup that employed hydrostatic bearings in a new fashion. A vibration control system was also required that would allow for thirty-six channels of sine-wave peak select control from acceleration, force-of-strain transducers. In addition, some 68 channels of peak limiting shutdown capability were needed for backup and monitoring of other data during the forced vibration test. Pretesting included analyses of the fixture design, overturning moment, control system capabilities, and response of the entire spacecraft/fixture/exciter system to the test environment. Closed-loop control for acoustic testing was a necessity due to the fact that the Viking spacecraft took up a major portion of the volume of the 10,000 cu ft chamber. The spacecraft emerged from testing undamaged.

Baseline Experiment for Active Control of Structural Vibrations

DTIC Science & Technology

1989-12-01

like to thank iy wife , Lynette, for marrying an engineer. Although she didn’t always understand what ! was U ii Avallab1tY CodeA . Dlst Special doing...actuators. The structural dynamics , haker 0 used for the modified ABE provided sufficient and predictable control force, and there are "off the shelf

Remote control circuit breaker evaluation testing. [for space shuttles

NASA Technical Reports Server (NTRS)

Bemko, L. M.

1974-01-01

Engineering evaluation tests were performed on several models/types of remote control circuit breakers marketed in an attempt to gain some insight into their potential suitability for use on the space shuttle vehicle. Tests included the measurement of several electrical and operational performance parameters under laboratory ambient, space simulation, acceleration and vibration environmental conditions.

The three-hinged arch as an example of piezomechanic passive controlled structure

NASA Astrophysics Data System (ADS)

Pagnini, Luisa Carlotta; Piccardo, Giuseppe

2016-09-01

Although piezoelectric transducers are employed in a variety of fields, their application for vibration control of civil or industrial structures has not yet been fully developed, at the best of authors' knowledge. Thanks to a new generation of ever more performing piezoceramic materials and to the recent development of scientific proposals based on a very simple technology, this paper presents a step forward to engineering applications for the control of structural systems. A three-hinged arch controlled by piezoelectric stack actuators and passive RL electrical circuits is chosen as a simple structural model that may represent the starting point for a generalization to the most common typologies of civil and industrial engineering structures. Based on the concept of electromechanical analogy, the evolution equations are obtained through a consistent Lagrangian approach. A multimodal vibration suppression is guaranteed by the spectral analogy between the mechanical and electrical components. Preliminary applications related to free oscillations, with one or more actuators on each member, seem to lead to excellent performance in terms of multimodal damping and dissipated energy.

Stochastic stability assessment of a semi-free piston engine generator concept

NASA Astrophysics Data System (ADS)

Kigezi, T. N.; Gonzalez Anaya, J. A.; Dunne, J. F.

2016-09-01

Small engines, as power generators with low-noise and vibration characteristics, are needed in two niche application areas: as electric vehicle range extenders and as domestic micro Combined Heat and Power systems. A recent semi-free piston design known as the AMOCATIC generator fully meets this requirement. The engine potentially allows for high energy conversion efficiencies at resonance derived from having a mass and spring assembly. As with free-piston engines in general, stability and control of piston motion has been cited as the prime challenge limiting the technology's widespread application. Using physical principles, we derive in this paper two important results: an energy balance criterion and a related general stability criterion for a semi-free piston engine. Control is achieved by systematically designing a Proportional Integral (PI) controller using a control-oriented engine model for which a specific stability condition is stated. All results are presented in closed form throughout the paper. Simulation results under stochastic pressure conditions show that the proposed energy balance, stability criterion, and PI controller, operate as predicted to yield stable engine operation at fixed compression ratio.

Demonstration of a Speckle Based Sensing with Pulse-Doppler Radar for Vibration Detection.

PubMed

Ozana, Nisan; Bauer, Reuven; Ashkenazy, Koby; Sasson, Nissim; Schwarz, Ariel; Shemer, Amir; Zalevsky, Zeev

2018-05-03

In previous works, an optical technique for extraction and separation of remote static vibrations has been demonstrated. In this paper, we will describe an approach in which RF speckle movement is used to extract remote vibrations of a static target. The use of conventional radar Doppler methods is not suitable for detecting vibrations of static targets. In addition, the speckle method has an important advantage, in that it is able to detect vibrations at far greater distances than what is normally detected in classical optical methods. The experiment described in this paper was done using a motorized vehicle, which engine was turned on and off. The results showed that the system was able to distinguish between the different engine states, and in addition, was able to determine the vibration frequency of the engine. The first step towards real time detection of human vital signs using RF speckle patterns is presented.

Turbine blade vibration dampening

DOEpatents

Cornelius, C.C.; Pytanowski, G.P.; Vendituoli, J.S.

1997-07-08

The present turbine wheel assembly increases component life and turbine engine longevity. The combination of the strap and the opening combined with the preestablished area of the outer surface of the opening and the preestablished area of the outer circumferential surface of the strap and the friction between the strap and the opening increases the life and longevity of the turbine wheel assembly. Furthermore, the mass ``M`` or combined mass ``CM`` of the strap or straps and the centrifugal force assist in controlling vibrations and damping characteristics. 5 figs.

Turbine blade vibration dampening

DOEpatents

Cornelius, Charles C.; Pytanowski, Gregory P.; Vendituoli, Jonathan S.

1997-07-08

The present turbine wheel assembly increases component life and turbine engine longevity. The combination of the strap and the opening combined with the preestablished area of the outer surface of the opening and the preestablished area of the outer circumferential surface of the strap and the friction between the strap and the opening increases the life and longevity of the turbine wheel assembly. Furthermore, the mass "M" or combined mass "CM" of the strap or straps and the centrifugal force assist in controlling vibrations and damping characteristics.

On-Orbit System Identification

NASA Technical Reports Server (NTRS)

Mettler, E.; Milman, M. H.; Bayard, D.; Eldred, D. B.

1987-01-01

Information derived from accelerometer readings benefits important engineering and control functions. Report discusses methodology for detection, identification, and analysis of motions within space station. Techniques of vibration and rotation analyses, control theory, statistics, filter theory, and transform methods integrated to form system for generating models and model parameters that characterize total motion of complicated space station, with respect to both control-induced and random mechanical disturbances.

A review and forecast of engine system research at the Army Propulsion Directorate

NASA Technical Reports Server (NTRS)

Bobula, George A.

1989-01-01

An account is given of the development status and achievements to date of the U.S. Army Propulsion Directorate's Small Turbine Engine Research (STER) programs, which are experimental investigations of the physics of entire engine systems from the viewpoints of component interactions and/or system dynamics. STER efforts are oriented toward the evaluation of complete turboshaft engine advanced concepts and are conducted at the ECRL-2 indoor, sea-level engine test facility. Attention is given to the results obtained by STER experiments concerned with IR-suppressing engine exhausts, a ceramic turbine-blade shroud, an active shaft-vibration control system, and a ceramic-matrix combustor liner.

Analyses of electromagnetic and piezoelectric systems for efficient vibration energy harvesting

NASA Astrophysics Data System (ADS)

Hadas, Z.; Smilek, J.; Rubes, O.

2017-05-01

The paper deals with analyses and evaluation of vibration energy harvesting systems which are based on electromagnetic and piezoelectric physical principles off electro-mechanical conversion. Energy harvesting systems are associated with wireless sensors and a monitoring of engineering objects. The most of engineering objects operate with unwanted mechanical vibrations. However, vibrations could provide an ambient source of energy which is converted into useful electricity. The use of electromagnetic and piezoelectric vibration energy harvesters is analyzed in this paper. Thee evaluated output power is used for a choice of the efficient system with respect to the character of vibrations and thee required power output.

Semi-active engine mount design using auxiliary magneto-rheological fluid compliance chamber

NASA Astrophysics Data System (ADS)

Mansour, H.; Arzanpour, S.; Golnaraghi, M. F.; Parameswaran, A. M.

2011-03-01

Engine mounts are used in the automotive industry to isolate engine and chassis by reducing the noise and vibration imposed from one to the other. This paper describes modelling, simulation and design of a semi-active engine mount that is designed specifically to address the complicated vibration pattern of variable displacement engines (VDE). The ideal isolation for VDE requires the stiffness to be switchable upon cylinder activation/deactivation operating modes. In order to have a modular design, the same hydraulic engine mount components are maintained and a novel auxiliary magneto-rheological (MR) fluid chamber is developed and retrofitted inside the pumping chamber. The new compliance chamber is a controllable pressure regulator, which can effectively alter the dynamic performance of the mount. Switching between different modes happens by turning the electrical current to the MR chamber magnetic coil on and off. A model has been developed for the passive hydraulic mount and then it is extended to include the MR auxiliary chamber as well. A proof-of-concept prototype of the design has been fabricated which validates the mathematical model. The results demonstrate unique capability of the developed semi-active mount to be used for VDE application.

ENGINEERING APPLICATIONS OF ANALOG COMPUTERS

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

Bryant, L.T.; Janicke, M.J.; Just, L.C.

1961-02-01

Six examples are given of the application of analog computers in the fields of reactor engineering, heat transfer, and dynamics: deceleration of a reactor control rod by dashpot, pressure variations through a packed bed, reactor kinetics over many decades with thermal feedback (simulation of a TREAT transient), vibrating system with two degrees of freedom, temperature distribution in a radiating fin, and temperature distribution in an irfinite slab with variable thermal properties. (D.L.C.)

Experience with Geared Propeller Drives for Aviation Engines

NASA Technical Reports Server (NTRS)

Kutzbach, K

1920-01-01

I. The development of the gear wheels: (a) bending stresses; (b) compressive stresses; (c) heating; (d) precision of manufacture. II. General arrangement of the gearing. III. Vibration in the shaft transmission. An overview is given of experience with geared propeller drives for aviation engines. The development of gear wheels is discussed with emphasis upon bending stresses, compressive stresses, heating, and precision in manufacturing. With respect to the general arrangement of gear drives for airplanes, some principal rules of mechanical engineering that apply with special force are noted. The primary vibrations in the shaft transmission are discussed. With respect to vibration, various methods for computing vibration frequency and the influence of elastic couplings are discussed.

640 x 480 PtSi infrared engine

NASA Astrophysics Data System (ADS)

Lang, Frank B.; Coyle, Peter J.; Stabile, Paul J.; Tower, John R.; Zubalsky, I.; Ornstein, Itzhak

1996-06-01

The design and performance of a compact, light-weight, low power infrared engine is presented. The 3 - 5 micron MWIR imaging subsystem consists of a Stirling-cooled, 640 (H) by 480 (V) staring PtSi infrared focal plane array (IRFPA) with associated drive and analog video processing electronics. The IR engine provides user-selectable integration time control. This infrared imaging subsystem is designed to be gimbal-mounted, and has been qualified to be operated in minus 10 Celsius to plus 50 Celsius environments. The infrared engine is also designed to meet the requirements of demanding shock and vibration environments.

Fundamental study of subharmonic vibration of order 1/2 in automatic transmissions for cars

NASA Astrophysics Data System (ADS)

Ryu, T.; Nakae, T.; Matsuzaki, K.; Nanba, A.; Takikawa, Y.; Ooi, Y.; Sueoka, A.

2016-09-01

A torque converter is an element that transfers torque from the engine to the gear train in the automatic transmission of an automobile. The damper spring of the lock-up clutch in the torque converter is used to effectively absorb the torsional vibration caused by engine combustion. A damper with low stiffness reduces fluctuations in rotational speed but is difficult to use because of space limitations. In order to address this problem, the damper is designed using a piecewise-linear spring with three stiffness stages. However, the damper causes a nonlinear vibration referred to as a subharmonic vibration of order 1/2. In the subharmonic vibration, the frequency is half that of the vibrations from the engine. In order to clarify the mechanism of the subharmonic vibration, in the present study, experiments are conducted using the fundamental experimental apparatus of a single-degree-of-freedom system with two stiffness stages. In the experiments, countermeasures to reduce the subharmonic vibration by varying the conditions of the experiments are also performed. The results of the experiments are evaluated through numerical analysis using the shooting method. The experimental and analytical results were found to be in close agreement.

A New 1000 F Magnetic Bearing Test Rig

NASA Technical Reports Server (NTRS)

Kascak, Albert F.; Montague, Gerald T.; Brown, Gerald V.; Palazzolo, Alan B.

1997-01-01

NASA and the Army are currently exploring the possibility of using magnetic bearings in gas turbine engines. The use of magnetic bearings in gas turbine engines could increase the reliability by eliminating the lubrication system. The use of magnetic bearings could also increase the speed and the size of the shafts in the engine, thus reducing vibrations and possibly eliminating third bearings. Magnetic bearings can apply forces to the shafts and move them so that blade tips and seals do not rub. This could be part of an active vibration cancellation system. Also, whirling (displacing the shaft center line) may delay rotating stall and increase the stall margin of the engine. Magnetic bearings coupled with an integral starter generator could result in a more efficient 'more electric' engine. The IHPTET program, a joint DOD-industry program, has identified a need for a high temperature, (as high as 1200 F), magnetic bearing that could be demonstrated in a phase m engine. A magnetic bearing is similar to an electric motor. The magnetic bearing has a laminated rotor and stator made out of cobalt steel. The stator has a series of coils of wire wound around it. These coils f u. a series of electromagnets around the circumference. These magnets exert a force on the rotor to keep the rotor in the center of the cavity. The centering force is commanded by a controller based on shaft position, (measured by displacement probes). The magnetic bearing can only pull and is basically unstable before active control is applied The engine shafts, bearings, and case form a flexible structure which contain a large number of modes. A controller is necessary to stabilize these modes. A power amplifier is also necessary to provide the current prescribed by the controller to the magnetic bearings. In case of very high loads, a conventional back up bearing will engage and stop the rotor and stator from rubbing.

Active Piezoelectric Vibration Control of Subscale Composite Fan Blades

NASA Technical Reports Server (NTRS)

Duffy, Kirsten P.; Choi, Benjamin B.; Provenza, Andrew J.; Min, James B.; Kray, Nicholas

2012-01-01

As part of the Fundamental Aeronautics program, researchers at NASA Glenn Research Center (GRC) are investigating new technologies supporting the development of lighter, quieter, and more efficient fans for turbomachinery applications. High performance fan blades designed to achieve such goals will be subjected to higher levels of aerodynamic excitations which could lead to more serious and complex vibration problems. Piezoelectric materials have been proposed as a means of decreasing engine blade vibration either through a passive damping scheme, or as part of an active vibration control system. For polymer matrix fiber composite blades, the piezoelectric elements could be embedded within the blade material, protecting the brittle piezoceramic material from the airflow and from debris. To investigate this idea, spin testing was performed on two General Electric Aviation (GE) subscale composite fan blades in the NASA GRC Dynamic Spin Rig Facility. The first bending mode (1B) was targeted for vibration control. Because these subscale blades are very thin, the piezoelectric material was surface-mounted on the blades. Three thin piezoelectric patches were applied to each blade two actuator patches and one small sensor patch. These flexible macro-fiber-composite patches were placed in a location of high resonant strain for the 1B mode. The blades were tested up to 5000 rpm, with patches used as sensors, as excitation for the blade, and as part of open- and closed-loop vibration control. Results show that with a single actuator patch, active vibration control causes the damping ratio to increase from a baseline of 0.3% critical damping to about 1.0% damping at 0 RPM. As the rotor speed approaches 5000 RPM, the actively controlled blade damping ratio decreases to about 0.5% damping. This occurs primarily because of centrifugal blade stiffening, and can be observed by the decrease in the generalized electromechanical coupling with rotor speed.

Hardware interface for isolation of vibrations in flexible manipulators: Development and applications

NASA Technical Reports Server (NTRS)

Manouchehri, Davoud; Lindsay, Thomas; Ghosh, David

1994-01-01

NASA's Langley Research Center (LaRC) is addressing the problem of isolating the vibrations of the Shuttle remote manipulator system (RMS) from its end-effector and/or payload by modeling an RMS flat-floor simulator with a dynamic payload. Analysis of the model can lead to control techniques that will improve the speed, accuracy, and safety of the RMS in capturing satellites and eventually facilitate berthing with the space station. Rockwell International Corporation, also involved in vibration isolation, has developed a hardware interface unit to isolate the end-effector from the vibrations of an arm on a Shuttle robotic tile processing system (RTPS). To apply the RTPS isolation techniques to long-reach arms like the RMS, engineers have modeled the dynamics of the hardware interface unit with simulation software. By integrating the Rockwell interface model with the NASA LaRC RMS simulator model, investigators can study the use of a hardware interface to isolate dynamic payloads from the RMS. The interface unit uses both active and passive compliance and damping for vibration isolation. Thus equipped, the RMS could be used as a telemanipulator with control characteristics for capture and berthing operations. The hardware interface also has applications in industry.

Blading System and Method For Controlling Structural Vibrations

NASA Technical Reports Server (NTRS)

Nguyen, Nhan (Inventor)

2000-01-01

A new blading system for controlling the structural vibrations in axial-flow compressors, turbines, or fans, as in aircraft engines and like turbomachines including a stator disc and a rotor disc is presented. The rotor disc defines several radial hubs that retain the rotor blading systems. Each blading system includes a blade formed of an airfoil, and a root attachment which is dimensioned to fit within, and to engage a corresponding hub. Viscoelastic dampers are selectively applied to the outer surfaces of the root attachment on which compressive or shear forces are likely to develop, intermediate the root attachment and the hub, for compression therebetween upon rotation of the rotor disc, in order to dampen structural vibrations. One advantage presented by the viscoelastic dampers lies in its simplicity, efficiency, cost effectiveness, and its ability to be retrofitted into existing turbomachines with minor surface treatment of the root attachments. Furthermore, since the dampers are not exposed to the inflowing airstream, they do not affect the aerodynamic performance of the turbomachine. Another feature of the damping system is that it provides a significant source of damping to minimize destructive structural vibrations, thereby increasing the durability of the turbomachine, and reducing acoustic noise accompanying high amplitude vibrations.

In situ damage monitoring in vibration mechanics: diagnostics and predictive maintenance

NASA Astrophysics Data System (ADS)

Basseville, M.; Benveniste, A.; Gach-Devauchelle, B.; Goursat, M.; Bonnecase, D.; Dorey, P.; Prevosto, M.; Olagnon, M.

1993-09-01

A system identification approach is presented for damage monitoring in vibration mechanics. Identification, detection, and diagnostics are performed using accelerometer measurements from the system at work so that the excitation is not controlled, usually not observed and may involve turbulent phenomena. Targeted applications include power engineering (rotating machines, core and pipes of nuclear power plants), civil engineering (large buildings subject to hurricanes or earthquakes, bridges, dams, offshore structures), aeronautics (wings and other structures subject to strength), automobile, rail transportation etc. The method is illustrated by a laboratory example, and the results of 3 years industrial usage. This paper is a progress report on a 10 year project involving three people almost permanently. We describe here the whole approach but omit the technical details which are available in previous papers.

The Impact of Complex Forcing on the Viscous Torsional Vibration Damper's Work in the Crankshaft of the Rotating Combustion Engine

NASA Astrophysics Data System (ADS)

Jagiełowicz-Ryznar, C.

2016-12-01

The numerical calculations results of torsional vibration of the multi-cylinder crankshaft in the serial combustion engine (MC), including a viscous damper (VD), at complex forcing, were shown. In fact, in the MC case the crankshaft rotation forcings spectrum is the sum of harmonic forcing whose amplitude can be compared with the amplitude of the 1st harmonic. A significant impact, in the engine operational velocity, on the vibration damping process of MC, may be the amplitude of the 2nd harmonic of a forcing moment. The calculations results of MC vibration, depending on the amplitude of the 2nd harmonic of the forcing moment, for the first form of the torsional vibration, were shown. Higher forms of torsional vibrations have no practical significance. The calculations assume the optimum damping coefficient VD, when the simple harmonic forcing is equal to the base critical velocity of the MC crankshaft.

The Study the Vibration Condition of the Blade of the Gas Turbine Engine with an All-metal Wire Rope Damper in the Area Mount of the Blade to the Disk

NASA Astrophysics Data System (ADS)

Melentjev, Vladimir S.; Gvozdev, Alexander S.

2018-01-01

Improving the reliability of modern turbine engines is actual task. This is achieved due to prevent a vibration damage of the operating blades. On the department of structure and design of aircraft engines have accumulated a lot of experimental data on the protection of the blades of the gas turbine engine from a vibration. In this paper we proposed a method for calculating the characteristics of wire rope dampers in the root attachment of blade of a gas turbine engine. The method is based on the use of the finite element method and transient analysis. Contact interaction (Lagrange-Euler method) between the compressor blade and the disc of the rotor has been taken into account. Contribution of contact interaction between details in damping of the system was measured. The proposed method provides a convenient way for the iterative selection of the required parameters the wire rope elastic-damping element. This element is able to provide the necessary protection from the vibration for the blade of a gas turbine engine.

Multiple-source multiple-harmonic active vibration control of variable section cylindrical structures: A numerical study

NASA Astrophysics Data System (ADS)

Liu, Jinxin; Chen, Xuefeng; Gao, Jiawei; Zhang, Xingwu

2016-12-01

Air vehicles, space vehicles and underwater vehicles, the cabins of which can be viewed as variable section cylindrical structures, have multiple rotational vibration sources (e.g., engines, propellers, compressors and motors), making the spectrum of noise multiple-harmonic. The suppression of such noise has been a focus of interests in the field of active vibration control (AVC). In this paper, a multiple-source multiple-harmonic (MSMH) active vibration suppression algorithm with feed-forward structure is proposed based on reference amplitude rectification and conjugate gradient method (CGM). An AVC simulation scheme called finite element model in-loop simulation (FEMILS) is also proposed for rapid algorithm verification. Numerical studies of AVC are conducted on a variable section cylindrical structure based on the proposed MSMH algorithm and FEMILS scheme. It can be seen from the numerical studies that: (1) the proposed MSMH algorithm can individually suppress each component of the multiple-harmonic noise with an unified and improved convergence rate; (2) the FEMILS scheme is convenient and straightforward for multiple-source simulations with an acceptable loop time. Moreover, the simulations have similar procedure to real-life control and can be easily extended to physical model platform.

Reliability-based optimization of an active vibration controller using evolutionary algorithms

NASA Astrophysics Data System (ADS)

Saraygord Afshari, Sajad; Pourtakdoust, Seid H.

2017-04-01

Many modern industrialized systems such as aircrafts, rotating turbines, satellite booms, etc. cannot perform their desired tasks accurately if their uninhibited structural vibrations are not controlled properly. Structural health monitoring and online reliability calculations are emerging new means to handle system imposed uncertainties. As stochastic forcing are unavoidable, in most engineering systems, it is often needed to take them into the account for the control design process. In this research, smart material technology is utilized for structural health monitoring and control in order to keep the system in a reliable performance range. In this regard, a reliability-based cost function is assigned for both controller gain optimization as well as sensor placement. The proposed scheme is implemented and verified for a wing section. Comparison of results for the frequency responses is considered to show potential applicability of the presented technique.

KENNEDY SPACE CENTER, FLA. - The crawler-transporter carrying Mobile Launcher Platform (MLP) number 3, with a set of twin solid rocket boosters bolted atop, crawls to the intersection in the crawlerway in support of the second engineering analysis vibration test on the crawler and MLP. From this perspective, the Launch Control Center (left) and the 525-foot-tall Vehicle Assembly Building (right) in the background appear dwarfed by the 184-foot-tall boosters. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-21

KENNEDY SPACE CENTER, FLA. - The crawler-transporter carrying Mobile Launcher Platform (MLP) number 3, with a set of twin solid rocket boosters bolted atop, crawls to the intersection in the crawlerway in support of the second engineering analysis vibration test on the crawler and MLP. From this perspective, the Launch Control Center (left) and the 525-foot-tall Vehicle Assembly Building (right) in the background appear dwarfed by the 184-foot-tall boosters. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - A crawler-transporter carrying Mobile Launcher Platform (MLP) number 3, with a set of twin solid rocket boosters bolted atop, crawls to the intersection in the crawlerway in support of the second engineering analysis vibration test on the crawler and MLP. From this perspective, the Launch Control Center (left) and the 525-foot-tall Vehicle Assembly Building (right) in the background appear dwarfed by the 184-foot-tall boosters. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-21

KENNEDY SPACE CENTER, FLA. - A crawler-transporter carrying Mobile Launcher Platform (MLP) number 3, with a set of twin solid rocket boosters bolted atop, crawls to the intersection in the crawlerway in support of the second engineering analysis vibration test on the crawler and MLP. From this perspective, the Launch Control Center (left) and the 525-foot-tall Vehicle Assembly Building (right) in the background appear dwarfed by the 184-foot-tall boosters. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

Research on vibration signal of engine based on subband energy method

NASA Astrophysics Data System (ADS)

Wu, Chunmei; Cui, Feng; Zhao, Yong; Fu, Baohong; Ma, Junchi; Yang, Guihua

2017-04-01

Based on the research of DA462 type engine cylinder and cylinder head vibration signal of the surface, the signal measured in the time domain and frequency domain are analyzed in detail, draw the following conclusions: the analysis of vibration signal of the subband energy method is applied to the engine, the concentration response of each of the motivation band can clearly be seen. Through the analysis we can see that the combustion excitation frequency response from 0k to 1K, the vibration influence on the body piston lateral impact force is mainly concentrated in 2K˜5K frequency range of Hz, valve opening and closing the excitation response frequency is mainly concentrated in the 3K˜4K range of Hz, and thus locating the valve clearance fault. This method is simple, accurate and practical for the post processing and analysis of vibration signals.

Analysis of Vibration and Noise of Construction Machinery Based on Ensemble Empirical Mode Decomposition and Spectral Correlation Analysis Method

NASA Astrophysics Data System (ADS)

Chen, Yuebiao; Zhou, Yiqi; Yu, Gang; Lu, Dan

In order to analyze the effect of engine vibration on cab noise of construction machinery in multi-frequency bands, a new method based on ensemble empirical mode decomposition (EEMD) and spectral correlation analysis is proposed. Firstly, the intrinsic mode functions (IMFs) of vibration and noise signals were obtained by EEMD method, and then the IMFs which have the same frequency bands were selected. Secondly, we calculated the spectral correlation coefficients between the selected IMFs, getting the main frequency bands in which engine vibration has significant impact on cab noise. Thirdly, the dominated frequencies were picked out and analyzed by spectral analysis method. The study result shows that the main frequency bands and dominated frequencies in which engine vibration have serious impact on cab noise can be identified effectively by the proposed method, which provides effective guidance to noise reduction of construction machinery.

Active Control of Jet Engine Inlet Flows

DTIC Science & Technology

2007-03-31

These S-shaped ducts do not provide a direct line of sight to the compressor blades , thus hiding the engine from incoming radar waves. Also, serpentine...circumferential distortion pattern acts as an unsteady forcing function, inducing blade vibration that can result in structural fatigue and failure 3. This...shortcoming occurs when the rotor blades pass through regions of reduced axial velocity (i.e., where the total pressure is low). In these areas, since the

Dual clearance squeeze film damper

NASA Technical Reports Server (NTRS)

Fleming, D. P. (Inventor)

1985-01-01

A dual clearance hydrodynamic liquid squeeze film damper for a gas turbine engine is described. Under normal operating conditions, the device functions as a conventional squeeze film damper, using only one of its oil films. When an unbalance reaches abusive levels, as may occur with a blade loss or foreign object damage, a second, larger clearance film becomes active, controlling vibration amplitudes in a near optimum manner until the engine can be safely shut down and repaired.

1. Credit PSR. This view displays the north and west ...

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

1. Credit PSR. This view displays the north and west facades of Test Stand "G" (Vibration Facility) as seen when looking east southeast (110°). Test Stand "G" no longer houses the vibrator; it now houses an autoclave due to the changing nature of the testing work. The Vibration Facility was Test Stand "G"'s historic function. Test Stand "E" is at the far right. The Vibration Facility subjected motor and engine assemblies to various vibration patterns in order to simulate flight conditions and evaluate the durability of engine and motor designs. - Jet Propulsion Laboratory Edwards Facility, Test Stand G, Edwards Air Force Base, Boron, Kern County, CA

Flow induced vibrations in the SSME injector heads

NASA Technical Reports Server (NTRS)

Lepore, Frank A.

1991-01-01

A description is given of the flowfield in the Space Shuttle Main Engine (SSME) powerhead, the mechanisms which control flow-induced vibrations, and previous experimental work. An in-depth description is given of the development phase of the program , which includes the analysis, design, and fabrication of liquid oxygen (LOX) posts models used in the experimental phase, as well as test facilities, equipment, and procedures used. Also covered is the experimental data analysis, which includes overall steady state powerhead flowfield as well as the high frequency response of the LOX posts.

Compendium of methods for applying measured data to vibration and acoustic problems

NASA Astrophysics Data System (ADS)

Dejong, R. G.

1985-10-01

The scope of this report includes the measurement, analysis and use of vibration and acoustic data. The purpose of this report is then two-fold. First, it provides introductory material in an easily understood manner to engineers, technicians, and their managers in areas other than their specialties relating to the measurement, analysis and use of vibration and acoustic data. Second, it provides a quick reference source for engineers, technicians and their managers in the areas of their specialties relating to the measurement, analysis and use of vibration and acoustic data.

Vibration isolation by exploring bio-inspired structural nonlinearity.

PubMed

Wu, Zhijing; Jing, Xingjian; Bian, Jing; Li, Fengming; Allen, Robert

2015-10-08

Inspired by the limb structures of animals/insects in motion vibration control, a bio-inspired limb-like structure (LLS) is systematically studied for understanding and exploring its advantageous nonlinear function in passive vibration isolation. The bio-inspired system consists of asymmetric articulations (of different rod lengths) with inside vertical and horizontal springs (as animal muscle) of different linear stiffness. Mathematical modeling and analysis of the proposed LLS reveal that, (a) the system has very beneficial nonlinear stiffness which can provide flexible quasi-zero, zero and/or negative stiffness, and these nonlinear stiffness properties are adjustable or designable with structure parameters; (b) the asymmetric rod-length ratio and spring-stiffness ratio present very beneficial factors for tuning system equivalent stiffness; (c) the system loading capacity is also adjustable with the structure parameters which presents another flexible benefit in application. Experiments and comparisons with existing quasi-zero-stiffness isolators validate the advantageous features above, and some discussions are also given about how to select structural parameters for practical applications. The results would provide an innovative bio-inspired solution to passive vibration control in various engineering practice.

Active control of counter-rotating open rotor interior noise in a Dornier 728 experimental aircraft

NASA Astrophysics Data System (ADS)

Haase, Thomas; Unruh, Oliver; Algermissen, Stephan; Pohl, Martin

2016-08-01

The fuel consumption of future civil aircraft needs to be reduced because of the CO2 restrictions declared by the European Union. A consequent lightweight design and a new engine concept called counter-rotating open rotor are seen as key technologies in the attempt to reach this ambitious goals. Bearing in mind that counter-rotating open rotor engines emit very high sound pressures at low frequencies and that lightweight structures have a poor transmission loss in the lower frequency range, these key technologies raise new questions in regard to acoustic passenger comfort. One of the promising solutions for the reduction of sound pressure levels inside the aircraft cabin are active sound and vibration systems. So far, active concepts have rarely been investigated for a counter-rotating open rotor pressure excitation on complex airframe structures. Hence, the state of the art is augmented by the preliminary study presented in this paper. The study shows how an active vibration control system can influence the sound transmission of counter-rotating open rotor noise through a complex airframe structure into the cabin. Furthermore, open questions on the way towards the realisation of an active control system are addressed. In this phase, an active feedforward control system is investigated in a fully equipped Dornier 728 experimental prototype aircraft. In particular, the sound transmission through the airframe, the coupling of classical actuators (inertial and piezoelectric patch actuators) into the structure and the performance of the active vibration control system with different error sensors are investigated. It can be shown that the active control system achieves a reduction up to 5 dB at several counter-rotating open rotor frequencies but also that a better performance could be achieved through further optimisations.

Engineering hurdles in contact and intraocular lens lathe design: the view ahead

NASA Astrophysics Data System (ADS)

Bradley, Norman D.; Keller, John R.; Ball, Gary A.

1994-05-01

Current trends in and intraocular lens design suggest ever- increasing demand for aspheric lens geometries - multisurface and/or toric surfaces - in a variety of new materials. As computer numeric controls (CNC) lathes and mills continue to evolve with he ophthalmic market, engineering hurdles present themselves to designers: Can hardware based upon single-point diamond turning accommodate the demands of software-driven designs? What are the limits of CNC resolution and repeatability in high-throughput production? What are the controlling factors in lathed, polish-free surface production? Emerging technologies in the lathed biomedical optics field are discussed along with their limitations, including refined diamond tooling, vibrational control, automation, and advanced motion control systems.

Journal of Engineering Thermophysics (Selected Articles),

DTIC Science & Technology

1983-05-20

A SURGE TEST OF A TWIN-SHAFT TURBOJET ENGINE ON GROUND TEST BED* Chiang Feng (Shengyang Aeroengine Company) ABSTRACT Instrument technique for...oscillogram for the static pressure behind the two compressors. This noise was analyzed and believed to have arisen from the vibrations of the rotating blades...booms are heard. The vibrational energy of the surge is enormous, especially in the range of 85-90% of rotational speed. One can feel the vibrations

Prediction of X-33 Engine Dynamic Environments

NASA Technical Reports Server (NTRS)

Shi, John J.

1999-01-01

Rocket engines normally have two primary sources of dynamic excitation. The first source is the injector and the combustion chambers that generate wide band random vibration. The second source is the turbopumps, which produce lower levels of wide band random vibration as well as sinusoidal vibration at frequencies related to the rotating speed and multiples thereof. Additionally, the pressure fluctuations due to flow turbulence and acoustics represent secondary sources of excitation. During the development stage, in order to design/size the rocket engine components, the local dynamic environments as well as dynamic interface loads have to be defined.

Dynamic Loads Generation for Multi-Point Vibration Excitation Problems

NASA Technical Reports Server (NTRS)

Shen, Lawrence

2011-01-01

A random-force method has been developed to predict dynamic loads produced by rocket-engine random vibrations for new rocket-engine designs. The method develops random forces at multiple excitation points based on random vibration environments scaled from accelerometer data obtained during hot-fire tests of existing rocket engines. This random-force method applies random forces to the model and creates expected dynamic response in a manner that simulates the way the operating engine applies self-generated random vibration forces (random pressure acting on an area) with the resulting responses that we measure with accelerometers. This innovation includes the methodology (implementation sequence), the computer code, two methods to generate the random-force vibration spectra, and two methods to reduce some of the inherent conservatism in the dynamic loads. This methodology would be implemented to generate the random-force spectra at excitation nodes without requiring the use of artificial boundary conditions in a finite element model. More accurate random dynamic loads than those predicted by current industry methods can then be generated using the random force spectra. The scaling method used to develop the initial power spectral density (PSD) environments for deriving the random forces for the rocket engine case is based on the Barrett Criteria developed at Marshall Space Flight Center in 1963. This invention approach can be applied in the aerospace, automotive, and other industries to obtain reliable dynamic loads and responses from a finite element model for any structure subject to multipoint random vibration excitations.

High temperature superconductors for magnetic suspension applications

NASA Technical Reports Server (NTRS)

Mcmichael, C. K.; Cooley, R. S.; Chen, Q. Y.; Ma, K. B.; Lamb, M. A.; Meng, R. L.; Chu, C. W.; Chu, W. K.

1994-01-01

High temperature superconductors (HTS) hold the promise for applications in magnetic levitation bearings, vibration damping, and torque coupling. Traditional magnetic suspension systems require active feedback and vibration controls in which power consumption and low frequency vibration are among the major engineering concerns. HTS materials have been demonstrated to be an enabling approach towards such problems due to their flux trapping properties. In our laboratory at TCSUH, we have been conducting a series of experiments to explore various mechanical applications using HTS. We have constructed a 30 lb. model flywheel levitated by a hybrid superconducting magnetic bearing (HSMB). We are also developing a levitated and vibration-dampled platform for high precision instrumentation. These applications would be ideal for space usages where ambient temperature is adequate for HTS to operate properly under greatly reduced cryogenic requirements. We will give a general overview of these potential applications and discuss the operating principles of the HTS devices we have developed.

Performance Analysis of AN Engine Mount Featuring ER Fluids and Piezoactuators

NASA Astrophysics Data System (ADS)

Choi, S. H.; Choi, Y. T.; Choi, S. B.; Cheong, C. C.

Conventional rubber mounts and various types of passive or semi-active hydraulic engine mounts for a passenger vehicle have their own functional aims on the limited frequency band in the broad engine operating frequency range. In order to achieve high system performance over all frequency ranges of the engine operation, a new type of engine mount featuring electro-rheological(ER) fluids and piezoactuators is proposed in this study. A mathematical model of the proposed engine mount is derived using the bond graph method which is inherently adequate to model the interconnected hydromechanical system. In the low frequency domain, the ER fluid is activated upon imposing an electric field for vibration isolation while the piezoactuator is activated in the high frequency domain. A neuro-control algorithm is utilized to determine control electric field for the ER fluid, and H∞ control technique is adopted for the piezoactuator Comparative works between the proposed and single-actuating(ER fluid only or piezoactuator only) engine mounts are undertaken by evaluating force transmissibility over a wide operating frequency range.

Vibration detecting apparatus for multi-rotor rotary piston engines

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

Fujimoto, Y.; Sasaki, H.; Karimata, Y.

1987-04-28

A multi-rotor rotary piston engine is described comprising rotor housings each having an inner wall surface of a two-lobe trochoidal form, an intermediate housing having opposite side surfaces and located between two adjacent ones of the rotor housings, a pair of side housings attached to outer surfaces of outermost rotor housings, rotors which are disposed in respective ones of the rotor housings and carried by an eccentric shaft, adjacent rotors each having a side surface adapted for sliding engagement with the side surfaces of the intermediate housing, vibration detecting means mounted on the intermediate housing for detecting engine vibrations, themore » vibration detecting means being oriented so that it has a sensitivity in the direction substantially perpendicular to the side surface of the intermediate housing.« less

Effect of structural flexibility on the design of vibration-isolating mounts for aircraft engines

NASA Technical Reports Server (NTRS)

Phillips, W. H.

1984-01-01

Previous analyses of the design of vibration-isolating mounts for a rear-mounted engine to decouple linear and rotational oscillations are extended to take into account flexibility of the engine-mount structure. Equations and curves are presented to allow the design of mount systems and to illustrate the results for a range of design conditions.

Vibrational and Rotational CARS Measurements of Nitrogen in Afterglow of Streamer Discharge in Atmospheric Pressure Fuel/Air Mixtures

DTIC Science & Technology

2012-01-01

in a variety of different ignition regimes, including pulsed detonation engines ( PDEs ) and automobile engines, with experiments demonstrating TPI to...Vibrational and rotational CARS measurements of nitrogen in afterglow of streamer discharge in atmospheric pressure fuel/air mixtures This article...DATE 2012 2. REPORT TYPE 3. DATES COVERED 00-00-2012 to 00-00-2012 4. TITLE AND SUBTITLE Vibrational and rotational CARS measurements of

The Shock and Vibration Digest, Volume 12, Number 9,

DTIC Science & Technology

1980-09-01

include diesel engine noise, process plant noise, and environ- dynamic mechanical properties of viscoelastic mate- mental noise and planning. rials...new numerical methods are presented in- plant noise control, design of facilities for noise in the twelve articles of the mathematics section. control...International Symposium for Innovative the seminar: 31 16 = ,,-,==. ’d-m w .’ " Dynamic Testing of Nuclear Power Plant Struc- ENVIRONMENTAL STRESS

Vibrational impacts of hush house operation

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

Witten, A.J.

1988-01-01

United States Air Force (USAF) facilities are required to test turboprop and turbojet engines before or after maintenance or repair and prior to installation on aircraft to ensure that no problems were introduced or remain uncorrected. This requirement prevents the installation of engines in aircraft which require further maintenance. There are a number of facilities in use by USAF for conducting engine diagnostic tests. The most modern of these facilities is the hush house which is a hangar-like structure designed to isolate the noise associated with extended engine operations from the surrounding environment. One type of hush house, the T-10,more » is of particular concern because of vibrational impacts to surrounding structures induced by subaudible sound (infrasound) emitted during operation. While these facilities fulfill the design requirement of reducing audible noise, serious siting problems have been reported at several installations because of infrasound-induced vibrations. The worst of these include the abandonment of an avionics laboratory because induced vibrations interfered with this facilities function and structural damage to a concrete block maintenance facility. This paper describes a predictive method for assessing vibration-driven structural impacts. 9 refs., 2 figs.« less

Software For Three-Dimensional Stress And Thermal Analyses

NASA Technical Reports Server (NTRS)

Banerjee, P. K.; Wilson, R. B.; Hopkins, D. A.

1994-01-01

BEST3D is advanced engineering software system for three-dimensional thermal and stress analyses, particularly of components of hot sections of gas-turbine engines. Utilizes boundary element method, offering, in many situations, more accuracy, efficiency, and ease of use than finite element method. Performs engineering analyses of following types: elastic, heat transfer, plastic, forced vibration, free vibration, and transient elastodynamic. Written in FORTRAN 77.

4. This photographic copy of an engineering drawing shows the ...

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

4. This photographic copy of an engineering drawing shows the plan and details for Test Stand "G" and the placement of the vibrator. California Institute of Technology, Jet Propulsion Laboratory, Plant Engineering: "Vibration Test Facility-Bldg E-72, Floor & Roof Plans, Sections, Details & Door Schedule," drawing no. E72/2-5, 21 May 1964. California Institute of Technology, Jet Propulsion Laboratory, Plant Engineering: engineering drawings of structures at JPL Edwards Facility. Drawings on file at JPL Plant Engineering, Pasadena, California. - Jet Propulsion Laboratory Edwards Facility, Test Stand G, Edwards Air Force Base, Boron, Kern County, CA

ENGINEERING APPLICATIONS OF ANALOG COMPUTERS

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

Bryant, L.T.; Janicke, M.J.; Just, L.C.

1963-10-31

Six experiments from the fields of reactor engineering, heat transfer, and dynamics are presented to illustrate the engineering applications of analog computers. The steps required for producing the analog solution are shown, as well as complete information for duplicating the solution. Graphical results are provided. The experiments include: deceleration of a reactor control rod, pressure variations through a packed bed, reactor kinetics over many decades with thermal feedback, a vibrating system with two degrees of freedom, temperature distribution in a radiating fin, temperature distribution in an infinite slab considering variable thermal properties, and iodine -xenon buildup in a reactor. (M.C.G.)

Innovative Techniques Simplify Vibration Analysis

NASA Technical Reports Server (NTRS)

2010-01-01

In the early years of development, Marshall Space Flight Center engineers encountered challenges related to components in the space shuttle main engine. To assess the problems, they evaluated the effects of vibration and oscillation. To enhance the method of vibration signal analysis, Marshall awarded Small Business Innovation Research (SBIR) contracts to AI Signal Research, Inc. (ASRI), in Huntsville, Alabama. ASRI developed a software package called PC-SIGNAL that NASA now employs on a daily basis, and in 2009, the PKP-Module won Marshall s Software of the Year award. The technology is also used in many industries: aircraft and helicopter, rocket engine manufacturing, transportation, and nuclear power."

A comparison of two adaptive algorithms for the control of active engine mounts

NASA Astrophysics Data System (ADS)

Hillis, A. J.; Harrison, A. J. L.; Stoten, D. P.

2005-08-01

This paper describes work conducted in order to control automotive active engine mounts, consisting of a conventional passive mount and an internal electromagnetic actuator. Active engine mounts seek to cancel the oscillatory forces generated by the rotation of out-of-balance masses within the engine. The actuator generates a force dependent on a control signal from an algorithm implemented with a real-time DSP. The filtered-x least-mean-square (FXLMS) adaptive filter is used as a benchmark for comparison with a new implementation of the error-driven minimal controller synthesis (Er-MCSI) adaptive controller. Both algorithms are applied to an active mount fitted to a saloon car equipped with a four-cylinder turbo-diesel engine, and have no a priori knowledge of the system dynamics. The steady-state and transient performance of the two algorithms are compared and the relative merits of the two approaches are discussed. The Er-MCSI strategy offers significant computational advantages as it requires no cancellation path modelling. The Er-MCSI controller is found to perform in a fashion similar to the FXLMS filter—typically reducing chassis vibration by 50-90% under normal driving conditions.

Composite 3D-printed metastructures for low-frequency and broadband vibration absorption

NASA Astrophysics Data System (ADS)

Matlack, Kathryn H.; Bauhofer, Anton; Krödel, Sebastian; Palermo, Antonio; Daraio, Chiara

2016-07-01

Architected materials that control elastic wave propagation are essential in vibration mitigation and sound attenuation. Phononic crystals and acoustic metamaterials use band-gap engineering to forbid certain frequencies from propagating through a material. However, existing solutions are limited in the low-frequency regimes and in their bandwidth of operation because they require impractical sizes and masses. Here, we present a class of materials (labeled elastic metastructures) that supports the formation of wide and low-frequency band gaps, while simultaneously reducing their global mass. To achieve these properties, the metastructures combine local resonances with structural modes of a periodic architected lattice. Whereas the band gaps in these metastructures are induced by Bragg scattering mechanisms, their key feature is that the band-gap size and frequency range can be controlled and broadened through local resonances, which are linked to changes in the lattice geometry. We demonstrate these principles experimentally, using advanced additive manufacturing methods, and inform our designs using finite-element simulations. This design strategy has a broad range of applications, including control of structural vibrations, noise, and shock mitigation.

The Physics of Vibration

NASA Astrophysics Data System (ADS)

Pippard, A. B.

1989-11-01

The study of vibration in physical systems is an important part of almost all fields in physics and engineering. This work, originally published in two volumes, examines the classical aspects in Part I and the quantum oscillator in Part II. The classical linear vibrator is treated first and the underlying unity of all linear oscillations in electrical, mechanical and acoustic systems is emphasized. Following this the book turns to the treatment of nonlinear vibrations, a field with which engineers and physicists are generally less familiar. In Part II the emphasis turns to quantum systems, that is those systems which can only be adequately described by quantum mechanics. The treatment concentrates on vibrations in atoms and molecules and their interaction with electromagnetic radiation. The similarities of classical and quantum methods are stressed and the limits of the classical treatment are examined. Throughout the book, each phenomenon discussed is illustrated with many examples and theory and experiment are compared. Although the reader may find that the physics discussed is demanding and the concepts are subtle in places, all mathematics used is familiar to both engineers and experimental scientists. Although not a textbook this is a useful introduction to the more advanced mathematical treatment of vibrations as it bridges the gap between the basic principles and more specialized concepts. It will be of great interest to advanced undergraduates and postgraduates as well as applied mathematicians, physicists and engineers in university and industry.

Comparison ofdvanced turboprop interior noise control ground and flight test data

NASA Technical Reports Server (NTRS)

Simpson, Myles A.; Tran, Boi N.

1992-01-01

Interior noise ground tests conducted on a DC-9 aircraft test section are described. The objectives were to study ground test and analysis techniques for evaluating the effectiveness of interior noise control treatments for advanced turboprop aircraft, and to study the sensitivity of the ground test results to changes in various test conditions. Noise and vibration measurements were conducted under simulated advanced turboprop excitation, for two interior noise control treatment configurations. These ground measurement results were compared with results of earlier UHB (Ultra High Bypass) Demonstrator flight sts with comparable interior treatment configurations. The Demonstrator is an MD-80 test aircraft with the left JT8D engine replaced with a prototype UHB advanced turboprop engine.

Comparison ofdvanced turboprop interior noise control ground and flight test data

NASA Astrophysics Data System (ADS)

Simpson, Myles A.; Tran, Boi N.

Interior noise ground tests conducted on a DC-9 aircraft test section are described. The objectives were to study ground test and analysis techniques for evaluating the effectiveness of interior noise control treatments for advanced turboprop aircraft, and to study the sensitivity of the ground test results to changes in various test conditions. Noise and vibration measurements were conducted under simulated advanced turboprop excitation, for two interior noise control treatment configurations. These ground measurement results were compared with results of earlier UHB (Ultra High Bypass) Demonstrator flight sts with comparable interior treatment configurations. The Demonstrator is an MD-80 test aircraft with the left JT8D engine replaced with a prototype UHB advanced turboprop engine.

Parametric study of fluid flow manipulation with piezoelectric macrofiber composite flaps

NASA Astrophysics Data System (ADS)

Sadeghi, O.; Tarazaga, P.; Stremler, M.; Shahab, S.

2017-04-01

Active Fluid Flow Control (AFFC) has received great research attention due to its significant potential in engineering applications. It is known that drag reduction, turbulence management, flow separation delay and noise suppression through active control can result in significantly increased efficiency of future commercial transport vehicles and gas turbine engines. In microfluidics systems, AFFC has mainly been used to manipulate fluid passing through the microfluidic device. We put forward a conceptual approach for fluid flow manipulation by coupling multiple vibrating structures through flow interactions in an otherwise quiescent fluid. Previous investigations of piezoelectric flaps interacting with a fluid have focused on a single flap. In this work, arrays of closely-spaced, free-standing piezoelectric flaps are attached perpendicular to the bottom surface of a tank. The coupling of vibrating flaps due to their interacting with the surrounding fluid is investigated in air (for calibration) and under water. Actuated flaps are driven with a harmonic input voltage, which results in bending vibration of the flaps that can work with or against the flow-induced bending. The size and spatial distribution of the attached flaps, and the phase and frequency of the input actuation voltage are the key parameters to be investigated in this work. Our analysis will characterize the electrohydroelastic dynamics of active, interacting flaps and the fluid motion induced by the system.

Thermal/structural Tailoring of Engine Blades (T/STAEBL) User's Manual

NASA Technical Reports Server (NTRS)

Brown, K. W.; Clevenger, W. B.; Arel, J. D.

1994-01-01

The Thermal/Structural Tailoring of Engine Blades (T/STAEBL) system is a family of computer programs executed by a control program. The T/STAEBL system performs design optimizations of cooled, hollow turbine blades and vanes. This manual contains an overview of the system, fundamentals of the data block structure, and detailed descriptions of the inputs required by the optimizer. Additionally, the thermal analysis input requirements are described as well as the inputs required to perform a finite element blade vibrations analysis.

A CWT-based methodology for piston slap experimental characterization

NASA Astrophysics Data System (ADS)

Buzzoni, M.; Mucchi, E.; Dalpiaz, G.

2017-03-01

Noise and vibration control in mechanical systems has become ever more significant for automotive industry where the comfort of the passenger compartment represents a challenging issue for car manufacturers. The reduction of piston slap noise is pivotal for a good design of IC engines. In this scenario, a methodology has been developed for the vibro-acoustic assessment of IC diesel engines by means of design changes in piston to cylinder bore clearance. Vibration signals have been analysed by means of advanced signal processing techniques taking advantage of cyclostationarity theory. The procedure departs from the analysis of the Continuous Wavelet Transform (CWT) in order to identify a representative frequency band of piston slap phenomenon. Such a frequency band has been exploited as the input data in the further signal processing analysis that involves the envelope analysis of the second order cyclostationary component of the signal. The second order harmonic component has been used as the benchmark parameter of piston slap noise. An experimental procedure of vibrational benchmarking is proposed and verified at different operational conditions in real IC engines actually equipped on cars. This study clearly underlines the crucial role of the transducer positioning when differences among real piston-to-cylinder clearances are considered. In particular, the proposed methodology is effective for the sensors placed on the outer cylinder wall in all the tested conditions.

A Tale of Two Masses

ERIC Educational Resources Information Center

Bryan, Kurt

2011-01-01

This article presents an application of standard undergraduate ODE techniques to a modern engineering problem, that of using a tuned mass damper to control the vibration of a skyscraper. This material can be used in any ODE course in which the students have been familiarized with basic spring-mass models, resonance, and linear systems of ODEs.…

The Shock and Vibration Digest, Volume 4, Number 5, May 1972.

DTIC Science & Technology

1972-05-01

capability to solve real-time on aircraft noise, its generation instrumentation problems found effects and control will be sur- In manufacturing plants...annoyance. Noise measurements indicate that the same manufacturing plantisto machine the the respondents, in general, properly identify modified... Manufacturing 1W San Diego, Calif. A. J. Favrata, SAE iiq. Meeting, SAE Internaional Conference on Noise Control Engineering, INCE 4-6 Wanington, D. C. Mi. .f

An Efficient Crankshaft Dynamic Analysis Using Substructuring with Ritz Vectors

NASA Astrophysics Data System (ADS)

MOURELATOS, Z. P.

2000-11-01

A structural analysis using dynamic substructuring with Ritz vectors is presented for predicting the dynamic response of an engine crankshaft, based on the finite-element method. A two-level dynamic substructuring is performed using a set of load-dependent Ritz vectors. The rotating crankshaft is properly coupled with the non-rotating, compliant engine block. The block compliance is represented by a distributed linear elastic foundation at each main bearing location. The stiffness of the elastic foundation can be different in the vertical and horizontal planes, thereby considering the anisotropy of the engine block compliance with respect to the crankshaft rotation. The analysis accounts for the kinematic non-linearity resulting from the crankangle-dependent circumferential contact location between each journal and the corresponding bore of the engine block. Crankshaft “bent” and block “misboring” effects due to manufacturing imperfections are considered in the analysis. The superior accuracy and reduced computational effort of the present method as compared with the equivalent superelement analysis in MSC/NASTRAN, are demonstrated using the free and forced vibrations of a slender cylindrical beam and free vibrations of a four-cylinder engine crankshaft. Subsequently, the accuracy of the present method in calculating the dynamic response of engine crankshafts is shown through comparisons between the analytical predictions and experimental results for the torsional vibrations of an in-line five cylinder engine and the bending vibrations of the crankshaft-flywheel assembly of a V6 engine.

NASA Puffin Electric Tailsitter VTOL Concept

NASA Technical Reports Server (NTRS)

Moore, Mark D.

2010-01-01

Electric propulsion offers dramatic new vehicle mission capabilities, not possible with turbine or reciprocating engines; including high reliability and efficiency, low engine weight and maintenance, low cooling drag and volume required, very low noise and vibration, and zero emissions. The only penalizing characteristic of electric propulsion is the current energy storage technology level, which is set to triple over the next 5-10 years through huge new investments in this field. Most importantly, electric propulsion offers incredible new degrees of freedom in aircraft system integration to achieve unprecedented levels of aerodynamic, propulsive, control, and structural synergistic coupling. A unique characteristic of electric propulsion is that the technology is nearly scale-free, permitting small motors to be parallelized for fail-safe redundancy, or distributed across the airframe for tightly coupled interdisciplinary functionality without significant impacts in motor-controller efficiency or specific weight. Maximizing the potential benefit of electric propulsion is dependent on applying this technology to synergistic mission concepts. The vehicle missions with the most benefit include those which constrain environmental impact (or limit noise, exhaust, or emission signatures) are short range, or where large differences exist in the propulsion system sizing between takeoff and cruise conditions. Electric propulsion offers the following unique capabilities that other propulsion systems can t provide for short range Vertical Takeoff and Landing (VTOL) aircraft; elimination of engine noise and emissions, drastic reduction in engine cooling and radiated heat, drastic reduction in vehicle vibration levels, drastic improvement in reliability and operating costs, variable speed output at full power, for improved cruise efficiency at low tip-speed, elimination of high/hot sizing penalty, and reduction of engine-out penalties.

Engineering the vibrational coherence of vision into a synthetic molecular device.

PubMed

Gueye, Moussa; Manathunga, Madushanka; Agathangelou, Damianos; Orozco, Yoelvis; Paolino, Marco; Fusi, Stefania; Haacke, Stefan; Olivucci, Massimo; Léonard, Jérémie

2018-01-22

The light-induced double-bond isomerization of the visual pigment rhodopsin operates a molecular-level optomechanical energy transduction, which triggers a crucial protein structure change. In fact, rhodopsin isomerization occurs according to a unique, ultrafast mechanism that preserves mode-specific vibrational coherence all the way from the reactant excited state to the primary photoproduct ground state. The engineering of such an energy-funnelling function in synthetic compounds would pave the way towards biomimetic molecular machines capable of achieving optimum light-to-mechanical energy conversion. Here we use resonance and off-resonance vibrational coherence spectroscopy to demonstrate that a rhodopsin-like isomerization operates in a biomimetic molecular switch in solution. Furthermore, by using quantum chemical simulations, we show why the observed coherent nuclear motion critically depends on minor chemical modifications capable to induce specific geometric and electronic effects. This finding provides a strategy for engineering vibrationally coherent motions in other synthetic systems.

Similitude design for the vibration problems of plates and shells: A review

NASA Astrophysics Data System (ADS)

Zhu, Yunpeng; Wang, You; Luo, Zhong; Han, Qingkai; Wang, Deyou

2017-06-01

Similitude design plays a vital role in the analysis of vibration and shock problems encountered in large engineering equipment. Similitude design, including dimensional analysis and governing equation method, is founded on the dynamic similitude theory. This study reviews the application of similitude design methods in engineering practice and summarizes the major achievements of the dynamic similitude theory in structural vibration and shock problems in different fields, including marine structures, civil engineering structures, and large power equipment. This study also reviews the dynamic similitude design methods for thin-walled and composite material plates and shells, including the most recent work published by the authors. Structure sensitivity analysis is used to evaluate the scaling factors to attain accurate distorted scaling laws. Finally, this study discusses the existing problems and the potential of the dynamic similitude theory for the analysis of vibration and shock problems of structures.

A multi-reference filtered-x-Newton narrowband algorithm for active isolation of vibration and experimental investigations

NASA Astrophysics Data System (ADS)

Wang, Chun-yu; He, Lin; Li, Yan; Shuai, Chang-geng

2018-01-01

In engineering applications, ship machinery vibration may be induced by multiple rotational machines sharing a common vibration isolation platform and operating at the same time, and multiple sinusoidal components may be excited. These components may be located at frequencies with large differences or at very close frequencies. A multi-reference filtered-x Newton narrowband (MRFx-Newton) algorithm is proposed to control these multiple sinusoidal components in an MIMO (multiple input and multiple output) system, especially for those located at very close frequencies. The proposed MRFx-Newton algorithm can decouple and suppress multiple sinusoidal components located in the same narrow frequency band even though such components cannot be separated from each other by a narrowband-pass filter. Like the Fx-Newton algorithm, good real-time performance is also achieved by the faster convergence speed brought by the 2nd-order inverse secondary-path filter in the time domain. Experiments are also conducted to verify the feasibility and test the performance of the proposed algorithm installed in an active-passive vibration isolation system in suppressing the vibration excited by an artificial source and air compressor/s. The results show that the proposed algorithm not only has comparable convergence rate as the Fx-Newton algorithm but also has better real-time performance and robustness than the Fx-Newton algorithm in active control of the vibration induced by multiple sound sources/rotational machines working on a shared platform.

Identification of Rotorcraft Structural Dynamics from Flight and Wind Tunnel Data

NASA Technical Reports Server (NTRS)

McKillip, Robert M., Jr.

1997-01-01

Excessive vibration remains one one of the most difficult problems that faces the helicopter industry today, affecting all production helicopters at some phase of their development. Vibrations in rotating structures may arise from external periodic dynamic airloads whose frequencies are are close to the natural frequencies of the rotating system itself. The goal for the structures engineer would thus be to design a structure as free from resonance effects as possible. In the case of a helicopter rotor blade these dynamic loads are a consequence of asymmetric airload distribution on the rotor blade in forward flight, leading to a rich collection of higher harmonic airloads that force rotor and airframe response. Accurate prediction of the dynamic characteristics of a helicopter rotor blade will provide the opportunity to affect in a positive manner noise intensity, vibration level, durability, reliability and operating costs by reducing objectionable frequencies or moving them to a different frequency range and thus providing us with a lower vibration rotor. In fact, the dynamic characteristics tend to define the operating limits of a rotorcraft. As computing power has increased greatly over the last decade, researchers and engineers have turned to analyzing the vibrational characteristics of aerospace structures at the design and development stage of the production of an aircraft. Modern rotor blade construction methods lead to products with low mass and low inherent damping so careful design and analysis is required to avoid resonance and an undesirable dynamic performance. In addition, accurate modal analysis is necessary for several current approaches in elastic system identification and active control.

Broadband waveguide vibration sensor for turbine bearing health monitoring

NASA Astrophysics Data System (ADS)

Larsen, C.; Branch, N.

Mechanical waveguides have been demonstrated for monitoring turbine engine main shaft bearings. These devices are rugged metallic wires which can be installed inside the engine near the bearing and routed outside to the case where the electronics can be serviced. To date, the waveguide vibration sensor has been demonstrated on two engines with thrust bearings with seeded defects: a T63 and a Rolls Royce 501-KB5+ (industrial version of the T56).

Aero-Mechanical Coupling in a High-Speed Compressor

DTIC Science & Technology

2010-02-01

compressor for which this facility is being designed is a scale model of a single stage of a civil jet engine . A strong non-synchronous blade vibration was...Flutter and resonant vibration characteristics of engine blades . Journal of engineering for gas turbines and power, 119. Thermann, H. and Niehuis, R...changes in airfoil lift associated with the unsteady flow. The blade aerodynamics are approximated by a flat plate, however more complex shapes can be

An innovative multi dof TMD system for motorcycle handlebars designed to reduce structural vibrations and human exposure

NASA Astrophysics Data System (ADS)

Agostoni, S.; Cheli, F.; Leo, E.; Pezzola, M.

2012-08-01

Motor vehicle ride comfort is mainly affected by reciprocating engine inertia unbalances. These forces are transmitted to the driver through the main frame, the engine mounts, and the auxiliary sub systems—all components with which he physically comes into contact. On-road traction vehicle engines are mainly characterized by transient exercise. Thus, an excitation frequency range from 800 RPM (≈15 Hz for stationary vehicles) up to 15,000 RPM (≈250 Hz as a cut off condition) occurs. Several structural resonances are induced by the unbalancing forces spectrum, thus exposing the driver to amplified vibrations. The aim of this research is to reduce driver vibration exposure, by acting on the modal response of structures with which the driver comes into contact. An experimental methodology, capable of identifying local vibration modes was developed. The application of this methodology on a reference vehicle allows us to detect if/when/how the above mentioned resonances are excited. Numerical models were used to study structural modifications. In this article, a handlebar equipped with an innovative multi reciprocating tuned mass damper was optimized. All structural modifications were designed, developed and installed on a vehicle. Modal investigations were then performed in order to predict modification efficiency. Furthermore, functional solution efficiency was verified during sweep tests performed on a target vehicle, by means of a roller bench capable of replicating on-road loads. Three main investigation zones of the vehicle were detected and monitored using accelerometers: (1) engine mounts, to characterize vibration emissions; (2) bindings connecting the engine to the frame, in order to detect vibration transfer paths, with particular attention being paid to local dynamic amplifications due to compliances and (3) the terminal components with which the driver comes into contact.

The 58th Shock and Vibration Symposium, volume 1

NASA Technical Reports Server (NTRS)

Pilkey, Walter D. (Compiler); Pilkey, Barbara F. (Compiler)

1987-01-01

The proceedings of the 58th Shock and Vibration Symposium, held in Huntsville, Alabama, October 13 to 15, 1987 are given. Mechanical shock, dynamic analysis, space shuttle main engine vibration, isolation and damping, and analytical methods are discussed.

Investigation of difficult component effects on finite element model vibration prediction for the Bell AH-1G helicopter. Volume 1: Ground vibration test results

NASA Technical Reports Server (NTRS)

Dompka, R. V.

1989-01-01

Under the NASA-sponsored Design Analysis Methods for VIBrationS (DAMVIBS) program, a series of ground vibration tests and NASTRAN finite element model (FEM) correlations were conducted on the Bell AH-1G helicopter gunship to investigate the effects of difficult components on the vibration response of the airframe. Previous correlations of the AH-1G showed good agreement between NASTRAN and tests through 15 to 20 Hz, but poor agreement in the higher frequency range of 20 to 30 Hz. Thus, this effort emphasized the higher frequency airframe vibration response correlations and identified areas that need further R and T work. To conduct the investigations, selected difficult components (main rotor pylon, secondary structure, nonstructural doors/panels, landing gear, engine, fuel, etc.) were systematically removed to quantify their effects on overall vibratory response of the airframe. The entire effort was planned and documented, and the results reviewed by NASA and industry experts in order to ensure scientific control of the testing, analysis, and correlation exercise. In particular, secondary structure and damping had significant effects on the frequency response of the airframe above 15 Hz. Also, the nonlinear effects of thrust stiffening and elastomer mounts were significant on the low frequency pylon modes below main rotor 1p (5.4 Hz). The results of the ground vibration testing are presented.

Engineering science and mechanics; Proceedings of the International Symposium, Tainan, Republic of China, December 29-31, 1981. Parts 1 & 2

NASA Astrophysics Data System (ADS)

Hsia, H.-M.; Chou, Y.-L.; Longman, R. W.

1983-07-01

The topics considered are related to measurements and controls in physical systems, the control of large scale and distributed parameter systems, chemical engineering systems, aerospace science and technology, thermodynamics and fluid mechanics, and computer applications. Subjects in structural dynamics are discussed, taking into account finite element approximations in transient analysis, buckling finite element analysis of flat plates, dynamic analysis of viscoelastic structures, the transient analysis of large frame structures by simple models, large amplitude vibration of an initially stressed thick plate, nonlinear aeroelasticity, a sensitivity analysis of a combined beam-spring-mass structure, and the optimal design and aeroelastic investigation of segmented windmill rotor blades. Attention is also given to dynamics and control of mechanical and civil engineering systems, composites, and topics in materials. For individual items see A83-44002 to A83-44061

Lewis Structures Technology, 1988. Volume 2: Structural Mechanics

NASA Technical Reports Server (NTRS)

1988-01-01

Lewis Structures Div. performs and disseminates results of research conducted in support of aerospace engine structures. These results have a wide range of applicability to practitioners of structural engineering mechanics beyond the aerospace arena. The engineering community was familiarized with the depth and range of research performed by the division and its academic and industrial partners. Sessions covered vibration control, fracture mechanics, ceramic component reliability, parallel computing, nondestructive evaluation, constitutive models and experimental capabilities, dynamic systems, fatigue and damage, wind turbines, hot section technology (HOST), aeroelasticity, structural mechanics codes, computational methods for dynamics, structural optimization, and applications of structural dynamics, and structural mechanics computer codes.

Structural Acoustics and Vibrations

NASA Astrophysics Data System (ADS)

Chaigne, Antoine

This structural chapter is devoted to vibrations of structures and to their coupling with the acoustic field. Depending on the context, the radiated sound can be judged as desirable, as is mostly the case for musical instruments, or undesirable, like noise generated by machinery. In architectural acoustics, one main goal is to limit the transmission of sound through walls. In the automobile industry, the engineers have to control the noise generated inside and outside the passenger compartment. This can be achieved by means of passive or active damping. In general, there is a strong need for quieter products and better sound quality generated by the structures in our daily environment.

Structural Acoustics and Vibrations

NASA Astrophysics Data System (ADS)

Chaigne, Antoine

This chapter is devoted to vibrations of structures and to their coupling with the acoustic field. Depending on the context, the radiated sound can be judged as desirable, as is mostly the case for musical instruments, or undesirable, like noise generated by machinery. In architectural acoustics, one main goal is to limit the transmission of sound through walls. In the automobile industry, the engineers have to control the noise generated inside and outside the passenger compartment. This can be achieved by means of passive or active damping. In general, there is a strong need for quieter products and better sound quality generated by the structures in our daily environment.

Design of a vibration isolation system for a cycle ergometer to be used onboard the Space Shuttle

NASA Technical Reports Server (NTRS)

Pearson, Lillian; Tait, Steven; Trevino, Maurice

1991-01-01

Low frequency vibrations generated during exercise using the cycle ergometer onboard the Space Shuttle are disrupting sensitive microgravity experiments. The design team is asked by NASA/USRA to generate alternatives for the design of a vibration isolation system for the cycle ergometer. It is the design team's objective to present alternative designs and a problem solution for a vibration isolation system for an exercise cycle ergometer to be used onboard the Space Shuttle. In the development of alternative designs, the design team emphasizes passive systems as opposed to active control systems. This decision is made because the team feels that passive systems are less complex than active control systems, external energy sources are not required, and mass is reduced due to the lack of machinery such as servomotors or compressors typical of active control systems. Eleven alternative designs are developed by the design team. From these alternatives, three active control systems are included to compare the benefits of active and passive systems. Also included in the alternatives is an isolation system designed by an independent engineer that was acquired late in the project. The eight alternatives using passive isolation systems are narrowed down by selection criteria to four considered to be the most promising by the design team. A feasibility analysis is performed on these four passive isolation systems. Based on the feasibility analysis, a final design solution is chosen and further developed. From the development of the design, the design team has concluded that passive systems are not effective at isolating vibrations for the low frequencies considered for this project. Recommendations are made for guidelines of passive isolation design and application of such systems.

Resonance vibrations in intake and exhaust pipes of in-line engines III : the inlet process of a four-stroke-cycle engine

NASA Technical Reports Server (NTRS)

Lutz, O

1940-01-01

Using a previously developed method, the boundary process of four-stroke-cycle engines are set up. The results deviate considerably from those obtained under the assumption that the velocity fluctuation is proportional to the cylinder piston motion. The deviation is less at the position of resonance frequencies. By the method developed, the effect of the resonance vibrations on the volumetric efficiency can be demonstrated.

The impact of circulation control on rotary aircraft controls systems

NASA Technical Reports Server (NTRS)

Kingloff, R. F.; Cooper, D. E.

1987-01-01

Application of circulation to rotary wing systems is a new development. Efforts to determine the near and far field flow patterns and to analytically predict those flow patterns have been underway for some years. Rotary wing applications present a new set of challenges in circulation control technology. Rotary wing sections must accommodate substantial Mach number, free stream dynamic pressure and section angle of attack variation at each flight condition within the design envelope. They must also be capable of short term circulation blowing modulation to produce control moments and vibration alleviation in addition to a lift augmentation function. Control system design must provide this primary control moment, vibration alleviation and lift augmentation function. To accomplish this, one must simultaneously control the compressed air source and its distribution. The control law algorithm must therefore address the compressor as the air source, the plenum as the air pressure storage and the pneumatic flow gates or valves that distribute and meter the stored pressure to the rotating blades. Also, mechanical collective blade pitch, rotor shaft angle of attack and engine power control must be maintained.

Seismology in civil engineering

NASA Astrophysics Data System (ADS)

Dvorak, A.

Properties of soils and rocks exposed to vibrations in the practice of civil engineering are examined. Seismic and dynamic field investigations, determination of seismic and dynamic modulus of elasticity, coefficients of damping and absorption are studied. Seismic effects of blasting and of other sources of vibrations on structures and persons, application of rock-noise and dynamic tests of piles are studied.

Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: AMSU-A1 METSAT Instrument (S/N 105) Qualification, Level Vibration Tests of December 1998 (S/O 605445, OC-419)

NASA Technical Reports Server (NTRS)

Heffner, R. J.

1998-01-01

This is the Engineering Test Report, AMSU-AL METSAT Instrument (S/N 105) Qualification Level Vibration Tests of December 1998 (S/0 605445, OC-419), for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).

Vibration, acoustic, and shock design and test criteria for components on the Solid Rocket Boosters (SRB), Lightweight External Tank (LWT), and Space Shuttle Main Engines (SSME)

NASA Technical Reports Server (NTRS)

1984-01-01

The vibration, acoustics, and shock design and test criteria for components and subassemblies on the space shuttle solid rocket booster (SRB), lightweight tank (LWT), and main engines (SSME) are presented. Specifications for transportation, handling, and acceptance testing are also provided.

Vibration modelling and verifications for whole aero-engine

NASA Astrophysics Data System (ADS)

Chen, G.

2015-08-01

In this study, a new rotor-ball-bearing-casing coupling dynamic model for a practical aero-engine is established. In the coupling system, the rotor and casing systems are modelled using the finite element method, support systems are modelled as lumped parameter models, nonlinear factors of ball bearings and faults are included, and four types of supports and connection models are defined to model the complex rotor-support-casing coupling system of the aero-engine. A new numerical integral method that combines the Newmark-β method and the improved Newmark-β method (Zhai method) is used to obtain the system responses. Finally, the new model is verified in three ways: (1) modal experiment based on rotor-ball bearing rig, (2) modal experiment based on rotor-ball-bearing-casing rig, and (3) fault simulations for a certain type of missile turbofan aero-engine vibration. The results show that the proposed model can not only simulate the natural vibration characteristics of the whole aero-engine but also effectively perform nonlinear dynamic simulations of a whole aero-engine with faults.

Chalcogenide glass sensors for bio-molecule detection

NASA Astrophysics Data System (ADS)

Lucas, Pierre; Coleman, Garrett J.; Cantoni, Christopher; Jiang, Shibin; Luo, Tao; Bureau, Bruno; Boussard-Pledel, Catherine; Troles, Johann; Yang, Zhiyong

2017-02-01

Chalcogenide glasses constitute the only class of materials that remain fully amorphous while exhibiting broad optical transparency over the full infrared region from 2-20 microns. As such, they can be shaped into complex optical elements while retaining a clear optical window that encompass the vibrational signals of virtually any molecules. Chalcogenide glasses are therefore ideal materials for designing biological and chemical sensors based on vibrational spectroscopy. In this paper we review the properties of these glasses and the corresponding design of optical elements for bio-chemical sensing. Amorphous chalcogenides offer a very wide compositional landscape that permit to tune their physical properties to match specific demands for the production of optical devices. This includes tailoring the infrared window over specific ranges of wavelength such as the long-wave infrared region to capture important vibrational signal including the "signature region" of micro-organisms or the bending mode of CO2 molecules. Additionally, compositional engineering enables tuning the viscosity-temperature dependence of the glass melt in order to control the rheological properties that are fundamental to the production of glass elements. Indeed, exquisite control of the viscosity is key to the fabrication process of many optical elements such as fiber drawing, lens molding, surface embossing or reflow of microresonators. Optimal control of these properties then enables the design and fabrication of optimized infrared sensors such as Fiber Evanescent Wave Spectroscopy (FEWS) sensors, Whispering Gallery Modes (WGM) micro-resonator sensors, nanostructured surfaces for integrated optics and surface-enhanced processes, or lens molding for focused collection of infrared signals. Many of these sensor designs can be adapted to collect and monitor the vibrational signal of live microorganisms to study their metabolism in controlled environmental conditions. Further materials engineering enable the design of opto-electrophoretic sensors that permit simultaneous capture and detection of hazardous bio-molecules such as bacteria, virus and proteins using a conducting glass that serves as both an electrode and an optical elements. Upon adequate spectral analysis such as Principal Component Analysis (PCA) or Partial Least Square (PLS) regression these devices enable highly selective identification of hazardous microorganism such as different strains of bacteria and food pathogens.

Dynamic analysis of periodic vibration suppressors with multiple secondary oscillators

NASA Astrophysics Data System (ADS)

Ma, Jiangang; Sheng, Meiping; Guo, Zhiwei; Qin, Qi

2018-06-01

A periodic vibration suppressor with multiple secondary oscillators is examined in this paper to reduce the low-frequency vibration. The band-gap properties of infinite periodic structure and vibration transmission properties of finite periodic structure attached with secondary oscillators with arbitrary degree of freedom are thoroughly analyzed by the plane-wave-expansion method. A simply supported plate with a periodic rectangular array of vibration suppressors is considered. The dynamic model of this periodic structure is established and the equation of harmonic vibration response is theoretically derived and numerically examined. Compared with the simply supported plate without attached suppressors, the proposed plate can obtain better vibration control, and the vibration response can be effectively reduced in several frequency bands owing to the multiple band-gap property. By analyzing the modal properties of the periodic vibration suppressors, the relationship between modal frequencies and the parameters of spring stiffness and mass is established. With the numerical results, the design guidance of the locally resonant structure with multiple secondary oscillators is proposed to provide practical guidance for application. Finally, a practical periodic specimen is designed and fabricated, and then an experiment is carried out to validate the effectiveness of periodic suppressors in the reality. The results show that the experimental band gaps have a good coincidence with those in the theoretical model, and the low-frequency vibration of the plate with periodic suppressors can be effectively reduced in the tuned band gaps. Both the theoretical results and experimental results prove that the design method is effective and the structure with periodic suppressors has a promising application in engineering.

Accelerometer method and apparatus for integral display and control functions

NASA Astrophysics Data System (ADS)

Bozeman, Richard J., Jr.

1992-06-01

Vibration analysis has been used for years to provide a determination of the proper functioning of different types of machinery, including rotating machinery and rocket engines. A determination of a malfunction, if detected at a relatively early stage in its development, will allow changes in operating mode or a sequenced shutdown of the machinery prior to a total failure. Such preventative measures result in less extensive and/or less expensive repairs, and can also prevent a sometimes catastrophic failure of equipment. Standard vibration analyzers are generally rather complex, expensive, and of limited portability. They also usually result in displays and controls being located remotely from the machinery being monitored. Consequently, a need exists for improvements in accelerometer electronic display and control functions which are more suitable for operation directly on machines and which are not so expensive and complex. The invention includes methods and apparatus for detecting mechanical vibrations and outputting a signal in response thereto. The apparatus includes an accelerometer package having integral display and control functions. The accelerometer package is suitable for mounting upon the machinery to be monitored. Display circuitry provides signals to a bar graph display which may be used to monitor machine condition over a period of time. Control switches may be set which correspond to elements in the bar graph to provide an alert if vibration signals increase over the selected trip point. The circuitry is shock mounted within the accelerometer housing. The method provides for outputting a broadband analog accelerometer signal, integrating this signal to produce a velocity signal, integrating and calibrating the velocity signal before application to a display driver, and selecting a trip point at which a digitally compatible output signal is generated. The benefits of a vibration recording and monitoring system with controls and displays readily mountable on the machinery being monitored and having capabilities described will be appreciated by those working in the art.

Accelerometer method and apparatus for integral display and control functions

NASA Technical Reports Server (NTRS)

Bozeman, Richard J., Jr. (Inventor)

1992-01-01

Vibration analysis has been used for years to provide a determination of the proper functioning of different types of machinery, including rotating machinery and rocket engines. A determination of a malfunction, if detected at a relatively early stage in its development, will allow changes in operating mode or a sequenced shutdown of the machinery prior to a total failure. Such preventative measures result in less extensive and/or less expensive repairs, and can also prevent a sometimes catastrophic failure of equipment. Standard vibration analyzers are generally rather complex, expensive, and of limited portability. They also usually result in displays and controls being located remotely from the machinery being monitored. Consequently, a need exists for improvements in accelerometer electronic display and control functions which are more suitable for operation directly on machines and which are not so expensive and complex. The invention includes methods and apparatus for detecting mechanical vibrations and outputting a signal in response thereto. The apparatus includes an accelerometer package having integral display and control functions. The accelerometer package is suitable for mounting upon the machinery to be monitored. Display circuitry provides signals to a bar graph display which may be used to monitor machine condition over a period of time. Control switches may be set which correspond to elements in the bar graph to provide an alert if vibration signals increase over the selected trip point. The circuitry is shock mounted within the accelerometer housing. The method provides for outputting a broadband analog accelerometer signal, integrating this signal to produce a velocity signal, integrating and calibrating the velocity signal before application to a display driver, and selecting a trip point at which a digitally compatible output signal is generated. The benefits of a vibration recording and monitoring system with controls and displays readily mountable on the machinery being monitored and having capabilities described will be appreciated by those working in the art.

46 CFR 162.050-37 - Vibration test.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 6 2010-10-01 2010-10-01 false Vibration test. 162.050-37 Section 162.050-37 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL ENGINEERING EQUIPMENT Pollution Prevention Equipment § 162.050-37 Vibration test. (a...

The application of S-transformation and M-2DPCA in I.C. Engine fault diagnosis

NASA Astrophysics Data System (ADS)

Zhang, Shixiong; Cai, Yanping; Mu, Weijie

2017-04-01

According to the problem of parameter selection and feature extraction for vibration diagnosis of traditional internal combustion engine is discussed. The method based on S-transformation and Module Two Dimensional Principal Components Analysis (M-2DPCA) is proposed to carry out fault diagnosis of I.C. Engine valve mechanism. First of all, the method transfers cylinder surface vibration signals of I.C. into images through S-transform. The second, extracting the optimized projection vectors from the general distribution matrix G which is obtained by all sample sub-images, so that vibration spectrum images can be modularized using M-2DPCA. The last, these features matrix obtained from images project will served as the enters of nearest neighbor classifier, it is used to achieve fault types' division. The method is applied to the diagnosis example of the vibration signal of the valve mechanism eight operating modes, recognition rate up to 94.17 percent; the effectiveness of the proposed method is proved.

A feasibility work on the applications of MRE to automotive components

NASA Astrophysics Data System (ADS)

Kim, S. H.; Park, Y. J.; Cha, A. R.; Kim, G. W.; Bang, J. H.; Lim, C. S.; Choi, S. B.

2018-03-01

A feasibility work on the application of magneto-rheological elastomers (MREs) to automotive components, such as engine mounts is presented. While vehicle components require the high resonance frequency in terms of ride quality and handling, it is required to have the low resonance frequency to isolate the incoming vibration. With the conventional automotive technologies, it is challenging to combine these two conflicting performance trade-offs, ride quality including handling, and NVH (noise, vibration and harshness). Over the last decades, MREs, one of the new emerging smart materials, have been widely used to resolve this technical limitation. For example, an advanced engine mount was developed by using MRE to isolate the vibration transmitting from engines. In this paper, we will focus on rear cross member bushes, which is a key component for isolating the vibration from the road, and demonstrate their improved performance by utilizing MRE. The resonance frequency shift induced by the stiffness change of MRE will be presented through the frequency response functions estimated by simulation result.

A noninterference blade vibration measurement system for gas turbine engines

NASA Astrophysics Data System (ADS)

Watkins, William B.; Chi, Ray M.

1987-06-01

A noninterfering blade vibration system has been demonstrated in tests of a gas turbine first stage fan. Conceptual design of the system, including its theory, design of case mounted probes, and data acquisition and signal processing hardware was done in a previous effort. The current effort involved instrumentation of an engine fan stage with strain gages; data acquisition using shaft-mounted reference and case-mounted optical probes; recording of data on a wideband tape recorder; and posttest processing using off-line analysis in a facility computer and a minicomputer-based readout system designed for near- real-time readout. Results are presented in terms of true blade vibration frequencies, time and frequency dependent vibration amplitudes and comparison of the optical noninterference results with strain gage readings.

Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: AMSU-A2 METSAT Instrument (S/N 108) Acceptance Level Vibration Tests of Dec 1999/Jan 2000 (S/O 784077, OC-454)

NASA Technical Reports Server (NTRS)

Heffner, R.

2000-01-01

This is the Engineering Test Report, AMSU-A2 METSAT Instrument (S/N 108) Acceptance Level Vibration Test of Dec 1999/Jan 2000 (S/O 784077, OC-454), for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).

Stirling Engine Controller

NASA Technical Reports Server (NTRS)

Blaze, Gina M.

2004-01-01

Stirling technology is being developed to replace RTG s (Radioisotope Thermoelectric Generators), more specifically a stirling convertor, which is a stirling engine coupled to a linear alternator. Over the past three decades, the stirling engine has been designed to perform different functions. Stirling convertors have been designed to decrease fuel consumption in automobiles. They have also been designed for terrestrial and space applications. Currently NASA Glenn is using the convertor for space based applications. A stiring converter is a better means of power for deep space mission and "dusty" mission, like the Mars Rovers, than solar panels because it is not affected by dust. Spirit and Opportunity, two Mars rovers currently navigating the planet, are losing their ability to generate electricity because dust is collecting on their solar panels. Opportunity is losing more energy because its robotic arm has a heater with a switch that can not be turned off. The heater is not needed at night, but yet still runs. This generates a greater loss of electricity and in turn diminishes the performance of the rover. The stirling cycle has the potential to provide very efficient conversion of heat energy to electric a1 energy, more so than RTG's. The stirling engine converts the thermal energy produced by the decaying radioisotope to mechanical energy; the linear alternator converts this into electricity. convertor. Since the early 1990's tests have been performed to maximize the efficiency of the stirling converter. Many months, even years, are dedicated to preparing and performing tests. Currently, two stirling convertors #'s 13 and 14, which were developed by Stirling Technology Company, are on an extended operation test. As of June 7th, the two convertors reached 7,500 hours each of operation. Before the convertors could run unattended, many safety precautions had to be examined. So, special instrumentation and circuits were developed to detect off nominal conditions and also safely shutdown the engines. The test will last for a period of 8000 to 9000 hours. Other types of tests that have been performed are: performance mapping, controller development, launch environment, and vibration emissions testing. Currently, the thermo-mechanical system branch is housing a RG-350, a stirling convertor. The convertor was used in previous tests such as a Hall Thruster test, world s first integrated test of a dynamic power system with electric propulsion. Another test performed was to conclude if free piston stirling convertors can be synchronized for vibration balancing, with no thermodynamic or electrical connections and not cause both to shutdown if one failed. The ability to reduce vibration by synchronizing convertor operation but still be able to operate when one partner fails is pertinent in space and terrestrial applications. The convertor is now being brought back into operation and a controller is in the process of being developed. This convertor will be used as a testbed for new controllers. I worked with Mary Ellen Roth on the electric engineering aspects of the RG-350. My main goal was to enhance the data collection process. I worked on different aspects of the RG-350, with a main focus on the engine controller. I drew a schematic of the wire connections in the engine controller, using PCB Express, so that a plan could be devised to connect the power meter properly between the output of the engine and the engine controller. I measured the power using two different instruments: Valhalla Scientific power meter and Ohio Semitronics power measurement device. The convertor is connected to an Agilent 34970A Data Acquisition/Switch Unit, which allows the user to measure, record, and monitor voltage, current, frequency, and temperature. I assisted in preparing the Data Acquisition for general operation. I also helped test a panel of transducers, which will be placed in the rack that powers and monitors the convertor.

Environmental Testing of the NEXT PM1R Ion Engine

NASA Technical Reports Server (NTRS)

Snyder, John S.; Anderson, John R.; VanNoord, Jonathan L.; Soulas, George C.

2007-01-01

The NEXT propulsion system is an advanced ion propulsion system presently under development that is oriented towards robotic exploration of the solar system using solar electric power. The subsystem includes an ion engine, power processing unit, feed system components, and thruster gimbal. The Prototype Model engine PM1 was subjected to qualification-level environmental testing in 2006 to demonstrate compatibility with environments representative of anticipated mission requirements. Although the testing was largely successful, several issues were identified including the fragmentation of potting cement on the discharge and neutralizer cathode heater terminations during vibration which led to abbreviated thermal testing, and generation of particulate contamination from manufacturing processes and engine materials. The engine was reworked to address most of these findings, renamed PM1R, and the environmental test sequence was repeated. Thruster functional testing was performed before and after the vibration and thermal-vacuum tests. Random vibration testing, conducted with the thruster mated to the breadboard gimbal, was executed at 10.0 Grms for 2 min in each of three axes. Thermal-vacuum testing included three thermal cycles from 120 to 215 C with hot engine re-starts. Thruster performance was nominal throughout the test program, with minor variations in a few engine operating parameters likely caused by facility effects. There were no significant changes in engine performance as characterized by engine operating parameters, ion optics performance measurements, and beam current density measurements, indicating no significant changes to the hardware as a result of the environmental testing. The NEXT PM1R engine and the breadboard gimbal were found to be well-designed against environmental requirements based on the results reported herein. The redesigned cathode heater terminations successfully survived the vibration environments. Based on the results of this test program and confidence in the engineering solutions available for the remaining findings of the first test program, specifically the particulate contamination, the hardware environmental qualification program can proceed with confidence

The military operator's experience of reliability and maintainability characteristics

NASA Astrophysics Data System (ADS)

Jones, R. Mcc.

An account is given of the British Army's approach to the achievement of high reliability and maintainability in rotorcraft during the procurement process. Attention is given to experience accumulated to date with the Gazelle, Scout, Agusta A109A, and Lynx helicopters; these offer lessons with respect to the Gem engine, fuel filtering, vibration, and an aircraft flight control system.

Accurate acoustic power measurement for low-intensity focused ultrasound using focal axial vibration velocity

NASA Astrophysics Data System (ADS)

Tao, Chenyang; Guo, Gepu; Ma, Qingyu; Tu, Juan; Zhang, Dong; Hu, Jimin

2017-07-01

Low-intensity focused ultrasound is a form of therapy that can have reversible acoustothermal effects on biological tissue, depending on the exposure parameters. The acoustic power (AP) should be chosen with caution for the sake of safety. To recover the energy of counteracted radial vibrations at the focal point, an accurate AP measurement method using the focal axial vibration velocity (FAVV) is proposed in explicit formulae and is demonstrated experimentally using a laser vibrometer. The experimental APs for two transducers agree well with theoretical calculations and numerical simulations, showing that AP is proportional to the square of the FAVV, with a fixed power gain determined by the physical parameters of the transducers. The favorable results suggest that the FAVV can be used as a valuable parameter for non-contact AP measurement, providing a new strategy for accurate power control for low-intensity focused ultrasound in biomedical engineering.

Optical information processing at NASA Ames Research Center

NASA Technical Reports Server (NTRS)

Reid, Max B.; Bualat, Maria G.; Cho, Young C.; Downie, John D.; Gary, Charles K.; Ma, Paul W.; Ozcan, Meric; Pryor, Anna H.; Spirkovska, Lilly

1993-01-01

The combination of analog optical processors with digital electronic systems offers the potential of tera-OPS computational performance, while often requiring less power and weight relative to all-digital systems. NASA is working to develop and demonstrate optical processing techniques for on-board, real time science and mission applications. Current research areas and applications under investigation include optical matrix processing for space structure vibration control and the analysis of Space Shuttle Main Engine plume spectra, optical correlation-based autonomous vision for robotic vehicles, analog computation for robotic path planning, free-space optical interconnections for information transfer within digital electronic computers, and multiplexed arrays of fiber optic interferometric sensors for acoustic and vibration measurements.

Granular metamaterials for vibration mitigation

NASA Astrophysics Data System (ADS)

Gantzounis, G.; Serra-Garcia, M.; Homma, K.; Mendoza, J. M.; Daraio, C.

2013-09-01

Acoustic metamaterials that allow low-frequency band gaps are interesting for many practical engineering applications, where vibration control and sound insulation are necessary. In most prior studies, the mechanical response of these structures has been described using linear continuum approximations. In this work, we experimentally and theoretically address the formation of low-frequency band gaps in locally resonant granular crystals, where the dynamics of the system is governed by discrete equations. We investigate the quasi-linear behavior of such structures. The analysis shows that a stopband can be introduced at about one octave lower frequency than in materials without local resonances. Broadband and multi-frequency stopband characteristics can also be achieved by strategically tailoring the non-uniform local resonance parameters.

Development of the mechanical cryocooler system for the Sea Land Surface Temperature Radiometer

NASA Astrophysics Data System (ADS)

Camilletti, Adam; Burgess, Christopher; Donchev, Anton; Watson, Stuart; Weatherstone Akbar, Shane; Gamo-Albero, Victoria; Romero-Largacha, Victor; Caballero-Olmo, Gema

2014-11-01

The Sea Land Surface Temperature Radiometer is a dual view Earth observing instrument developed as part of the European Global Monitoring for Environment and Security programme. It is scheduled for launch on two satellites, Sentinel 3A and 3B in 2014. The instrument detectors are cooled to below 85 K by two split Stirling Cryocoolers running in hot redundancy. These coolers form part of a cryocooler system that includes a support structure and drive electronics. Aspects of the system design, including control and reduction of exported vibration are discussed; and results, including thermal performance and exported vibration from the Engineering Model Cryooler System test campaign are presented.

Noise control in aeroacoustics; Proceedings of the 1993 National Conference on Noise Control Engineering, NOISE-CON 93, Williamsburg, VA, May 2-5, 1993

NASA Technical Reports Server (NTRS)

Hubbard, Harvey H. (Editor)

1993-01-01

In the conference over 100 papers were presented in eight sessions: (1) Emission: Noise Sources; (2) Physical Phenomena; (3) Noise ControlElements; (4) Vibration and Shock: Generation, Transmission, Isolation, and Reduction; (5) Immission: Physical Aspects of Environmental Noise; (6) Immission: Effects of Noise; (7) Analysis; and (8) Requirements. In addition, the distinguished lecture series included presentations on the High Speed Civil Transport and on research from the United Kingdom on aircraft noise effects.

Large space structures and systems in the space station era: A bibliography with indexes (supplement 03)

NASA Technical Reports Server (NTRS)

1991-01-01

Bibliographies and abstracts are listed for 1221 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1991 and June 30, 1991. Topics covered include large space structures and systems, space stations, extravehicular activity, thermal environments and control, tethering, spacecraft power supplies, structural concepts and control systems, electronics, advanced materials, propulsion, policies and international cooperation, vibration and dynamic controls, robotics and remote operations, data and communication systems, electric power generation, space commercialization, orbital transfer, and human factors engineering.

Flexible structure control experiments using a real-time workstation for computer-aided control engineering

NASA Technical Reports Server (NTRS)

Stieber, Michael E.

1989-01-01

A Real-Time Workstation for Computer-Aided Control Engineering has been developed jointly by the Communications Research Centre (CRC) and Ruhr-Universitaet Bochum (RUB), West Germany. The system is presently used for the development and experimental verification of control techniques for large space systems with significant structural flexibility. The Real-Time Workstation essentially is an implementation of RUB's extensive Computer-Aided Control Engineering package KEDDC on an INTEL micro-computer running under the RMS real-time operating system. The portable system supports system identification, analysis, control design and simulation, as well as the immediate implementation and test of control systems. The Real-Time Workstation is currently being used by CRC to study control/structure interaction on a ground-based structure called DAISY, whose design was inspired by a reflector antenna. DAISY emulates the dynamics of a large flexible spacecraft with the following characteristics: rigid body modes, many clustered vibration modes with low frequencies and extremely low damping. The Real-Time Workstation was found to be a very powerful tool for experimental studies, supporting control design and simulation, and conducting and evaluating tests withn one integrated environment.

Partial filling of a honeycomb structure by granular materials for vibration and noise reduction

NASA Astrophysics Data System (ADS)

Koch, Sebastian; Duvigneau, Fabian; Orszulik, Ryan; Gabbert, Ulrich; Woschke, Elmar

2017-04-01

In this paper, the damping effect of granular materials is explored to reduce the vibration and noise of mechanical structures. To this end, a honeycomb structure with high stiffness is used to contain a granular filling which presents the possiblity for the distribution of the granular material to be designed. As a particular application example, the oil pan bottom of a combustion engine is used to investigate the influence on the vibration behavior and the sound emission. The effect of the honeycomb structure along with the granular mass, distribution, and type on the vibration behaviour of the structure is investigated via laser scanning vibrometry. From this, an optimized filling is determined and then its noise suppression level validated on an engine test bench through measurements with an acoustic array.

Enhancing light-harvesting power with coherent vibrational interactions: A quantum heat engine picture

NASA Astrophysics Data System (ADS)

Killoran, N.; Huelga, S. F.; Plenio, M. B.

2015-10-01

Recent evidence suggests that quantum effects may have functional importance in biological light-harvesting systems. Along with delocalized electronic excitations, it is now suspected that quantum coherent interactions with certain near-resonant vibrations may contribute to light-harvesting performance. However, the actual quantum advantage offered by such coherent vibrational interactions has not yet been established. We investigate a quantum design principle, whereby coherent exchange of single energy quanta between electronic and vibrational degrees of freedom can enhance a light-harvesting system's power above what is possible by thermal mechanisms alone. We present a prototype quantum heat engine which cleanly illustrates this quantum design principle and quantifies its quantum advantage using thermodynamic measures of performance. We also demonstrate the principle's relevance in parameter regimes connected to natural light-harvesting structures.

Prevalence of Hand-transmitted Vibration Exposure among Grass-cutting Workers using Objective and Subjective Measures

NASA Astrophysics Data System (ADS)

Azmir, N. A.; Yahya, M. N.

2017-01-01

Extended exposure to hand-transmitted vibration from vibrating machine is associated with an increased occurrence of symptoms of occupational disease related to hand disorder. The present case study is to determine the prevalence and correlation of significant subjective as well as objective variables that induce to hand arm vibration syndrome (HAVS) among hand-held grass-cutting workers in Malaysia. Thus, recommendations are made for grass-cutting workers and grass maintenance service management based on findings. A cross sectional study using adopted subjective Hand Arm Vibration Exposure Risk Assessment (HAVERA) questionnaire from Vibration Injury Network on hand disorder signs and symptoms was distributed to a sample of one hundred and sixty eight male workers from grass and turf maintenance industry that use vibrating machine as part of their work. For objective measure, hand-transmitted vibration measurement was collected on site during operation by the following ISO 5349-1, 2001. Two groups were identified in this research comprising of high exposure group and low-moderate exposure group. Workers also gave information about their personal identification, social history, workers’ health, occupational history and machine safety inspection. There was positive HAVS symptoms relationship between the low-moderate exposure group and high exposure group among hand-held grass-cutting workers. The prevalence ratio (PR) was considered high for experiencing white colour change at fingers and fingers go numb which are 3.63 (1.41 to 9.39) and 4.24 (2.18 to 8.27), respectively. The estimated daily vibration exposure, A(8) differs between 2.1 to 20.7 ms-2 for right hand while 2.7 to 29.1 ms-2 for left hand. The subjects claimed that the feel of numbness at left hand is much stronger compared to right hand. The results suggest that HAVS is diagnosed in Malaysia especially in agriculture sector. The A(8) indicates that the exposure value is more than exposure limit value which is 5 ms-2. Thus, control measure such as engineering and administrative control should be implemented to reduce the severity of hand-transmitted vibration hazard.

Integrated Vehicle Ground Vibration Testing in Support of Launch Vehicle Loads and Controls Analysis

NASA Technical Reports Server (NTRS)

Askins, Bruce R.; Davis, Susan R.; Salyer, Blaine H.; Tuma, Margaret L.

2008-01-01

All structural systems possess a basic set of physical characteristics unique to that system. These unique physical characteristics include items such as mass distribution and damping. When specified, they allow engineers to understand and predict how a structural system behaves under given loading conditions and different methods of control. These physical properties of launch vehicles may be predicted by analysis or measured by certain types of tests. Generally, these properties are predicted by analysis during the design phase of a launch vehicle and then verified by testing before the vehicle becomes operational. A ground vibration test (GVT) is intended to measure by test the fundamental dynamic characteristics of launch vehicles during various phases of flight. During the series of tests, properties such as natural frequencies, mode shapes, and transfer functions are measured directly. These data will then be used to calibrate loads and control systems analysis models for verifying analyses of the launch vehicle. NASA manned launch vehicles have undergone ground vibration testing leading to the development of successful launch vehicles. A GVT was not performed on the inaugural launch of the unmanned Delta III which was lost during launch. Subsequent analyses indicated had a GVT been performed, it would have identified instability issues avoiding loss of the vehicle. This discussion will address GVT planning, set-up, execution and analyses, for the Saturn and Shuttle programs, and will also focus on the current and on-going planning for the Ares I and V Integrated Vehicle Ground Vibration Test (IVGVT).

Design and engineering of organic molecules for customizable Terahertz tags

NASA Astrophysics Data System (ADS)

Ray, Shaumik; Dash, Jyotirmayee; Nallappan, Kathirvel; Kaware, Vaibhav; Basutkar, Nitin; Ambade, Ashootosh; Joshi, Kavita; Pesala, Bala

2014-03-01

Terahertz (THz) frequency band lies between the microwave and infrared region of the electromagnetic spectrum. Molecules having strong resonances in this frequency range are ideal for realizing "Terahertz tags" which can be easily incorporated into various materials. THz spectroscopy of molecules, especially at frequencies below 10 THz, provides valuable information on the low frequency vibrational modes, viz. intermolecular vibrational modes, hydrogen bond stretching, torsional vibrations in several chemical and biological compounds. So far there have been very few attempts to engineer molecules which can demonstrate customizable resonances in the THz frequency region. In this paper, Diamidopyridine (DAP) based molecules are used as a model system to demonstrate engineering of THz resonances (< 10 THz) by fine-tuning the molecular mass and bond strengths. Density Functional Theory (DFT) simulations have been carried out to explain the origin of THz resonances and factors contributing to the shift in resonances due to the addition of various functional groups. The design approach presented here can be easily extended to engineer various organic molecules suitable for THz tags application.

Control of Inflow Distortion in a Scarf Inlet

NASA Technical Reports Server (NTRS)

Gerhold, Carl H.; Clark, Lorenzo R.; Biedron, Robert T.

2002-01-01

The scarf inlet has the potential to reduce aircraft inlet noise radiation to the ground by reflecting it into the space above the engine. Without forward motion of the engine, the non-symmetry of the inlet causes inflow distortion which generates noise that is greater than the noise reduction of the scarf. However, acoustic evaluations of aircraft engines are often done on static test stands. A method to reduce inflow distortion by boundary layer suction is proposed and evaluated using a model of a high bypass ratio engine located in an anechoic chamber. The design goal of the flow control system is to make the inflow to the inlet circumferentially uniform and to eliminate reversed flow. This minimizes the inflow distortion and allows for acoustic evaluation of the scarf inlet on a static test stand. The inlet boundary layer suction effectiveness is evaluated both by aerodynamic and by acoustic measurements. Although the design goal is not met, the control system is found to have a beneficial effect on the engine operation, reducing blade stall and speed variation. This is quantified by two acoustic benefits, reduction both of the variability of tone noise and of the low frequency wideband noise due to the inflow distortion. It is felt that a compromise in the manufacture of the control hardware contributes to the inability of the control system to perform as expected from the analysis. The control system with sufficient authority is felt to have the potential to permit reliable acoustic testing in a static configuration of engines with non-symmetric inlets. Because the control system can improve operation of the engine, it may also have the potential to reduce noise and vibration and enhance engine longevity during low speed ground operations in the terminal area.

14 CFR 23.907 - Propeller vibration and fatigue.

Code of Federal Regulations, 2013 CFR

2013-01-01

... based on direct testing of the propeller on the airplane and engine installation for which approval is... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Propeller vibration and fatigue. 23.907... General § 23.907 Propeller vibration and fatigue. This section does not apply to fixed-pitch wood...

14 CFR 23.907 - Propeller vibration and fatigue.

Code of Federal Regulations, 2014 CFR

2014-01-01

... based on direct testing of the propeller on the airplane and engine installation for which approval is... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Propeller vibration and fatigue. 23.907... General § 23.907 Propeller vibration and fatigue. This section does not apply to fixed-pitch wood...

The National Aeronautics and Space Administration interdisciplinary studies in space technology at the University of Kansas

NASA Technical Reports Server (NTRS)

Barr, B. G.

1974-01-01

A broad range of research projects contained in a cooperative space technology program at the University of Kansas are reported as they relate to the following three areas of interdisciplinary interest: (1) remote sensing of earth resources; (2) stability and control of light and general aviation aircraft; and (3) the vibrational response characteristics of aeronautical and space vehicles. Details of specific research efforts are given under their appropriate departments, among which are aerospace engineering, chemical and petroleum engineering, environmental health, water resources, the remote sensing laboratory, and geoscience applications studies.

Overview of Lightweight Structures for Rotorcraft Engines and Drivetrains

NASA Technical Reports Server (NTRS)

Roberts, Gary D.

2011-01-01

This is an overview presentation of research being performed in the Advanced Materials Task within the NASA Subsonic Rotary Wing Project. This research is focused on technology areas that address both national goals and project goals for advanced rotorcraft. Specific technology areas discussed are: (1) high temperature materials for advanced turbines in turboshaft engines; (2) polymer matrix composites for lightweight drive system components; (3) lightweight structure approaches for noise and vibration control; and (4) an advanced metal alloy for lighter weight bearings and more reliable mechanical components. An overview of the technology in each area is discussed, and recent accomplishments are presented.

Active Narrow-Band Vibration Isolation of Large Engineering Structures

NASA Technical Reports Server (NTRS)

Rahman, Zahidul; Spanos, John

1994-01-01

We present a narrow-band tracking control method using a variant of the Least Mean Squares (LMS) algorithm to isolate slowly changing periodic disturbances from engineering structures. The advantage of the algorithm is that it has a simple architecture and is relatively easy to implement while it can isolate disturbances on the order of 40-50 dB over decades of frequency band. We also present the results of an experiment conducted on a flexible truss structure. The average disturbance rejection achieved is over 40 dB over the frequency band of 5 Hz to 50 Hz.

Analysis of interior noise ground and flight test data for advanced turboprop aircraft applications

NASA Technical Reports Server (NTRS)

Simpson, M. A.; Tran, B. N.

1991-01-01

Interior noise ground tests conducted on a DC-9 aircraft test section are described. The objectives were to study ground test and analysis techniques for evaluating the effectiveness of interior noise control treatments for advanced turboprop aircraft, and to study the sensitivity of the ground test results to changes in various test conditions. Noise and vibration measurements were conducted under simulated advanced turboprop excitation, for two interior noise control treatment configurations. These ground measurement results were compared with results of earlier UHB (Ultra High Bypass) Demonstrator flight tests with comparable interior treatment configurations. The Demonstrator is an MD-80 test aircraft with the left JT8D engine replaced with a prototype UHB advanced turboprop engine.

Analysis of interior noise ground and flight test data for advanced turboprop aircraft applications

NASA Astrophysics Data System (ADS)

Simpson, M. A.; Tran, B. N.

1991-08-01

Interior noise ground tests conducted on a DC-9 aircraft test section are described. The objectives were to study ground test and analysis techniques for evaluating the effectiveness of interior noise control treatments for advanced turboprop aircraft, and to study the sensitivity of the ground test results to changes in various test conditions. Noise and vibration measurements were conducted under simulated advanced turboprop excitation, for two interior noise control treatment configurations. These ground measurement results were compared with results of earlier UHB (Ultra High Bypass) Demonstrator flight tests with comparable interior treatment configurations. The Demonstrator is an MD-80 test aircraft with the left JT8D engine replaced with a prototype UHB advanced turboprop engine.

Development of the Larzac Engine Rig for Compressor Stall Testing

DTIC Science & Technology

2011-12-01

due to high vibration levels. Most pressure and all temperature sensors were of conventional type, providing analogue output signals, but of...Must have enough thermal stability to withstand the flow temperature at the particular location. 4. Must be stable in relation to engine vibration ...Instabilities in an Aeroengine ”, ICIASF ’97 Record, IEEE Publications 1997. 7. Hoess, B., Leinhos, D., Fottner, L., 2000, “Stall Inception in the

Control of equipment isolation system using wavelet-based hybrid sliding mode control

NASA Astrophysics Data System (ADS)

Huang, Shieh-Kung; Loh, Chin-Hsiung

2017-04-01

Critical non-structural equipment, including life-saving equipment in hospitals, circuit breakers, computers, high technology instrumentations, etc., is vulnerable to strong earthquakes, and on top of that, the failure of the vibration-sensitive equipment will cause severe economic loss. In order to protect vibration-sensitive equipment or machinery against strong earthquakes, various innovative control algorithms are developed to compensate the internal forces that to be applied. These new or improved control strategies, such as the control algorithms based on optimal control theory and sliding mode control (SMC), are also developed for structures engineering as a key element in smart structure technology. The optimal control theory, one of the most common methodologies in feedback control, finds control forces through achieving a certain optimal criterion by minimizing a cost function. For example, the linear-quadratic regulator (LQR) was the most popular control algorithm over the past three decades, and a number of modifications have been proposed to increase the efficiency of classical LQR algorithm. However, except to the advantage of simplicity and ease of implementation, LQR are susceptible to parameter uncertainty and modeling error due to complex nature of civil structures. Different from LQR control, a robust and easy to be implemented control algorithm, SMC has also been studied. SMC is a nonlinear control methodology that forces the structural system to slide along surfaces or boundaries; hence this control algorithm is naturally robust with respect to parametric uncertainties of a structure. Early attempts at protecting vibration-sensitive equipment were based on the use of existing control algorithms as described above. However, in recent years, researchers have tried to renew the existing control algorithms or developing a new control algorithm to adapt the complex nature of civil structures which include the control of both structures and non-structural components. The aim of this paper is to develop a hybrid control algorithm on the control of both structures and equipments simultaneously to overcome the limitations of classical feedback control through combining the advantage of classic LQR and SMC. To suppress vibrations with the frequency contents of strong earthquakes differing from the natural frequencies of civil structures, the hybrid control algorithms integrated with the wavelet-base vibration control algorithm is developed. The performance of classical, hybrid, and wavelet-based hybrid control algorithms as well as the responses of structure and non-structural components are evaluated and discussed through numerical simulation in this study.

Dynamic coordinated control during mode transition process for a compound power-split hybrid electric vehicle

NASA Astrophysics Data System (ADS)

Su, Yanzhao; Hu, Minghui; Su, Ling; Qin, Datong; Zhang, Tong; Fu, Chunyun

2018-07-01

The fuel economy of the hybrid electric vehicles (HEVs) can be effectively improved by the mode transition (MT). However, for a power-split powertrain whose power-split transmission is directly connected to the engine, the engine ripple torque (ERT), inconsistent dynamic characteristics (IDC) of engine and motors, model estimation inaccuracies (MEI), system parameter uncertainties (SPU) can cause jerk and vibration of transmission system during the MT process, which will reduce the driving comfort and the life of the drive parts. To tackle these problems, a dynamic coordinated control strategy (DCCS), including a staged engine torque feedforward and feedback estimation (ETFBC) and an active damping feedback compensation (ADBC) based on drive shaft torque estimation (DSTE), is proposed. And the effectiveness of this strategy is verified using a plant model. Firstly, the powertrain plant model is established, and the MT process and problems are analyzed. Secondly, considering the characteristics of the engine torque estimation (ETE) model before and after engine ignition, a motor torque compensation control based on the staged ERT estimation is developed. Then, considering the MEI, SPU and the load change, an ADBC based on a real-time nonlinear reduced-order robust observer of the DSTE is designed. Finally, the simulation results show that the proposed DCCS can effectively improve the driving comfort.

Dynamically variable negative stiffness structures.

PubMed

Churchill, Christopher B; Shahan, David W; Smith, Sloan P; Keefe, Andrew C; McKnight, Geoffrey P

2016-02-01

Variable stiffness structures that enable a wide range of efficient load-bearing and dexterous activity are ubiquitous in mammalian musculoskeletal systems but are rare in engineered systems because of their complexity, power, and cost. We present a new negative stiffness-based load-bearing structure with dynamically tunable stiffness. Negative stiffness, traditionally used to achieve novel response from passive structures, is a powerful tool to achieve dynamic stiffness changes when configured with an active component. Using relatively simple hardware and low-power, low-frequency actuation, we show an assembly capable of fast (<10 ms) and useful (>100×) dynamic stiffness control. This approach mitigates limitations of conventional tunable stiffness structures that exhibit either small (<30%) stiffness change, high friction, poor load/torque transmission at low stiffness, or high power active control at the frequencies of interest. We experimentally demonstrate actively tunable vibration isolation and stiffness tuning independent of supported loads, enhancing applications such as humanoid robotic limbs and lightweight adaptive vibration isolators.

Development of a novel multi-layer MRE isolator for suppression of building vibrations under seismic events

NASA Astrophysics Data System (ADS)

Yang, Jian; Sun, Shuaishuai; Tian, Tongfei; Li, Weihua; Du, Haiping; Alici, Gursel; Nakano, Masami

2016-03-01

Protecting civil engineering structures from uncontrollable events such as earthquakes while maintaining their structural integrity and serviceability is very important; this paper describes the performance of a stiffness softening magnetorheological elastomer (MRE) isolator in a scaled three storey building. In order to construct a closed-loop system, a scaled three storey building was designed and built according to the scaling laws, and then four MRE isolator prototypes were fabricated and utilised to isolate the building from the motion induced by a scaled El Centro earthquake. Fuzzy logic was used to output the current signals to the isolators, based on the real-time responses of the building floors, and then a simulation was used to evaluate the feasibility of this closed loop control system before carrying out an experimental test. The simulation and experimental results showed that the stiffness softening MRE isolator controlled by fuzzy logic could suppress structural vibration well.

Research of rotating machinery vibration parameters - Shaft speed relationship

NASA Astrophysics Data System (ADS)

Kostyukov, V. N.; Kostyukov, A. V.; Zaytsev, A. V.; Teterin, A. O.

2017-08-01

The paper considers the relationship between the parameters of the vibration arising in rotating machinery during operation and the shaft speed. The goal of this paper is to determine the dependence of the vibration parameters on the shaft speed for solving applied engineering problems. To properly evaluate the technical condition of bearing assemblies, we should take into account the pattern of the rotating machinery vibration parameters-shaft speed relationship, which will allow creating new diagnostic features, the totality of which will ensure an increased reliability of diagnosis. We took the check for a correlation between the factor and resultative feature parameters as the correlation analysis method. A high pair linear correlation between the diagnostic features (acceleration, velocity, displacement) and the shaft speed was determined on the basis of the check for correlation between the vibration parameters and the shaft speed, and also the linear correlation coefficients can be used to solve the applied engineering problems of diagnosing the bearing assemblies of the rotating machinery.

Experimental and analytical study of secondary path variations in active engine mounts

NASA Astrophysics Data System (ADS)

Hausberg, Fabian; Scheiblegger, Christian; Pfeffer, Peter; Plöchl, Manfred; Hecker, Simon; Rupp, Markus

2015-03-01

Active engine mounts (AEMs) provide an effective solution to further improve the acoustic and vibrational comfort of passenger cars. Typically, adaptive feedforward control algorithms, e.g., the filtered-x-least-mean-squares (FxLMS) algorithm, are applied to cancel disturbing engine vibrations. These algorithms require an accurate estimate of the AEM active dynamic characteristics, also known as the secondary path, in order to guarantee control performance and stability. This paper focuses on the experimental and theoretical study of secondary path variations in AEMs. The impact of three major influences, namely nonlinearity, change of preload and component temperature, on the AEM active dynamic characteristics is experimentally analyzed. The obtained test results are theoretically investigated with a linear AEM model which incorporates an appropriate description for elastomeric components. A special experimental set-up extends the model validation of the active dynamic characteristics to higher frequencies up to 400 Hz. The theoretical and experimental results show that significant secondary path variations are merely observed in the frequency range of the AEM actuator's resonance frequency. These variations mainly result from the change of the component temperature. As the stability of the algorithm is primarily affected by the actuator's resonance frequency, the findings of this paper facilitate the design of AEMs with simpler adaptive feedforward algorithms. From a practical point of view it may further be concluded that algorithmic countermeasures against instability are only necessary in the frequency range of the AEM actuator's resonance frequency.

Application of analysis techniques for low frequency interior noise and vibration of commercial aircraft

NASA Technical Reports Server (NTRS)

Landmann, A. E.; Tillema, H. F.; Macgregor, G. R.

1992-01-01

Finite element analysis (FEA), statistical energy analysis (SEA), and a power flow method (computer program PAIN) were used to assess low frequency interior noise associated with advanced propeller installations. FEA and SEA models were used to predict cabin noise and vibration and evaluate suppression concepts for structure-borne noise associated with the shaft rotational frequency and harmonics (less than 100 Hz). SEA and PAIN models were used to predict cabin noise and vibration and evaluate suppression concepts for airborne noise associated with engine radiated propeller tones. Both aft-mounted and wing-mounted propeller configurations were evaluated. Ground vibration test data from a 727 airplane modified to accept a propeller engine were used to compare with predictions for the aft-mounted propeller. Similar data from the 767 airplane was used for the wing-mounted comparisons.

Enhancing light-harvesting power with coherent vibrational interactions: A quantum heat engine picture

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

Killoran, N.; Huelga, S. F.; Plenio, M. B.

Recent evidence suggests that quantum effects may have functional importance in biological light-harvesting systems. Along with delocalized electronic excitations, it is now suspected that quantum coherent interactions with certain near-resonant vibrations may contribute to light-harvesting performance. However, the actual quantum advantage offered by such coherent vibrational interactions has not yet been established. We investigate a quantum design principle, whereby coherent exchange of single energy quanta between electronic and vibrational degrees of freedom can enhance a light-harvesting system’s power above what is possible by thermal mechanisms alone. We present a prototype quantum heat engine which cleanly illustrates this quantum design principlemore » and quantifies its quantum advantage using thermodynamic measures of performance. We also demonstrate the principle’s relevance in parameter regimes connected to natural light-harvesting structures.« less

Investigation of difficult component effects on finite element model vibration prediction for the Bell AG-1G helicopter. Volume 2: Correlation results

NASA Technical Reports Server (NTRS)

Dompka, R. V.

1989-01-01

Under the NASA-sponsored DAMVIBS (Design Analysis Methods for VIBrationS) program, a series of ground vibration tests and NASTRAN finite element model (FEM) correlations were conducted on the Bell AH-1G helicopter gunship to investigate the effects of difficult components on the vibration response of the airframe. Previous correlations of the AG-1G showed good agreement between NASTRAN and tests through 15 to 20 Hz, but poor agreement in the higher frequency range of 20 to 30 Hz. Thus, this effort emphasized the higher frequency airframe vibration response correlations and identified areas that need further R and T work. To conduct the investigations, selected difficult components (main rotor pylon, secondary structure, nonstructural doors/panels, landing gear, engine, furl, etc.) were systematically removed to quantify their effects on overall vibratory response of the airframe. The entire effort was planned and documented, and the results reviewed by NASA and industry experts in order to ensure scientific control of the testing, analysis, and correlation exercise. In particular, secondary structure and damping had significant effects on the frequency response of the airframe above 15 Hz. Also, the nonlinear effects of thrust stiffening and elastomer mounts were significant on the low frequency pylon modes below main rotor 1p (5.4 Hz). The results of the NASTRAN FEM correlations are given.

An investigation of crankshaft oscillations for cylinder health diagnostics

NASA Astrophysics Data System (ADS)

Geveci, Mert; Osburn, Andrew W.; Franchek, Matthew A.

2005-09-01

The vibrational characteristics of an internal combustion engine crankshaft are investigated from a cylinder health diagnostics point of view. Experimental results from a six-cylinder industrial diesel engine are presented to demonstrate the effects of cylinder imbalance on the individual harmonic components of the engine speed signal. A crank-angle domain numerical model of the crankshaft dynamics for a six-cylinder industrial diesel engine is also adopted to establish the effects of continuous low-power production in individual cylinders of a multi-cylinder engine. Outline of a diagnostics algorithm that makes use of the properties of crankshaft vibration behaviour is provided. In particular, crank-angle domain notch filters are employed to extact the harmonic components of engine speed. The outlined method can be implemented for individual cylinder health diagnostics across a family of multi-cylinder engines and can be formulated to handle changes in crankshaft characteristics due to replacement of mechanical components and/or wear.

Structural Noise and Acoustic Characteristics Improvement of Transport Power Plants

NASA Astrophysics Data System (ADS)

Chaynov, N. D.; Markov, V. A.; Savastenko, A. A.

2018-03-01

Noise reduction generated during the operation of various machines and mechanisms is an urgent task with regard to the power plants and, in particular, to internal combustion engines. Sound emission from the surfaces vibration of body parts is one of the main noise manifestations of the running engine and it is called a structural noise. The vibration defining of the outer surfaces of complex body parts and the calculation of their acoustic characteristics are determined with numerical methods. At the same time, realization of finite and boundary elements methods combination turned out to be very effective. The finite element method is used in calculating the structural elements vibrations, and the boundary elements method is used in the structural noise calculation. The main conditions of the methodology and the results of the structural noise analysis applied to a number of automobile engines are shown.

Lewis Structures Technology, 1988. Volume 3: Structural Integrity Fatigue and Fracture Wind Turbines HOST

NASA Technical Reports Server (NTRS)

1988-01-01

The charter of the Structures Division is to perform and disseminate results of research conducted in support of aerospace engine structures. These results have a wide range of applicability to practioners of structural engineering mechanics beyond the aerospace arena. The specific purpose of the symposium was to familiarize the engineering structures community with the depth and range of research performed by the division and its academic and industrial partners. Sessions covered vibration control, fracture mechanics, ceramic component reliability, parallel computing, nondestructive evaluation, constitutive models and experimental capabilities, dynamic systems, fatigue and damage, wind turbines, hot section technology (HOST), aeroelasticity, structural mechanics codes, computational methods for dynamics, structural optimization, and applications of structural dynamics, and structural mechanics computer codes.

46 CFR 169.625 - Compartments containing diesel machinery.

Code of Federal Regulations, 2011 CFR

2011-10-01

... stresses induced by weight and engine vibration and to minimize transfer of vibration to the supporting..., and be installed so that the ordinary collection of water in the bilge will not trap the duct. Where...

46 CFR 169.625 - Compartments containing diesel machinery.

Code of Federal Regulations, 2010 CFR

2010-10-01

... stresses induced by weight and engine vibration and to minimize transfer of vibration to the supporting..., and be installed so that the ordinary collection of water in the bilge will not trap the duct. Where...

Ground test for vibration control demonstrator

NASA Astrophysics Data System (ADS)

Meyer, C.; Prodigue, J.; Broux, G.; Cantinaud, O.; Poussot-Vassal, C.

2016-09-01

In the objective of maximizing comfort in Falcon jets, Dassault Aviation is developing an innovative vibration control technology. Vibrations of the structure are measured at several locations and sent to a dedicated high performance vibration control computer. Control laws are implemented in this computer to analyse the vibrations in real time, and then elaborate orders sent to the existing control surfaces to counteract vibrations. After detailing the technology principles, this paper focuses on the vibration control ground demonstration that was performed by Dassault Aviation in May 2015 on Falcon 7X business jet. The goal of this test was to attenuate vibrations resulting from fixed forced excitation delivered by shakers. The ground test demonstrated the capability to implement an efficient closed-loop vibration control with a significant vibration level reduction and validated the vibration control law design methodology. This successful ground test was a prerequisite before the flight test demonstration that is now being prepared. This study has been partly supported by the JTI CleanSky SFWA-ITD.

International Conference of Applied Science and Technology for Infrastructure Engineering

NASA Astrophysics Data System (ADS)

Elvina Santoso, Shelvy; Hardianto, Ekky

2017-11-01

Preface: International Conference of Applied Science and Technology for Infrastructure Engineering (ICASIE) 2017. The International Conference of Applied Science and Technology for Infrastructure Engineering (ICASIE) 2017 has been scheduled and successfully taken place at Swiss-Bell Inn Hotel, Surabaya, Indonesia, on August 5th 2017 organized by Department of Civil Infrastructure Engineering, Faculty of Vocation, Institut Teknologi Sepuluh Nopember (ITS). This annual event aims to create synergies between government, private sectors; employers; practitioners; and academics. This conference has different theme each year and “MATERIAL FOR INFRASTUCTURE ENGINEERING” will be taken for this year’s main theme. In addition, we also provide a platform for various other sub-theme topic including but not limited to Geopolymer Concrete and Materials Technology, Structural Dynamics, Engineering, and Sustainability, Seismic Design and Control of Structural Vibrations, Innovative and Green Buildings, Project Management, Transportation and Highway Engineering, Geotechnical Engineering, Water Engineering and Resources Management, Surveying and Geospatial Engineering, Coastal Engineering, Geophysics, Energy, Electronic and Mechatronic, Industrial Process, and Data Mining. List of Organizers, Journal Editors, Steering Committee, International Scientific Committee, Chairman, Keynote Speakers are available in this pdf.

Active Vibration Isolation Devices with Inertial Servo Actuators

NASA Astrophysics Data System (ADS)

Melik-Shakhnazarov, V. A.; Strelov, V. I.; Sofiyanchuk, D. V.; Tregubenko, A. A.

2018-03-01

The use of active vibration isolation devices (AVIDs) in aerospace engineering is subject to the following restrictions. First, the volume for installing additional devices is always limited in instrument racks and compartments. Secondly, in many cases, it is impossible to add supports for servo actuators for fundamental or design considerations. In the paper, it has been shown that this problem can be solved if the inertial servo actuators are used in AVIDs instead of reference actuators. A transfer function has been theoretically calculated for an AVID controlled by inertial actuators. It has been shown that the volume of a six-mode single-housing AVID with inertial actuators can be 2-2.5 times smaller than that of devices with support actuators.

Experiments in Sound and Structural Vibrations Using an Air-Analog Model Ducted Propulsion System

DTIC Science & Technology

2007-08-01

Department of Aerospace S~and Mechanical Engineering I 20070904056 I EXPERIMENTS IN SOUND AND STRUCTURAL VIBRATIONS USING AN AIR -ANALOG MODEL DUCTED...SOUND AND STRUCTURAL * VIBRATIONS USING AN AIR -ANALOG MODEL DUCTED PROPULSION SYSTEM FINAL TECHNICAL REPORT Prepared by: Scott C. Morris Assistant...Vibration Using Air - 5b. GRANT NUMBER Analog Model Ducted Propulsion Systems N00014-1-0522 5C. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER

Detecting the crankshaft torsional vibration of diesel engines for combustion related diagnosis

NASA Astrophysics Data System (ADS)

Charles, P.; Sinha, Jyoti K.; Gu, F.; Lidstone, L.; Ball, A. D.

2009-04-01

Early fault detection and diagnosis for medium-speed diesel engines is important to ensure reliable operation throughout the course of their service. This work presents an investigation of the diesel engine combustion related fault detection capability of crankshaft torsional vibration. The encoder signal, often used for shaft speed measurement, has been used to construct the instantaneous angular speed (IAS) waveform, which actually represents the signature of the torsional vibration. Earlier studies have shown that the IAS signal and its fast Fourier transform (FFT) analysis are effective for monitoring engines with less than eight cylinders. The applicability to medium-speed engines, however, is strongly contested due to the high number of cylinders and large moment of inertia. Therefore the effectiveness of the FFT-based approach has further been enhanced by improving the signal processing to determine the IAS signal and subsequently tested on a 16-cylinder engine. In addition, a novel method of presentation, based on the polar coordinate system of the IAS signal, has also been introduced; to improve the discrimination features of the faults compared to the FFT-based approach of the IAS signal. The paper discusses two typical experimental studies on 16- and 20-cylinder engines, with and without faults, and the diagnosis results by the proposed polar presentation method. The results were also compared with the earlier FFT-based method of the IAS signal.

James Webb Space Telescope Mid Infra-Red Instrument Pulse-Tube Cryocooler Electronics

NASA Technical Reports Server (NTRS)

Harvey, D.; Flowers, T.; Liu, N.; Moore, K.; Tran, D.; Valenzuela, P.; Franklin, B.; Michaels, D.

2013-01-01

The latest generation of long life, space pulse-tube cryocoolers require electronics capable of controlling self-induced vibration down to a fraction of a newton and coldhead temperature with high accuracy down to a few kelvin. Other functions include engineering diagnostics, heater and valve control, telemetry and safety protection of the cryocooler subsystem against extreme environments and operational anomalies. The electronics are designed to survive the thermal, vibration, shock and radiation environment of launch and orbit, while providing a design life in excess of 10 years on-orbit. A number of our current generation high reliability radiation-hardened electronics units are in various stages of integration on several space flight payloads. This paper describes the features and performance of our latest flight electronics designed for the pulse-tube cryocooler that is the pre-cooler for a closed cycle Joule-Thomson cooler providing 6K cooling for the James Webb Space Telescope (JWST) Mid Infra-Red Instrument (MIRI). The electronics is capable of highly accurate temperature control over the temperature range from 4K to 15K. Self-induced vibration is controlled to low levels on all harmonics up to the 16th. A unique active power filter controls peak-to-peak reflected ripple current on the primary power bus to a very low level. The 9 kg unit is capable of delivering 360W continuous power to NGAS's 3-stage pulse-tube High-Capacity Cryocooler (HCC).

Design features of fans, blowers, and compressors

NASA Astrophysics Data System (ADS)

Cheremisinoff, N. P.; Cheremisinoff, P. N.

Fan engineering and compression machines are discussed. Basic aspects of fan performance and design are reviewed, and the design and performance characteristics of radial-flow fans, axial-flow fans, and controllable pitch fans are examined in detail. Air-conditioning systems are discussed, and noise, vibration, and mechanical considerations in fans are extensively examined. The thermodynamic principles governing compression machines are reviewed, and piston compressors, rotary compressors, blowers, and centrifugal compressors are discussed.

Noise control in aeroacoustics; Proceedings of the 1993 National Conference on Noise Control Engineering, NOISE-CON 93, Williamsburg, VA, May 2-5, 1993

NASA Astrophysics Data System (ADS)

Hubbard, Harvey H.

In the conference over 100 papers were presented in eight sessions: (1) Emission: Noise Sources; (2) Physical Phenomena; (3) Noise ControlElements; (4) Vibration and Shock: Generation, Transmission, Isolation, and Reduction; (5) Immission: Physical Aspects of Environmental Noise; (6) Immission: Effects of Noise; (7) Analysis; and (8) Requirements. In addition, the distinguished lecture series included presentations on the High Speed Civil Transport and on research from the United Kingdom on aircraft noise effects. For individual titles, see A95-90089 through A95-90141.

Voyager: Vibration Acoustics and Pyro Shock Testing

NASA Image and Video Library

2017-07-05

An engineer works on vibration acoustics and pyro shock testing for one of NASA's Voyager spacecraft on November 18, 1976. Several of the spacecraft's science instruments are visible at left. https://photojournal.jpl.nasa.gov/catalog/PIA21733

Minimizing the effects of pile driving vibrations : research spotlight.

DOT National Transportation Integrated Search

2013-11-01

Engineers must take care that the vibrations from pile driving : operations during bridge construction do not damage underground : utilities or cause settlement in the foundations of nearby structures. : In this project, researchers developed a simpl...

Influence analysis of electronically and vibrationally excited particles on the ignition of methane and hydrogen under the conditions of a gas turbine engine

NASA Astrophysics Data System (ADS)

Deminskii, M. A.; Konina, K. M.; Potapkin, B. V.

2018-03-01

The vibronic and electronic energy relaxation phenomena in the specific conditions of a gas turbine engine were investigated in this paper. The plasma-chemical mechanism has been augmented with the results of recent investigations of the processes that involve electronically and vibrationally excited species. The updated mechanism was employed for the computer simulation of plasma-assisted combustion of hydrogen-air and methane-air mixtures under high pressure and in the range of initial temperatures T  =  500-900 K. The updated mechanism was verified using the experimental data. The influence of electronically excited nitrogen on the ignition delay time was analyzed. The rate coefficient of the vibration-vibration exchange between N2 and HO2 was calculated as well as the rate coefficient of HO2 decomposition.

Cell viability viscoelastic measurement in a rheometer used to stress and engineer tissues at low sonic frequencies.

PubMed

Klemuk, Sarah A; Jaiswal, Sanyukta; Titze, Ingo R

2008-10-01

Effects of vibration on human vocal fold extracellular matrix composition and the resultant tissue viscoelastic properties are difficult to study in vivo. Therefore, an in vitro bioreactor, simulating the in vivo physiological environment, was explored. A stress-controlled commercial rheometer was used to administer shear vibrations to living tissues at stresses and frequencies corresponding to male phonation, while simultaneously measuring tissue viscoelastic properties. Tissue environment was evaluated and adjustments made in order to sustain cell life for short term experimentation up to 6 h. Cell nutrient medium evaporation, osmolality, pH, and cell viability of cells cultured in three-dimensional synthetic scaffolds were quantified under comparably challenging environments to the rheometer bioreactor for 4 or 6 h. The functionality of the rheometer bioreactor was demonstrated by applying three vibration regimes to cell-seeded three-dimensional substrates for 2 h. Resulting strain was quantified throughout the test period. Rheologic data and cell viability are reported for each condition, and future improvements are discussed.

Three Axes MEMS Combined Sensor for Electronic Stability Control System

NASA Astrophysics Data System (ADS)

Jeong, Heewon; Goto, Yasushi; Aono, Takanori; Nakamura, Toshiaki; Hayashi, Masahide

A microelectromechanical systems (MEMS) combined sensor measuring two-axis accelerations and an angular rate (rotation) has been developed for an electronic stability control system of automobiles. With the recent trend to mount the combined sensors in the engine compartment, the operation temperature range increased drastically, with the request of immunity to environmental disturbances such as vibration. In this paper, we report the combined sensor which has a gyroscopic part and two acceleration parts in single die. A deformation-robust MEMS structure has been adopted to achieve stable operation under wide temperature range (-40 to 125°C) in the engine compartment. A package as small as 10 × 19 × 4 mm is achieved by adopting TSV (through silicon via) and WLP (wafer-level package) technologies with enough performance as automotive grade.

Sound vibration signal processing for detection and identification detonation (knock) to optimize performance Otto engine

NASA Astrophysics Data System (ADS)

Sujono, A.; Santoso, B.; Juwana, W. E.

2016-03-01

Problems of detonation (knock) on Otto engine (petrol engine) is completely unresolved problem until now, especially if want to improve the performance. This research did sound vibration signal processing engine with a microphone sensor, for the detection and identification of detonation. A microphone that can be mounted is not attached to the cylinder block, that's high temperature, so that its performance will be more stable, durable and inexpensive. However, the method of analysis is not very easy, because a lot of noise (interference). Therefore the use of new methods of pattern recognition, through filtration, and the regression function normalized envelope. The result is quite good, can achieve a success rate of about 95%.

Advanced active health monitoring system of liquid rocket engines

NASA Astrophysics Data System (ADS)

Qing, Xinlin P.; Wu, Zhanjun; Beard, Shawn; Chang, Fu-Kuo

2008-11-01

An advanced SMART TAPE system has been developed for real-time in-situ monitoring and long term tracking of structural integrity of pressure vessels in liquid rocket engines. The practical implementation of the structural health monitoring (SHM) system including distributed sensor network, portable diagnostic hardware and dedicated data analysis software is addressed based on the harsh operating environment. Extensive tests were conducted on a simulated large booster LOX-H2 engine propellant duct to evaluate the survivability and functionality of the system under the operating conditions of typical liquid rocket engines such as cryogenic temperature, vibration loads. The test results demonstrated that the developed SHM system could survive the combined cryogenic temperature and vibration environments and effectively detect cracks as small as 2 mm.

Performance and Environmental Test Results of the High Voltage Hall Accelerator Engineering Development Unit

NASA Technical Reports Server (NTRS)

Kamhawi, Hani; Haag, Thomas; Huang, Wensheng; Shastry, Rohit; Pinero, Luis; Peterson, Todd; Mathers, Alex

2012-01-01

NASA Science Mission Directorate's In-Space Propulsion Technology Program is sponsoring the development of a 3.5 kW-class engineering development unit Hall thruster for implementation in NASA science and exploration missions. NASA Glenn and Aerojet are developing a high fidelity high voltage Hall accelerator that can achieve specific impulse magnitudes greater than 2,700 seconds and xenon throughput capability in excess of 300 kilograms. Performance, plume mappings, thermal characterization, and vibration tests of the high voltage Hall accelerator engineering development unit have been performed. Performance test results indicated that at 3.9 kW the thruster achieved a total thrust efficiency and specific impulse of 58%, and 2,700 sec, respectively. Thermal characterization tests indicated that the thruster component temperatures were within the prescribed material maximum operating temperature limits during full power thruster operation. Finally, thruster vibration tests indicated that the thruster survived the 3-axes qualification full-level random vibration test series. Pre and post-vibration test performance mappings indicated almost identical thruster performance. Finally, an update on the development progress of a power processing unit and a xenon feed system is provided.

Engineering of Impulse Mechanism for Mechanical Hander Power Tools

NASA Astrophysics Data System (ADS)

Nikolaevich Drozdov, Anatoliy

2018-03-01

The solution to the problem of human security in cities should be considered on the basis of an integrated and multidisciplinary approach, including issues of security and ecology in the application of technical means used to ensure the viability and development of technocracy. In this regard, an important task is the creation of a safe technique with improved environmental properties with high technological characteristics. This primarily relates to mechanised tool — the division of technological machines with built in engines is that their weight is fully or partially perceived by the operator’s hands, making the flow and control of the car. For this subclass of machines is characterized by certain features: a built-in motor, perception of at least part of their weight by the operator during the work, the implementation of feeding and management at the expense of the muscular power of the operator. Therefore, among the commonly accepted technical and economic characteristics, machines in this case, important ergonomic (ergonomics), regulation of levels which ensures the safety of the operator. To ergonomics include vibration, noise characteristics, mass, and force feeding machine operator. Vibration is a consequence of the dynamism of the system operator machine - processed object (environment) in which the engine energy is redistributed among all the structures, causing their instability. In the machine vibration caused by technological and constructive (transformative mechanisms) unbalance of individual parts of the drive, the presence of technological and design (impact mechanisms) clearances and other reasons. This article describes a new design of impulse mechanism for hander power tools (wrenches, screwdrivers) with enhanced torque. The article substantiates a simulation model of dynamic compression process in an operating chamber during impact, provides simulation results and outlines further lines of research.

Life cycle analysis of mitigation methodologies for railway rolling noise and groundbourne vibration.

PubMed

Tuler, Mariana Valente; Kaewunruen, Sakdirat

2017-04-15

Negative outcomes such as noise and vibration generated by railways have become a challenge for both industry and academia in order to guarantee that the railway system can accomplish its purposes and at the same time provide comfort for users and people living in the neighbourhood along the railway corridor. The research interest on this field has been increasing and the advancement in noise and vibration mitigation methodologies can be observed using various engineering techniques that are constantly put into test to solve such effects. In contrast, the life cycle analysis of the mitigation measures has not been thoroughly carried out. There is also a lack of detailed evaluation in the efficiency of various mechanisms for controlling rolling noise and ground-borne vibration. This research is thus focussed on the evaluation of materials used, the total cost associated with the maintenance of such the measures and the carbon footprint left for each type of mechanism. The insight into carbon footprint together with life cycle cost will benefit decision making process for the industry in the selection of optimal and suitable mechanism since the environmental impact is a growing concern around the world. Copyright © 2016 Elsevier Ltd. All rights reserved.

Possible improvements in gasoline engines

NASA Technical Reports Server (NTRS)

Ziembinski, S

1923-01-01

High-compression engines are investigated with the three main objects being elimination of vibration, increase of maximum efficiency, and conservation of this efficiency at the highest possible speeds.

Nonlinear Thermoelastic Model for SMAs and SMA Hybrid Composites

NASA Technical Reports Server (NTRS)

Turner, Travis L.

2004-01-01

A constitutive mathematical model has been developed that predicts the nonlinear thermomechanical behaviors of shape-memory-alloys (SMAs) and of shape-memory-alloy hybrid composite (SMAHC) structures, which are composite-material structures that contain embedded SMA actuators. SMAHC structures have been investigated for their potential utility in a variety of applications in which there are requirements for static or dynamic control of the shapes of structures, control of the thermoelastic responses of structures, or control of noise and vibrations. The present model overcomes deficiencies of prior, overly simplistic or qualitative models that have proven ineffective or intractable for engineering of SMAHC structures. The model is sophisticated enough to capture the essential features of the mechanics of SMAHC structures yet simple enough to accommodate input from fundamental engineering measurements and is in a form that is amenable to implementation in general-purpose structural analysis environments.

Real-time micro-vibration multi-spot synchronous measurement within a region based on heterodyne interference

NASA Astrophysics Data System (ADS)

Lan, Ma; Xiao, Wen; Chen, Zonghui; Hao, Hongliang; Pan, Feng

2018-01-01

Real-time micro-vibration measurement is widely used in engineering applications. It is very difficult for traditional optical detection methods to achieve real-time need in a relatively high frequency and multi-spot synchronous measurement of a region at the same time,especially at the nanoscale. Based on the method of heterodyne interference, an experimental system of real-time measurement of micro - vibration is constructed to satisfy the demand in engineering applications. The vibration response signal is measured by combing optical heterodyne interferometry and a high-speed CMOS-DVR image acquisition system. Then, by extracting and processing multiple pixels at the same time, four digital demodulation technique are implemented to simultaneously acquire the vibrating velocity of the target from the recorded sequences of images. Different kinds of demodulation algorithms are analyzed and the results show that these four demodulation algorithms are suitable for different interference signals. Both autocorrelation algorithm and cross-correlation algorithm meet the needs of real-time measurements. The autocorrelation algorithm demodulates the frequency more accurately, while the cross-correlation algorithm is more accurate in solving the amplitude.

Special Section dedicated to the 11th International Conference on Vibration Problems (ICOVP-2013)

NASA Astrophysics Data System (ADS)

Dimitrovová, Zuzana; Gonçalves, Rodrigo

2015-01-01

This section contains the first set of selected papers from the 11th edition of the biennial International Conference series on Vibration Problems (ICOVP-2013), which was held at the Instituto Superior Técnico in Lisbon, Portugal, on 9-12 September 2013, and was jointly organized by the Civil Engineering Department of the Universidade Nova de Lisboa and the Institute of Mechanical Engineering at the Instituto Superior Técnico. A second set of papers will be included in a forthcoming issue.

Wakata on Cycle Ergometer with Vibration Isolation System (CEVIS)

NASA Image and Video Library

2009-03-30

ISS018-E-043723 (30 March 2009) --- Japan Aerospace Exploration Agency (JAXA) astronaut Koichi Wakata, Expedition 18/19 flight engineer, exercises on the Cycle Ergometer with Vibration Isolation System (CEVIS) in the Destiny laboratory of the International Space Station.

Lateral vibration control of a precise machine using magneto-rheological mounts featuring multiple directional damping effect

NASA Astrophysics Data System (ADS)

Kim, Hyung Tae; Jeong, An Mok; Kim, Hyo Young; An, Jong Wook; Kim, Cheol Ho; Jin, Kyung Chan; Choi, Seung-Bok

2018-03-01

In a previous work, magneto-rheological (MR) dampers were originally designed and implemented for reducing the vertical low-frequency vibration occurring in precise semi-conductor manufacturing equipment. To reduce the vibrations, an isolator levitated the manufacturing machine from the floor using pneumatic pressure which cut off the external vibration, while the MR damper was used to decrease the transient response of the isolator. However, it has been found that the MR damper also provides a damping effect on the lateral vibration induced by the high-speed plane motions. Therefore, in this work both vertical and lateral vibrations are controlled using the yield and shear stresses of the lateral directions generated from the MR fluids by applying a magnetic field. After deriving a vibration control model, an overall control logic is formulated considering both vertical and lateral vibrations. In this control strategy, a feedback loop associated with the laser sensor is used for vertical vibration control, while a feed-forward loop with the motion information is used for lateral vibration control. The experimental results show that the proposed concept is highly effective for lateral vibration control using the damping effect on multiple directions.

Onboard System Evaluation of Rotors Vibration, Engines (OBSERVE) monitoring System

DTIC Science & Technology

1992-07-01

consists of a Data Acquisiiton Unit (DAU), Control and Display Unit ( CADU ), Universal Tracking Devices (UTD), Remote Cockpit Display (RCD) and a PC...and Display Unit ( CADU ) - The CADU provides data storage and a graphical user interface neccesary to display both the measured data and diagnostic...information. The CADU has an interface to a Credit Card Memory (CCM) which operates similar to a disk drive, allowing the storage of data and programs. The

The Shock and Vibration Bulletin. Part 3. Invited Papers, Pyrotechnic Shock, Pyrotechnic Shock Workshop

DTIC Science & Technology

1986-08-01

Technology Laboratory, Watertown, MA AIR FORCE BASIC RESEARCH IN DYNAMICS AND CONTROL OF LARGE SPACE STRUCTURES Anthony K. Amos, Boiling Air Force Base...Engineering, Watchun$, NJ TEMPERATURE SHIFT CONSIDERATIONS FOR DAMPING MATERIALS L. Rogers, Air Force Wright Aeronautictl Laboratories, Wright...INDUCED CAVITY ACOUSTICS L.L. Shaw,. Air Force Wr4ht Aeroaauical Laborawrics, Wri•ht-Paucswon AFB. OH i 4i SESSION CHAIRMEN AND COCHAIRMEN 56th Shock and

Lewis Structures Technology, 1988. Volume 1: Structural Dynamics

NASA Technical Reports Server (NTRS)

1988-01-01

The specific purpose of the symposium was to familiarize the engineering structures community with the depth and range of research performed by the Structures Division of the Lewis Research Center and its academic and industrial partners. Sessions covered vibration control, fracture mechanics, ceramic component reliability, parallel computing, nondestructive testing, dynamical systems, fatigue and damage, wind turbines, hot section technology, structural mechanics codes, computational methods for dynamics, structural optimization, and applications of structural dynamics.

Experimental and numerical study on vibration of the full-revolving propulsion ship stern

NASA Astrophysics Data System (ADS)

Liu, Chang-qing; Che, Chi-dong; Shen, Xiao-han

2015-03-01

In order to solve the severe vibration problems of an ocean engineering ship with a full-revolving propulsion system, the navigation tests, including forced vibration response test and modal test, are carried out in its stern. It is concluded from the comparison of the time-domain waveform and spectrum from different measurement points that three main factors lead to a high-level stern vibration. Firstly, the specific dynamic stiffness of a water tank is relatively small compared with its neighbor hold, which makes it act like a vibration isolator preventing vibrational energy transmitting to the main hold. Secondly, there exists high-density local modes in the working frequency range of the main engine and thus the local resonance occurs. Thirdly, the abnormal engagement of gears caused by the large deflection of the shaft bearing due to its low mounting rigidity leads to violent extra impulse excitations at high speeds. Then the modification against the dynamic defects is given by simply improving the specific stiffness of the water tanks. And the effect is validated by the FEM calculation. Some important experience is obtained with the problems being solved, which is useful in the design of ships with the same propulsion system. It is also believed that the dynamic consideration is as important as the static analysis for the ships, and that most of the vibration problems may be avoided with a proper acoustic design.

Vehicle Engine Classification Using Spectral Tone-Pitch Vibration Indexing and Neural Network*

PubMed Central

Wei, Jie; Vongsy, Karmon; Mendoza-Schrock, Olga; Liu, Chi-Him

2015-01-01

As a non-invasive and remote sensor, the Laser Doppler Vibrometer (LDV) has found a broad spectrum of applications in various areas such as civil engineering, biomedical engineering, and even security and restoration within art museums. LDV is an ideal sensor to detect threats earlier and provide better protection to society, which is of utmost importance to military and law enforcement institutions. However, the use of LDV in situational surveillance, in particular vehicle classification, is still in its infancy due to the lack of systematic investigations on its behavioral properties. In this work, as a result of the pilot project initiated by Air Force Research Laboratory, the innate features of LDV data from many vehicles are examined, beginning with an investigation of feature differences compared to human speech signals. A spectral tone-pitch vibration indexing scheme is developed to capture the engine’s periodic vibrations and the associated fundamental frequencies over the vehicles’ surface. A two-layer feed-forward neural network with 20 intermediate neurons is employed to classify vehicles’ engines based on their spectral tone-pitch indices. The classification results using the proposed approach over the complete LDV dataset collected by the project are exceedingly encouraging; consistently higher than 96% accuracies are attained for all four types of engines collected from this project. PMID:26788417

Infrared vibrational nanocrystallography and nanoimaging

PubMed Central

Muller, Eric A.; Pollard, Benjamin; Bechtel, Hans A.; van Blerkom, Peter; Raschke, Markus B.

2016-01-01

Molecular solids and polymers can form low-symmetry crystal structures that exhibit anisotropic electron and ion mobility in engineered devices or biological systems. The distribution of molecular orientation and disorder then controls the macroscopic material response, yet it is difficult to image with conventional techniques on the nanoscale. We demonstrated a new form of optical nanocrystallography that combines scattering-type scanning near-field optical microscopy with both optical antenna and tip-selective infrared vibrational spectroscopy. From the symmetry-selective probing of molecular bond orientation with nanometer spatial resolution, we determined crystalline phases and orientation in aggregates and films of the organic electronic material perylenetetracarboxylic dianhydride. Mapping disorder within and between individual nanoscale domains, the correlative hybrid imaging of nanoscale heterogeneity provides insight into defect formation and propagation during growth in functional molecular solids. PMID:27730212

Coupled multi-disciplinary simulation of composite engine structures in propulsion environment

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Singhal, Surendra N.

1992-01-01

A computational simulation procedure is described for the coupled response of multi-layered multi-material composite engine structural components which are subjected to simultaneous multi-disciplinary thermal, structural, vibration, and acoustic loadings including the effect of hostile environments. The simulation is based on a three dimensional finite element analysis technique in conjunction with structural mechanics codes and with acoustic analysis methods. The composite material behavior is assessed at the various composite scales, i.e., the laminate/ply/constituents (fiber/matrix), via a nonlinear material characterization model. Sample cases exhibiting nonlinear geometrical, material, loading, and environmental behavior of aircraft engine fan blades, are presented. Results for deformed shape, vibration frequency, mode shapes, and acoustic noise emitted from the fan blade, are discussed for their coupled effect in hot and humid environments. Results such as acoustic noise for coupled composite-mechanics/heat transfer/structural/vibration/acoustic analyses demonstrate the effectiveness of coupled multi-disciplinary computational simulation and the various advantages of composite materials compared to metals.

The effect of concurrent bandwidth feedback on learning the lane-keeping task in a driving simulator.

PubMed

de Groot, Stefan; de Winter, Joost C F; López García, José Manuel; Mulder, Max; Wieringa, Peter A

2011-02-01

The aim of this study was to investigate whether concurrent bandwidth feedback improves learning of the lane-keeping task in a driving simulator. Previous research suggests that bandwidth feedback improves learning and that off-target feedback is superior to on-target feedback. This study aimed to extend these findings for the lane-keeping task. Participants without a driver's license drove five 8-min lane-keeping sessions in a driver training simulator: three practice sessions, an immediate retention session, and a delayed retention session I day later. There were four experimental groups (n=15 per group): (a) on-target, receiving seat vibrations when the center of the car was within 0.5 m of the lane center; (b) off-target, receiving seat vibrations when the center of the car was more than 0.5 m away from the lane center; (c) control, receiving no vibrations; and (d) realistic, receiving seat vibrations depending on engine speed. During retention, all groups were provided with the realistic vibrations. During practice, on-target and off-target groups had better lane-keeping performance than the nonaugmented groups, but this difference diminished in the retention phase. Furthermore, during late practice and retention, the off-target group outperformed the on-target group.The off-target group had a higher rate of steering reversal and higher steering entropy than the nonaugmented groups, whereas no clear group differences were found regarding mean speed, mental workload, or self-reported measures. Off-target feedback is superior to on-target feedback for learning the lane-keeping task. This research provides knowledge to researchers and designers of training systems about the value of feedback in simulator-based training of vehicular control.

Effect of Blowing on Boundary Layer of Scarf Inlet

NASA Technical Reports Server (NTRS)

Gerhold, Carl H.; Clark, Lorenzo R.

2004-01-01

When aircraft operate in stationary or low speed conditions, airflow into the engine accelerates around the inlet lip and pockets of turbulence that cause noise and vibration can be ingested. This problem has been encountered with engines equipped with the scarf inlet, both in full scale and in model tests, where the noise produced during the static test makes it difficult to assess the noise reduction performance of the scarf inlet. NASA Langley researchers have implemented boundary layer control in an attempt to reduce the influence of the flow nonuniformity in a 12-in. diameter model of a high bypass fan engine mounted in an anechoic chamber. Static pressures and boundary layer profiles were measured in the inlet and far field acoustic measurements were made to assess the effectiveness of the blowing treatment. The blowing system was found to lack the authority to overcome the inlet distortions. Methods to improve the implementation of boundary layer control to reduce inlet distortion are discussed.

Advances in engineering science, volume 1

NASA Technical Reports Server (NTRS)

1976-01-01

Proceedings from a conference on engineering advances are presented, including materials science, fracture mechanics, and impact and vibration testing. The tensile strength and moisture transport of laminates are also discussed.

Two Mathematical Models of Nonlinear Vibrations

NASA Technical Reports Server (NTRS)

Brugarolas, Paul; Bayard, David; Spanos, John; Breckenridge, William

2007-01-01

Two innovative mathematical models of nonlinear vibrations, and methods of applying them, have been conceived as byproducts of an effort to develop a Kalman filter for highly precise estimation of bending motions of a large truss structure deployed in outer space from a space-shuttle payload bay. These models are also applicable to modeling and analysis of vibrations in other engineering disciplines, on Earth as well as in outer space.

KENNEDY SPACE CENTER, FLA. - The crawler transporter slowly moves the Mobile Launcher Platform (MLP), carrying a set of twin solid rocket boosters, along the crawlerway in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-17

KENNEDY SPACE CENTER, FLA. - The crawler transporter slowly moves the Mobile Launcher Platform (MLP), carrying a set of twin solid rocket boosters, along the crawlerway in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

Advances in Ceramic Matrix Composite Blade Damping Characteristics for Aerospace Turbomachinery Applications

NASA Technical Reports Server (NTRS)

Min, James B.; Harris, Donald L.; Ting, J. M.

2011-01-01

For advanced aerospace propulsion systems, development of ceramic matrix composite integrally-bladed turbine disk technology is attractive for a number of reasons. The high strength-to-weight ratio of ceramic composites helps to reduce engine weight and the one-piece construction of a blisk will result in fewer parts count, which should translate into reduced operational costs. One shortcoming with blisk construction, however, is that blisks may be prone to high cycle fatigue due to their structural response to high vibration environments. Use of ceramic composites is expected to provide some internal damping to reduce the vibratory stresses encountered due to unsteady flow loads through the bladed turbine regions. A goal of our research was to characterize the vibration viscous damping behavior of C/SiC composites. The vibration damping properties were measured and calculated. Damping appeared to decrease with an increase in the natural frequency. While the critical damping amount of approximately 2% is required for typical aerospace turbomachinery engines, the C/SiC damping at high frequencies was less than 0.2% from our study. The advanced high-performance aerospace propulsion systems almost certainly will require even more damping than what current vehicles require. A purpose of this paper is to review some work on C/SiC vibration damping by the authors for the NASA CMC turbine blisk development program and address an importance of the further investigation of the blade vibration damping characteristics on candidate CMC materials for the NASA s advanced aerospace turbomachinery engine systems.

Vibrational energy transfer from photoexcited carbon nanotubes to proteins observed by coherent phonon spectroscopy

NASA Astrophysics Data System (ADS)

Nakayama, Tomohito; Yoshizawa, Shunsuke; Hirano, Atsushi; Tanaka, Takeshi; Shiraki, Kentaro; Hase, Muneaki

2017-12-01

Vibrational energy transfer from photoexcited single-wall carbon nanotubes (SWCNTs) to coupled proteins is a key to engineering thermally induced biological reactions, for example, in photothermal therapy. Here, we explored vibrational energy transfer from photoexcited SWCNTs to different adsorbed biological materials by means of a femtosecond pump-probe technique. We show that the vibrational relaxation time of the radial breathing modes in SWCNTs depends significantly on the structure of the coupled materials, that is, proteins or biopolymers, indicating that the vibrational energy transfer is governed by overlapping of the phonon densities of states of the SWCNTs and coupled materials.

Estimating Vibrational Powers Of Parts In Fluid Machinery

NASA Technical Reports Server (NTRS)

Harvey, S. A.; Kwok, L. C.

1995-01-01

In new method of estimating vibrational power associated with component of fluid-machinery system, physics of flow through (or in vicinity of) component regarded as governing vibrations. Devised to generate scaling estimates for design of new parts of rocket engines (e.g., pumps, combustors, nozzles) but applicable to terrestrial pumps, turbines, and other machinery in which turbulent flows and vibrations caused by such flows are significant. Validity of method depends on assumption that fluid flows quasi-steadily and that flow gives rise to uncorrelated acoustic powers in different parts of pump.

System and method of active vibration control for an electro-mechanically cooled device

DOEpatents

Lavietes, Anthony D.; Mauger, Joseph; Anderson, Eric H.

2000-01-01

A system and method of active vibration control of an electro-mechanically cooled device is disclosed. A cryogenic cooling system is located within an environment. The cooling system is characterized by a vibration transfer function, which requires vibration transfer function coefficients. A vibration controller generates the vibration transfer function coefficients in response to various triggering events. The environments may differ by mounting apparatus, by proximity to vibration generating devices, or by temperature. The triggering event may be powering on the cooling system, reaching an operating temperature, or a reset action. A counterbalance responds to a drive signal generated by the vibration controller, based on the vibration signal and the vibration transfer function, which adjusts vibrations. The method first places a cryogenic cooling system within a first environment and then generates a first set of vibration transfer function coefficients, for a vibration transfer function of the cooling system. Next, the cryogenic cooling system is placed within a second environment and a second set of vibration transfer function coefficients are generated. Then, a counterbalance is driven, based on the vibration transfer function, to reduce vibrations received by a vibration sensitive element.

A novel vibration measurement and active control method for a hinged flexible two-connected piezoelectric plate

NASA Astrophysics Data System (ADS)

Qiu, Zhi-cheng; Wang, Xian-feng; Zhang, Xian-Min; Liu, Jin-guo

2018-07-01

A novel non-contact vibration measurement method using binocular vision sensors is proposed for piezoelectric flexible hinged plate. Decoupling methods of the bending and torsional low frequency vibration on measurement and driving control are investigated, using binocular vision sensors and piezoelectric actuators. A radial basis function neural network controller (RBFNNC) is designed to suppress both the larger and the smaller amplitude vibrations. To verify the non-contact measurement method and the designed controller, an experimental setup of the flexible hinged plate with binocular vision is constructed. Experiments on vibration measurement and control are conducted by using binocular vision sensors and the designed RBFNNC controllers, compared with the classical proportional and derivative (PD) control algorithm. The experimental measurement results demonstrate that the binocular vision sensors can detect the low-frequency bending and torsional vibration effectively. Furthermore, the designed RBF can suppress the bending vibration more quickly than the designed PD controller owing to the adjustment of the RBF control, especially for the small amplitude residual vibrations.

Research of vibration controlling based on programmable logic controller for electrostatic precipitator

NASA Astrophysics Data System (ADS)

Zhang, Zisheng; Li, Yanhu; Li, Jiaojiao; Liu, Zhiqiang; Li, Qing

2013-03-01

In order to improve the reliability, stability and automation of electrostatic precipitator, circuits of vibration motor for ESP and vibration control ladder diagram program are investigated using Schneider PLC with high performance and programming software of Twidosoft. Operational results show that after adopting PLC, vibration motor can run automatically; compared with traditional control system of vibration based on single-chip microcomputer, it has higher reliability, better stability and higher dust removal rate, when dust emission concentrations <= 50 mg m-3, providing a new method for vibration controlling of ESP.

Advanced Vibration Analysis Tool Developed for Robust Engine Rotor Designs

NASA Technical Reports Server (NTRS)

Min, James B.

2005-01-01

The primary objective of this research program is to develop vibration analysis tools, design tools, and design strategies to significantly improve the safety and robustness of turbine engine rotors. Bladed disks in turbine engines always feature small, random blade-to-blade differences, or mistuning. Mistuning can lead to a dramatic increase in blade forced-response amplitudes and stresses. Ultimately, this results in high-cycle fatigue, which is a major safety and cost concern. In this research program, the necessary steps will be taken to transform a state-of-the-art vibration analysis tool, the Turbo- Reduce forced-response prediction code, into an effective design tool by enhancing and extending the underlying modeling and analysis methods. Furthermore, novel techniques will be developed to assess the safety of a given design. In particular, a procedure will be established for using natural-frequency curve veerings to identify ranges of operating conditions (rotational speeds and engine orders) in which there is a great risk that the rotor blades will suffer high stresses. This work also will aid statistical studies of the forced response by reducing the necessary number of simulations. Finally, new strategies for improving the design of rotors will be pursued.

Amplitude control of the track-induced self-excited vibration for a maglev system.

PubMed

Zhou, Danfeng; Li, Jie; Zhang, Kun

2014-09-01

The Electromagnet Suspension (EMS) maglev train uses controlled electromagnetic forces to achieve suspension, and self-excited vibration may occur due to the flexibility of the track. In this article, the harmonic balance method is applied to investigate the amplitude of the self-excited vibration, and it is found that the amplitude of the vibration depends on the voltage of the power supplier. Based on this observation, a vibration amplitude control method, which controls the amplitude of the vibration by adjusting the voltage of the power supplier, is proposed to attenuate the vibration. A PI controller is designed to control the amplitude of the vibration at a given level. The effectiveness of this method shows a good prospect for its application to commercial maglev systems. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

Design of sidewall treatment of cabin noise control of a twin engine turboprop aircraft

NASA Technical Reports Server (NTRS)

Vaicaitis, R.; Slazak, M.

1983-01-01

An analytical procedure was used to predict the noise transmission into the cabin of a twin engine general aviation aircraft. This model was then used to optimize the interior A weighted noise levels to an average value of about 85 dBA. The surface pressure noise spectral levels were selected utilizing experimental flight data and empirical predictions. The add on treatments considered in this optimization study include aluminum honeycomb panels, constrained layer damping tape, porous acoustic blankets, acoustic foams, septum barriers and limp trim panels which are isolated from the vibration of the main sidewall structure. To reduce the average noise level in the cabin from about 102 kBA (baseline) to 85 dBA (optimized), the added weight of the noise control treatment is about 2% of the total gross takeoff weight of the aircraft.

Design of sidewall treatment of cabin noise control of a twin engine turboprop aircraft

NASA Astrophysics Data System (ADS)

Vaicaitis, R.; Slazak, M.

1983-12-01

An analytical procedure was used to predict the noise transmission into the cabin of a twin engine general aviation aircraft. This model was then used to optimize the interior A weighted noise levels to an average value of about 85 dBA. The surface pressure noise spectral levels were selected utilizing experimental flight data and empirical predictions. The add on treatments considered in this optimization study include aluminum honeycomb panels, constrained layer damping tape, porous acoustic blankets, acoustic foams, septum barriers and limp trim panels which are isolated from the vibration of the main sidewall structure. To reduce the average noise level in the cabin from about 102 kBA (baseline) to 85 dBA (optimized), the added weight of the noise control treatment is about 2% of the total gross takeoff weight of the aircraft.

Three-dimensional manipulation of single cells using surface acoustic waves.

PubMed

Guo, Feng; Mao, Zhangming; Chen, Yuchao; Xie, Zhiwei; Lata, James P; Li, Peng; Ren, Liqiang; Liu, Jiayang; Yang, Jian; Dao, Ming; Suresh, Subra; Huang, Tony Jun

2016-02-09

The ability of surface acoustic waves to trap and manipulate micrometer-scale particles and biological cells has led to many applications involving "acoustic tweezers" in biology, chemistry, engineering, and medicine. Here, we present 3D acoustic tweezers, which use surface acoustic waves to create 3D trapping nodes for the capture and manipulation of microparticles and cells along three mutually orthogonal axes. In this method, we use standing-wave phase shifts to move particles or cells in-plane, whereas the amplitude of acoustic vibrations is used to control particle motion along an orthogonal plane. We demonstrate, through controlled experiments guided by simulations, how acoustic vibrations result in micromanipulations in a microfluidic chamber by invoking physical principles that underlie the formation and regulation of complex, volumetric trapping nodes of particles and biological cells. We further show how 3D acoustic tweezers can be used to pick up, translate, and print single cells and cell assemblies to create 2D and 3D structures in a precise, noninvasive, label-free, and contact-free manner.

Dynamically variable negative stiffness structures

PubMed Central

Churchill, Christopher B.; Shahan, David W.; Smith, Sloan P.; Keefe, Andrew C.; McKnight, Geoffrey P.

2016-01-01

Variable stiffness structures that enable a wide range of efficient load-bearing and dexterous activity are ubiquitous in mammalian musculoskeletal systems but are rare in engineered systems because of their complexity, power, and cost. We present a new negative stiffness–based load-bearing structure with dynamically tunable stiffness. Negative stiffness, traditionally used to achieve novel response from passive structures, is a powerful tool to achieve dynamic stiffness changes when configured with an active component. Using relatively simple hardware and low-power, low-frequency actuation, we show an assembly capable of fast (<10 ms) and useful (>100×) dynamic stiffness control. This approach mitigates limitations of conventional tunable stiffness structures that exhibit either small (<30%) stiffness change, high friction, poor load/torque transmission at low stiffness, or high power active control at the frequencies of interest. We experimentally demonstrate actively tunable vibration isolation and stiffness tuning independent of supported loads, enhancing applications such as humanoid robotic limbs and lightweight adaptive vibration isolators. PMID:26989771

Dynamic modeling and vibration characteristics analysis of the aero-engine dual-rotor system with Fan blade out

NASA Astrophysics Data System (ADS)

Yu, Pingchao; Zhang, Dayi; Ma, Yanhong; Hong, Jie

2018-06-01

Fan Blade Out (FBO) from a running rotor of the turbofan engine will not only introduce the sudden unbalance and inertia asymmetry into the rotor, but also apply large impact load and induce rotor-to-stator rubbing on the rotor, which makes the mass, gyroscopic and stiffness matrixes of the dynamic equation become time-varying and highly nonlinear, consequently leads to the system's complicated vibration. The dynamic analysis of the aero-engine rotor system is one essential requirement of the authorities and is vital to the aero-engine's safety. The paper aims at studying the dynamic responses of the complicated dual-rotor systems at instantaneous and windmilling statuses when FBO event occurs. The physical process and mechanical characteristics of the FBO event are described qualitatively, based on which the dynamic modeling for an aero-engine dual-rotor system is carried out considering several excitations caused by FBO. Meanwhile the transient response during the instantaneous status and steady-state response at the windmilling status are obtained. The results reveal that the sudden unbalance can induce impact load to the rotor, and lead to the sharp increase of the vibration amplitude and reaction force. The rub-impact will apply constraint effects on the rotor and restrict the transient vibration amplitude, while the inertia asymmetry has little influence on the transient response. When the rotor with huge unbalance operates at windmilling status, the rub-impact turns to be the main factor determining the rotor's dynamic behavior, and several potential motion states, such as instable dry whip, intermittent rubbing and synchronous full annular rubbing would happen on certain conditions.

Comparative analysis of the operation efficiency of the continuous and relay control systems of a multi-axle wheeled vehicle suspension

NASA Astrophysics Data System (ADS)

Zhileykin, M. M.; Kotiev, G. O.; Nagatsev, M. V.

2018-02-01

In order to improve the efficiency of the multi-axle wheeled vehicles (MWV) automotive engineers are increasing their cruising speed. One of the promising ways to improve ride comfort of the MWV is the development of the dynamic active suspension systems and control laws for such systems. Here, by the dynamic control systems we mean the systems operating in real time mode and using current (instantaneous) values of the state variables. The aim of the work is to develop the MWV suspension optimal control laws that would reduce vibrations on the driver’s seat at kinematic excitation. The authors have developed the optimal control laws for damping the oscillations of the MWV body. The developed laws allow reduction of the vibrations on the driver’s seat and increase in the maximum speed of the vehicle. The laws are characterized in that they allow generating the control inputs in real time mode. The authors have demonstrated the efficiency of the proposed control laws by means of mathematical simulation of the MWV driving over unpaved road with kinematic excitation. The proposed optimal control laws can be used in the MWV suspension control systems with magnetorheological shock absorbers or controlled hydropneumatic springs. Further evolution of the research line can be the development of the energy-efficient MWV suspension control systems with continuous control input on the vehicle body.

Particle damping applied research on mining dump truck vibration control

NASA Astrophysics Data System (ADS)

Song, Liming; Xiao, Wangqiang; Guo, Haiquan; Yang, Zhe; Li, Zeguang

2018-05-01

Vehicle vibration characteristics has become an important evaluation indexes of mining dump truck. In this paper, based on particle damping technology, mining dump truck vibration control was studied by combining the theoretical simulation with actual testing, particle damping technology was successfully used in mining dump truck cab vibration control. Through testing results analysis, with a particle damper, cab vibration was reduced obviously, the methods and basis were provided for vehicle vibration control research and particle damping technology application.

Research on the fault diagnosis of bearing based on wavelet and demodulation

NASA Astrophysics Data System (ADS)

Li, Jiapeng; Yuan, Yu

2017-05-01

As a most commonly-used machine part, antifriction bearing is extensively used in mechanical equipment. Vibration signal analysis is one of the methods to monitor and diagnose the running status of antifriction bearings. Therefore, using wavelet analysis for demising is of great importance in the engineering practice. This paper firstly presented the basic theory of wavelet analysis to study the transformation, decomposition and reconstruction of wavelet. In addition, edition software LabVIEW was adopted to conduct wavelet and demodulation upon the vibration signal of antifriction bearing collected. With the combination of Hilbert envelop demodulation analysis, the fault character frequencies of the demised signal were extracted to conduct fault diagnosis analysis, which serves as a reference for the wavelet and demodulation of the vibration signal in engineering practice.

Applications of Composite Materials in Helicopter Construction (Les Applications des Materiaux Composite dans la Construction des Helicopteres),

DTIC Science & Technology

1983-11-21

TRANSLATION TITLE: APPLICATIONS OF COMPOSITE MATERIALS IN HELICOPTER CONSTRUCTION LES APPLICATIONS DES MATERTAUX COMWSITE DANS LA CONSTRUCTION DES...International Symposium on Design and Use of Kevlar in Aircraft, Geneva, 12 October 1982 [Beziac, Gilbert;* Les applications des mat6riaux composite...the pilot’s orders to the engine and the rotors. --Rear rotor Conventional or "faired propeller" type with its overall pitch control --Vibration

The use of telemetry in testing in high performance racing engines

NASA Astrophysics Data System (ADS)

Hauser, E.

Telemetry measurement data in mobile application and under difficult environmental conditions were recorded. All relevant racing car and engine parameters were measured: pressure, stress, temperature, acceleration, ignition, number of revolutions, control of electronic injection, and flow measurements on the car body. The difficult measuring conditions due to high voltage ignition, mechanical loads and vibrations impose special requirements on a telemetry system built in racing cars. It has to be compact, flexible, light, and mechanically robust and has to fulfil special sheilding conditions. The measured data are transfered to a stationary measurement car via a radio line, involving RF communication problems. The measured data are directly displayed and evaluated in the measurement car.

A new reference tip-timing test bench and simulator for blade synchronous and asynchronous vibrations

NASA Astrophysics Data System (ADS)

Hajnayeb, Ali; Nikpour, Masood; Moradi, Shapour; Rossi, Gianluca

2018-02-01

The blade tip-timing (BTT) measurement technique is at present the most promising technique for monitoring the blades of axial turbines and aircraft engines in operating conditions. It is generally used as an alternative to strain gauges in turbine testing. By conducting a comparison with the standard methods such as those based on strain gauges, one determines that the technique is not intrusive and does not require a complicated installation process. Despite its superiority to other methods, the experimental performance analysis of a new BTT method needs a test stand that includes a reference measurement system (e.g. strain gauges equipped with telemetry or other complex optical measurement systems, like rotating laser Doppler vibrometers). In this article, a new reliable, low-cost BTT test setup is proposed for simulating and analyzing blade vibrations based on kinematic inversion. In the proposed test bench, instead of the blades vibrating, it is the BTT sensor that vibrates. The vibration of the sensor is generated by a shaker and can therefore be easily controlled in terms of frequency, amplitude and waveform shape. The amplitude of vibration excitation is measured by a simple accelerometer. After introducing the components of the simulator, the proposed test bench is used in practice to simulate both synchronous and asynchronous vibration scenarios. Then two BTT methods are used to evaluate the quality of the acquired data. The results demonstrate that the proposed setup is able to generate simulated pulse sequences which are almost the same as those generated by the conventional BTT systems installed around a bladed disk. Moreover, the test setup enables its users to evaluate BTT methods by using a limited number of sensors. This significantly reduces the total costs of the experiments.

Plasma Chemistry of Vibrationally Nonequilibrium Molecules

DTIC Science & Technology

1993-11-01

WL-TR-93-2116 PLASMA CHEMISTRY OF VIBRATIONALLY NONEQUILIBRIUM MOLECULES AD-A279 630--, J. WILLIAM RICH DEPARTMENT OF MECHANICAL ENGINEERING D THE...1AT9E L. REPORT TYPE AND DATES COVERED ONLY Man"_November 1993 Final 09 July 1990_- 08 July 1993 4 MITL AND SUBTITLE S. FUNDNG NUMERS & Plasma Chemistry of...k14. SUBIECT TERMS 15. NUMBER OF PAGES Molecular Energy Transfer; Plasma Chemistry ; Ionization; 4% Vibrational Relaxation; Nitric Oxide; Carbon

Research about vibration characteristics of timing chain system based on short-time Fourier transform

NASA Astrophysics Data System (ADS)

Xi, Jiaxin; Liu, Ning

2017-09-01

Vibration characteristic of timing chain system is very important for an engine. In this study, we used a bush roller chain drive system as an example to explain how to use mulitybody dynamic techniques and short-time Fourier transform to investigate vibration characteristics of timing chain system. Multibody dynamic simulation data as chain tension force and external excitation sources curves were provided for short-time Fourier transform study. The study results of short-time Fourier transform illustrate that there are two main vibration frequency domain of timing chain system, one is the low frequency vibration caused by crankshaft sprocket velocity and camshaft sprocket torque. Another is vibration around 1000Hz lead by hydraulic tensioner. Hence, short-time Fourier transform method is useful for basic research of vibration characteristics for timing chain system.

Identification of Bearing Failure Using Signal Vibrations

NASA Astrophysics Data System (ADS)

Yani, Irsyadi; Resti, Yulia; Burlian, Firmansyah

2018-04-01

Vibration analysis can be used to identify damage to mechanical systems such as journal bearings. Identification of failure can be done by observing the resulting vibration spectrum by measuring the vibration signal occurring in a mechanical system Bearing is one of the engine elements commonly used in mechanical systems. The main purpose of this research is to monitor the bearing condition and to identify bearing failure on a mechanical system by observing the resulting vibration. Data collection techniques based on recordings of sound caused by the vibration of the mechanical system were used in this study, then created a database system based bearing failure due to vibration signal recording sounds on a mechanical system The next step is to group the bearing damage by type based on the databases obtained. The results show the percentage of success in identifying bearing damage is 98 %.

Effects of vibration and shock on the performance of gas-bearing space-power Brayton cycle turbomachinery. 2: Sinusoidal and random vibration

NASA Technical Reports Server (NTRS)

Tessarzik, J. M.; Chiang, T.; Badgley, R. H.

1973-01-01

The vibration response of a gas-bearing rotor-support system was analyzed experimentally documented for sinusoidal and random vibration environments. The NASA Brayton Rotating Unit (BRU), 36,000 rpm; 10 KWe turbogenerator; was subjected in the laboratory to sinusoidal and random vibrations to evaluate the capability of the BRU to (1) survive the vibration levels expected to be encountered during periods of nonoperation and (2) operate satisfactorily (that is, without detrimental bearing surface contacts) at the vibration levels expected during normal BRU operation. Response power spectral density was calculated for specified input random excitation, with particular emphasis upon the dynamic motions of the thrust bearing runner and stator. A three-mass model with nonlinear representation of the engine isolator mounts was used to calculate axial rotor-bearing shock response.

Ride Dynamics and Evaluation of Human Exposure to Whole Body Vibration. Change 1

DTIC Science & Technology

2012-04-03

vehicle specification and/or the detailed test plan. This (half-round obstacle) accelerometer will be low-pass filtered ( post test ) at 30 Hz...Engineers TARADCOM Tank-Automotive Research and Development Command TOP Test Operations Procedure VDV Vibration Dose Value WBV Whole Body...

ISS Expedition 18 Sandra Magnus on the Treadmill Vibration Isolation and Stabilization (TVIS) in Service Module (SM)

NASA Image and Video Library

2009-02-12

ISS018-E-030101 (12 Feb. 2009) --- Astronaut Sandra Magnus, Expedition 18 flight engineer, equipped with a bungee harness, exercises on the Treadmill Vibration Isolation System (TVIS) in the Zvezda Service Module of the International Space Station.

ISS Expedition 18 Sandra Magnus on the Treadmill Vibration Isolation and Stabilization (TVIS) in Service Module (SM)

NASA Image and Video Library

2009-02-12

ISS018-E-030096 (12 Feb. 2009) --- Astronaut Sandra Magnus, Expedition 18 flight engineer, equipped with a bungee harness, exercises on the Treadmill Vibration Isolation System (TVIS) in the Zvezda Service Module of the International Space Station.

Construction vibration attenuation with distance and its effect on the quality of early-age concrete.

DOT National Transportation Integrated Search

2011-06-01

Damage to structures due to vibrations from pile driving operations is of great concern to engineers. This : research has stemmed from the need to address potential damage to concrete-filled pipe piles and recently : placed concrete structures that c...

Construction and Characterization of a Novel Vocal Fold Bioreactor

PubMed Central

Zerdoum, Aidan B.; Tong, Zhixiang; Bachman, Brendan; Jia, Xinqiao

2014-01-01

In vitro engineering of mechanically active tissues requires the presentation of physiologically relevant mechanical conditions to cultured cells. To emulate the dynamic environment of vocal folds, a novel vocal fold bioreactor capable of producing vibratory stimulations at fundamental phonation frequencies is constructed and characterized. The device is composed of a function generator, a power amplifier, a speaker selector and parallel vibration chambers. Individual vibration chambers are created by sandwiching a custom-made silicone membrane between a pair of acrylic blocks. The silicone membrane not only serves as the bottom of the chamber but also provides a mechanism for securing the cell-laden scaffold. Vibration signals, generated by a speaker mounted underneath the bottom acrylic block, are transmitted to the membrane aerodynamically by the oscillating air. Eight identical vibration modules, fixed on two stationary metal bars, are housed in an anti-humidity chamber for long-term operation in a cell culture incubator. The vibration characteristics of the vocal fold bioreactor are analyzed non-destructively using a Laser Doppler Vibrometer (LDV). The utility of the dynamic culture device is demonstrated by culturing cellular constructs in the presence of 200-Hz sinusoidal vibrations with a mid-membrane displacement of 40 µm. Mesenchymal stem cells cultured in the bioreactor respond to the vibratory signals by altering the synthesis and degradation of vocal fold-relevant, extracellular matrix components. The novel bioreactor system presented herein offers an excellent in vitro platform for studying vibration-induced mechanotransduction and for the engineering of functional vocal fold tissues. PMID:25145349

Construction and characterization of a novel vocal fold bioreactor.

PubMed

Zerdoum, Aidan B; Tong, Zhixiang; Bachman, Brendan; Jia, Xinqiao

2014-08-01

In vitro engineering of mechanically active tissues requires the presentation of physiologically relevant mechanical conditions to cultured cells. To emulate the dynamic environment of vocal folds, a novel vocal fold bioreactor capable of producing vibratory stimulations at fundamental phonation frequencies is constructed and characterized. The device is composed of a function generator, a power amplifier, a speaker selector and parallel vibration chambers. Individual vibration chambers are created by sandwiching a custom-made silicone membrane between a pair of acrylic blocks. The silicone membrane not only serves as the bottom of the chamber but also provides a mechanism for securing the cell-laden scaffold. Vibration signals, generated by a speaker mounted underneath the bottom acrylic block, are transmitted to the membrane aerodynamically by the oscillating air. Eight identical vibration modules, fixed on two stationary metal bars, are housed in an anti-humidity chamber for long-term operation in a cell culture incubator. The vibration characteristics of the vocal fold bioreactor are analyzed non-destructively using a Laser Doppler Vibrometer (LDV). The utility of the dynamic culture device is demonstrated by culturing cellular constructs in the presence of 200-Hz sinusoidal vibrations with a mid-membrane displacement of 40 µm. Mesenchymal stem cells cultured in the bioreactor respond to the vibratory signals by altering the synthesis and degradation of vocal fold-relevant, extracellular matrix components. The novel bioreactor system presented herein offers an excellent in vitro platform for studying vibration-induced mechanotransduction and for the engineering of functional vocal fold tissues.

Optimal active vibration absorber: Design and experimental results

NASA Technical Reports Server (NTRS)

Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.

1992-01-01

An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.

Whole-body vibration of locomotive engineers.

PubMed

Sorainen, E; Rytkönen, E

1999-01-01

Vibration of the seat and the body of a diesel locomotive and an electric locomotive were measured while driving on the railways of Eastern Finland. At the speed of 120 km/h for the diesel locomotive and 140 km/h for the electric locomotive (the greatest permissible speeds) the vibration of the seat was tangent to the "fatigue-decreased proficiency boundary" of the international standard ISO 2631/1(1) in the side-to-side direction in one-third octave bands of 1-1.6 Hz. The frequency response measurements between the body of the locomotive and the seat indicated that the seat did not reduce side-to-side vibration of the body at low frequencies where the vibration was most harmful.

Fiberoptic characteristics for extreme operating environments

NASA Technical Reports Server (NTRS)

Delcher, R. C.

1992-01-01

Fiberoptics could offer several major benefits for cryogenic liquid-fueled rocket engines, including lightning immunity, weight reduction, and the possibility of implementing a number of new measurements for engine condition monitoring. The technical feasibility of using fiberoptics in the severe environments posed by cryogenic liquid-fueled rocket engines was determined. The issues of importance and subsequent requirements for this use of fiberoptics were compiled. These included temperature ranges, moisture embrittlement succeptability, and the ability to withstand extreme shock and vibration levels. Different types of optical fibers were evaluated and several types of optical fibers' ability to withstand use in cryogenic liquid-fueled rocket engines was demonstrated through environmental testing of samples. This testing included: cold-bend testing, moisture embrittlement testing, temperature cycling, temperature extremes testing, vibration testing, and shock testing. Three of five fiber samples withstood the tests to a level proving feasibility, and two of these remained intact in all six of the tests. A fiberoptic bundle was also tested, and completed testing without breakage. Preliminary cabling and harnessing for fiber protection was also demonstrated. According to cable manufacturers, the successful -300 F cold bend, vibration, and shock tests are the first instance of any major fiberoptic cable testing below roughly -55 F. This program has demonstrated the basic technical feasibility of implementing optical fibers on cryogenic liquid-fueled rocket engines, and a development plan is included highlighting requirements and issues for such an implementation.

Optical radar-based device for measuring automobile belt displacement in real time

NASA Astrophysics Data System (ADS)

Brennan, Brian W.; Gentile, John R.

1999-02-01

Ford Motor Company had a requirement to measure fan belt vibration on their 4.6 liter Cobra-Mustang engine. While this sensor was to be used in the laboratory, it would also be used for field testing of this engine. The general operation temperature was -40 to 120 degrees C, but there was an engine 'soak-back' requirement of up to 200 degrees C. The vibration requirement was 3g continuous at 10 Hz with 20g shock. Humidity was 0-95 percent. Without active cooling, the temperature environment eliminated engine mounted electronics and with it some more common approaches such as laser triangulation based sensing. A laser radar concept was developed which features remotely located electronics, fiber optic delivery and return of the signal and an engine mounted optic head. The three lens design of the receive optics is a compromise choice designed to maximize power at the receiver over the full travel of the belt. The electronic scheme consists of a time-to-amplitude converter based on a precise time interval derived from the phase difference of logic level pulse trains which in turn are formed by the 'exclusive O Ring' of the transmit and receive pulses. In practice, a 10 MHz pulse train is transmitted to the vibrating belt which coupled with some fast electronics results in about 1 0.1 mm resolution, sufficient for this application.

Robust adaptive vibration control of a flexible structure.

PubMed

Khoshnood, A M; Moradi, H M

2014-07-01

Different types of L1 adaptive control systems show that using robust theories with adaptive control approaches has produced high performance controllers. In this study, a model reference adaptive control scheme considering robust theories is used to propose a practical control system for vibration suppression of a flexible launch vehicle (FLV). In this method, control input of the system is shaped from the dynamic model of the vehicle and components of the control input are adaptively constructed by estimating the undesirable vibration frequencies. Robust stability of the adaptive vibration control system is guaranteed by using the L1 small gain theorem. Simulation results of the robust adaptive vibration control strategy confirm that the effects of vibration on the vehicle performance considerably decrease without the loss of the phase margin of the system. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Fault Diagnosis of Demountable Disk-Drum Aero-Engine Rotor Using Customized Multiwavelet Method.

PubMed

Chen, Jinglong; Wang, Yu; He, Zhengjia; Wang, Xiaodong

2015-10-23

The demountable disk-drum aero-engine rotor is an important piece of equipment that greatly impacts the safe operation of aircraft. However, assembly looseness or crack fault has led to several unscheduled breakdowns and serious accidents. Thus, condition monitoring and fault diagnosis technique are required for identifying abnormal conditions. Customized ensemble multiwavelet method for aero-engine rotor condition identification, using measured vibration data, is developed in this paper. First, customized multiwavelet basis function with strong adaptivity is constructed via symmetric multiwavelet lifting scheme. Then vibration signal is processed by customized ensemble multiwavelet transform. Next, normalized information entropy of multiwavelet decomposition coefficients is computed to directly reflect and evaluate the condition. The proposed approach is first applied to fault detection of an experimental aero-engine rotor. Finally, the proposed approach is used in an engineering application, where it successfully identified the crack fault of a demountable disk-drum aero-engine rotor. The results show that the proposed method possesses excellent performance in fault detection of aero-engine rotor. Moreover, the robustness of the multiwavelet method against noise is also tested and verified by simulation and field experiments.

Control of the induced microgravity environment of the Man Tended Free Flyer (MTFF)

NASA Technical Reports Server (NTRS)

Schlund, Juergen

1988-01-01

Induced disturbance sources have been identified on board the Man Tended Free Flyer (MTFF). Vibration responses at sensitive payload/spacecraft interfaces have been predicted by the application of an empirically found spacecraft dynamic transfer function. Vibrations from fluid loops (Freon, water) and of reaction wheels are assessed to be the main contributors to the induced microgravity environment. The expected payload acceleration response amplitudes presented here are more than one hundred times higher than the admissible values given by the MTFF system requirement, not considering the structural striction-friction effects which could be avoided by appropriate design. Real responses will be significantly lower because the derivation of excitation and transmission functions are based on worst case assumptions. The results indicate that future activities must be concentrated on equipment design improvement and the implementation of vibration reduction along the disturbance transmission path. The activities must be accompanied by early equipment and assembly development tests and transmissibility measurements with the integrated spacecraft engineering and structural models in order to improve the accuracy of payload response predictions.

Methodology of Dynamic Monitoring of Structures in the Vicinity of Hydrotechnical Works - Selected Case Studies

NASA Astrophysics Data System (ADS)

Wyjadłowski, Marek

2017-12-01

The constant development of geotechnical technologies imposes the necessity of monitoring techniques to provide a proper quality and the safe execution of geotechnical works. Several monitoring methods enable the preliminary design of work process and current control of hydrotechnical works (pile driving, sheet piling, ground improvement methods). Wave parameter measurements and/or continuous histogram recording of shocks and vibrations and its dynamic impact on engineering structures in the close vicinity of the building site enable the modification of the technology parameters, such as vibrator frequency or hammer drop height. Many examples of practical applications have already been published and provide a basis for the formulation of guidelines, for work on the following sites. In the current work the author's experience gained during sheet piling works for the reconstruction of City Channel in Wrocław (Poland) was presented. The examples chosen describe ways of proceedings in the case of new and old residential buildings where the concrete or masonry walls were exposed to vibrations and in the case of the hydrotechnical structures (sluices, bridges).

78 FR 2198 - Airworthiness Directives; Turbomeca S.A. Turboshaft Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-10

... high GG speed (NG) rating vibration check. (f) Definition Level 3 maintenance on the GG rotating... performing a high gas generator speed (NG) rating vibration check. This AD was prompted by several reports of... bearing failures have occurred following ``Level 3'' maintenance actions on the GG rotating assembly. Some...

Construction Vibration Impacts on the Center for Integrated Nanotechnologies.

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

Hearne, Sean J.; Kostranchuk, Theodore; Jungjohann, Katherine Leigh

Under the direction of the James W. Todd, Assistant Manager for Engineering within the National Nuclear Security Administration Sandia Field Office, the team listed above has performed the attached study to evaluate the vibration sensitivity of the Center for Integrated Nanotechnolog ies and propose possible mitigation strategies .

Etched optical fiber vibration sensor to monitor health condition of beam like structures

NASA Astrophysics Data System (ADS)

Putha, Kishore; Dantala, Dinakar; Kamineni, Srimannarayana; Pachava, Vengal Rao

2013-06-01

Using a center etched single mode optical fiber, a simple vibration senor is designed to monitor the vibrations of a simply supported beam. The sensor has high linear response to the axial displacement of about 0.8 mm with a sensitivity of 32 mV/10 μm strain. The sensor is tested for periodic and suddenly released forces, and the results are found to coincide with the theoretical values. This simple design, small in size and low cost sensor may find applications in industry and civil engineering to monitor the vibrations of the beam structures and bridges.

Experimental evaluation of a tuned electromagnetic damper for vibration control of cryogenic turbopump rotors

NASA Technical Reports Server (NTRS)

Dirusso, Eliseo; Brown, Gerald V.

1990-01-01

Experiments were performed on a passive tuned electromagnetic damper that could be used for damping rotor vibrations in cryogenic turbopumps for rocket engines. The tests were performed in a rig that used liquid nitrogen to produce cryogenic turbopump temperatures. This damper is most effective at cryogenic temperatures and is not a viable damper at room temperature. The unbalanced amplitude response of the rotor shaft was measured for undamped (baseline) and damped conditions at the critical speeds of the rotor (approx. 5900 to 6400 rpm) and the data were compared. The tests were performed for a speed range between 900 and 10 000 rpm. The tests revealed that the damper is very effective for damping single-mode narrow bandwidth amplitude response but is less effective in damping broadband response or multimode amplitude response.

Microgravity Vibration Control and Civil Applications

NASA Technical Reports Server (NTRS)

Whorton, Mark Stephen; Alhorn, Dean Carl

1998-01-01

Controlling vibration of structures is essential for both space structures as well as terrestrial structures. Due to the ambient acceleration levels anticipated for the International Space Station, active vibration isolation is required to provide a quiescent acceleration environment for many science experiments. An overview is given of systems developed and flight tested in orbit for microgravity vibration isolation. Technology developed for vibration control of flexible space structures may also be applied to control of terrestrial structures such as buildings and bridges subject to wind loading or earthquake excitation. Recent developments in modern robust control for flexible space structures are shown to provide good structural vibration control while maintaining robustness to model uncertainties. Results of a mixed H-2/H-infinity control design are provided for a benchmark problem in structural control for earthquake resistant buildings.

Strain Gage Signal Interpretation.

DTIC Science & Technology

1986-02-01

blades and vanes in many engines have been collected, played back and examined. The engine types encompass GE’s stable of turbine engines from the small...aeromechanical engineer . 1.3 SUMMARY OF RESULTS Strain gage signals from vibrating rotor blades and vanes were collected, examined, classified, and generalized...turboprops, to turbojets and to the large high bypass turbofan engines . Test conditions include all the phases that are investigated

High force vibration testing with wide frequency range

DOEpatents

Romero, Edward F.; Jepsen, Richard A.; Gregory, Danny Lynn

2013-04-02

A shaker assembly for vibration testing includes first and second shakers, where the first shaker includes a piezo-electric material for generating vibration. A support structure permits a test object to be supported for vibration of the test object by both shakers. An input permits an external vibration controller to control vibration of the shakers.

Measurement of Vibrations from the 8- by 6-Foot Supersonic Wind Tunnel

NASA Image and Video Library

1950-07-21

Reverend Henry Birkenhauer and E.F. Carome measure ground vibrations on West 220th Street caused by the operation of the 8- by 6-Foot Supersonic Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. The 8- by 6 was the laboratory’s first large supersonic wind tunnel. It was also the NACA’s most powerful supersonic tunnel, and the NACA’s first facility capable of running an engine at supersonic speeds. The 8- by 6 was originally an open-throat and non-return tunnel. This meant that the supersonic air flow was blown through the test section and out the other end into the atmosphere. Complaints from the local community led to the installation of a muffler at the tunnel exit and the eventual addition of a return leg. Reverend Brikenhauer, a seismologist, and Carome, an electrical technician were brought in from John Carroll University to take vibration measurements during the 8- by 6 tunnel’s first run with a supersonic engine. They found that the majority of the vibrations came from the air and not the ground. The tunnel’s original muffler offered some relief during the facility checkout runs, but it proved inadequate during the operation of an engine in the test section. Tunnel operation was suspended until a new muffler was designed and installed. The NACA researchers, however, were pleased with the tunnel’s operation. They claimed it was the first time a jet engine was operated in an airflow faster than Mach 2.

Engineering Design Handbook: Environmental Series. Part Three. Induced Environmental Factors

DTIC Science & Technology

1976-01-20

beams are combined on a photo- detector, a beat frequency at 25 MHz is produced. Periodic motion of the reflecting surface then modulates sidebands...about the 25-MHz beat frequency. The ampli- tude and frequency of the vibration are determined by demodulation of the phase-modulated 25-MHz signal...VibrationBulletin, No. 41, Part 6 (December 1970), pp. 29-34. 70. E. G Fischer, "Sine Beat Vibration Testing Related to Earthquake Response Spectra

A Resonant Synchronous Vibration Based Approach for Rotor Imbalance Detection

NASA Technical Reports Server (NTRS)

Luo, Huangeng; Rodriquez, Hector; Hallman, Darren; Lewicki, David G.

2006-01-01

This paper presents a methodology of detecting rotor imbalances, such as mass imbalance and crack-induced imbalance, using shaft synchronous vibrations. An iterative scheme is developed to identify parameters from measured synchronous vibration data. A detection system is integrated by using state-of-the-art commercial analysis equipment. A laboratory rotor test rig is used to verify the system integration and algorithm validation. A real engine test has been carried out and the results are reported.

Shock and Vibration Symposium (59th) Held in Albuquerque, New Mexico on 18-20 October 1988. Volume 3

DTIC Science & Technology

1988-10-01

N. F. Rieger Statistical Energy Analysis : An Overview of Its Development and Engineering Applications J. E. Manning DATA BASES DOE/DOD Environmental...Vibroacoustic Response Using the Finite Element Method and Statistical Energy Analysis F. L. Gloyna Study of Helium Effect on Spacecraft Random Vibration...Analysis S. A. Wilkerson vi DYNAMIC ANALYSIS Modeling of Vibration Transmission in a Damped Beam Structure Using Statistical Energy Analysis S. S

KENNEDY SPACE CENTER, FLA. - Framed between palm trees, solid rocket boosters loom above the Mobile Launcher Platform (MLP) as the crawler transporter slowly moves it along the crawlerway. The journey is in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-17

KENNEDY SPACE CENTER, FLA. - Framed between palm trees, solid rocket boosters loom above the Mobile Launcher Platform (MLP) as the crawler transporter slowly moves it along the crawlerway. The journey is in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - The crawler transporter slowly moves the Mobile Launcher Platform (MLP), carrying a set of twin solid rocket boosters, away from the Vehicle Assembly Building (VAB) in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-17

KENNEDY SPACE CENTER, FLA. - The crawler transporter slowly moves the Mobile Launcher Platform (MLP), carrying a set of twin solid rocket boosters, away from the Vehicle Assembly Building (VAB) in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - The crawler transporter has slowly moved the Mobile Launcher Platform (MLP), carrying a set of twin solid rocket boosters, out of the Vehicle Assembly Building (VAB) in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-17

KENNEDY SPACE CENTER, FLA. - The crawler transporter has slowly moved the Mobile Launcher Platform (MLP), carrying a set of twin solid rocket boosters, out of the Vehicle Assembly Building (VAB) in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - The crawler transporter is slowly moving the Mobile Launcher Platform (MLP), carrying a set of twin solid rocket boosters, out of the Vehicle Assembly Building (VAB) in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-17

KENNEDY SPACE CENTER, FLA. - The crawler transporter is slowly moving the Mobile Launcher Platform (MLP), carrying a set of twin solid rocket boosters, out of the Vehicle Assembly Building (VAB) in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - The crawler transporter slowly moves the Mobile Launcher Platform (MLP), carrying a set of twin solid rocket boosters, out of the Vehicle Assembly Building (VAB) in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-17

KENNEDY SPACE CENTER, FLA. - The crawler transporter slowly moves the Mobile Launcher Platform (MLP), carrying a set of twin solid rocket boosters, out of the Vehicle Assembly Building (VAB) in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

14 CFR 23.1193 - Cowling and nacelle.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) Each cowling must be constructed and supported so that it can resist any vibration, inertia, and air... engines must be designed and constructed so that with the landing gear retracted, a fire in the engine...

Specialized data analysis of SSME and advanced propulsion system vibration measurements

NASA Technical Reports Server (NTRS)

Coffin, Thomas; Swanson, Wayne L.; Jong, Yen-Yi

1993-01-01

The basic objectives of this contract were to perform detailed analysis and evaluation of dynamic data obtained during Space Shuttle Main Engine (SSME) test and flight operations, including analytical/statistical assessment of component dynamic performance, and to continue the development and implementation of analytical/statistical models to effectively define nominal component dynamic characteristics, detect anomalous behavior, and assess machinery operational conditions. This study was to provide timely assessment of engine component operational status, identify probable causes of malfunction, and define feasible engineering solutions. The work was performed under three broad tasks: (1) Analysis, Evaluation, and Documentation of SSME Dynamic Test Results; (2) Data Base and Analytical Model Development and Application; and (3) Development and Application of Vibration Signature Analysis Techniques.

An investigation of adaptive controllers for helicopter vibration and the development of a new dual controller

NASA Technical Reports Server (NTRS)

Mookerjee, P.; Molusis, J. A.; Bar-Shalom, Y.

1985-01-01

An investigation of the properties important for the design of stochastic adaptive controllers for the higher harmonic control of helicopter vibration is presented. Three different model types are considered for the transfer relationship between the helicopter higher harmonic control input and the vibration output: (1) nonlinear; (2) linear with slow time varying coefficients; and (3) linear with constant coefficients. The stochastic controller formulations and solutions are presented for a dual, cautious, and deterministic controller for both linear and nonlinear transfer models. Extensive simulations are performed with the various models and controllers. It is shown that the cautious adaptive controller can sometimes result in unacceptable vibration control. A new second order dual controller is developed which is shown to modify the cautious adaptive controller by adding numerator and denominator correction terms to the cautious control algorithm. The new dual controller is simulated on a simple single-control vibration example and is found to achieve excellent vibration reduction and significantly improves upon the cautious controller.

Mode-selective control of thermal Brownian vibration of micro-resonator (Generation of a thermal no-equilibrium state by mechanical feedback control)

NASA Astrophysics Data System (ADS)

Kawamura, Y.; Kanegae, R.

2017-09-01

Recently, there have been various attempts to dampen the vibration amplitude of the Brownian motion of a microresonator below the thermal vibration amplitude, with the goal of reaching the quantum ground vibration level. To further develop the approach of reaching the quantum ground state, it is essential to clarify whether or not coupling exists between the different vibration modes of the resonator. In this paper, the mode-selective control of thermal Brownian vibration is shown. The first and the second vibration modes of a micro-cantilever moved by a random Brownian motion are cooled selectively and independently below the thermal vibration amplitude, as determined by the statistical thermodynamic theory, using a mechanical feedback control method. This experimental result shows that the thermal no-equilibrium condition was generated by mechanical feedback control.

Integrated passive/active vibration absorber for multi-story buildings

NASA Technical Reports Server (NTRS)

Lee-Glauser, Gina J.; Ahmadi, Goodarz; Horta, Lucas G.

1995-01-01

Passive isolator, active vibration absorber, and an integrated passive/active (hybrid) control are studied for their effectiveness in reducing structural vibration under seismic excitations. For the passive isolator, a laminated rubber bearing base isolator which has been studied and used extensively by researchers and seismic designers is considered. An active vibration absorber concept, which can provide guaranteed closed-loop stability with minimum knowledge of the controlled system, is used to reduce the passive isolator displacement and to suppress the top floor vibration. A three-story building model is used for the numerical simulation. The performance of an active vibration absorber and a hybrid vibration controller in reducing peak structural responses is compared with the passively isolated structural response and with absence of vibration control systems under the N00W component of El Centro 1940 and N90W component of the Mexico City earthquake excitation records. The results show that the integrated passive/active vibration control system is most effective in suppressing the peak structural acceleration for the El Centro 1940 earthquake when compared with the passive or active vibration absorber alone. The active vibration absorber, however, is the only system that suppresses the peak acceleration of the structure for the Mexico City 1985 earthquake.

High Speed Balancing Applied to the T700 Engine

NASA Technical Reports Server (NTRS)

Walton, J.; Lee, C.; Martin, M.

1989-01-01

The work performed under Contracts NAS3-23929 and NAS3-24633 is presented. MTI evaluated the feasibility of high-speed balancing for both the T700 power turbine rotor and the compressor rotor. Modifications were designed for the existing Corpus Christi Army Depot (CCAD) T53/T55 high-speed balancing system for balancing T700 power turbine rotors. Tests conducted under these contracts included a high-speed balancing evaluation for T700 power turbines in the Army/NASA drivetrain facility at MTI. The high-speed balancing tests demonstrated the reduction of vibration amplitudes at operating speed for both low-speed balanced and non-low-speed balanced T700 power turbines. In addition, vibration data from acceptance tests of T53, T55, and T700 engines were analyzed and a vibration diagnostic procedure developed.

Hybrid time-variant reliability estimation for active control structures under aleatory and epistemic uncertainties

NASA Astrophysics Data System (ADS)

Wang, Lei; Xiong, Chuang; Wang, Xiaojun; Li, Yunlong; Xu, Menghui

2018-04-01

Considering that multi-source uncertainties from inherent nature as well as the external environment are unavoidable and severely affect the controller performance, the dynamic safety assessment with high confidence is of great significance for scientists and engineers. In view of this, the uncertainty quantification analysis and time-variant reliability estimation corresponding to the closed-loop control problems are conducted in this study under a mixture of random, interval, and convex uncertainties. By combining the state-space transformation and the natural set expansion, the boundary laws of controlled response histories are first confirmed with specific implementation of random items. For nonlinear cases, the collocation set methodology and fourth Rounge-Kutta algorithm are introduced as well. Enlightened by the first-passage model in random process theory as well as by the static probabilistic reliability ideas, a new definition of the hybrid time-variant reliability measurement is provided for the vibration control systems and the related solution details are further expounded. Two engineering examples are eventually presented to demonstrate the validity and applicability of the methodology developed.

Adaptive PI control strategy for flat permanent magnet linear synchronous motor vibration suppression

NASA Astrophysics Data System (ADS)

Meng, Fanwei; Liu, Chengying; Li, Zhijun; Wang, Liping

2013-01-01

Due to low damping ratio, flat permanent magnet linear synchronous motor's vibration is difficult to be damped and the accuracy is limited. The vibration suppressing results are not good enough in the existing research because only the longitudinal direction vibration is considered while the normal direction vibration is neglected. The parameters of the direct-axis current controller are set to be the same as those of the quadrature-axis current controller commonly. This causes contradiction between signal noise and response. To suppress the vibration, the electromagnetic force model of the flat permanent magnet synchronous linear motor is formulated first. Through the analysis of the effect that direct-axis current noise and quadrature-axis current noise have on both direction vibration, it can be declared that the conclusion that longitudinal direction vibration is only related to the quadrature-axis current noise while the normal direction vibration is related to both the quadrature-axis current noise and direct-axis current noise. Then, the simulation test on current loop with a low-pass filter is conducted and the results show that the low-pass filter can not suppress the vibration but makes the vibration more severe. So a vibration suppressing strategy that the proportional gain of direct-axis current controller adapted according to quadrature-axis reference current is proposed. This control strategy can suppress motor vibration by suppressing direct-axis current noise. The experiments results about the effect of K p and T i on normal direction vibration, longitudinal vibration and the position step response show that this strategy suppresses vibration effectively while the motor's motion performance is not affected. The maximum reduction of vibration can be up to 40%. In addition, current test under rated load condition is also conducted and the results show that the control strategy can avoid the conflict between the direct-axis current and the quadrature-axis current under typical load. Adaptive PI control strategy can effectively suppress the flat permanent magnet linear synchronous motor's vibration without affecting the motor's performance.

Control System Damps Vibrations

NASA Technical Reports Server (NTRS)

Kopf, E. H., Jr.; Brown, T. K.; Marsh, E. L.

1983-01-01

New control system damps vibrations in rotating equipment with help of phase-locked-loop techniques. Vibrational modes are controlled by applying suitable currents to drive motor. Control signals are derived from sensors mounted on equipment.

Multi-Plane High Speed Balancing Techniques and the Use of a High Specific Stiffness Ti-Borsic Material for Vibration Control.

DTIC Science & Technology

1980-02-01

maneuver conditions, and transmit the net axial thrust force between the turbine and fan sections due to pressure and aero dynamic gas loads . 49 Lm...stiffness composite material shaft. Both~~ balancing demonstration and the composite shaft design ad as their objective the management of small turbofan ...CONFIGURATIONS 99 LIST OF ILLUSTRATIONS Figure Title Page 1 High Speed Balancing Program Schedule 4 2 Teledyne CAE Model 471-11DX Turbofan Engine

Aerospace applications of integer and combinatorial optimization

NASA Technical Reports Server (NTRS)

Padula, S. L.; Kincaid, R. K.

1995-01-01

Research supported by NASA Langley Research Center includes many applications of aerospace design optimization and is conducted by teams of applied mathematicians and aerospace engineers. This paper investigates the benefits from this combined expertise in solving combinatorial optimization problems. Applications range from the design of large space antennas to interior noise control. A typical problem, for example, seeks the optimal locations for vibration-damping devices on a large space structure and is expressed as a mixed/integer linear programming problem with more than 1500 design variables.

Vibration control of rotor shaft

NASA Technical Reports Server (NTRS)

Nonami, K.

1985-01-01

Suppression of flexural forced vibration or the self-excited vibration of a rotating shaft system not by passive elements but by active elements is described. The distinctive feature of this method is not to dissipate the vibration energy but to provide the force cancelling the vibration displacement and the vibration velocity through the bearing housing in rotation. Therefore the bearings of this kind are appropriately named Active Control Bearings. A simple rotor system having one disk at the center of the span on flexible supports is investigated in this paper. The actuators of the electrodynamic transducer are inserted in the sections of the bearing housing. First, applying the optimal regulator of optimal control theory, the flexural vibration control of the rotating shaft and the vibration control of support systems are performed by the optimal state feedback system using these actuators. Next, the quasi-modal control based on a modal analysis is applied to this rotor system. This quasi-modal control system is constructed by means of optimal velocity feedback loops. The differences between optimal control and quasi-modal control are discussed and their merits and demerits are made clear. Finally, the experiments are described concerning only the optimal regulator method.

Repairing the vibratory vocal fold.

PubMed

Long, Jennifer L

2018-01-01

A vibratory vocal fold replacement would introduce a new treatment paradigm for structural vocal fold diseases such as scarring and lamina propria loss. This work implants a tissue-engineered replacement for vocal fold lamina propria and epithelium in rabbits and compares histology and function to injured controls and orthotopic transplants. Hypotheses were that the cell-based implant would engraft and control the wound response, reducing fibrosis and restoring vibration. Translational research. Rabbit adipose-derived mesenchymal stem cells (ASC) were embedded within a three-dimensional fibrin gel, forming the cell-based outer vocal fold replacement (COVR). Sixteen rabbits underwent unilateral resection of vocal fold epithelium and lamina propria, as well as reconstruction with one of three treatments: fibrin glue alone with healing by secondary intention, replantation of autologous resected vocal fold cover, or COVR implantation. After 4 weeks, larynges were examined histologically and with phonation. Fifteen rabbits survived. All tissues incorporated well after implantation. After 1 month, both graft types improved histology and vibration relative to injured controls. Extracellular matrix (ECM) of the replanted mucosa was disrupted, and ECM of the COVR implants remained immature. Immune reaction was evident when male cells were implanted into female rabbits. Best histologic and short-term vibratory outcomes were achieved with COVR implants containing male cells implanted into male rabbits. Vocal fold cover replacement with a stem cell-based tissue-engineered construct is feasible and beneficial in acute rabbit implantation. Wound-modifying behavior of the COVR implant is judged to be an important factor in preventing fibrosis. NA. Laryngoscope, 128:153-159, 2018. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

High-Temperature Magnetic Bearings Being Developed for Gas Turbine Engines

NASA Technical Reports Server (NTRS)

Kascak, Albert F.

1998-01-01

Magnetic bearings are the subject of a new NASA Lewis Research Center and U.S. Army thrust with significant industry participation, and cooperation with other Government agencies. The NASA/Army emphasis is on high-temperature applications for future gas turbine engines. Magnetic bearings could increase the reliability and reduce the weight of these engines by eliminating the lubrication system. They could also increase the DN (diameter of bearing times the rpm) limit on engine speed and allow active vibration cancellation systems to be used, resulting in a more efficient, "more electric" engine. Finally, the Integrated High Performance Turbine Engine Technology (IHPTET) program, a joint Department of Defense/industry program, identified a need for a high-temperature (1200 F) magnetic bearing that could be demonstrated in their Phase III engine. This magnetic bearing is similar to an electric motor. It has a laminated rotor and stator made of cobalt steel. Wound around the stator's circumference are a series of electrical wire coils which form a series of electric magnets that exert a force on the rotor. A probe senses the position of the rotor, and a feedback controller keeps it centered in the cavity. The engine rotor, bearings, and casing form a flexible structure with many modes. The bearing feedback controller, which could cause some of these modes to become unstable, could be adapted to varying flight conditions to minimize seal clearances and monitor the health of the system.

Seismic isolation device having charging function by a transducer

NASA Astrophysics Data System (ADS)

Yamaguchi, Takashi; Miura, Nanako; Takahashi, Masaki

2016-04-01

In late years, many base isolated structures are planned as the seismic design, because they suppress vibration response significantly against large earthquake. To achieve greater safety, semi-active or active vibration control system is installed in the structures as earthquake countermeasures. Semi-active and active vibration control systems are more effective than passive vibration control system to large earthquake in terms of vibration reduction. However semi-active and active vibration control system cannot operate as required when external power supply is cut off. To solve the problem of energy consumption, we propose a self-powered active seismic isolation floor which achieve active control system using regenerated vibration energy. This device doesn't require external energy to produce control force. The purpose of this study is to propose the seismic isolation device having charging function and to optimize the control system and passive elements such as spring coefficients and damping coefficients using genetic algorithm. As a result, optimized model shows better performance in terms of vibration reduction and electric power regeneration than the previous model. At the end of this paper, the experimental specimen of the proposed isolation device is shown.

Adaptive positive position feedback control with a feedforward compensator of a magnetostrictive beam for vibration suppression

NASA Astrophysics Data System (ADS)

Bian, Leixiang; Zhu, Wei

2018-07-01

In this paper, a Fe–Ga alloy magnetostrictive beam is designed as an actuator to restrain the vibration of a supported mass. Dynamic modeling of the system based on the transfer matrix method of multibody system is first shown, and then a hybrid controller is developed to achieve vibration control. The proposed vibration controller combines a multi-mode adaptive positive position feedback (APPF) with a feedforward compensator. In the APPF control, an adaptive natural frequency estimator based on the recursive least-square method is developed to be used. In the feedforward compensator, the hysteresis of the magnetostrictive beam is linearized based on a Bouc–Wen model. The further remarkable vibration suppression capability of the proposed hybrid controller is demonstrated experimentally and compared with the positive position feedback controller. Experiment results show that the proposed controller is applicable to the magnetostrictive beam for improving vibration control effectiveness.

An impulsive receptance technique for the time domain computation of the vibration of a whole aero-engine model with nonlinear bearings

NASA Astrophysics Data System (ADS)

Hai, Pham Minh; Bonello, Philip

2008-12-01

The direct study of the vibration of real engine structures with nonlinear bearings, particularly aero-engines, has been severely limited by the fact that current nonlinear computational techniques are not well-suited for complex large-order systems. This paper introduces a novel implicit "impulsive receptance method" (IRM) for the time domain analysis of such structures. The IRM's computational efficiency is largely immune to the number of modes used and dependent only on the number of nonlinear elements. This means that, apart from retaining numerical accuracy, a much more physically accurate solution is achievable within a short timeframe. Simulation tests on a realistically sized representative twin-spool aero-engine showed that the new method was around 40 times faster than a conventional implicit integration scheme. Preliminary results for a given rotor unbalance distribution revealed the varying degree of journal lift, orbit size and shape at the example engine's squeeze-film damper bearings, and the effect of end-sealing at these bearings.

Experimental analysis of thread movement in bolted connections due to vibrations

NASA Technical Reports Server (NTRS)

Ramsey, G. ED; Jenkins, Robert C.

1995-01-01

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

High-Temperature Alloys for Automotive Stirling Engines

NASA Technical Reports Server (NTRS)

Stephens, J. R.; Titran, R. H.

1986-01-01

Stirling engine is external-combustion engine that offers fuel economy, low emissions, low noise, and low vibrations. One of most critical areas in engine development concerns material selection for component parts. Alloys CG-27 and XF-818 identified capable of withstanding rigorous requirements of automotive Stirling engine. Alloys chosen for availability, performance, and manufacturability. Advanced iron-base alloys have potential for variety of applications, including stationary solar-power systems.

Multi-objective optimization of piezoelectric circuitry network for mode delocalization and suppression of bladed disk

NASA Astrophysics Data System (ADS)

Yoo, David; Tang, J.

2017-04-01

Since weakly-coupled bladed disks are highly sensitive to the presence of uncertainties, they can easily undergo vibration localization. When vibration localization occurs, vibration modes of bladed disk become dramatically different from those under the perfectly periodic condition, and the dynamic response under engine-order excitation is drastically amplified. In previous studies, it is investigated that amplified vibration response can be suppressed by connecting piezoelectric circuitry into individual blades to induce the damped absorber effect, and localized vibration modes can be alleviated by integrating piezoelectric circuitry network. Delocalization of vibration modes and vibration suppression of bladed disk, however, require different optimal set of circuit parameters. In this research, multi-objective optimization approach is developed to enable finding the best circuit parameters, simultaneously achieving both objectives. In this way, the robustness and reliability in bladed disk can be ensured. Gradient-based optimizations are individually developed for mode delocalization and vibration suppression, which are then integrated into multi-objective optimization framework.

Modeling and Application of Piezoelectric Materials in Repair of Engineering Structures

NASA Astrophysics Data System (ADS)

Wu, Nan

The shear horizontal wave propagation and vibration of piezoelectric coupled structures under an open circuit electrical boundary condition are studied. Following the studies on the dynamic response of piezoelectric coupled structures, the repair of both crack/notch and delaminated structures using piezoelectric materials are conducted. The main contribution was the proposed the active structural repair design using piezoelectric materials for different structures. An accurate model for the piezoelectric effect on the shear wave propagation is first proposed to guide the application of piezoelectric materials as sensors and actuators in the repair of engineering structures. A vibration analysis of a circular steel substrate surface bonded by a piezoelectric layer with open circuit is presented. The mechanical models and solutions for the wave propagation and vibration analysis of piezoelectric coupled structures are established based on the Kirchhoff plate model and Maxwell equation. Following the studies of the dynamic response of piezoelectric coupled structures, a close-loop feedback control repair methodology is proposed for a vibrating delaminated beam structure by using piezoelectric patches. The electromechanical characteristic of the piezoelectric material is employed to induce a local shear force above the delamination area via an external actuation voltage, which is designed as a feedback of the deflection of a vibrating beam and a delaminated plate, to reduce the stress singularity around the delamination tips. Furthermore, an experimental realization of an effective repair of a notched cantilever beam structure subjected to a dynamic loading by use of piezoelectric patches is reported. A small piezoelectric patch used as a sensor is placed on the notch position to monitor the severity of the stress singularity around the notch area by measuring the charge output on the sensor, and a patch used as an actuator is located around the notch area to generate a required bending moment by employing an actuation voltage to reduce the stress singularity at the notch position. The actuation voltage on the actuator is designed from a feedback circuit process. Through the analytical model, FEM simulation and experimental studies, the active structural repair method using piezoelectric materials is realized and proved to be feasible and practical.

The efficiency evaluation of support vibration isolation with mechanic inertial motion converter for vibroactive process equipment

NASA Astrophysics Data System (ADS)

Buryan, Yu. A.; Babichev, D. O.; Silkov, M. V.; Shtripling, L. O.; Kalashnikov, B. A.

2017-08-01

This research refers to the problems of processing equipment protection from vibration influence. The theory issues of vibration isolation for vibroactive objects such as engines, pumps, compressors, fans, piping, etc. are considered. The design of the perspective air spring with the parallel mounted mechanical inertial motion converter is offered. The mathematical model of the suspension, allowing selecting options to reduce the factor of the force transmission to the base in a certain frequency range is obtained.

Random vibration (stress screening) of printed wiring assemblies

NASA Technical Reports Server (NTRS)

Bastien, Gilbert J.

1988-01-01

The results of a random vibration test screening (RVSS) study of the determination of the upper and lower vibration limits on printed wiring assemblies (PWA) are summarized. The study results are intended to serve as a guide for engineers and designers who make decisions on PWA features that need to withstand the stresses of dynamic testing and screening. The maximum allowable PWA deflection, G levels, and PSD levels are compared to the expected or actual levels to determine if deleterious effects will occur.

Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection.

PubMed

Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

2016-12-16

In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering.

Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection

PubMed Central

Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

2016-01-01

In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering. PMID:27999245

Study on Nonlinear Vibration Analysis of Gear System with Random Parameters

NASA Astrophysics Data System (ADS)

Tong, Cao; Liu, Xiaoyuan; Fan, Li

2018-03-01

In order to study the dynamic characteristics of gear nonlinear vibration system and the influence of random parameters, firstly, a nonlinear stochastic vibration analysis model of gear 3-DOF is established based on Newton’s Law. And the random response of gear vibration is simulated by stepwise integration method. Secondly, the influence of stochastic parameters such as meshing damping, tooth side gap and excitation frequency on the dynamic response of gear nonlinear system is analyzed by using the stability analysis method such as bifurcation diagram and Lyapunov exponent method. The analysis shows that the stochastic process can not be neglected, which can cause the random bifurcation and chaos of the system response. This study will provide important reference value for vibration engineering designers.

Noise and Vibration Risk Prevention Virtual Web for Ubiquitous Training

ERIC Educational Resources Information Center

Redel-Macías, María Dolores; Cubero-Atienza, Antonio J.; Martínez-Valle, José Miguel; Pedrós-Pérez, Gerardo; del Pilar Martínez-Jiménez, María

2015-01-01

This paper describes a new Web portal offering experimental labs for ubiquitous training of university engineering students in work-related risk prevention. The Web-accessible computer program simulates the noise and machine vibrations met in the work environment, in a series of virtual laboratories that mimic an actual laboratory and provide the…

Wakata uses Treadmill Vibration Isolation and Stabilization (TVIS)

NASA Image and Video Library

2009-03-22

ISS018-E-042662 (22 March 2009) --- Japan Aerospace Exploration Agency (JAXA) astronaut Koichi Wakata, Expedition 18 flight engineer, equipped with a bungee harness, exercises on the Treadmill Vibration Isolation System (TVIS) in the Zvezda Service Module of the International Space Station while Space Shuttle Discovery (STS-119) remains docked with the station.

An online condition monitoring system implemented an internet connectivity and FTP for low speed slew bearing

NASA Astrophysics Data System (ADS)

Caesarendra, W.; Kosasih, B.; Tjahjowidodo, T.; Ariyanto, M.; Daryl, LWQ; Pamungkas, D.

2018-04-01

Rapid and reliable information in slew bearing maintenance is not trivial issue. This paper presents the online monitoring system to assist maintenance engineer in order to monitor the bearing condition of low speed slew bearing in sheet metal company. The system is able to pass the vibration information from the place where the bearing and accelerometer sensors are attached to the data center; and from the data center it can be access by opening the online monitoring website from any place and by any person. The online monitoring system is built using some programming languages such as C language, MATLAB, PHP, HTML and CSS. Generally, the flow process is start with the automatic vibration data acquisition; then features are calculated from the acquired vibration data. These features are then sent to the data center; and form the data center, the vibration features can be seen through the online monitoring website. This online monitoring system has been successfully applied in School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong.

Actively controlled vibration welding system and method

DOEpatents

Cai, Wayne W.; Kang, Bongsu; Tan, Chin-An

2013-04-02

A vibration welding system includes a controller, welding horn, an active material element, and anvil assembly. The assembly may include an anvil body connected to a back plate and support member. The element, e.g., a piezoelectric stack or shape memory alloy, is positioned with respect to the assembly. The horn vibrates in a desirable first direction to form a weld on a work piece. The element controls any vibrations in a second direction by applying calibrated response to the anvil body in the second direction. A method for controlling undesirable vibrations in the system includes positioning the element with respect to the anvil assembly, connecting the anvil body to the support member through the back plate, vibrating the horn in a desirable first direction, and transmitting an input signal to the element to control vibration in an undesirable second direction.

Seminar on Understanding Digital Control and Analysis in Vibration Test Systems

NASA Technical Reports Server (NTRS)

1975-01-01

The advantages of the digital methods over the analog vibration methods are demonstrated. The following topics are covered: (1) methods of computer-controlled random vibration and reverberation acoustic testing, (2) methods of computer-controlled sinewave vibration testing, and (3) methods of computer-controlled shock testing. General algorithms are described in the form of block diagrams and flow diagrams.

Self Diagnostic Accelerometer Ground Testing on a C-17 Aircraft Engine

NASA Technical Reports Server (NTRS)

Tokars, Roger P.; Lekki, John D.

2013-01-01

The self diagnostic accelerometer (SDA) developed by the NASA Glenn Research Center was tested for the first time in an aircraft engine environment as part of the Vehicle Integrated Propulsion Research (VIPR) program. The VIPR program includes testing multiple critical flight sensor technologies. One such sensor, the accelerometer, measures vibrations to detect faults in the engine. In order to rely upon the accelerometer, the health of the accelerometer must be ensured. Sensor system malfunction is a significant contributor to propulsion in flight shutdowns (IFSD) which can lead to aircraft accidents when the issue is compounded with an inappropriate crew response. The development of the SDA is important for both reducing the IFSD rate, and hence reducing the rate at which this component failure type can put an aircraft in jeopardy, and also as a critical enabling technology for future automated malfunction diagnostic systems. The SDA is a sensor system designed to actively determine the accelerometer structural health and attachment condition, in addition to making vibration measurements. The SDA uses a signal conditioning unit that sends an electrical chirp to the accelerometer and recognizes changes in the response due to changes in the accelerometer health and attachment condition. In an effort toward demonstrating the SDAs flight worthiness and robustness, multiple SDAs were mounted and tested on a C-17 aircraft engine. The engine test conditions varied from engine off, to idle, to maximum power. The two SDA attachment conditions used were fully tight and loose. The newly developed SDA health algorithm described herein uses cross correlation pattern recognition to discriminate a healthy from a faulty SDA. The VIPR test results demonstrate for the first time the robustness of the SDA in an engine environment characterized by high vibration levels.

Self diagnostic accelerometer ground testing on a C-17 aircraft engine

NASA Astrophysics Data System (ADS)

Tokars, Roger P.; Lekki, John D.

The self diagnostic accelerometer (SDA) developed by the NASA Glenn Research Center was tested for the first time in an aircraft engine environment as part of the Vehicle Integrated Propulsion Research (VIPR) program. The VIPR program includes testing multiple critical flight sensor technologies. One such sensor, the accelerometer, measures vibrations to detect faults in the engine. In order to rely upon the accelerometer, the health of the accelerometer must be ensured. Sensor system malfunction is a significant contributor to propulsion in flight shutdowns (IFSD) which can lead to aircraft accidents when the issue is compounded with an inappropriate crew response. The development of the SDA is important for both reducing the IFSD rate, and hence reducing the rate at which this component failure type can put an aircraft in jeopardy, and also as a critical enabling technology for future automated malfunction diagnostic systems. The SDA is a sensor system designed to actively determine the accelerometer structural health and attachment condition, in addition to making vibration measurements. The SDA uses a signal conditioning unit that sends an electrical chirp to the accelerometer and recognizes changes in the response due to changes in the accelerometer health and attachment condition. In an effort toward demonstrating the SDA's flight worthiness and robustness, multiple SDAs were mounted and tested on a C-17 aircraft engine. The engine test conditions varied from engine off, to idle, to maximum power. The two SDA attachment conditions used were fully tight and loose. The newly developed SDA health algorithm described herein uses cross correlation pattern recognition to discriminate a healthy from a faulty SDA. The VIPR test results demonstrate for the first time the robustness of the SDA in an engine environment characterized by high vibration levels.

Experimental Studies on Dynamic Vibration Absorber using Shape Memory Alloy (NiTi) Springs

NASA Astrophysics Data System (ADS)

Kumar, V. Raj; Kumar, M. B. Bharathi Raj; Kumar, M. Senthil

2011-10-01

Shape memory alloy (SMA) springs have been used as actuators in many applications although their use in the vibration control area is very recent. Since shape memory alloys differ from conventional alloy materials in many ways, the traditional design approach for springs is not completely suitable for designing SMA springs. Some vibration control concepts utilizing unique characteristics of SMA's will be presented in this paper. A dynamic vibration absorber (DVA) using shape memory alloy (SMA) actuator is developed for attenuation of vibration in a cantilever beam. The design procedure of the DVA is presented. The system consists of a cantilever beam which is considered to generate the real-time vibration using shaker. A SMA spring is used with a mass attached to its end. The stiffness of the SMA spring is dynamically varied in such a way to attenuate the vibration. Both simulation and experimentation are carried out using PID controller. The experiments were carried out by interfacing the experimental setup with a computer using LabVIEW software, Data acquisition and control are implemented using a PCI data acquisition card. Standard PID controllers have been used to control the vibration of the beam. Experimental results are used to demonstrate the effectiveness of the controllers designed and the usefulness of the proposed test platform by exciting the structure at resonance. In experimental setup, an accelerometer is used to measure the vibration which is fed to computer and correspondingly the SMA spring is actuated to change its stiffness to control the vibration. The results obtained illustrate that the developed DVA using SMA actuator is very effective in reducing structural response and have great potential to be an active vibration control medium.

Experimental Studies on Dynamic Vibration Absorber using Shape Memory Alloy (NiTi) Springs

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

Kumar, V. Raj; Kumar, M. B. Bharathi Raj; Kumar, M. Senthil

2011-10-20

Shape memory alloy (SMA) springs have been used as actuators in many applications although their use in the vibration control area is very recent. Since shape memory alloys differ from conventional alloy materials in many ways, the traditional design approach for springs is not completely suitable for designing SMA springs. Some vibration control concepts utilizing unique characteristics of SMA's will be presented in this paper.A dynamic vibration absorber (DVA) using shape memory alloy (SMA) actuator is developed for attenuation of vibration in a cantilever beam. The design procedure of the DVA is presented. The system consists of a cantilever beammore » which is considered to generate the real-time vibration using shaker. A SMA spring is used with a mass attached to its end. The stiffness of the SMA spring is dynamically varied in such a way to attenuate the vibration. Both simulation and experimentation are carried out using PID controller. The experiments were carried out by interfacing the experimental setup with a computer using LabVIEW software, Data acquisition and control are implemented using a PCI data acquisition card. Standard PID controllers have been used to control the vibration of the beam. Experimental results are used to demonstrate the effectiveness of the controllers designed and the usefulness of the proposed test platform by exciting the structure at resonance. In experimental setup, an accelerometer is used to measure the vibration which is fed to computer and correspondingly the SMA spring is actuated to change its stiffness to control the vibration. The results obtained illustrate that the developed DVA using SMA actuator is very effective in reducing structural response and have great potential to be an active vibration control medium.« less

Analytical design and evaluation of an active control system for helicopter vibration reduction and gust response alleviation

NASA Technical Reports Server (NTRS)

Taylor, R. B.; Zwicke, P. E.; Gold, P.; Miao, W.

1980-01-01

An analytical study was conducted to define the basic configuration of an active control system for helicopter vibration and gust response alleviation. The study culminated in a control system design which has two separate systems: narrow band loop for vibration reduction and wider band loop for gust response alleviation. The narrow band vibration loop utilizes the standard swashplate control configuration to input controller for the vibration loop is based on adaptive optimal control theory and is designed to adapt to any flight condition including maneuvers and transients. The prime characteristics of the vibration control system is its real time capability. The gust alleviation control system studied consists of optimal sampled data feedback gains together with an optimal one-step-ahead prediction. The prediction permits the estimation of the gust disturbance which can then be used to minimize the gust effects on the helicopter.

Farfield Ion Current Density Measurements before and after the NASA HiVHAc EDU2 Vibration Test

NASA Technical Reports Server (NTRS)

Huang, Wensheng; Kamhawi, Hani; Shastry, Rohit

2012-01-01

There is an increasing need to characterize the plasma plume of the NASA HiVHAc thruster in order to better understand the plasma physics and to obtain data for spacecraft interaction studies. To address this need, the HiVHAc research team is in the process of developing a number of plume diagnostic systems. This paper presents the initial results of the farfield current density probe diagnostic system. Farfield current density measurements were carried out before and after a vibration test of the HiVHAc engineering development unit 2 that simulate typical launch conditions. The main purposes of the current density measurements were to evaluate the thruster plume divergence and to investigate any changes in the plasma plume that may occur as a result of the vibration test. Radial sweeps, as opposed to the traditional polar sweeps, were performed during these tests. The charged-weighted divergence angles were found to vary from 16 to 28 degrees. Charge density profiles measured pre- and post-vibration-test were found to be in excellent agreement. This result, alongside thrust measurements reported in a companion paper, confirm that the operation of the HiVHAc engineering development unit 2 were not altered by full-level/random vibration testing.

Physics and Process Modeling (PPM) and Other Propulsion R and T. Volume 1; Materials Processing, Characterization, and Modeling; Lifting Models

NASA Technical Reports Server (NTRS)

1997-01-01

This CP contains the extended abstracts and presentation figures of 36 papers presented at the PPM and Other Propulsion R&T Conference. The focus of the research described in these presentations is on materials and structures technologies that are parts of the various projects within the NASA Aeronautics Propulsion Systems Research and Technology Base Program. These projects include Physics and Process Modeling; Smart, Green Engine; Fast, Quiet Engine; High Temperature Engine Materials Program; and Hybrid Hyperspeed Propulsion. Also presented were research results from the Rotorcraft Systems Program and work supported by the NASA Lewis Director's Discretionary Fund. Authors from NASA Lewis Research Center, industry, and universities conducted research in the following areas: material processing, material characterization, modeling, life, applied life models, design techniques, vibration control, mechanical components, and tribology. Key issues, research accomplishments, and future directions are summarized in this publication.

Effects of whole body vibration training on postural control in older individuals: a 1 year randomized controlled trial.

PubMed

Bogaerts, An; Verschueren, Sabine; Delecluse, Christophe; Claessens, Albrecht L; Boonen, Steven

2007-07-01

This randomized controlled trial investigated the effects of a 12 month whole body vibration training program on postural control in healthy older adults. Two hundred and twenty people were randomly assigned to a whole body vibration group (n=94), a fitness group (n=60) or a control group (n=66). The whole body vibration and fitness groups trained three times a week for 1 year. The vibration group performed exercises on a vibration platform and the fitness group performed cardiovascular, strength, balance and stretching exercises. Balance was measured using dynamic computerized posturography at baseline and after 6 and 12 months. Whole body vibration training was associated with reduced falls frequency on a moving platform when vision was disturbed and improvements in the response to toes down rotations at the ankle induced by the moving platform. The fitness group showed reduced falls frequency on the moving surface when vision was disturbed. Thus, whole body vibration training may improve some aspects of postural control in community dwelling older individuals.

Modulating the Behaviors of Mesenchymal Stem Cells Via the Combination of High-Frequency Vibratory Stimulations and Fibrous Scaffolds

PubMed Central

Tong, Zhixiang; Duncan, Randall L.

2013-01-01

We are interested in the in vitro engineering of artificial vocal fold tissues via the strategic combination of multipotent mesenchymal stem cells (MSCs), physiologically relevant mechanical stimulations, and biomimetic artificial matrices. We have constructed a vocal fold bioreactor that is capable of imposing vibratory stimulations on the cultured cells at human phonation frequencies. Separately, fibrous poly (ɛ-caprolactone) (PCL) scaffolds emulating the ligamentous structure of the vocal fold were prepared by electrospinning, were incorporated in the vocal fold bioreactor, and were driven into a wave-like motion in an axisymmetrical fashion by the oscillating air. MSC-laden PCL scaffolds were subjected to vibrations at 200 Hz with a normal center displacement of ∼40 μm for a total of 7 days. A continuous (CT) or a 1 h-on-1 h-off (OF) regime with a total dynamic culture time of 12 h per day was applied. The dynamic loading did not cause any physiological trauma to the cells. Immunohistotochemical staining revealed the reinforcement of the actin filament and the enhancement of α5β1 integrin expression under selected dynamic culture conditions. Cellular expression of essential vocal fold extracellular matrix components, such as elastin, hyaluronic acid, and matrix metalloproteinase-1, was significantly elevated as compared with the static controls, and the OF regime is more conducive to matrix production than the CT vibration mode. Analyses of genes of typical fibroblast hallmarks (tenascin-C, collagen III, and procollagen I) as well as markers for MSC differentiation into nonfibroblastic lineages confirmed MSCs' adaptation of fibroblastic behaviors. Overall, the high-frequency vibratory stimulation, when combined with a synthetic fibrous scaffold, serves as a potent modulator of MSC functions. The novel bioreactor system presented here, as a versatile, yet well-controlled model, offers an in vitro platform for understanding vibration-induced mechanotransduction and for engineering of functional vocal fold tissues. PMID:23516973

Vibration effects of the space shuttle main engine high pressure oxidizer turbopump bellows

NASA Technical Reports Server (NTRS)

Harp, J. A.

1978-01-01

A welded metal bellows was subjected to a series of vibration tests in a 400 psi oxygen environment to evaluate the effects of the bellows convolutes rubbing on the damper ring in the high pressure oxidizer turbopump of the space shuttle main engine. The bellows was subjected to approximately 2 million cycles at 0.007 in. double amplitude displacement during this series of tests, at a frequency of 400 Hz. Intrumentation of the test specimen revealed no significant heat buildup caused by the rubbing of the bellows convolutes on the damper ring. A final destruct test was made to determine if a fire would result if the bellows ruptured in the 400 psi oxygen environment, thus exposing a fresh metal surface. The vibration input was changed to 0.8 in. double amplitude displacement at 20 Hz to intentionally rupture the bellows. Failure occurred after 2.5 sec; no fire or heat buildup was encountered.

Feedback on the Surveillance 8 challenge: Vibration-based diagnosis of a Safran aircraft engine

NASA Astrophysics Data System (ADS)

Antoni, Jérôme; Griffaton, Julien; André, Hugo; Avendaño-Valencia, Luis David; Bonnardot, Frédéric; Cardona-Morales, Oscar; Castellanos-Dominguez, German; Daga, Alessandro Paolo; Leclère, Quentin; Vicuña, Cristián Molina; Acuña, David Quezada; Ompusunggu, Agusmian Partogi; Sierra-Alonso, Edgar F.

2017-12-01

This paper presents the content and outcomes of the Safran contest organized during the International Conference Surveillance 8, October 20-21, 2015, at the Roanne Institute of Technology, France. The contest dealt with the diagnosis of a civil aircraft engine based on vibration data measured in a transient operating mode and provided by Safran. Based on two independent exercises, the contest offered the possibility to benchmark current diagnostic methods on real data supplemented with several challenges. Outcomes of seven competing teams are reported and discussed. The object of the paper is twofold. It first aims at giving a picture of the current state-of-the-art in vibration-based diagnosis of rolling-element bearings in nonstationary operating conditions. Second, it aims at providing the scientific community with a benchmark and some baseline solutions. In this respect, the data used in the contest are made available as supplementary material.

Noise control using a plate radiator and an acoustic resonator

NASA Technical Reports Server (NTRS)

Pla, Frederic G. (Inventor)

1996-01-01

An active noise control subassembly for reducing noise caused by a source (such as an aircraft engine) independent of the subassembly. A noise radiating panel is bendably vibratable to generate a panel noise canceling at least a portion of the source noise. A piezoceramic actuator plate is connected to the panel. A front plate is spaced apart from the panel and the first plate, is positioned generally between the source noise and the panel, and has a sound exit port. A first pair of spaced-apart side walls each generally abut the panel and the front plate so as to generally enclose a front cavity to define a resonator.

Natural convection in low-g environments

NASA Technical Reports Server (NTRS)

Grodzka, P. G.; Bannister, T. C.

1974-01-01

The present state of knowledge in the area of low-g natural convection is reviewed, taking into account a number of experiments conducted during the Apollo 14, 16, and 17 space flights. Convections due to steady low-g accelerations are considered. Steady g-levels result from spacecraft rotation, gravity gradients, solar wind, and solar pressure. Varying g-levels are produced by engine burns, attitude control maneuvers, and onboard vibrations from machinery or astronaut movement. Thermoacoustic convection in a low-g environment is discussed together with g-jitter convection, surface tension-driven convection, electrohydrodynamics under low-g conditions, phase change convection, and approaches for the control and the utilization of convection in space.

Effect of Blast-Induced Vibration from New Railway Tunnel on Existing Adjacent Railway Tunnel in Xinjiang, China

NASA Astrophysics Data System (ADS)

Liang, Qingguo; Li, Jie; Li, Dewu; Ou, Erfeng

2013-01-01

The vibrations of existing service tunnels induced by blast-excavation of adjacent tunnels have attracted much attention from both academics and engineers during recent decades in China. The blasting vibration velocity (BVV) is the most widely used controlling index for in situ monitoring and safety assessment of existing lining structures. Although numerous in situ tests and simulations had been carried out to investigate blast-induced vibrations of existing tunnels due to excavation of new tunnels (mostly by bench excavation method), research on the overall dynamical response of existing service tunnels in terms of not only BVV but also stress/strain seemed limited for new tunnels excavated by the full-section blasting method. In this paper, the impacts of blast-induced vibrations from a new tunnel on an existing railway tunnel in Xinjiang, China were comprehensively investigated by using laboratory tests, in situ monitoring and numerical simulations. The measured data from laboratory tests and in situ monitoring were used to determine the parameters needed for numerical simulations, and were compared with the calculated results. Based on the results from in situ monitoring and numerical simulations, which were consistent with each other, the original blasting design and corresponding parameters were adjusted to reduce the maximum BVV, which proved to be effective and safe. The effect of both the static stress before blasting vibrations and the dynamic stress induced by blasting on the total stresses in the existing tunnel lining is also discussed. The methods and related results presented could be applied in projects with similar ground and distance between old and new tunnels if the new tunnel is to be excavated by the full-section blasting method.

Active vibration control of thin-plate structures with partial SCLD treatment

NASA Astrophysics Data System (ADS)

Lu, Jun; Wang, Pan; Zhan, Zhenfei

2017-02-01

To effectively suppress the low-frequency vibration of a thin-plate, the strategy adopted is to develop a model-based approach to the investigation on the active vibration control of a clamped-clamped plate with partial SCLD treatment. Firstly, a finite element model is developed based on the constitutive equations of elastic, piezoelectric and viscoelastic materials. The characteristics of viscoelastic materials varying with temperature and frequency are described by GHM damping model. A low-dimensional real modal control model which can be used as the basis for active vibration control is then obtained from the combined reduction. The emphasis is placed on the feedback control system to attenuate the vibration of plates with SCLD treatments. A modal controller in conjunction with modal state estimator is designed to solve the problem of full state feedback, making it much more feasible to real-time control. Finally, the theoretical model is verified by modal test, and an active vibration control is validated by hardware-in-the-loop experiment under different external excitations. The numerical and experimental study demonstrate how the piezoelectric actuators actively control the lower modes (first bending and torsional modes) using modal controller, while the higher frequency vibration attenuated by viscoelastic passive damping layer.

An application of holographic interferometry for dynamic vibration analysis of a jet engine turbine compressor rotor

NASA Astrophysics Data System (ADS)

Fein, Howard

2003-09-01

Holographic Interferometry has been successfully employed to characterize the materials and behavior of diverse types of structures under dynamic stress. Specialized variations of this technology have also been applied to define dynamic and vibration related structural behavior. Such applications of holographic technique offer some of the most effective methods of modal and dynamic analysis available. Real-time dynamic testing of the modal and mechanical behavior of jet engine turbine, rotor, vane, and compressor structures has always required advanced instrumentation for data collection in either simulated flight operation test or computer-based modeling and simulations. Advanced optical holography techniques are alternate methods which result in actual full-field behavioral data in a noninvasive, noncontact environment. These methods offer significant insight in both the development and subsequent operational test and modeling of advanced jet engine turbine and compressor rotor structures and their integration with total vehicle system dynamics. Structures and materials can be analyzed with very low amplitude excitation and the resultant data can be used to adjust the accuracy of mathematically derived structural and behavioral models. Holographic Interferometry offers a powerful tool to aid in the developmental engineering of turbine rotor and compressor structures for high stress applications. Aircraft engine applications in particular most consider operational environments where extremes in vibration and impulsive as well as continuous mechanical stress can affect both operation and structural stability. These considerations present ideal requisites for analysis using advanced holographic methods in the initial design and test of turbine rotor components. Holographic techniques are nondestructive, real-time, and definitive in allowing the identification of vibrational modes, displacements, and motion geometries. Such information can be crucial to the determination of mechanical configurations and designs as well as critical operational parameters of turbine structural components or unit turbine components fabricated from advanced and exotic new materials or using new fabrication methods. Anomalous behavioral characteristics can be directly related to hidden structural or mounting anomalies and defects.

Use of nanoscale mechanical stimulation for control and manipulation of cell behaviour.

PubMed

Childs, Peter G; Boyle, Christina A; Pemberton, Gabriel D; Nikukar, Habib; Curtis, Adam S G; Henriquez, Fiona L; Dalby, Matthew J; Reid, Stuart

2016-04-01

The ability to control cell behaviour, cell fate and simulate reliable tissue models in vitro remains a significant challenge yet is crucial for various applications of high throughput screening e.g. drug discovery. Mechanotransduction (the ability of cells to convert mechanical forces in their environment to biochemical signalling) represents an alternative mechanism to attain this control with such studies developing techniques to reproducibly control the mechanical environment in techniques which have potential to be scaled. In this review, the use of techniques such as finite element modelling and precision interferometric measurement are examined to provide context for a novel technique based on nanoscale vibration, also known as "nanokicking". Studies have shown this stimulus to alter cellular responses in both endothelial and mesenchymal stem cells (MSCs), particularly in increased proliferation rate and induced osteogenesis respectively. Endothelial cell lines were exposed to nanoscale vibration amplitudes across a frequency range of 1-100 Hz, and MSCs primarily at 1 kHz. This technique provides significant potential benefits over existing technologies, as cellular responses can be initiated without the use of expensive engineering techniques and/or chemical induction factors. Due to the reproducible and scalable nature of the apparatus it is conceivable that nanokicking could be used for controlling cell behaviour within a wide array of high throughput procedures in the research environment, within drug discovery, and for clinical/therapeutic applications. The results discussed within this article summarise the potential benefits of using nanoscale vibration protocols for controlling cell behaviour. There is a significant need for reliable tissue models within the clinical and pharma industries, and the control of cell behaviour and stem cell differentiation would be highly beneficial. The full potential of this method of controlling cell behaviour has not yet been realised. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Low back cutaneous vibration and its effect on trunk postural control.

PubMed

Cornwall, Adam R; Gregory, Diane E

2017-08-01

The current study investigated the effects of a low back pain (LBP) vibration modality on trunk motor control. Trunk repositioning error and responses to a sudden loading trunk perturbation were evaluated pre- and post-vibration (15min vibration exposure while sitting on a standard chair) as well as when concurrent cutaneous low back vibration was applied. Only minor effects were observed post-vibration when compared to pre-vibration. However, when vibration was applied at the same time as the sudden trunk perturbations, lumbar erector spinae and external oblique muscles were significantly more delayed in activating following the perturbation. In addition, the resting muscle activation prior to the trunk perturbation was higher in both the back extensor and abdominal muscles when concurrent vibration was applied. These findings suggest that cutaneous low back vibration significantly alters motor control responses and this should be considered before implementing cutaneous vibration as a low back pain management strategy. Copyright © 2017. Published by Elsevier B.V.

Simultaneous Measurement of Multiple Mechanical Properties of Single Cells Using AFM by Indentation and Vibration.

PubMed

Zhang, Chuang; Shi, Jialin; Wang, Wenxue; Xi, Ning; Wang, Yuechao; Liu, Lianqing

2017-12-01

The mechanical properties of cells, which are the main characteristics determining their physical performance and physiological functions, have been actively studied in the fields of cytobiology and biomedical engineering and for the development of medicines. In this study, an indentation-vibration-based method is proposed to simultaneously measure the mechanical properties of cells in situ, including cellular mass (m), elasticity (k), and viscosity (c). The proposed measurement method is implemented based on the principle of forced vibration stimulated by simple harmonic force using an atomic force microscope (AFM) system integrated with a piezoelectric transducer as the substrate vibrator. The corresponding theoretical model containing the three mechanical properties is derived and used to perform simulations and calculations. Living and fixed human embryonic kidney 293 (HEK 293) cells were subjected to indentation and vibration to measure and compare their mechanical parameters and verify the proposed approach. The results that the fixed sample cells are more viscous and elastic than the living sample cells and the measured mechanical properties of cell are consistent within, but not outside of the central region of the cell, are in accordance with the previous studies. This work provides an approach to simultaneous measurement of the multiple mechanical properties of single cells using an integrated AFM system based on the principle force vibration and thickness-corrected Hertz model. This study should contribute to progress in biomedical engineering, cytobiology, medicine, early diagnosis, specific therapy and cell-powered robots.

KENNEDY SPACE CENTER, FLA. - Mobile Launcher Platform (MLP) number 3 and a set of twin solid rocket boosters, atop the crawler-transporter, inch along the crawlerway in support of the second engineering analysis vibration test on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A (on the horizon) and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-21

KENNEDY SPACE CENTER, FLA. - Mobile Launcher Platform (MLP) number 3 and a set of twin solid rocket boosters, atop the crawler-transporter, inch along the crawlerway in support of the second engineering analysis vibration test on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A (on the horizon) and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - Mobile Launcher Platform (MLP) number 3 and a set of twin solid rocket boosters, atop the crawler-transporter, inch along the crawlerway in support of the second engineering analysis vibration test on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A (framed between the boosters), and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-21

KENNEDY SPACE CENTER, FLA. - Mobile Launcher Platform (MLP) number 3 and a set of twin solid rocket boosters, atop the crawler-transporter, inch along the crawlerway in support of the second engineering analysis vibration test on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A (framed between the boosters), and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - The crawler transporter slowly moves the Mobile Launcher Platform (MLP), carrying a set of twin solid rocket boosters, along the crawlerway in support of engineering analysis vibration tests on the crawler and MLP. In the distance, at left, is Launch Pad 39A. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-17

KENNEDY SPACE CENTER, FLA. - The crawler transporter slowly moves the Mobile Launcher Platform (MLP), carrying a set of twin solid rocket boosters, along the crawlerway in support of engineering analysis vibration tests on the crawler and MLP. In the distance, at left, is Launch Pad 39A. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - Mobile Launcher Platform (MLP) number 3 and a set of twin solid rocket boosters, atop the crawler-transporter, crawls away from the Vehicle Assembly Building in support of the second engineering analysis vibration test on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-21

KENNEDY SPACE CENTER, FLA. - Mobile Launcher Platform (MLP) number 3 and a set of twin solid rocket boosters, atop the crawler-transporter, crawls away from the Vehicle Assembly Building in support of the second engineering analysis vibration test on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - Mobile Launcher Platform (MLP) number 3 and a set of twin solid rocket boosters, atop the crawler-transporter, inch away from the Vehicle Assembly Building (VAB) in support of the second engineering analysis vibration test on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-21

KENNEDY SPACE CENTER, FLA. - Mobile Launcher Platform (MLP) number 3 and a set of twin solid rocket boosters, atop the crawler-transporter, inch away from the Vehicle Assembly Building (VAB) in support of the second engineering analysis vibration test on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - Carrying a set of twin solid rocket boosters, the crawler transporter slowly moves the Mobile Launcher Platform (MLP) past the NASA-KSC News Center where the U.S. flag flies daily. The journey is in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-17

KENNEDY SPACE CENTER, FLA. - Carrying a set of twin solid rocket boosters, the crawler transporter slowly moves the Mobile Launcher Platform (MLP) past the NASA-KSC News Center where the U.S. flag flies daily. The journey is in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - As the crawler transporter slowly moves the Mobile Launcher Platform (MLP) out of the Vehicle Assembly Building, the two solid rocket boosters on top are framed in the doorway. The move is in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-17

KENNEDY SPACE CENTER, FLA. - As the crawler transporter slowly moves the Mobile Launcher Platform (MLP) out of the Vehicle Assembly Building, the two solid rocket boosters on top are framed in the doorway. The move is in support of engineering analysis vibration tests on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

Low voltage 30-cm ion thruster development. [including performance and structural integrity (vibration) tests

NASA Technical Reports Server (NTRS)

King, H. J.

1974-01-01

The basic goal was to advance the development status of the 30-cm electron bombardment ion thruster from a laboratory model to a flight-type engineering model (EM) thruster. This advancement included the more conventional aspects of mechanical design and testing for launch loads, weight reduction, fabrication process development, reliability and quality assurance, and interface definition, as well as a relatively significant improvement in thruster total efficiency. The achievement of this goal was demonstrated by the successful completion of a series of performance and structural integrity (vibration) tests. In the course of the program, essentially every part and feature of the original 30-cm Thruster was critically evaluated. These evaluations, led to new or improved designs for the ion optical system, discharge chamber, cathode isolator vaporizer assembly, main isolator vaporizer assembly, neutralizer assembly, packaging for thermal control, electrical terminations and structure.

Space power demonstrator engine, phase 1

NASA Technical Reports Server (NTRS)

1987-01-01

The design, analysis, and preliminary test results for a 25 kWe Free-Piston Stirling engine with integral linear alternators are described. The project is conducted by Mechanical Technology under the direction of LeRC as part of the SP-100 Nuclear Space Power Systems Program. The engine/alternator system is designed to demonstrate the following performance: (1) 25 kWe output at a specific weight less than 8 kg/kW; (2) 25 percent efficiency at a temperature ratio of 2.0; (3) low vibration (amplitude less than .003 in); (4) internal gas bearings (no wear, no external pump); and (5) heater temperature/cooler temperature from 630 to 315 K. The design approach to minimize vibration is a two-module engine (12.5 kWe per module) in a linearly-opposed configuration with a common expansion space. The low specific weight is obtained at high helium pressure (150 bar) and high frequency (105 Hz) and by using high magnetic strength (samarium cobalt) alternator magnets. Engine tests began in June 1985; 16 months following initiation of engine and test cell design. Hydrotest and consequent engine testing to date has been intentionally limited to half pressure, and electrical power output is within 15 to 20 percent of design predictions.

Fault Diagnosis of Demountable Disk-Drum Aero-Engine Rotor Using Customized Multiwavelet Method

PubMed Central

Chen, Jinglong; Wang, Yu; He, Zhengjia; Wang, Xiaodong

2015-01-01

The demountable disk-drum aero-engine rotor is an important piece of equipment that greatly impacts the safe operation of aircraft. However, assembly looseness or crack fault has led to several unscheduled breakdowns and serious accidents. Thus, condition monitoring and fault diagnosis technique are required for identifying abnormal conditions. Customized ensemble multiwavelet method for aero-engine rotor condition identification, using measured vibration data, is developed in this paper. First, customized multiwavelet basis function with strong adaptivity is constructed via symmetric multiwavelet lifting scheme. Then vibration signal is processed by customized ensemble multiwavelet transform. Next, normalized information entropy of multiwavelet decomposition coefficients is computed to directly reflect and evaluate the condition. The proposed approach is first applied to fault detection of an experimental aero-engine rotor. Finally, the proposed approach is used in an engineering application, where it successfully identified the crack fault of a demountable disk-drum aero-engine rotor. The results show that the proposed method possesses excellent performance in fault detection of aero-engine rotor. Moreover, the robustness of the multiwavelet method against noise is also tested and verified by simulation and field experiments. PMID:26512668

ER fluid applications to vibration control devices and an adaptive neural-net controller

NASA Astrophysics Data System (ADS)

Morishita, Shin; Ura, Tamaki

1993-07-01

Four applications of electrorheological (ER) fluid to vibration control actuators and an adaptive neural-net control system suitable for the controller of ER actuators are described: a shock absorber system for automobiles, a squeeze film damper bearing for rotational machines, a dynamic damper for multidegree-of-freedom structures, and a vibration isolator. An adaptive neural-net control system composed of a forward model network for structural identification and a controller network is introduced for the control system of these ER actuators. As an example study of intelligent vibration control systems, an experiment was performed in which the ER dynamic damper was attached to a beam structure and controlled by the present neural-net controller so that the vibration in several modes of the beam was reduced with a single dynamic damper.

Mechanical Response of Elastomers to Magnetic Fields

NASA Technical Reports Server (NTRS)

Munoz, B. C.; Jolly, M. R.

1996-01-01

Elastomeric materials represent an important class of engineering materials, which are widely used to make components of structures, machinery, and devices for vibration and noise control. Elastomeric material possessing conductive or magnetic properties have been widely used in applications such as conductive and magnetic tapes, sensors, flexible permanent magnets, etc. Our interest in these materials has focussed on understanding and controlling the magnitude and directionality of their response to applied magnetic fields. The effect of magnetic fields on the mechanical properties of these materials has not been the subject of many published studies. Our interest and expertise in controllable fluids have given us the foundation to make a transition to controllable elastomers. Controllable elastomers are materials that exhibit a change in mechanical properties upon application of an external stimuli, in this case a magnetic field. Controllable elastomers promise to have more functionality than conventional elastomers and therefore could share the broad industrial application base with conventional elastomers. As such, these materials represent an attractive class of smart materials, and may well be a link that brings the applications of modern control technologies, intelligent structures and smart materials to a very broad industrial area. This presentation will cover our research work in the area of controllable elastomers at the Thomas Lord Research Center. More specifically, the presentation will discuss the control of mechanical properties and mathematical modeling of the new materials prepared in our laboratories along with experiments to achieve adaptive vibration control using the new materials.

Vibration Control via Stiffness Switching of Magnetostrictive Transducers

NASA Technical Reports Server (NTRS)

Scheidler, Justin J.; Asnani, Vivake M.; Dapino, Marcelo J.

2016-01-01

This paper presents a computational study of structural vibration control that is realized by switching a magnetostrictive transducer between high and low stiffness states. Switching is accomplished by either changing the applied magnetic field with a voltage excitation or changing the shunt impedance on the transducer's coil (i.e., the magnetostrictive material's magnetic boundary condition). Switched-stiffness vibration control is simulated using a lumped mass supported by a damper and the magnetostrictive transducer (mount), which is represented by a nonlinear, electromechanical model. Free vibration of the mass is calculated while varying the mount's stiffness according to a reference switched-stiffness vibration control law. The results reveal that switching the magnetic field produces the desired change in stiffness, but also an undesired actuation force that can significantly degrade the vibration control. Hence, a modified switched-stiffness control law that accounts for the actuation force is proposed and implemented for voltage-controlled stiffness switching. The influence of the magnetomechanical bias condition is also discussed. Voltage-controlled stiffness switching is found to introduce damping equivalent to a viscous damping factor up to about 0.25; this is shown to primarily result from active vibration reduction caused by the actuation force. The merit of magnetostrictive switched-stiffness vibration control is then quantified by comparing the results of voltage- and shunt-controlled stiffness switching to the performance of optimal magnetostrictive shunt damping.

Actively Controlled Magnetic Vibration-Isolation System

NASA Technical Reports Server (NTRS)

Grodsinky, Carlos M.; Logsdon, Kirk A.; Wbomski, Joseph F.; Brown, Gerald V.

1993-01-01

Prototype magnetic suspension system with active control isolates object from vibrations in all six degrees of freedom at frequencies as low as 0.01 Hz. Designed specifically to protect instruments aboard spacecraft by suppressing vibrations to microgravity levels; basic control approach used for such terrestrial uses as suppression of shocks and other vibrations in trucks and railroad cars.

Power efficient control algorithm of electromechanical unbalance vibration exciter with induction motor

NASA Astrophysics Data System (ADS)

Topovskiy, V. V.; Simakov, G. M.

2017-10-01

A control algorithm of an electromechanical unbalance vibration exciter that provides a free rotational movement is offered in the paper. The unbalance vibration exciter control system realizing a free rotational movement has been synthesized. The structured modeling of the synthesized system has been carried out and its transients are presented. The advantages and disadvantages of the proposed control algorithm applied to the unbalance vibration exciter are shown.

Experimental validation of structural optimization methods

NASA Technical Reports Server (NTRS)

Adelman, Howard M.

1992-01-01

The topic of validating structural optimization methods by use of experimental results is addressed. The need for validating the methods as a way of effecting a greater and an accelerated acceptance of formal optimization methods by practicing engineering designers is described. The range of validation strategies is defined which includes comparison of optimization results with more traditional design approaches, establishing the accuracy of analyses used, and finally experimental validation of the optimization results. Examples of the use of experimental results to validate optimization techniques are described. The examples include experimental validation of the following: optimum design of a trussed beam; combined control-structure design of a cable-supported beam simulating an actively controlled space structure; minimum weight design of a beam with frequency constraints; minimization of the vibration response of helicopter rotor blade; minimum weight design of a turbine blade disk; aeroelastic optimization of an aircraft vertical fin; airfoil shape optimization for drag minimization; optimization of the shape of a hole in a plate for stress minimization; optimization to minimize beam dynamic response; and structural optimization of a low vibration helicopter rotor.

Three-dimensional manipulation of single cells using surface acoustic waves

PubMed Central

Guo, Feng; Mao, Zhangming; Chen, Yuchao; Xie, Zhiwei; Lata, James P.; Li, Peng; Ren, Liqiang; Liu, Jiayang; Yang, Jian; Dao, Ming; Suresh, Subra; Huang, Tony Jun

2016-01-01

The ability of surface acoustic waves to trap and manipulate micrometer-scale particles and biological cells has led to many applications involving “acoustic tweezers” in biology, chemistry, engineering, and medicine. Here, we present 3D acoustic tweezers, which use surface acoustic waves to create 3D trapping nodes for the capture and manipulation of microparticles and cells along three mutually orthogonal axes. In this method, we use standing-wave phase shifts to move particles or cells in-plane, whereas the amplitude of acoustic vibrations is used to control particle motion along an orthogonal plane. We demonstrate, through controlled experiments guided by simulations, how acoustic vibrations result in micromanipulations in a microfluidic chamber by invoking physical principles that underlie the formation and regulation of complex, volumetric trapping nodes of particles and biological cells. We further show how 3D acoustic tweezers can be used to pick up, translate, and print single cells and cell assemblies to create 2D and 3D structures in a precise, noninvasive, label-free, and contact-free manner. PMID:26811444

Advanced Health Management System for the Space Shuttle Main Engine

NASA Technical Reports Server (NTRS)

Davidson, Matt; Stephens, John

2004-01-01

Boeing-Canoga Park (BCP) and NASA-Marshall Space Flight Center (NASA-MSFC) are developing an Advanced Health Management System (AHMS) for use on the Space Shuttle Main Engine (SSME) that will improve Shuttle safety by reducing the probability of catastrophic engine failures during the powered ascent phase of a Shuttle mission. This is a phased approach that consists of an upgrade to the current Space Shuttle Main Engine Controller (SSMEC) to add turbomachinery synchronous vibration protection and addition of a separate Health Management Computer (HMC) that will utilize advanced algorithms to detect and mitigate predefined engine anomalies. The purpose of the Shuttle AHMS is twofold; one is to increase the probability of successfully placing the Orbiter into the intended orbit, and the other is to increase the probability of being able to safely execute an abort of a Space Transportation System (STS) launch. Both objectives are achieved by increasing the useful work envelope of a Space Shuttle Main Engine after it has developed anomalous performance during launch and the ascent phase of the mission. This increase in work envelope will be the result of two new anomaly mitigation options, in addition to existing engine shutdown, that were previously unavailable. The added anomaly mitigation options include engine throttle-down and performance correction (adjustment of engine oxidizer to fuel ratio), as well as enhanced sensor disqualification capability. The HMC is intended to provide the computing power necessary to diagnose selected anomalous engine behaviors and for making recommendations to the engine controller for anomaly mitigation. Independent auditors have assessed the reduction in Shuttle ascent risk to be on the order of 40% with the combined system and a three times improvement in mission success.

Vibration Control of Deployable Astromast Boom: Preliminary Experiments

NASA Technical Reports Server (NTRS)

Swaminadham, M.; Hamilton, David A.

1994-01-01

This paper deals with the dynamic characterization of a flexible aerospace solar boom. The modeling issues and sine dwell vibration testing to determine natural frequencies and mode shapes of a continuous-longer on deployable ASTROMAST lattice boom are discussed. The details of the proof-of-concept piezoelectric active vibration experiments on a simple cantilever beam to control its vibrations are presented. The control parameters like voltage to the controller crystal and its location are investigated, to determine the effectiveness of control element to suppress selected resonant vibrations of the test specimen. Details of this experiment and plans for its future adaptation to the prototype structure are also discussed.

Vibration testing of the JE-M-604-4-IUE rocket motor (Thiokol P/N E 28639-03)

NASA Technical Reports Server (NTRS)

Alt, R. E.; Tosh, J. T.

1976-01-01

The NASA International Ultraviolet Explorer (IUE) rocket motor (TE-M-604-4), a solid fuel, spherical rocket motor, was vibration tested in the Impact, Vibration, and Acceleration (IVA) Test Unit of the von Karman Gas Dynamics Facility (VKF). The objective of the test program was to subject the motor to qualification levels of sinusoidal and random vibration prior to the altitude firing of the motor in the Propulsion Development Test Cell (T-3), Engine Test Facility (ETF), AEDC. The vibration testing consisted of a low level sine survey from 5 to 2,000 Hz, followed by a qualification level sine sweep and qualification level random vibration. A second low level sine survey followed the qualification level testing. This sequence of testing was accomplished in each of three orthogonal axes. No motor problems were observed due to the imposition of these dynamic environments.

Force Limited Vibration Testing Monograph

NASA Technical Reports Server (NTRS)

Scharton, Terry D.

1997-01-01

The practice of limiting the shaker force in vibration tests was investigated at the NASA Jet Propulsion Laboratory (JPL) in 1990 after the mechanical failure of an aerospace component during a vibration test. Now force limiting is used in almost every major vibration test at JPL and in many vibration tests at NASA Goddard Space Flight Center (GSFC) and at many aerospace contractors. The basic ideas behind force limiting have been in the literature for several decades, but the piezo-electric force transducers necessary to conveniently implement force limiting have been available only in the last decade. In 1993, funding was obtained from the NASA headquarters Office of Chief Engineer to develop and document the technology needed to establish force limited vibration testing as a standard approach available to all NASA centers and aerospace contractors. This monograph is the final report on that effort and discusses the history, theory, and applications of the method in some detail.

Real-Time Performance of Mechatronic PZT Module Using Active Vibration Feedback Control.

PubMed

Aggogeri, Francesco; Borboni, Alberto; Merlo, Angelo; Pellegrini, Nicola; Ricatto, Raffaele

2016-09-25

This paper proposes an innovative mechatronic piezo-actuated module to control vibrations in modern machine tools. Vibrations represent one of the main issues that seriously compromise the quality of the workpiece. The active vibration control (AVC) device is composed of a host part integrated with sensors and actuators synchronized by a regulator; it is able to make a self-assessment and adjust to alterations in the environment. In particular, an innovative smart actuator has been designed and developed to satisfy machining requirements during active vibration control. This study presents the mechatronic model based on the kinematic and dynamic analysis of the AVC device. To ensure a real time performance, a H2-LQG controller has been developed and validated by simulations involving a machine tool, PZT actuator and controller models. The Hardware in the Loop (HIL) architecture is adopted to control and attenuate the vibrations. A set of experimental tests has been performed to validate the AVC module on a commercial machine tool. The feasibility of the real time vibration damping is demonstrated and the simulation accuracy is evaluated.

Active vibration control for piezoelectricity cantilever beam: an adaptive feedforward control method

NASA Astrophysics Data System (ADS)

Zhu, Qiao; Yue, Jun-Zhou; Liu, Wei-Qun; Wang, Xu-Dong; Chen, Jun; Hu, Guang-Di

2017-04-01

This work is focused on the active vibration control of piezoelectric cantilever beam, where an adaptive feedforward controller (AFC) is utilized to reject the vibration with unknown multiple frequencies. First, the experiment setup and its mathematical model are introduced. Due to that the channel between the disturbance and the vibration output is unknown in practice, a concept of equivalent input disturbance (EID) is employed to put an equivalent disturbance into the input channel. In this situation, the vibration control can be achieved by setting the control input be the identified EID. Then, for the EID with known multiple frequencies, the AFC is introduced to perfectly reject the vibration but is sensitive to the frequencies. In order to accurately identify the unknown frequencies of EID in presence of the random disturbances and un-modeled nonlinear dynamics, the time-frequency-analysis (TFA) method is employed to precisely identify the unknown frequencies. Consequently, a TFA-based AFC algorithm is proposed to the active vibration control with unknown frequencies. Finally, four cases are given to illustrate the efficiency of the proposed TFA-based AFC algorithm by experiment.

Real-Time Performance of Mechatronic PZT Module Using Active Vibration Feedback Control

PubMed Central

Aggogeri, Francesco; Borboni, Alberto; Merlo, Angelo; Pellegrini, Nicola; Ricatto, Raffaele

2016-01-01

This paper proposes an innovative mechatronic piezo-actuated module to control vibrations in modern machine tools. Vibrations represent one of the main issues that seriously compromise the quality of the workpiece. The active vibration control (AVC) device is composed of a host part integrated with sensors and actuators synchronized by a regulator; it is able to make a self-assessment and adjust to alterations in the environment. In particular, an innovative smart actuator has been designed and developed to satisfy machining requirements during active vibration control. This study presents the mechatronic model based on the kinematic and dynamic analysis of the AVC device. To ensure a real time performance, a H2-LQG controller has been developed and validated by simulations involving a machine tool, PZT actuator and controller models. The Hardware in the Loop (HIL) architecture is adopted to control and attenuate the vibrations. A set of experimental tests has been performed to validate the AVC module on a commercial machine tool. The feasibility of the real time vibration damping is demonstrated and the simulation accuracy is evaluated. PMID:27681732

Active Control of Panel Vibrations Induced by a Boundary Layer Flow

NASA Technical Reports Server (NTRS)

Chow, Pao-Liu

1998-01-01

In recent years, active and passive control of sound and vibration in aeroelastic structures have received a great deal of attention due to many potential applications to aerospace and other industries. There exists a great deal of research work done in this area. Recent advances in the control of sound and vibration can be found in the several conference proceedings. In this report we will summarize our research findings supported by the NASA grant NAG-1-1175. The problems of active and passive control of sound and vibration has been investigated by many researchers for a number of years. However, few of the articles are concerned with the sound and vibration with flow-structure interaction. Experimental and numerical studies on the coupling between panel vibration and acoustic radiation due to flow excitation have been done by Maestrello and his associates at NASA/Langley Research Center. Since the coupled system of nonlinear partial differential equations is formidable, an analytical solution to the full problem seems impossible. For this reason, we have to simplify the problem to that of the nonlinear panel vibration induced by a uniform flow or a boundary-layer flow with a given wall pressure distribution. Based on this simplified model, we have been able to study the control and stabilization of the nonlinear panel vibration, which have not been treated satisfactorily by other authors. The vibration suppression will clearly reduce the sound radiation power from the panel. The major research findings will be presented in the next three sections. In Section II we shall describe our results on the boundary control of nonlinear panel vibration, with or without flow excitation. Section III is concerned with active control of the vibration and sound radiation from a nonlinear elastic panel. A detailed description of our work on the parametric vibrational control of nonlinear elastic panel will be presented in Section IV. This paper will be submitted to the Journal of Acoustic Society of America for publication.

Compact Active Vibration Control System for a Flexible Panel

NASA Technical Reports Server (NTRS)

Schiller, Noah H. (Inventor); Cabell, Randolph H. (Inventor); Perey, Daniel F. (Inventor)

2014-01-01

A diamond-shaped actuator for a flexible panel has an inter-digitated electrode (IDE) and a piezoelectric wafer portion positioned therebetween. The IDE and/or the wafer portion are diamond-shaped. Point sensors are positioned with respect to the actuator and measure vibration. The actuator generates and transmits a cancelling force to the panel in response to an output signal from a controller, which is calculated using a signal describing the vibration. A method for controlling vibration in a flexible panel includes connecting a diamond-shaped actuator to the flexible panel, and then connecting a point sensor to each actuator. Vibration is measured via the point sensor. The controller calculates a proportional output voltage signal from the measured vibration, and transmits the output signal to the actuator to substantially cancel the vibration in proximity to each actuator.

Method of multi-mode vibration control for the carbody of high-speed electric multiple unit trains

NASA Astrophysics Data System (ADS)

Gong, Dao; Zhou, Jinsong; Sun, Wenjing; Sun, Yu; Xia, Zhanghui

2017-11-01

A method of multi-mode vibration control for the carbody of high-speed electric multiple unit (EMU) trains by using the onboard and suspended equipments as dynamic vibration absorbers (DVAs) is proposed. The effect of the multi-mode vibration on the ride quality of a high-speed EMU train was studied, and the target modes of vibration control were determined. An equivalent mass identification method was used to determine the equivalent mass for the target modes at the device installation positions. To optimize the vibration acceleration response of the carbody, the natural frequencies and damping ratios of the lateral and vertical vibration were designed based on the theory of dynamic vibration absorption. In order to realize the optimized design values of the natural frequencies for the lateral and vertical vibrations simultaneously, a new type of vibration absorber was designed in which a belleville spring and conventional rubber parts are connected in parallel. This design utilizes the negative stiffness of the belleville spring. Results show that, as compared to rigid equipment connections, the proposed method effectively reduces the multi-mode vibration of a carbody in a high-speed EMU train, thereby achieving the control objectives. The ride quality in terms of the lateral and vertical vibration of the carbody is considerably improved. Moreover, the optimal value of the damping ratio is effective in dissipating the vibration energy, which reduces the vibration of both the carbody and the equipment.

Potential regenerative rehabilitation technology: implications of mechanical stimuli to tissue health

PubMed Central

2014-01-01

Background Mechanical loads induced through muscle contraction, vibration, or compressive forces are thought to modulate tissue plasticity. With the emergence of regenerative medicine, there is a need to understand the optimal mechanical environment (vibration, load, or muscle force) that promotes cellular health. To our knowledge no mechanical system has been proposed to deliver these isolated mechanical stimuli in human tissue. We present the design, performance, and utilization of a new technology that may be used to study localized mechanical stimuli on human tissues. A servo-controlled vibration and limb loading system were developed and integrated into a single instrument to deliver vibration, compression, or muscle contractile loads to a single limb (tibia) in humans. The accuracy, repeatability, transmissibility, and safety of the mechanical delivery system were evaluated on eight individuals with spinal cord injury (SCI). Findings The limb loading system was linear, repeatable, and accurate to less than 5, 1, and 1 percent of full scale, respectively, and transmissibility was excellent. The between session tests on individuals with spinal cord injury (SCI) showed high intra-class correlations (>0.9). Conclusions All tests supported that therapeutic loads can be delivered to a lower limb (tibia) in a safe, accurate, and measureable manner. Future collaborations between engineers and cellular physiologists will be important as research programs strive to determine the optimal mechanical environment for developing cells and tissues in humans. PMID:24894666

Positioning and Microvibration Control by Electromagnets of an Air Spring Vibration Isolation System

NASA Technical Reports Server (NTRS)

Watanabe, Katsuhide; Cui, Weimin; Haga, Takahide; Kanemitsu, Yoichi; Yano, Kenichi

1996-01-01

Active positioning and microvibration control has been attempted by electromagnets equipped in a bellows-type, air-spring vibration isolation system. Performance tests have been carried out to study the effects. The main components of the system's isolation table were four electromagnetic actuators and controllers. The vibration isolation table was also equipped with six acceleration sensors for detecting microvibration of the table. The electromagnetic actuators were equipped with bellows-type air springs for passive support of the weight of the item placed on the table, with electromagnets for active positioning, as well as for microvibration control, and relative displacement sensors. The controller constituted a relative feedback system for positioning control and an absolute feedback system for vibration isolation control. In the performance test, a 1,490 kg load (net weight of 1,820 kg) was placed on the vibration isolation table, and both the positioning and microvibration control were carried out electromagnetically. Test results revealed that the vibration transmission was reduced by 95%.

Vibration Control via Stiffness Switching of Magnetostrictive Transducers

NASA Technical Reports Server (NTRS)

Scheidler, Justin J.; Asnani, Vivake M.; Dapino, Marcelo J.

2016-01-01

In this paper, a computational study is presented of structural vibration control that is realized by switching a magnetostrictive transducer between high and low stiffness states. Switching is accomplished by either changing the applied magnetic field with a voltage excitation or changing the shunt impedance on the transducer's coil (i.e., the magnetostrictive material's magnetic boundary condition). Switched-stiffness vibration control is simulated using a lumped mass supported by a damper and the magnetostrictive transducer (mount), which is represented by a nonlinear, electromechanical model. Free vibration of the mass is calculated while varying the mount's stiffness according to a reference switched-stiffness vibration control law. The results reveal that switching the magnetic field produces the desired change in stiffness, but also an undesired actuation force that can significantly degrade the vibration control. Hence, a modified switched-stiffness control law that accounts for the actuation force is proposed and implemented for voltage-controlled stiffness switching. The influence of the magneto-mechanical bias condition is also discussed. Voltage-controlled stiffness switching is found to introduce damping equivalent to a viscous damping factor up to about 0.13; this is shown to primarily result from active vibration reduction caused by the actuation force. The merit of magnetostrictive switched-stiffness vibration control is then quantified by comparing the results of voltage- and shunt-controlled stiffness switching to the performance of optimal magnetostrictive shunt damping. For the cases considered, optimal resistive shunt damping performed considerably better than both voltage- and shunt-controlled stiffness switching.

Hybrid active vibration control of rotorbearing systems using piezoelectric actuators

NASA Technical Reports Server (NTRS)

Palazzolo, A. B.; Jagannathan, S.; Kascak, A. F.; Montague, G. T.; Kiraly, L. J.

1993-01-01

The vibrations of a flexible rotor are controlled using piezoelectric actuators. The controller includes active analog components and a hybrid interface with a digital computer. The computer utilizes a grid search algorithm to select feedback gains that minimize a vibration norm at a specific operating speed. These gains are then downloaded as active stillnesses and dampings with a linear fit throughout the operating speed range to obtain a very effective vibration control.

Demonstration of active vibration control on a stirling-cycle cryocooler testbed

NASA Technical Reports Server (NTRS)

Johnson, Bruce G.; Flynn, Frederick J.; Gaffney, Monique S.; Johnson, Dean L.; Ross, Ronald G., Jr.

1992-01-01

SatCon Technology Corporation has demonstrated excellent vibration reduction performance using active control on the JPL Stirling-cycle cryocooler testbed. The authors address the use of classical narrowband feedback control to meet the cryocooler vibration specifications using one cryocooler in a self-cancellation configuration. Similar vibration reduction performance was obtained using a cryocooler back-to-back configuration by actively controlling a reaction mass actuator that was used to mimic the second cooler.

PREFACE: International Conference on Vibration Problems (ICOVP-2015)

NASA Astrophysics Data System (ADS)

2015-12-01

Vibrations produced by operating machine cause deleterious effect including excessive stresses in mechanical components and reduce the machine performance. Hence, it is important to minimize the vibrations to improve the machine performance. Machines need the materials wherein vibration characteristics such as frequency and amplitude are lower. The vibration characteristics depend on strength and other elastic constants. Therefore, study of the relation between vibration characteristics and the elastic constants of the material is very much important. In the domain of seismology, the knowledge of vibrations associated with an earthquake is needed for the mitigation plans. With the increased use of strong and light weight structures especially in defence and aero-space engineering applications, wherein, precision is very important, problems of vibrations arise. The knowledge of quality (mechanical properties) of bones comes from the study of vibrations in it. This knowledge may, for exmple, help to answer bone tissue remodelling problems. Unfortunately, vibrations mostly deal with destructive areas such as manufacturing industry, seismology, and bonemechanics. These days, mathematics has become a very important tool for Non- Destructive Evaluation (NDE) in the destructive areas. A very common issue in the said domains is that the pertinent problems result in non-linear coupled differential equations which are not easily solvable. Keeping the above facts in mind, the Department of Mathematics, Kakatiya University has organized the International Conference on Vibration Problems (ICOVP-2015) from February, 18-20, 2015 in collaboration with the Department of Mechanical Engineering, Kakatiya University, and Von-Karman Society, West Bengal. This association has already succeeded in organizing the Wave Mechanics and Vibration Conference (WMVC) in the year 2010. In the Conference, new research results were presented by the experts from eight countries. There were more than 150 participants from India and abroad. The infrastructure facilities, administrative help, and financial support provided by Kakatiya University are gratefully acknowledged. The financial support received from Telangana State Council of Higher Education, University Grant Commission (UGC), National Board for Higher Mathematics (NBHM), Department of Atomic Energy (DAE), Ministry of Earth Sciences, and State Bank of Hyderabad are thankfully acknowledged. The thanks are due to all the speakers and participants who have come to this place by performing long journies and facing many inconveniences. Thanks are also due to International Scientific Committee members, reviewers, local organizing committee members, the members of organizing sub committees, supporting staff, research scholars, and the students for their help. This Conference Series is the outcome of the contributions from the conference and is broadly classified into five sections containing the papers from Solid Mechanics (SM), Fluid Mechanics (FM), Mechanical Engineering (ME), Applied Mathematics(AM), and Physics(PH). All efforts have been made to maintain the consiouness and standards that are the Hallmarks of Institute of Physics (IOP). We appreciate the efforts of Dr.B.Sandhya Rani, Dr.G.Rajitha, and Ms. Hari Priya, research scholors in the Department of Mathematics, Kakatiya University for checking the typos and pointing out the numerous errors. We also appreciate Dr.D.Rajaiah and Mr.D.Ranadheer, research scholors, in the Department for their efforts in the preparation of some LaTeX files. International Conference on Vibration Problems (ICOVP-2015).

Monitoring techniques for the X-29A aircraft's high-speed rotating power takeoff shaft

NASA Technical Reports Server (NTRS)

Voracek, David F.

1990-01-01

The experimental X-29A forward swept-wing aircraft has many unique and critical systems that require constant monitoring during ground or flight operation. One such system is the power takeoff shaft, which is the mechanical link between the engine and the aircraft-mounted accessory drive. The X-29A power takeoff shaft opertes in a range between 0 and 16,810 rpm, is longer than most jet engine power takeoff shafts, and is made of graphite epoxy material. Since the X-29A aircraft operates on a single engine, failure of the shaft during flight could lead to loss of the aircraft. The monitoring techniques and test methods used during power takeoff shaft ground and flight operations are discussed. Test data are presented in two case studies where monitoring and testing of the shaft dynamics proved instrumental in discovering and isolating X-29A power takeoff shaft problems. The first study concerns the installation of an unbalanced shaft. The effect of the unbalance on the shaft vibration data and the procedure used to correct the problem are discussed. The second study deals with the shaft exceeding the established vibration limits during flight. This case study found that the vibration of connected rotating machinery unbalances contributed to the excessive vibration level of the shaft. The procedures used to identify the contributions of other rotating machinery unbalances to the power takeoff shaft unbalance are discussed.

Experimental Investigation of the Vibration Characteristics of Four Designs of Turbine Blades and of the Effect Produced by Varying the Axial Spacing Between Nozzle Blades and Turbine Blades.

NASA Technical Reports Server (NTRS)

Morgan, W C; Morse, C R

1952-01-01

An investigation was made to determine the effects of varying the spacing between the nozzle blades and the turbine blades of a turbo-jet engine on turbine-blade vibration for four turbine-blade designs of different degrees of stiffness. In general, there was a tendency toward increase in occurrence of vibration with decrease in spacing. The effect was most evident in the case of the turbine blades that had greater stiffness.

The effect of engine spin direction on the dynamics of powered two wheelers

NASA Astrophysics Data System (ADS)

Massaro, Matteo; Marconi, Edoardo

2018-04-01

The effect of engine spin direction on the dynamics of powered two wheelers is investigated in terms of steady-state points (equilibria), vibration modes (stability), manoeuvre time (performance/manoeuvrability) and handling. The goal is to assess and quantify the advantage sometimes claimed for the 'counter-rotating' engine configuration, where the engine spins in the opposite direction with respect to wheels, against the 'conventional' configuration, where the engine spins in the same direction of wheels.

Metal Injection Molding for Superalloy Jet Engine Components

DTIC Science & Technology

2006-05-01

single vanes. The vanes are subject to high vibration stresses and thus require reliable fatigue strength. Therefore the quality of the material must meet...Injection Molding for Superalloy Jet Engine Components 9 - 12 RTO-MP-AVT-139 UNCLASSIFIED/UNLIMITED UNCLASSIFIED/UNLIMITED MTU AeroEngines copyright...Sikorski Max Kraus Dr. Claus Müller MTU Aero Engines GmbH Munich, Germany 15.05. - 17.05.2006 MTU AeroEngines copyright ©2 AVT – 139 on “Cost Effective

Integrated cable vibration control system using wireless sensors

NASA Astrophysics Data System (ADS)

Jeong, Seunghoo; Cho, Soojin; Sim, Sung-Han

2017-04-01

As the number of long-span bridges is increasing worldwide, maintaining their structural integrity and safety become an important issue. Because the stay cable is a critical member in most long-span bridges and vulnerable to wind-induced vibrations, vibration mitigation has been of interest both in academia and practice. While active and semi-active control schemes are known to be quite effective in vibration reduction compared to the passive control, requirements for equipment including data acquisition, control devices, and power supply prevent a widespread adoption in real-world applications. This study develops an integrated system for vibration control of stay-cables using wireless sensors implementing a semi-active control. Arduino, a low-cost single board system, is employed with a MEMS digital accelerometer and a Zigbee wireless communication module to build the wireless sensor. The magneto-rheological (MR) damper is selected as a damping device, controlled by an optimal control algorithm implemented on the Arduino sensing system. The developed integrated system is tested in a laboratory environment using a cable to demonstrate the effectiveness of the proposed system on vibration reduction. The proposed system is shown to reduce the vibration of stay-cables with low operating power effectively.

Decentralized semi-active damping of free structural vibrations by means of structural nodes with an on/off ability to transmit moments

NASA Astrophysics Data System (ADS)

Poplawski, Blazej; Mikułowski, Grzegorz; Mróz, Arkadiusz; Jankowski, Łukasz

2018-02-01

This paper proposes, tests numerically and verifies experimentally a decentralized control algorithm with local feedback for semi-active mitigation of free vibrations in frame structures. The algorithm aims at transferring the vibration energy of low-order, lightly-damped structural modes into high-frequency modes of vibration, where it is quickly damped by natural mechanisms of material damping. Such an approach to mitigation of vibrations, known as the prestress-accumulation release (PAR) strategy, has been earlier applied only in global control schemes to the fundamental vibration mode of a cantilever beam. In contrast, the decentralization and local feedback allows the approach proposed here to be applied to more complex frame structures and vibration patterns, where the global control ceases to be intuitively obvious. The actuators (truss-frame nodes with controllable ability to transmit moments) are essentially unblockable hinges that become unblocked only for very short time periods in order to trigger local modal transfer of energy. The paper proposes a computationally simple model of the controllable nodes, specifies the control performance measure, yields basic characteristics of the optimum control, proposes the control algorithm and then tests it in numerical and experimental examples.

Analytic Methods for Predicting Significant Multi-Quanta Effects in Collisional Molecular Energy Transfer

NASA Technical Reports Server (NTRS)

Bieniek, Ronald J.

1996-01-01

Collision-induced transitions can significantly affect molecular vibrational-rotational populations and energy transfer in atmospheres and gaseous systems. This, in turn. can strongly influence convective heat transfer through dissociation and recombination of diatomics. and radiative heat transfer due to strong vibrational coupling. It is necessary to know state-to-state rates to predict engine performance and aerothermodynamic behavior of hypersonic flows, to analyze diagnostic radiative data obtained from experimental test facilities, and to design heat shields and other thermal protective systems. Furthermore, transfer rates between vibrational and translational modes can strongly influence energy flow in various 'disturbed' environments, particularly where the vibrational and translational temperatures are not equilibrated.

Externally tuned vibration absorber

DOEpatents

Vincent, Ronald J.

1987-09-22

A vibration absorber unit or units are mounted on the exterior housing of a hydraulic drive system of the type that is powered from a pressure wave generated, e.g., by a Stirling engine. The hydraulic drive system employs a piston which is hydraulically driven to oscillate in a direction perpendicular to the axis of the hydraulic drive system. The vibration absorbers each include a spring or other resilient member having one side affixed to the housing and another side to which an absorber mass is affixed. In a preferred embodiment, a pair of vibration absorbers is employed, each absorber being formed of a pair of leaf spring assemblies, between which the absorber mass is suspended.

Control of cell behaviour through nanovibrational stimulation: nanokicking

NASA Astrophysics Data System (ADS)

Robertson, Shaun N.; Campsie, Paul; Childs, Peter G.; Madsen, Fiona; Donnelly, Hannah; Henriquez, Fiona L.; Mackay, William G.; Salmerón-Sánchez, Manuel; Tsimbouri, Monica P.; Williams, Craig; Dalby, Matthew J.; Reid, Stuart

2018-05-01

Mechanical signals are ubiquitous in our everyday life and the process of converting these mechanical signals into a biological signalling response is known as mechanotransduction. Our understanding of mechanotransduction, and its contribution to vital cellular responses, is a rapidly expanding field of research involving complex processes that are still not clearly understood. The use of mechanical vibration as a stimulus of mechanotransduction, including variation of frequency and amplitude, allows an alternative method to control specific cell behaviour without chemical stimulation (e.g. growth factors). Chemical-independent control of cell behaviour could be highly advantageous for fields including drug discovery and clinical tissue engineering. In this review, a novel technique is described based on nanoscale sinusoidal vibration. Using finite-element analysis in conjunction with laser interferometry, techniques that are used within the field of gravitational wave detection, optimization of apparatus design and calibration of vibration application have been performed. We further discuss the application of nanovibrational stimulation, or `nanokicking', to eukaryotic and prokaryotic cells including the differentiation of mesenchymal stem cells towards an osteoblast cell lineage. Mechanotransductive mechanisms are discussed including mediation through the Rho-A kinase signalling pathway. Optimization of this technique was first performed in two-dimensional culture using a simple vibration platform with an optimal frequency and amplitude of 1 kHz and 22 nm. A novel bioreactor was developed to scale up cell production, with recent research demonstrating that mesenchymal stem cell differentiation can be efficiently triggered in soft gel constructs. This important step provides first evidence that clinically relevant (three-dimensional) volumes of osteoblasts can be produced for the purpose of bone grafting, without complex scaffolds and/or chemical induction. Initial findings have shown that nanovibrational stimulation can also reduce biofilm formation in a number of clinically relevant bacteria. This demonstrates additional utility of the bioreactor to investigate mechanotransduction in other fields of research. This article is part of a discussion meeting issue `The promises of gravitational-wave astronomy'.

Control of cell behaviour through nanovibrational stimulation: nanokicking.

PubMed

Robertson, Shaun N; Campsie, Paul; Childs, Peter G; Madsen, Fiona; Donnelly, Hannah; Henriquez, Fiona L; Mackay, William G; Salmerón-Sánchez, Manuel; Tsimbouri, Monica P; Williams, Craig; Dalby, Matthew J; Reid, Stuart

2018-05-28

Mechanical signals are ubiquitous in our everyday life and the process of converting these mechanical signals into a biological signalling response is known as mechanotransduction. Our understanding of mechanotransduction, and its contribution to vital cellular responses, is a rapidly expanding field of research involving complex processes that are still not clearly understood. The use of mechanical vibration as a stimulus of mechanotransduction, including variation of frequency and amplitude, allows an alternative method to control specific cell behaviour without chemical stimulation (e.g. growth factors). Chemical-independent control of cell behaviour could be highly advantageous for fields including drug discovery and clinical tissue engineering. In this review, a novel technique is described based on nanoscale sinusoidal vibration. Using finite-element analysis in conjunction with laser interferometry, techniques that are used within the field of gravitational wave detection, optimization of apparatus design and calibration of vibration application have been performed. We further discuss the application of nanovibrational stimulation, or 'nanokicking', to eukaryotic and prokaryotic cells including the differentiation of mesenchymal stem cells towards an osteoblast cell lineage. Mechanotransductive mechanisms are discussed including mediation through the Rho-A kinase signalling pathway. Optimization of this technique was first performed in two-dimensional culture using a simple vibration platform with an optimal frequency and amplitude of 1 kHz and 22 nm. A novel bioreactor was developed to scale up cell production, with recent research demonstrating that mesenchymal stem cell differentiation can be efficiently triggered in soft gel constructs. This important step provides first evidence that clinically relevant (three-dimensional) volumes of osteoblasts can be produced for the purpose of bone grafting, without complex scaffolds and/or chemical induction. Initial findings have shown that nanovibrational stimulation can also reduce biofilm formation in a number of clinically relevant bacteria. This demonstrates additional utility of the bioreactor to investigate mechanotransduction in other fields of research.This article is part of a discussion meeting issue 'The promises of gravitational-wave astronomy'. © 2018 The Author(s).

Structural health monitoring (vibration) as a tool for identifying structural alterations of the lumbar spine: a twin control study.

PubMed

Kawchuk, Gregory N; Hartvigsen, Jan; Edgecombe, Tiffany; Prasad, Narasimha; van Dieen, Jaap H

2016-03-11

Structural health monitoring (SHM) is an engineering technique used to identify mechanical abnormalities not readily apparent through other means. Recently, SHM has been adapted for use in biological systems, but its invasive nature limits its clinical application. As such, the purpose of this project was to determine if a non-invasive form of SHM could identify structural alterations in the spines of living human subjects. Lumbar spines of 10 twin pairs were visualized by magnetic resonance imaging then assessed by a blinded radiologist to determine whether twin pairs were structurally concordant or discordant. Vibration was then applied to each subject's spine and the resulting response recorded from sensors overlying lumbar spinous processes. The peak frequency, area under the curve and the root mean square were computed from the frequency response function of each sensor. Statistical analysis demonstrated that in twins whose structural appearance was discordant, peak frequency was significantly different between twin pairs while in concordant twins, no outcomes were significantly different. From these results, we conclude that structural changes within the spine can alter its vibration response. As such, further investigation of SHM to identify spinal abnormalities in larger human populations is warranted.

Exact analytical solution of shear-induced flexural vibration of functionally graded piezoelectric beam

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

Sharma, Pankaj, E-mail: psharma@rtu.ac.in; Parashar, Sandeep Kumar, E-mail: parashar2@yahoo.com

The priority of this paper is to obtain the exact analytical solution for free flexural vibration of FGPM beam actuated using the d{sub 15} effect. In piezoelectric actuators, the potential use of d{sub 15} effect has been of particular interest for engineering applications since shear piezoelectric coefficient d15 is much higher than the other piezoelectric coupling constants d{sub 31} and d{sub 33}. The applications of shear actuators are to induce and control the flexural vibrations of beams and plates. In this study, a modified Timoshenko beam theory is used where electric potential is assumed to vary sinusoidaly along the thicknessmore » direction. The material properties are assumed to be graded across the thickness in accordance with power law distribution. Hamilton's principle is employed to obtain the equations of motion along with the associated boundary conditions for FGPM beams. Exact analytical solution is derived thus obtained equations of motion. Results for clamped-clamped and clamped-free boundary conditions are presented. The presented result and method shell serve as benchmark for comparing the results obtained from the other approximate methods.« less

Finite element based model predictive control for active vibration suppression of a one-link flexible manipulator.

PubMed

Dubay, Rickey; Hassan, Marwan; Li, Chunying; Charest, Meaghan

2014-09-01

This paper presents a unique approach for active vibration control of a one-link flexible manipulator. The method combines a finite element model of the manipulator and an advanced model predictive controller to suppress vibration at its tip. This hybrid methodology improves significantly over the standard application of a predictive controller for vibration control. The finite element model used in place of standard modelling in the control algorithm provides a more accurate prediction of dynamic behavior, resulting in enhanced control. Closed loop control experiments were performed using the flexible manipulator, instrumented with strain gauges and piezoelectric actuators. In all instances, experimental and simulation results demonstrate that the finite element based predictive controller provides improved active vibration suppression in comparison with using a standard predictive control strategy. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Free vibration of laminated composite stiffened hyperbolic paraboloid shell panel with cutout

NASA Astrophysics Data System (ADS)

Sahoo, Sarmila

2016-08-01

Composite shell structures are extensively used in aerospace, civil, marine and other engineering applications. In practical civil engineering applications, the necessity of covering large column free open areas is often an issue and hyperbolic paraboloid shells are used as roofing units. Quite often, to save weight and also to provide a facility for inspection, cutouts are provided in shell panels. The paper considers free vibration characteristics of stiffened composite hyperbolic paraboloid shell panel with cutout in terms of natural frequency and mode shapes. A finite element code is developed for the purpose by combining an eight noded curved shell element with a three noded curved beam element. The size of the cutouts and their positions with respect to the shell centre are varied for different edge conditions to arrive at a set of inferences of practical engineering significances.

Buck-boost converter for simultaneous semi-active vibration control and energy harvesting for electromagnetic regenerative shock absorber

NASA Astrophysics Data System (ADS)

Li, Peng; Zhang, Chongxiao; Kim, Junyoung; Yu, Liangyao; Zuo, Lei

2014-04-01

Regenerative semi-active suspensions can capture the previously dissipated vibration energy and convert it to usable electrical energy for powering on-board electronic devices, while achieve both the better ride comfort and improved road handling performance at the same time when certain control is applied. To achieve this objective, the power electronics interface circuit connecting the energy harvester and the electrical loads, which can perform simultaneous vibration control and energy harvesting function is in need. This paper utilized a buck-boost converter for simultaneous semi-active vibration control and energy harvesting with electromagnetic regenerative shock absorber, which utilizes a rotational generator to converter the vibration energy to electricity. It has been found that when the circuit works in discontinuous current mode (DCM), the ratio between the input voltage and current is only related to the duty cycle of the switch pulse width modulation signal. Using this property, the buck-boost converter can be used to perform semi-active vibration control by controlling the load connected between the terminals of the generator in the electromagnetic shock absorber. While performing the vibration control, the circuit always draw current from the shock absorber and the suspension remain dissipative, and the shock absorber takes no additional energy to perform the vibration control. The working principle and dynamics of the circuit has been analyzed and simulations were performed to validate the concept.

A fuzzy model of superelastic shape memory alloys for vibration control in civil engineering applications

NASA Astrophysics Data System (ADS)

Ozbulut, O. E.; Mir, C.; Moroni, M. O.; Sarrazin, M.; Roschke, P. N.

2007-06-01

Two experimental test programs are conducted to collect data and simulate the dynamic behavior of CuAlBe shape memory alloy (SMA) wires. First, in order to evaluate the effect of temperature changes on superelastic SMA wires, a large number of cyclic, sinusoidal, tensile tests are performed at 1 Hz. These tests are conducted in a controlled environment at 0, 25 and 50 °C with three different strain amplitudes. Second, in order to assess the dynamic effects of the material, a series of laboratory experiments is conducted on a shake table with a scale model of a three-story structure that is stiffened with SMA wires. Data from these experiments are used to create fuzzy inference systems (FISs) that can predict hysteretic behavior of CuAlBe wire. Both fuzzy models employ a total of three input variables (strain, strain-rate, and temperature or pre-stress) and an output variable (predicted stress). Gaussian membership functions are used to fuzzify data for each of the input and output variables. Values of the initially assigned membership functions are adjusted using a neural-fuzzy procedure to more accurately predict the correct stress level in the wires. Results of the trained FISs are validated using test results from experimental records that had not been previously used in the training procedure. Finally, a set of numerical simulations is conducted to illustrate practical use of these wires in a civil engineering application. The results reveal the applicability for structural vibration control of pseudoelastic CuAlBe wire whose highly nonlinear behavior is modeled by a simple, accurate, and computationally efficient FIS.

Smart vibration control analysis of seismic response using MR dampers in the elevated highway bridge structures

NASA Astrophysics Data System (ADS)

Yan, Shi; Zhang, Hai

2005-05-01

The magnetorheological (MR) damper is on of the smart controllers used widely in civil engineering structures. These kinds of dampers are applied in the paper in the elevated highway bridge (EHB) with rubber bearing support piers to mitigate damages of the bridge during the severe earthquake ground motion. The dynamic calculating model and equation of motion for the EHB system are set up theoretically and the LQR semi-active control algorithm of seismic response for the EHB system is developed to reduce effectively the responses of the structure. The non-linear calculation model of the piers that rigid degradation is considered and numerical simulative calculation are carried out by Matlab program. The number and location as well as the maximum control forces of the MR dampers, which are the most important parameters for the controlled system, are determined and the rubber bearing and connection forms of the damper play also important rule in the control efficiency. A real EHB structure that is located in Anshan city, Liaoning province in China is used as an example to be calculated under different earthquake records. The results of the calculation show that it is effective to reduce seismic responses of the EHB system by combining the rubber bearing isolation with semi-active MR control technique under the earthquake ground motion. The locations of MR dampers and structural parameters will influence seriously to the effects of structural vibration control.

Measuring System Value in the Ares 1 Rocket Using an Uncertainty-Based Coupling Analysis Approach

NASA Astrophysics Data System (ADS)

Wenger, Christopher

Coupling of physics in large-scale complex engineering systems must be correctly accounted for during the systems engineering process to ensure no unanticipated behaviors or unintended consequences arise in the system during operation. Structural vibration of large segmented solid rocket motors, known as thrust oscillation, is a well-documented problem that can affect the health and safety of any crew onboard. Within the Ares 1 rocket, larger than anticipated vibrations were recorded during late stage flight that propagated from the engine chamber to the Orion crew module. Upon investigation engineers found the root cause to be the structure of the rockets feedback onto fluid flow within the engine. The goal of this paper is to showcase a coupling strength analysis from the field of Multidisciplinary Design Optimization to identify the major impacts that caused the Thrust Oscillation event in the Ares 1. Once identified an uncertainty analysis of the coupled system using an uncertainty based optimization technique is used to identify the likelihood of occurrence for these strong or weak interactions to take place.

Department of the Air Force Justification of Estimates for Fiscal Year 1982 Submitted to Congress January 1981.

DTIC Science & Technology

1981-01-01

51’ 7.6 TOTAL 159.6 B. Equipment (Non add) 1. Active Control Hardware LS (30.0) 2. Tiltmeters LS (20.0) 3. Accelerometers LS (40.0) C. Design (Non...p, rtion of the MSHP consists of two missions each involving the launch of two payloads ( sensor module and liquid engine module) by a non-standard...of non-contract vibration sensors , accelerometers, aind tern- I>er,)turo sensors with associated monitors and alarms will be installed on all ma Vtr

Sharipov holds an Electronic Box Assembly from the TVIS in the SM during Expedition 10

NASA Image and Video Library

2005-02-17

ISS010-E-18167 (17 February 2005) --- Cosmonaut Salizhan S. Sharipov, Expedition 10 flight engineer representing Russia's Federal Space Agency, holds an Electronic Box Assembly, and Violation Isolation and Stabilization (VIS) Controller Assembly, which is part of the Treadmill Vibration Isolation System (TVIS) in the Zvezda Service Module of the International Space Station (ISS). Also in view is a VIS/TM data cable and VIS/TM power cable. This box receives power and distributes it between the treadmill and the VIS subassemblies.

Aerospace Applications of Integer and Combinatorial Optimization

NASA Technical Reports Server (NTRS)

Padula, S. L.; Kincaid, R. K.

1995-01-01

Research supported by NASA Langley Research Center includes many applications of aerospace design optimization and is conducted by teams of applied mathematicians and aerospace engineers. This paper investigates the benefits from this combined expertise in formulating and solving integer and combinatorial optimization problems. Applications range from the design of large space antennas to interior noise control. A typical problem, for example, seeks the optimal locations for vibration-damping devices on an orbiting platform and is expressed as a mixed/integer linear programming problem with more than 1500 design variables.

Aerospace applications on integer and combinatorial optimization

NASA Technical Reports Server (NTRS)

Padula, S. L.; Kincaid, R. K.

1995-01-01

Research supported by NASA Langley Research Center includes many applications of aerospace design optimization and is conducted by teams of applied mathematicians and aerospace engineers. This paper investigates the benefits from this combined expertise in formulating and solving integer and combinatorial optimization problems. Applications range from the design of large space antennas to interior noise control. A typical problem. for example, seeks the optimal locations for vibration-damping devices on an orbiting platform and is expressed as a mixed/integer linear programming problem with more than 1500 design variables.

Recent Advances In Structural Vibration And Failure Mode Control In Mainland China: Theory, Experiments And Applications

NASA Astrophysics Data System (ADS)

Li, Hui; Ou, Jinping

2008-07-01

A number of researchers have been focused on structural vibration control in the past three decades over the world and fruit achievements have been made. This paper introduces the recent advances in structural vibration control including passive, active and semiactive control in mainland China. Additionally, the co-author extends the structural vibration control to failure mode control. The research on the failure mode control is also involved in this paper. For passive control, this paper introduces full scale tests of buckling-restrained braces conducted to investigate the performance of the dampers and the second-editor of the Code of Seismic Design for Buildings. For active control, this paper introduces the HMD system for wind-induced vibration control of the Guangzhou TV tower. For semiactive control, the smart damping devices, algorithms for semi-active control, design methods and applications of semi-active control for structures are introduced in this paper. The failure mode control for bridges is also introduced.

Coagulation measurement from whole blood using vibrating optical fiber in a disposable cartridge.

PubMed

Yaraş, Yusuf Samet; Gündüz, Ali Bars; Sağlam, Gökhan; Ölçer, Selim; Civitçi, Fehmi; Baris, İbrahim; Yaralioğlu, Göksenin; Urey, Hakan

2017-11-01

In clinics, blood coagulation time measurements are performed using mechanical measurements with blood plasma. Such measurements are challenging to do in a lab-on-a-chip (LoC) system using a small volume of whole blood. Existing LoC systems use indirect measurement principles employing optical or electrochemical methods. We developed an LoC system using mechanical measurements with a small volume of whole blood without requiring sample preparation. The measurement is performed in a microfluidic channel where two fibers are placed inline with a small gap in between. The first fiber operates near its mechanical resonance using remote magnetic actuation and immersed in the sample. The second fiber is a pick-up fiber acting as an optical sensor. The microfluidic channel is engineered innovatively such that the blood does not block the gap between the vibrating fiber and the pick-up fiber, resulting in high signal-to-noise ratio optical output. The control plasma test results matched well with the plasma manufacturer's datasheet. Activated-partial-thromboplastin-time tests were successfully performed also with human whole blood samples, and the method is proven to be effective. Simplicity of the cartridge design and cost of readily available materials enable a low-cost point-of-care device for blood coagulation measurements. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Acoustic and vibrational damping in porous solids.

PubMed

Göransson, Peter

2006-01-15

A porous solid may be characterized as an elastic-viscoelastic and acoustic-viscoacoustic medium. For a flexible, open cell porous foam, the transport of energy is carried both through the sound pressure waves propagating through the fluid in the pores, and through the elastic stress waves carried through the solid frame of the material. For a given situation, the balance between energy dissipated through vibration of the solid frame, changes in the acoustic pressure and the coupling between the waves varies with the topological arrangement, choice of material properties, interfacial conditions, etc. Engineering of foams, i.e. designs built on systematic and continuous relationships between polymer chemistry, processing, micro-structure, is still a vision for the future. However, using state-of-the-art simulation techniques, multiple layer arrangements of foams may be tuned to provide acoustic and vibrational damping at a low-weight penalty. In this paper, Biot's modelling of porous foams is briefly reviewed from an acoustics and vibrations perspective with a focus on the energy dissipation mechanisms. Engineered foams will be discussed in terms of results from simulations performed using finite element solutions. A layered vehicle-type structure is used as an example.

Experiments on vibration control of a piezoelectric laminated paraboloidal shell

NASA Astrophysics Data System (ADS)

Yue, Honghao; Lu, Yifan; Deng, Zongquan; Tzou, Hornsen

2017-01-01

A paraboloidal shell plays a key role in aerospace and optical structural systems applied to large optical reflector, communications antenna, rocket fairing, missile radome, etc. Due to the complexity of analytical procedures, an experimental study of active vibration control of a piezoelectric laminated paraboloidal shell by positive position feedback is carried out. Sixteen PVDF patches are laminated inside and outside of the shell, in which eight of them are used as sensors and eight as actuators to control the vibration of the first two natural modes. Lower natural frequencies and vibration modes of the paraboloidal shell are obtained via the frequency response function analysis by Modal VIEW software. A mathematical model of the control system is formulated by means of parameter identification. The first shell mode is controlled as well as coupled the first and second modes based on the positive position feedback (PPF) algorithm. To minimize the control energy consumption in orbit, an adaptive modal control method is developed in this study by using the PPF in laboratory experiments. The control system collects vibration signals from the piezoelectric sensors to identify location(s) of the largest vibration amplitudes and then select the best two from eight PVDF actuators to apply control forces so that the modal vibration suppression could be accomplished adaptively and effectively.

Integrated identification, modeling and control with applications

NASA Astrophysics Data System (ADS)

Shi, Guojun

This thesis deals with the integration of system design, identification, modeling and control. In particular, six interdisciplinary engineering problems are addressed and investigated. Theoretical results are established and applied to structural vibration reduction and engine control problems. First, the data-based LQG control problem is formulated and solved. It is shown that a state space model is not necessary to solve this problem; rather a finite sequence from the impulse response is the only model data required to synthesize an optimal controller. The new theory avoids unnecessary reliance on a model, required in the conventional design procedure. The infinite horizon model predictive control problem is addressed for multivariable systems. The basic properties of the receding horizon implementation strategy is investigated and the complete framework for solving the problem is established. The new theory allows the accommodation of hard input constraints and time delays. The developed control algorithms guarantee the closed loop stability. A closed loop identification and infinite horizon model predictive control design procedure is established for engine speed regulation. The developed algorithms are tested on the Cummins Engine Simulator and desired results are obtained. A finite signal-to-noise ratio model is considered for noise signals. An information quality index is introduced which measures the essential information precision required for stabilization. The problems of minimum variance control and covariance control are formulated and investigated. Convergent algorithms are developed for solving the problems of interest. The problem of the integrated passive and active control design is addressed in order to improve the overall system performance. A design algorithm is developed, which simultaneously finds: (i) the optimal values of the stiffness and damping ratios for the structure, and (ii) an optimal output variance constrained stabilizing controller such that the active control energy is minimized. A weighted q-Markov COVER method is introduced for identification with measurement noise. The result is use to develop an iterative closed loop identification/control design algorithm. The effectiveness of the algorithm is illustrated by experimental results.

Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: AMSU-A1 EOS Instrument, (S/N 202) Qualification Level Vibration Tests of August/September 1998, (S/O 565632, OC-417) Plus Addendum A

NASA Technical Reports Server (NTRS)

Heffer, R.

1998-01-01

The purpose of this report is to present a qualification level vibration testing performed on the S/N 202, EOS AMSU-A1 Instrument was vibration tested to qualification levels per the Ref. 1 shop order. The instrument withstood the 8 g sine sweep test, the 7.5 Grms random vibration test, and the 18.75 g sine burst test in each of the three orthogonal axes. Some loss of transmissibility, however, is seen in the lower reflector after Z-axis random vibration. The test sequence was not without incidence. Failure of Channel 7 in the Limited Performance Test (LPT) performed after completion of the 1 st (X-axis) axis vibration sequence, required replacement of the DRO and subsequent re-testing of the instrument. The post-vibration comprehensive performance test (CPT) was successfully run after completion of the three axes of vibration with the replacement component installed in the instrument. Passing the CPT signified the successful completion of the S/N 202 A1 qualification vibration testing.

Differential effect of muscle vibration on intracortical inhibitory circuits in humans

PubMed Central

Rosenkranz, Karin; Rothwell, John C

2003-01-01

Low amplitude muscle vibration (0.5 ms; 80 Hz; duration 1.5 s) was applied in turn to each of three different intrinsic hand muscles (first dorsal interosseus, FDI; abductor pollicis brevis, APB; and abductor digiti minimi, ADM) in order to test its effect on the EMG responses evoked by transcranial magnetic stimulation (TMS). Recordings were also taken from flexor and extensor carpi radialis (FCR and ECR, respectively). We evaluated the amplitude of motor evoked potentials (MEPs) produced by a single TMS pulse, short interval intracortical inhibition and facilitation (SICI and ICF) and long interval intracortical inhibition (LICI). TMS pulses were applied 1 s after the start of vibration with subjects relaxed throughout. Vibration increased the amplitude of MEPs evoked in the vibrated muscle (162 ± 6 % of MEP with no vibration; mean ± s.e.m.), but suppressed MEPs in the two non-vibrated hand muscles (72 ± 9 %). Compared with no vibration (test response reduced to 51 ± 5 % of control), there was less SICI in the vibrated muscle (test response reduced to 92 ± 28 % of control) and more in the non-vibrated hand muscles (test response reduced to 27 ± 5 % of control). The opposite occurred for LICI: compared with the no vibration condition (test response reduced to 33 ± 6 % control), there was more LICI in the vibrated muscle (test response reduced to 17 ± 3 % control) than in the non-vibrated hand muscles (test response reduced to 80 ± 11 % control) even when the intensity of the test stimulus was adjusted to compensate for the changes in baseline MEP. There was no effect on ICF. Cutaneous stimulation of the index finger (80 Hz, 1.5 s duration, twice sensory threshold) had no consistent differential effect on any of the parameters. We conclude that vibratory input from muscle can differentially modulate excitability in motor cortical circuits. PMID:12821723

The landscape of nonlinear structural dynamics: an introduction

PubMed Central

Butlin, T.; Woodhouse, J.; Champneys, A. R.

2015-01-01

Nonlinear behaviour is ever-present in vibrations and other dynamical motions of engineering structures. Manifestations of nonlinearity include amplitude-dependent natural frequencies, buzz, squeak and rattle, self-excited oscillation and non-repeatability. This article primarily serves as an extended introduction to a theme issue in which such nonlinear phenomena are highlighted through diverse case studies. More ambitiously though, there is another goal. Both the engineering context and the mathematical techniques that can be used to identify, analyse, control or exploit these phenomena in practice are placed in the context of a mind-map, which has been created through expert elicitation. This map, which is available in software through the electronic supplementary material, attempts to provide a practitioner’s guide to what hitherto might seem like a vast and complex research landscape. PMID:26303925

The landscape of nonlinear structural dynamics: an introduction.

PubMed

Butlin, T; Woodhouse, J; Champneys, A R

2015-09-28

Nonlinear behaviour is ever-present in vibrations and other dynamical motions of engineering structures. Manifestations of nonlinearity include amplitude-dependent natural frequencies, buzz, squeak and rattle, self-excited oscillation and non-repeatability. This article primarily serves as an extended introduction to a theme issue in which such nonlinear phenomena are highlighted through diverse case studies. More ambitiously though, there is another goal. Both the engineering context and the mathematical techniques that can be used to identify, analyse, control or exploit these phenomena in practice are placed in the context of a mind-map, which has been created through expert elicitation. This map, which is available in software through the electronic supplementary material, attempts to provide a practitioner's guide to what hitherto might seem like a vast and complex research landscape. © 2015 The Authors.

DELTA-DIESEL ENGINE LIGHT TRUCK APPLICATION Contract DE-FC05-97OR22606 Final Report

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

Hakim, Nabil Balnaves, Mike

2003-05-27

DELTA Diesel Engine Light Truck Application End of Contract Report DE-FC05-97-OR22606 EXECUTIVE SUMMARY This report is the final technical report of the Diesel Engine Light Truck Application (DELTA) program under contract DE-FC05-97-OR22606. During the course of this contract, Detroit Diesel Corporation analyzed, designed, tooled, developed and applied the ''Proof of Concept'' (Generation 0) 4.0L V-6 DELTA engine and designed the successor ''Production Technology Demonstration'' (Generation 1) 4.0L V-6 DELTA engine. The objectives of DELTA Program contract DE-FC05-97-OR22606 were to: Demonstrate production-viable diesel engine technologies, specifically intended for the North American LDT and SUV markets; Demonstrate emissions compliance with significant fuelmore » economy advantages. With a clean sheet design, DDC produced the DELTA engine concept promising the following attributes: 30-50% improved fuel economy; Low cost; Good durability and reliability; Acceptable noise, vibration and harshness (NVH); State-of-the-art features; Even firing, 4 valves per cylinder; High pressure common rail fuel system; Electronically controlled; Turbocharged, intercooled, cooled EGR; Extremely low emissions via CLEAN Combustion{copyright} technology. To demonstrate the engine technology in the SUV market, DDC repowered a 1999 Dodge Durango with the DELTA Generation 0 engine. Fuel economy improvements were approximately 50% better than the gasoline engine replaced in the vehicle.« less

Actuator placement for active sound and vibration control of cylinders

NASA Technical Reports Server (NTRS)

Kincaid, Rex K.

1995-01-01

Active structural acoustic control is a method in which the control inputs (used to reduce interior noise) are applied directly to a vibrating structural acoustic system. The control concept modeled in this work is the application of in-plane force inputs to piezoceramic patches bonded to the wall of a vibrating cylinder. The cylinder is excited by an exterior noise source -- an acoustic monopole -- located near the outside of the cylinder wall. The goal is to determine the force inputs and sites for the piezoelectric actuators so that (1) the interior noise is effectively damped; (2) the level of vibration of the cylinder shell is not increased; and (3) the power requirements needed to drive the actuators are not excessive. We studied external monopole excitations at two frequencies. A cylinder resonance of 100 Hz, where the interior acoustic field is driven in multiple, off-resonance cylinder cavity modes, and a cylinder resonance of 200 Hz are characterized by both near and off-resonance cylinder vibration modes which couple effectively with a single, dominant, low-order acoustic cavity mode at resonance. Previous work has focused almost exclusively on meeting objective (1) and solving a complex least-squares problem to arrive at an optimal force vector for a given set of actuator sites. In addition, it has been noted that when the cavity mode couples with cylinder vibration modes (our 200 Hz case) control spillover may occur in higher order cylinder shell vibrational modes. How to determine the best set of actuator sites to meet objectives (1)-(3) is the main contribution of our research effort. The selection of the best set of actuator sites from a set of potential sites is done via two metaheuristics -- simulated annealing and tabu search. Each of these metaheuristics partitions the set of potential actuator sites into two disjoint sets: those that are selected to control the noise (on) and those that are not (off). Next, each metaheuristic attempts to improve this initial solution by calculating the change in the objective value when one selected actuator site is turned off and one actuator site that previously was not selected is turned on. All such pairwise exchanges are performed and the exchange that improves the objective the most is made. Eventually the search is unable to improve the objective value and a local optimum (with respect to pairwise exchanges) is reached. Both simulated annealing and tabu search provide mechanisms to escape local optima and allow the search to continue until (hopefully) a global optimum is found. Our experiments with the 100 Hz and 200 Hz cases confirm that both metaheuristics are able to uncover better solutions than those selected based upon engineering judgement alone. In addition, the high quality solutions generated by these metaheuristics, when minimizing interior noise, do not further excite the cylinder shell. Thus, we are able to meet objective (2) without imposing an additional constraint or forming a multiobjective performance measure. An additional observation is that in many cases the amplitude and phase values for several chosen actuator sites were nearly identical. This natural grouping means that fewer control channels are needed and the resulting control system is simpler. Currently no power requirements have been set, so objective (3) cannot be addressed. A set of experiments is planned with a laboratory test article (a cylinder). For these experiments the transfer matrices will be generated experimentally. It is hoped that the predicted performance of the best actuator sites found by our metaheuristics will correlate well with the measured performance.

Flow-induced Vibration of SSME Main Injector Liquid-oxygen Posts

NASA Technical Reports Server (NTRS)

Chen, S. S.; Jendrzejczyk, J. A.; Wambsganss, M. W.

1985-01-01

The liquid-oxygen (LOX) posts are exposed to hot hydrogen flowing over the tubes on its way to the combustion chamber. Fatigue cracking of some LOX posts was observed after test firing of the SSMEs. A current design modification consists of attaching impingement shields to the LOX posts in the outer row. The modification improved the vibration/fatigue problem of the LOX posts, but resulted in an increased pressure drop that ultimately shortened the life expectancy of other components. A fundamental study of vibration of the LOX posts was initiated to understand the flow-induced vibration problem and to develop techniques to avoid detrimental vibrational effects with the overall objective of improving engine life. This effort, including an assessment of the problem, scoping calculation and experiment, and a work plan for an integrated theoretical/experimental study of the problem is summarized.

KENNEDY SPACE CENTER, FLA. - Mobile Launcher Platform (MLP) number 3 and a set of twin solid rocket boosters, atop the crawler-transporter, crawl out of the Vehicle Assembly Building (VAB) in support of the second engineering analysis vibration test on the crawler and MLP. In the background is another MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-21

KENNEDY SPACE CENTER, FLA. - Mobile Launcher Platform (MLP) number 3 and a set of twin solid rocket boosters, atop the crawler-transporter, crawl out of the Vehicle Assembly Building (VAB) in support of the second engineering analysis vibration test on the crawler and MLP. In the background is another MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - The crawler transporter slowly moves the Mobile Launcher Platform (MLP), carrying a set of twin solid rocket boosters, away from the Vehicle Assembly Building (VAB) in support of engineering analysis vibration tests on the crawler and MLP. On either side of the boosters on the horizon can be seen the two launch pads. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-17

KENNEDY SPACE CENTER, FLA. - The crawler transporter slowly moves the Mobile Launcher Platform (MLP), carrying a set of twin solid rocket boosters, away from the Vehicle Assembly Building (VAB) in support of engineering analysis vibration tests on the crawler and MLP. On either side of the boosters on the horizon can be seen the two launch pads. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - A Kennedy Space Center technician monitors the performance of a crawler-transporter as it moves Mobile Launcher Platform (MLP) number 3, with a set of twin solid rocket boosters bolted atop, to the intersection in the crawlerway during the second engineering analysis vibration test on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A, and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-21

KENNEDY SPACE CENTER, FLA. - A Kennedy Space Center technician monitors the performance of a crawler-transporter as it moves Mobile Launcher Platform (MLP) number 3, with a set of twin solid rocket boosters bolted atop, to the intersection in the crawlerway during the second engineering analysis vibration test on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A, and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - Mobile Launcher Platform (MLP) number 3 and a set of twin solid rocket boosters bolted to it, atop the crawler-transporter, inches along the crawlerway in support of the second engineering analysis vibration test on the crawler and MLP. The MLP is viewed from the KSC News Center across the turn basin. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-21

KENNEDY SPACE CENTER, FLA. - Mobile Launcher Platform (MLP) number 3 and a set of twin solid rocket boosters bolted to it, atop the crawler-transporter, inches along the crawlerway in support of the second engineering analysis vibration test on the crawler and MLP. The MLP is viewed from the KSC News Center across the turn basin. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - A Kennedy Space Center technician walks towards the intersection of the crawlerway beside a crawler-transporter moving Mobile Launcher Platform (MLP) number 3, with a set of twin solid rocket boosters bolted atop, during the second engineering analysis vibration test on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A, and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-21

KENNEDY SPACE CENTER, FLA. - A Kennedy Space Center technician walks towards the intersection of the crawlerway beside a crawler-transporter moving Mobile Launcher Platform (MLP) number 3, with a set of twin solid rocket boosters bolted atop, during the second engineering analysis vibration test on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A, and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

KENNEDY SPACE CENTER, FLA. - Mobile Launcher Platform (MLP) number 3 and a set of twin solid rocket boosters, atop the crawler-transporter, inch along the crawlerway in support of the second engineering analysis vibration test on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A (on the horizon at right; Pad 39B is at far left), and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

NASA Image and Video Library

2003-11-21

KENNEDY SPACE CENTER, FLA. - Mobile Launcher Platform (MLP) number 3 and a set of twin solid rocket boosters, atop the crawler-transporter, inch along the crawlerway in support of the second engineering analysis vibration test on the crawler and MLP. The crawler is moving at various speeds up to 1 mph in an effort to achieve vibration data gathering goals as it leaves the VAB, travels toward Launch Pad 39A (on the horizon at right; Pad 39B is at far left), and then returns. The boosters are braced at the top for stability. The primary purpose of these rollout tests is to gather data to develop future maintenance requirements on the transport equipment and the flight hardware. Various parts of the MLP and crawler transporter have been instrumented with vibration data collection equipment.

Active vibration control for flexible rotor by optimal direct-output feedback control

NASA Technical Reports Server (NTRS)

Nonami, Kenzou; Dirusso, Eliseo; Fleming, David P.

1989-01-01

Experimental research tests were performed to actively control the rotor vibrations of a flexible rotor mounted on flexible bearing supports. The active control method used in the tests is called optimal direct-output feedback control. This method uses four electrodynamic actuators to apply control forces directly to the bearing housings in order to achieve effective vibration control of the rotor. The force actuators are controlled by an analog controller that accepts rotor displacement as input. The controller is programmed with experimentally determined feedback coefficients; the output is a control signal to the force actuators. The tests showed that this active control method reduced the rotor resonance peaks due to unbalance from approximately 250 micrometers down to approximately 25 micrometers (essentially runout level). The tests were conducted over a speed range from 0 to 10,000 rpm; the rotor system had nine critical speeds within this speed range. The method was effective in significantly reducing the rotor vibration for all of the vibration modes and critical speeds.

Active vibration control for flexible rotor by optimal direct-output feedback control

NASA Technical Reports Server (NTRS)

Nonami, K.; Dirusso, E.; Fleming, D. P.

1989-01-01

Experimental research tests were performed to actively control the rotor vibrations of a flexible rotor mounted on flexible bearing supports. The active control method used in the tests is called optimal direct-output feedback control. This method uses four electrodynamic actuators to apply control forces directly to the bearing housings in order to achieve effective vibration control of the rotor. The force actuators are controlled by an analog controller that accepts rotor displacement as input. The controller is programmed with experimentally determined feedback coefficients; the output is a control signal to the force actuators. The tests showed that this active control method reduced the rotor resonance peaks due to unbalance from approximately 250 microns down to approximately 25 microns (essentially runout level). The tests were conducted over a speed range from 0 to 10,000 rpm; the rotor system had nine critical speeds within this speed range. The method was effective in significantly reducing the rotor vibration for all of the vibration modes and critical speeds.

Note: Real time control of a tunable vibration absorber based on magnetorheological elastomer for suppressing tonal vibrations

NASA Astrophysics Data System (ADS)

Kim, Young-Keun; Bae, Hyo-In; Koo, Jeong-Hoi; Kim, Kyung-Soo; Kim, Soohyun

2012-04-01

An adaptive tunable vibration absober based on magnetorheological elastomer (MRE) is designed as an intelligent device for auto-tuning itself to the time-varying harmonic disturbance force to reduce the unwanted vibration of the primary system in the steady state. The objectives of this note are to develop and implement a continuous control method for a MRE tunable vibration absorber (TVA) and to evaluate its performance in suppressing time-varying tonal vibrations. In the proposed control, the stiffness of MREs is continuously varied based on a nonlinear tuning function that relates the response of the system to the input magnetic field density. Through experiments, it will be shown that the proposed MRE TVA reduces in real time the transmission of a time-varying excited vibration of 48-55 Hz, which shows the potential applicability of the MRE in reducing unwanted vibration to precision devices.

Anti-vibration gloves?

PubMed

Hewitt, Sue; Dong, Ren G; Welcome, Daniel E; McDowell, Thomas W

2015-03-01

For exposure to hand-transmitted vibration (HTV), personal protective equipment is sold in the form of anti-vibration (AV) gloves, but it remains unclear how much these gloves actually reduce vibration exposure or prevent the development of hand-arm vibration syndrome in the workplace. This commentary describes some of the issues that surround the classification of AV gloves, the assessment of their effectiveness and their applicability in the workplace. The available information shows that AV gloves are unreliable as devices for controlling HTV exposures. Other means of vibration control, such as using alternative production techniques, low-vibration machinery, routine preventative maintenance regimes, and controlling exposure durations are far more likely to deliver effective vibration reductions and should be implemented. Furthermore, AV gloves may introduce some adverse effects such as increasing grip force and reducing manual dexterity. Therefore, one should balance the benefits of AV gloves and their potential adverse effects if their use is considered. © Crown copyright 2014.

Adaptive vibration control of structures under earthquakes

NASA Astrophysics Data System (ADS)

Lew, Jiann-Shiun; Juang, Jer-Nan; Loh, Chin-Hsiung

2017-04-01

techniques, for structural vibration suppression under earthquakes. Various control strategies have been developed to protect structures from natural hazards and improve the comfort of occupants in buildings. However, there has been little development of adaptive building control with the integration of real-time system identification and control design. Generalized predictive control, which combines the process of real-time system identification and the process of predictive control design, has received widespread acceptance and has been successfully applied to various test-beds. This paper presents a formulation of the predictive control scheme for adaptive vibration control of structures under earthquakes. Comprehensive simulations are performed to demonstrate and validate the proposed adaptive control technique for earthquake-induced vibration of a building.

Hybrid PD and effective multi-mode positive position feedback control for slewing and vibration suppression of a smart flexible manipulator

NASA Astrophysics Data System (ADS)

Lou, Jun-qiang; Wei, Yan-ding; Yang, Yi-ling; Xie, Feng-ran

2015-03-01

A hybrid control strategy for slewing and vibration suppression of a smart flexible manipulator is presented in this paper. It consists of a proportional derivative controller to realize motion control, and an effective multi-mode positive position feedback (EMPPF) controller to suppress the multi-mode vibration. Rather than treat each mode equally as the standard multi-mode PPF, the essence of the EMPPF is that control forces of different modes are applied according to the mode parameters of the respective modes, so the vibration modes with less vibration energy receive fewer control forces. Stability conditions for the close loop system are established through stability analysis. Optimal parameters of the EMPPF controller are obtained using the method of root locus analysis. The performance of the proposed strategy is demonstrated by simulation and experiments. Experimental results show that the first two vibration modes of the manipulator are effectively suppressed. The setting time of the setup descends approximately 55%, reaching 3.12 s from 5.67 s.

Actuator placement in prestressed adaptive trusses for vibration control

NASA Technical Reports Server (NTRS)

Jalihal, P.; Utku, Senol; Wada, Ben K.

1993-01-01

This paper describes the optimal location selection of actuators for vibration control in prestressed adaptive trusses. Since prestressed adaptive trusses are statically indeterminate, the actuators to be used for vibration control purposes must work against (1) existing static axial prestressing forces, (2) static axial forces caused by the actuation, and (3) dynamic axial forces caused by the motion of the mass. In statically determinate adaptive trusses (1) and (2) are non - existing. The actuator placement problem in statically indeterminate trusses is therefore governed by the actuation energy and the actuator strength requirements. Assuming output feedback type control of selected vibration modes in autonomous systems, a procedure is given for the placement of vibration controlling actuators in prestressed adaptive trusses.

Dynamics Control Approaches to Improve Vibratory Environment of the Helicopter Aircrew

NASA Astrophysics Data System (ADS)

Wickramasinghe, Viresh Kanchana

Although helicopter has become a versatile mode of aerial transportation, high vibration levels leads to poor ride quality for its passengers and aircrew. Undesired vibration transmitted through the helicopter seats have been known to cause fatigue and discomfort to the aircrew in the short-term as well as neck strain and back pain injuries due to long-term exposure. This research study investigated the use of novel active as well as passive methodologies integrated in helicopter seats to mitigate the aircrew exposure to high vibration levels. Due to significantly less certification effort required to modify the helicopter seat structure, application of novel technologies to the seat is more practical compared to flight critical components such as the main rotor to reduce aircrew vibration. In particular, this research effort developed a novel adaptive seat mount approach based on active vibration control technology. This novel design that incorporated two stacked piezoelectric actuators as active struts increases the bending stiffness to avoid the low frequency resonance while generating forces to counteract higher harmonic vibration peaks. A real-time controller implemented using a feed-forward algorithm based on adaptive notches counteracted the forced vibration peaks while a robust feedback control algorithm suppressed the resonance modes. The effectiveness of the adaptive seat mount system was demonstrated through extensive closed-loop control tests on a full-scale helicopter seat using representative helicopter floor vibration profiles. Test results concluded that the proposed adaptive seat mount approach based on active control technology is a viable solution for the helicopter seat vibration control application. In addition, a unique flight test using a Bell-412 helicopter demonstrated that the aircrew is exposed to high levels of vibration during flight and that the whole body vibration spectrum varied substantially depending on operating conditions as well as the aircrew configurations. This investigation also demonstrated the suitability of integrating novel energy absorbing cushion materials to the seat as a low cost solution to improve aircrew vibration suppression. Therefore, it was recommended to pursue certification of novel seat cushion materials as a near-term solution to mitigate undesirable occupational health hazards in helicopter aircrew due to vibration exposure.

Active Control of Inlet Noise on the JT15D Turbofan Engine

NASA Technical Reports Server (NTRS)

Smith, Jerome P.; Hutcheson, Florence V.; Burdisso, Ricardo A.; Fuller, Chris R.

1999-01-01

This report presents the key results obtained by the Vibration and Acoustics Laboratories at Virginia Tech over the year from November 1997 to December 1998 on the Active Noise Control of Turbofan Engines research project funded by NASA Langley Research Center. The concept of implementing active noise control techniques with fuselage-mounted error sensors is investigated both analytically and experimentally. The analytical part of the project involves the continued development of an advanced modeling technique to provide prediction and design guidelines for application of active noise control techniques to large, realistic high bypass engines of the type on which active control methods are expected to be applied. Results from the advanced analytical model are presented that show the effectiveness of the control strategies, and the analytical results presented for fuselage error sensors show good agreement with the experimentally observed results and provide additional insight into the control phenomena. Additional analytical results are presented for active noise control used in conjunction with a wavenumber sensing technique. The experimental work is carried out on a running JT15D turbofan jet engine in a test stand at Virginia Tech. The control strategy used in these tests was the feedforward Filtered-X LMS algorithm. The control inputs were supplied by single and multiple circumferential arrays of acoustic sources equipped with neodymium iron cobalt magnets mounted upstream of the fan. The reference signal was obtained from an inlet mounted eddy current probe. The error signals were obtained from a number of pressure transducers flush-mounted in a simulated fuselage section mounted in the engine test cell. The active control methods are investigated when implemented with the control sources embedded within the acoustically absorptive material on a passively-lined inlet. The experimental results show that the combination of active control techniques with fuselage-mounted error sensors and passive control techniques is an effective means of reducing radiated noise from turbofan engines. Strategic selection of the location of the error transducers is shown to be effective for reducing the radiation towards particular directions in the farfield. An analytical model is used to predict the behavior of the control system and to guide the experimental design configurations, and the analytical results presented show good agreement with the experimentally observed results.

Boundary control of anti-symmetric vibration of satellite with flexible appendages in planar motion with exponential stability

NASA Astrophysics Data System (ADS)

Rad, Hossein Kaviani; Salarieh, Hassan; Alasty, Aria; Vatankhah, Ramin

2018-06-01

In this research, we have investigated the planar maneuver of a flexible satellite with appendages anti-symmetric vibration. The hybrid governing equations are comprised of coupled partial and ordinary differential equations which are derived by employing Hamilton's principle. In this paper, control goals are the tracking desired pitch angle along with the flexible appendages vibration suppression simultaneously by using only one control torque which is applied to the central hub. The boundary control is proposed to fulfill these control aims; furthermore, this boundary control ensures that spillover instability phenomenon is eliminated, and in-domain sensors and actuators implement are excluded. Indeed, the proposed boundary control is able to stabilize an infinite number of vibration modes, which is one of the important benefits of the proposed control when it is considered that different factors including external disturbances and even the satellite maneuver can excite the various vibration modes of the flexible appendages and consequently the excitement of the high order vibration modes will be possible. Lyapunov's direct method is used to prove the exponential stability; moreover, this Proof is achieved in absence of any damping effect in modeling the vibrations of flexible appendages. In addition, the procedure for finding the boundary control coefficients which ensures the exponential stability is provided. Eventually, numerical simulations are presented to illustrate the effectiveness of the proposed boundary control.

Detecting of transient vibration signatures using an improved fast spatial-spectral ensemble kurtosis kurtogram and its applications to mechanical signature analysis of short duration data from rotating machinery

NASA Astrophysics Data System (ADS)

Chen, BinQiang; Zhang, ZhouSuo; Zi, YanYang; He, ZhengJia; Sun, Chuang

2013-10-01

Detecting transient vibration signatures is of vital importance for vibration-based condition monitoring and fault detection of the rotating machinery. However, raw mechanical signals collected by vibration sensors are generally mixtures of physical vibrations of the multiple mechanical components installed in the examined machinery. Fault-generated incipient vibration signatures masked by interfering contents are difficult to be identified. The fast kurtogram (FK) is a concise and smart gadget for characterizing these vibration features. The multi-rate filter-bank (MRFB) and the spectral kurtosis (SK) indicator of the FK are less powerful when strong interfering vibration contents exist, especially when the FK are applied to vibration signals of short duration. It is encountered that the impulsive interfering contents not authentically induced by mechanical faults complicate the optimal analyzing process and lead to incorrect choosing of the optimal analysis subband, therefore the original FK may leave out the essential fault signatures. To enhance the analyzing performance of FK for industrial applications, an improved version of fast kurtogram, named as "fast spatial-spectral ensemble kurtosis kurtogram", is presented. In the proposed technique, discrete quasi-analytic wavelet tight frame (QAWTF) expansion methods are incorporated as the detection filters. The QAWTF, constructed based on dual tree complex wavelet transform, possesses better vibration transient signature extracting ability and enhanced time-frequency localizability compared with conventional wavelet packet transforms (WPTs). Moreover, in the constructed QAWTF, a non-dyadic ensemble wavelet subband generating strategy is put forward to produce extra wavelet subbands that are capable of identifying fault features located in transition-band of WPT. On the other hand, an enhanced signal impulsiveness evaluating indicator, named "spatial-spectral ensemble kurtosis" (SSEK), is put forward and utilized as the quantitative measure to select optimal analyzing parameters. The SSEK indicator is robuster in evaluating the impulsiveness intensity of vibration signals due to its better suppressing ability of Gaussian noise, harmonics and sporadic impulsive shocks. Numerical validations, an experimental test and two engineering applications were used to verify the effectiveness of the proposed technique. The analyzing results of the numerical validations, experimental tests and engineering applications demonstrate that the proposed technique possesses robuster transient vibration content detecting performance in comparison with the original FK and the WPT-based FK method, especially when they are applied to the processing of vibration signals of relative limited duration.

Ultrasonic Vibration Assisted Grinding of Bio-ceramic Materials: Modeling, Simulation, and Experimental Investigations on Edge Chipping

NASA Astrophysics Data System (ADS)

Tesfay, Hayelom D.

Bio-ceramics are those engineered materials that find their applications in the field of biomedical engineering or medicine. They have been widely used in dental restorations, repairing bones, joint replacements, pacemakers, kidney dialysis machines, and respirators. etc. due to their physico-chemical properties, such as excellent corrosion resistance, good biocompatibility, high strength and high wear resistance. Because of their inherent brittleness and hardness nature they are difficult to machine to exact sizes and dimensions. Abrasive machining processes such as grinding is one of the most widely used manufacturing processes for bioceramics. However, the principal technical challenge resulted from these machining is edge chipping. Edge chipping is a common edge failure commonly observed during the machining of bio-ceramic materials. The presence of edge chipping on bio-ceramic products affects dimensional accuracy, increases manufacturing cost, hider their industrial applications and causes potential failure during service. To overcome these technological challenges, a new ultrasonic vibration-assisted grinding (UVAG) manufacturing method has been developed and employed in this research. The ultimate aim of this study is to develop a new cost-effective manufacturing process relevant to eliminate edge chippings in grinding of bio-ceramic materials. In this dissertation, comprehensive investigations will be carried out using experimental, theoretical, and numerical approaches to evaluate the effect of ultrasonic vibrations on edge chipping of bioceramics. Moreover, effects of nine input variables (static load, vibration frequency, grinding depth, spindle speed, grinding distance, tool speed, grain size, grain number, and vibration amplitude) on edge chipping will be studied based on the developed models. Following a description of previous research and existing approaches, a series of experimental tests on three bio-ceramic materials (Lava, partially fired Lava, and Alumina) were conducted. Based on the experimental results, analytical models for UVAG and CG (conventional grinding without ultrasonic vibration) processes were developed. As for the numerical study, an extended finite element method (XFEM) based on Virtual Crack Closure Technique (VCCT) in ABAQUS was used to model the formation of edge chippings both for UVAG and CG processes. The experimental results are compared against the numerical FEA and the analytical models. The experimental, theoretical, and computational simulation results revealed that the edge chipping size of bioceramics can be significantly reduced with the assistance of ultrasonic vibration. The investigation procedures and the results obtained in this dissertation would be used as a reference and practical guidance for choosing reasonable process variables as well as designing mathematical (analytical and numerical) models in manufacturing industries and academic institutions when the edge chippings of brittle materials are expected to be controlled.

CCD high-speed videography system with new concepts and techniques

NASA Astrophysics Data System (ADS)

Zheng, Zengrong; Zhao, Wenyi; Wu, Zhiqiang

1997-05-01

A novel CCD high speed videography system with brand-new concepts and techniques is developed by Zhejiang University recently. The system can send a series of short flash pulses to the moving object. All of the parameters, such as flash numbers, flash durations, flash intervals, flash intensities and flash colors, can be controlled according to needs by the computer. A series of moving object images frozen by flash pulses, carried information of moving object, are recorded by a CCD video camera, and result images are sent to a computer to be frozen, recognized and processed with special hardware and software. Obtained parameters can be displayed, output as remote controlling signals or written into CD. The highest videography frequency is 30,000 images per second. The shortest image freezing time is several microseconds. The system has been applied to wide fields of energy, chemistry, medicine, biological engineering, aero- dynamics, explosion, multi-phase flow, mechanics, vibration, athletic training, weapon development and national defense engineering. It can also be used in production streamline to carry out the online, real-time monitoring and controlling.

Human-simulated intelligent control of train braking response of bridge with MRB

NASA Astrophysics Data System (ADS)

Li, Rui; Zhou, Hongli; Wu, Yueyuan; Wang, Xiaojie

2016-04-01

The urgent train braking could bring structural response menace to the bridge under passive control. Based on the analysis of breaking dynamics of a train-bridge vibration system, a magnetorheological elastomeric bearing (MRB) whose mechanical parameters are adjustable is designed, tested and modeled. A finite element method (FEM) is carried out to model and optimize a full scale vibration isolation system for railway bridge based on MRB. According to the model above, we also consider the effect of different braking stop positions on the vibration isolation system and classify the bridge longitudinal vibration characteristics into several cases. Because the train-bridge vibration isolation system has multiple vibration states and strongly coupling with nonlinear characteristics, a human-simulated intelligent control (HSIC) algorithm for isolating the bridge vibration under the impact of train braking is proposed, in which the peak shear force of pier top, the displacement of beam and the acceleration of beam are chosen as control goals. The simulation of longitudinal vibration control system under the condition of train braking is achieved by MATLAB. The results indicate that different braking stop positions significantly affect the vibration isolation system and the structural response is the most drastic when the train stops at the third cross-span. With the proposed HSIC smart isolation system, the displacement of bridge beam and peak shear force of pier top is reduced by 53.8% and 34.4%, respectively. Moreover, the acceleration of bridge beam is effectively controlled within limited range.

Study of inducer load and stress, volume 2

NASA Technical Reports Server (NTRS)

1972-01-01

A program of analysis, design, fabrication and testing has been conducted to develop computer programs for predicting rocket engine turbopump inducer hydrodynamic loading, stress magnitude and distribution, and vibration characteristics. Methods of predicting blade loading, stress, and vibration characteristics were selected from a literature search and used as a basis for the computer programs. An inducer, representative of typical rocket engine inducers, was designed, fabricated, and tested with special instrumentation selected to provide measurements of blade surface pressures and stresses. Data from the tests were compared with predicted values and the computer programs were revised as required to improve correlation. For Volume 1 see N71-20403. For Volume 2 see N71-20404.

Low Head, Vortex Induced Vibrations River Energy Converter

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

Bernitsas, Michael B.; Dritz, Tad

2006-06-30

Vortex Induced Vibrations Aquatic Clean Energy (VIVACE) is a novel, demonstrated approach to extracting energy from water currents. This invention is based on a phenomenon called Vortex Induced Vibrations (VIV), which was first observed by Leonardo da Vinci in 1504AD. He called it ‘Aeolian Tones.’ For decades, engineers have attempted to prevent this type of vibration from damaging structures, such as offshore platforms, nuclear fuel rods, cables, buildings, and bridges. The underlying concept of the VIVACE Converter is the following: Strengthen rather than spoil vortex shedding; enhance rather than suppress VIV; harness rather than mitigate VIV energy. By maximizing andmore » utilizing this unique phenomenon, VIVACE takes this “problem” and successfully transforms it into a valuable resource for mankind.« less

Patellar tendon vibration reduces the increased facilitation from quadriceps to soleus in post-stroke hemiparetic individuals.

PubMed

Maupas, Eric; Dyer, Joseph-Omer; Melo, Sibele de Andrade; Forget, Robert

2017-09-01

Stimulation of the femoral nerve in healthy people can facilitate soleus H-reflex and electromyography (EMG) activity. In stroke patients, such facilitation of transmission in spinal pathways linking the quadriceps and soleus muscles is enhanced and related to co-activation of knee and ankle extensors while sitting and walking. Soleus H-reflex facilitation can be depressed by vibration of the quadriceps in healthy people, but the effects of such vibration have never been studied on the abnormal soleus facilitation observed in people after stroke. To determine whether vibration of the quadriceps can modify the enhanced heteronymous facilitation of the soleus muscle observed in people with spastic stroke after femoral nerve stimulation and compare post-vibration effects on soleus facilitation in control and stroke individuals. Modulation of voluntary soleus EMG activity induced by femoral nerve stimulation (2×motor threshold) was assessed before, during and after vibration of the patellar tendon in 10 healthy controls and 17 stroke participants. Voluntary soleus EMG activity was facilitated by femoral nerve stimulation in 4/10 (40%) controls and 11/17 (65%) stroke participants. The level of facilitation was greater in the stroke than control group. Vibration significantly reduced early heteronymous facilitation in both groups (50% of pre-vibration values). However, the delay in recovery of soleus facilitation after vibration was shorter for the stroke than control group. The control condition with the vibrator turned off had no effect on the modulation. Patellar tendon vibration can reduce the facilitation between knee and ankle extensors, which suggests effective presynaptic inhibition but decreased post-activation depression in the lower limb of people after chronic hemiparetic stroke. Further studies are warranted to determine whether such vibration could be used to reduce the abnormal extension synergy of knee and ankle extensors in people after hemiparetic stroke. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Adaptive vibration suppression system: an iterative control law for a piezoelectric actuator shunted by a negative capacitor.

PubMed

Kodejska, Milos; Mokry, Pavel; Linhart, Vaclav; Vaclavik, Jan; Sluka, Tomas

2012-12-01

An adaptive system for the suppression of vibration transmission using a single piezoelectric actuator shunted by a negative capacitance circuit is presented. It is known that by using a negative-capacitance shunt, the spring constant of a piezoelectric actuator can be controlled to extreme values of zero or infinity. Because the value of spring constant controls a force transmitted through an elastic element, it is possible to achieve a reduction of transmissibility of vibrations through the use of a piezoelectric actuator by reducing its effective spring constant. Narrow frequency range and broad frequency range vibration isolation systems are analyzed, modeled, and experimentally investigated. The problem of high sensitivity of the vibration control system to varying operational conditions is resolved by applying an adaptive control to the circuit parameters of the negative capacitor. A control law that is based on the estimation of the value of the effective spring constant of a shunted piezoelectric actuator is presented. An adaptive system which achieves a self-adjustment of the negative capacitor parameters is presented. It is shown that such an arrangement allows the design of a simple electronic system which offers a great vibration isolation efficiency under variable vibration conditions.

Technology Transferred to the Kirby Company

NASA Technical Reports Server (NTRS)

1996-01-01

NASA Lewis Research Center's Propulsion Systems Branch, evaluated the structural and vibration characteristics of the Kirby Model G-4 fan. Modes of vibration and resonance potential were evaluated in the Holography Test Lab at Lewis. As a result of the Lewis tests and rotor structural evaluation, Kirby engineers gained new insights into their existing design, enabling them to develop a more robust fan for use in their vacuum cleaners.

The Shock and Vibration Digest. Volume 16, Number 12

DTIC Science & Technology

1984-12-01

speed, spring constant of meshing gear teeth, and mass of the Dept. of Applied Mathematical Studies , Univ of rotating years. All of these factors are...interest that stress concentration factors in civil, mechanical, naval, and aeronautical Most graduate engineers have learned that conformal structural...branes. Conformal mapping has also been used Applcaton f th coforal appig tchnque recently to study the vibration characteristics of is straightforward

Research on mining truck vibration control based on particle damping

NASA Astrophysics Data System (ADS)

Liming, Song; Wangqiang, Xiao; Zeguang, Li; Haiquan, Guo; Zhe, Yang

2018-03-01

More and more attentions were got by people about the research on mining truck driving comfort. As the vibration transfer terminal, cab is one of the important part of mining truck vibration control. In this paper, based on particle damping technology and its application characteristics, through the discrete element modeling, DEM & FEM coupling simulation and analysis, lab test verification and actual test in the truck, particle damping technology was successfully used in driver’s seat base of mining truck, cab vibration was reduced obviously, meanwhile applied research and method of particle damping technology in mining truck vibration control were provided.

A Resonant Damping Study Using Piezoelectric Materials

NASA Technical Reports Server (NTRS)

Min, J. B.; Duffy, K. P.; Choi, B. B.; Morrison, C. R.; Jansen, R. H.; Provenza, A. J.

2008-01-01

Excessive vibration of turbomachinery blades causes high cycle fatigue (HCF) problems requiring damping treatments to mitigate vibration levels. Based on the technical challenges and requirements learned from previous turbomachinery blade research, a feasibility study of resonant damping control using shunted piezoelectric patches with passive and active control techniques has been conducted on cantilever beam specimens. Test results for the passive damping circuit show that the optimum resistive shunt circuit reduces the third bending resonant vibration by almost 50%, and the optimum inductive circuit reduces the vibration by 90%. In a separate test, active control reduced vibration by approximately 98%.

Reduction of the Radiating Sound of a Submerged Finite Cylindrical Shell Structure by Active Vibration Control

PubMed Central

Kim, Heung Soo; Sohn, Jung Woo; Jeon, Juncheol; Choi, Seung-Bok

2013-01-01

In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs) were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water. PMID:23389344