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2009-05-19
Journal Article
2009-01-2070
Tao Peng, Teik C. Lim
The noise and vibration response of hypoid or bevel geared rotor system, primarily excited by transmission error (TE), and mesh vector and stiffness variations, can be affected significantly by the coupling between the driveline rotor dynamics and gear vibratory response. This is because of the inherent design comprising of non-parallel rotational axes and time-varying as well as spatial-varying gear mesh characteristics. One of the important factors of the driveline system dynamics is the rotor gyroscopic effect that has not been studied extensively in traditional gear dynamics. To address this gap in the literature, this paper attempts to examine the influence of incorporating gyroscopic terms in the hypoid gear dynamic simulation. A multi-degrees-of-freedom, multi-body dynamic model is used as a generalized representation of a hypoid geared rotor system.
2009-05-19
Journal Article
2009-01-2111
Unnikrishnan Kuttan Chandrika, Jay Kim
A new algorithm to detect and to quantify the seriousness of the detected squeak and rattle (S&R) events was developed. A T-F analysis technique called AWT, the Zwicker loudness model and leaky integration are employed to define new concepts we called transient specific loudness time histories and perceived transient loudness time history. The detection threshold of the perceived transient loudness was identified by a clever interpretation of jury test results. The proposed algorithm showed a good promise producing results that are well correlated with the jury tests. The new algorithm developed in this work will be able to automate detection and rating of the S&R events with good accuracy and with minimum possibility of false alarm under normal operating conditions
2005-05-16
Technical Paper
2005-01-2300
Yi Wang, Teik C. Lim, Mark L. Clapper, Nae-Ming Shiau, Paul Braunwart, Yuejun Lee
A new multi-level substructuring approach is proposed to predict the NVH response of driveline systems for the purpose of analyzing rear axle gear whine concern. The fundamental approach is rooted in the spectral-based compliance coupling theory for combining the dynamics of two adjacent subsystems. This proposed scheme employs test-based frequency response functions of individual subsystems, including gear pairs, propshaft, control arms and axle tube, in free-free state as sequential building blocks to synthesize the complete system NVH response. Using an existing driveline design, the salient features of this substructuring approach is demonstrated. Specifically, the synthesized results for the pinion-propshaft assembly and complete vehicle system are presented. The predictions are seen to be in excellent agreement with the experimental data from direct vehicle measurements.
2014-09-16
Technical Paper
2014-01-2174
Nicholas Ernest, Kelly Cohen, Corey Schumacher, David Casbeer
Abstract Looking forward to an autonomous Unmanned Combat Aerial Vehicle (UCAV) for future applications, it becomes apparent that on-board intelligent controllers will be necessary for these advanced systems. LETHA (Learning Enhanced Tactical Handling Algorithm) was created to develop intelligent managers for these advanced unmanned craft through the novel means of a genetic cascading fuzzy system. In this approach, a genetic algorithm creates rule bases and optimizes membership functions for multiple fuzzy logic systems, whose inputs and outputs feed into one another alongside crisp data. A simulation space referred to as HADES (Hoplological Autonomous Defend and Engage Simulation) was created in which LETHA can train the UCAVs intelligent controllers.
2013-05-13
Journal Article
2013-01-1951
Guohua Sun, Mingfeng Li, Teik C. Lim, Ming-Ran Lee, Ming Cheng, Wayne Vanhaaften, Takeshi Abe
Active noise control (ANC) technique with the filtered-x least mean square (FXLMS) algorithm has proven its efficiency and drawn increasingly interests in vehicle noise control applications. However, many vehicle interior and/or exterior noises are exhibiting non-Gaussian type with impulsive characteristic, such as diesel knocking noise, injector ticking, impulsive crank-train noise, gear rattle, and road bumps, etc. Therefore, the conventional FXLMS algorithm that is based on the assumption of deterministic and/or Gaussian signal may not be appropriate for tackling this type of impulsive noise. In this paper, an ANC system configured with modified FXLMS (MFXLMS) algorithm by adding thresholds on reference and error signal paths is proposed for impulsive noise control. To demonstrate the effectiveness of the proposed algorithm, an experimental study is conducted in the laboratory.
2013-05-13
Journal Article
2013-01-1895
Yawen Wang, Teik C. Lim, Junyi Yang
A multi-point hypoid gear mesh model based on 3-dimensional loaded tooth contact analysis is incorporated into a coupled multi-body dynamic and vibration hypoid gear model to predict more detailed dynamic behavior of each tooth pair. To validate the accuracy of the proposed model, the time-averaged mesh parameters are applied to linear time-invariant (LTI) analysis and the dynamic responses, such as dynamic mesh force, dynamic transmission error, are computed, which demonstrates good agreement with that predicted by single-point mesh model. Furthermore, a nonlinear time-varying (NLTV) dynamic analysis is performed considering the effect of backlash nonlinearity and time-varying mesh parameters, such as mesh stiffness, transmission error, mesh point and line-of-action. Simulation results show that the time history of the mesh parameters and dynamic mesh force for each pair of teeth within a full engagement cycle can be simulated.
2009-05-19
Technical Paper
2009-01-2145
Jie Duan, Mingfeng Li, Teik C. Lim, Ming-Ran Lee, Wayne Vanhaaften, Ming-Te Cheng, Takeshi Abe
An enhanced, frequency domain filtered-x least mean square (LMS) algorithm is proposed as the basis for an active control system for treating powertrain noise. There are primarily three advantages of this approach: (i) saving of computing time especially for long controller’s filter length; (ii) more accurate estimation of the gradient due to the sample averaging of the whole data block; and (iii) capacity for rapid convergence when the adaptation parameter is correctly adjusted for each frequency bin. Unlike traditional active noise control techniques for suppressing response, the proposed frequency domain FXLMS algorithm is targeted at tuning vehicle interior response in order to achieve a desirable sound quality. The proposed control algorithm is studied numerically by applying the analysis to treat vehicle interior noise represented by either measured or predicted cavity acoustic transfer functions.
1993-03-01
Technical Paper
930581
Diaa M. Hosny, Richard W. Young, null
Modeling of liner cavitation corrosion is of increasing significance since new engine design trends could aggravate the problem. Cavitation corrosion is of a complex nature and is affected by numerous coupled factors. A system approach to analyze and assess cavitation corrosion damage is deemed necessary. The approach accounts for the macroscopic and microscopic aspects of the phenomenon that include modeling of piston dynamics, liner transient vibration, pressure wave propagation, bubble dynamics and their effect on material damage. Though detection methods can provide crucial insight of factors that influence the cavitation problem, analysis methods are required at the initial design stage to provide overall engine design optimization and reduce prototype development cost and time. This analytical diagnostic approach provides a powerful tool to give valuable and relatively quick insight in solving engine liner cavitation corrosion problems.
1997-05-20
Technical Paper
971958
Michael Yang, Randall Allemang, David Brown
The perturbed boundary condition (PBC) model updating procedure has been developed to correct the finite element model [1]. The use of additional structural configurations adds more experimental information about the system and so better updating results can be expected. While it works well for simulated examples, practical limitations and additional requirements arise when it is used to update engineering structures. In this paper, the merits and the practical limitations of the techmques will be discussed in depth through the updating of a simulated system where the “measured” data is generated by computer and a real test structure where the experimentally measured data is noisy and distorted due to leakage. Useful suggestions and recommendations are drawn to guide the model updating of practical engineering structures.
1997-05-20
Technical Paper
971956
Drew A. Crafton, Jingdong Ding, Jay H. Kim
In highly reverberant enclosures, the identification of noise sources is a difficult and time consuming task. One effective approach is the Inverse Frequency Response Function (IFRF) method. This technique uses the inverse of an acoustic FRF matrix, that when multiplied by operating pressure response data reveals the noise source locations. Under highly reverberant conditions the deployment of a sound absorbing body is especially useful in reducing the effects of resonant modes that obscure important information in the FRFs. Without the absorption, the IFRF method becomes practically difficult to perform in these environments due to poor conditioning of the FRF matrix. This study investigates the feasibility of using Boundary Element and Finite Element Methods to establish the frequency response functions between selected panel points and microphones in the array.
1997-02-24
Technical Paper
971132
Ronald L. Huston, Ashraf M. Genaidy
This paper discusses design parameters for automotive seats intended to simultaneously meet three design objectives: comfort, safety, and health. (“Health” refers to long-term spinal support and vibration attenuation.) For comfort, various ergonomic and human factors considerations are discussed ranging from seat dimensions and adjustments to cushioning and occupant perceptions of comfort. For safety, the principal consideration is the effectiveness of the seat in providing spinal support during accidents-particularly in rear-end collisions. An additional safety consideration is the ability of the seat to keep an occupant “in position” during an accident. Finally, for health concerns, the focus is upon maintenance of spinal stability, seat ergonomics, and road induced vibration attenuation. The paper presents design parameters satisfying these design objectives.
1994-04-01
Technical Paper
941221
Atam P. Dhawan, Kevin R. Wheeler, Timothy F. Doniere
The High Pressure Oxidizer Turbine (HPOT) discharge temperature of the Space Shuttle Main Engine (SSME) was estimated using Radial Basis Function Neural Networks (RBFNN) during the startup transient. Estimation was performed for both nominal engine operation and during simulated input sensor failures. The K-means clustering algorithm was used on the data to determine the location of the basis function centers. The performance of the RBFNN is compared with that of a feedforward neural network trained with the Quickprop learning algorithm.
1994-04-01
Technical Paper
941220
A. J. Helmicki, S. Jaweed, K. Kolcio
Abstract A rigorous propulsion system modelling method suitable for control and condition monitoring purposes is developed. Previously developed control oriented methods yielding nominal models for gaseous medium propulsion systems are extended to include both nominal and anomalous models for liquid mediums in the following two ways. First, thermodynamic and fluid dynamic properties for liquids such as liquid hydrogen are incorporated into the governing equations. Second, anomalous conditions are captured in ways compatible with existing system theoretic design and analysis tools so that anomalous models can be constructed. Applications to the nominal SSME HPFP and degraded HPFP are considered as an example.
1995-05-01
Technical Paper
951271
Shumin Li, William Fladung, David Brown, Richard Bono
A testing procedure has been developed for measuring rotation/moment impedance functions. At connection points between components, both rotations and moments have important contributions in describing the dynamic characteristics of a coupled system. Analytically, both rotations and moments are included at connection points and are necessary for achieving a high fidelity model of a system. Experimentally, these effects have been historically neglected since no acceptable rotational transducers exist. If high fidelity impedance models are to be developed from experimental data, it is important to measure rotational impedance functions. In this paper a testing method is developed which uses the motion of a rigid body attached at a point of interest to determine displacements, forces, rotations and moments at the point of interest.
1996-02-01
Technical Paper
960041
Jeremy Williams
Order based torsional vibration analysis codes require a separate, non-linear model to compute single cylinder excitation torque for input. The slider crank mechanism model is typically derived using a crankshaft constant angular velocity assumption. Additionally, the equation describing this constant speed mechanism is derived in an approximate form. An exact model for the slider crank mechanism turning at non-constant speed is used in an iterative procedure with an order based impedance model torsional analysis code to quantify the effects of these assumptions. Results are presented for an in-line six diesel engine, and generalized where possible.
1998-10-19
Technical Paper
982612
Y. Liao, S. M. Jeng, M. A. Jog, M. A. Benjamin
The instability of a viscous liquid jet surrounded by a swirling air stream subject to a 3-D disturbance is predicted by a linear stability model. The effect of flow conditions, fluid properties and nozzle geometry on the disintegration of the liquid jet are investigated by conducting a parametric study. It is observed that the relative velocity between the liquid and gas phases promotes the interfacial aerodynamic instability. The predicted range of wave numbers in which asymmetric modes have higher growth rates than the axisymmetric mode and dominate the instability agrees very well with experimental data. The density ratio significantly enhances the instability as does the axial Weber number. Liquid viscosity inhibits the disintegration process and damps higher helical modes more significantly than the axisymmetric mode. It is observed that air swirl has a stabilizing effect on the liquid jet.
2004-06-15
Technical Paper
2004-01-2177
Woojin Park, Devender Singh
A manual task can be performed based on alternative movement techniques. Ergonomic human motion simulation requires consideration of alternative movement techniques, because they could bring different biomechanical, physiological, and psychophysical consequences. A method for identifying movement techniques from existing motion data was developed. The method is based on a JCV (Joint Contribution Vector) index and statistical clustering. A JCV quantifies a motion's underlying movement technique by computing contributions of individual body joint DOFs (degree-of-freedom) to the achievement of the task goal. Given a set of motions (motion capture data) achieving the same or similar task goals, alternative movement techniques can be identified by 1) representing the motions in terms of JCV and 2) performing a statistical clustering analysis. Performance of this movement technique identification method was evaluated based on a set of stoop and squat lifting motions.
2003-05-05
Technical Paper
2003-01-1731
Ren Pan, Teik C. Lim, Keith A. Hollman, Rodney C. Glover
A spectral-based substructuring approach applying linear frequency response functions (FRF) is proposed for improving the accuracy of simulating the dynamics of coupled systems. The method also applies a least square singular value decomposition (SVD) scheme to overcome the inherent computational deficiency in the basic substructuring formulation. The computational problem is caused by the magnification of measurement errors during any one of the matrix inversion calculations required for this method. The primary objective of applying this approach is to examine the possibility of analyzing higher frequency response that is normally not possible using conventional modeling technique such as the direct finite and boundary element, and lumped parameter techniques. In this study, additional concepts are also evaluated to quantify the limitations and range of applicability of the proposed substructuring approach for simulating the vibration response of complex powertrain structures.
2007-05-15
Technical Paper
2007-01-2420
Mingfeng Li, Teik C. Lim, Jun Wang
This paper discusses an enhanced active vibration control concept to suppress the dynamic response associated with gear mesh frequencies. In active control application, the control of dynamic gear mesh tonal response is essentially the rejection or suppression of periodical disturbance. Our active control experimental work shows that the existence of un-controlled harmonic result in the increase at these harmonics when applying direct control to the target mesh frequencies. To address this problem, the effect of the existence of un-correlated harmonic components in error signal when applying active control to suppress the target gear mesh harmonics is examined. The proposed adaptive controller that is designed specifically for tackling gear mesh frequency vibrations is based on an enhanced filtered-x least mean square algorithm (FXLMS) with frequency estimation to synthesize the required reference signal.
2007-05-15
Technical Paper
2007-01-2321
Xiangdong Zhu, Jay Kim
The analytic wavelet transform (AWT) is a wavelet transform that works much like a transient Fourier transform. Therefore the AWT enables utilizing advantages of both the wavelet transform and Fourier transform. A special form of AWT developed for transient vibration and acoustics signal analyses is applied to various engineering signals in this paper. Application examples include a general time-frequency (T-F) analysis, analysis of exposures to impulsive vibrations and noises, and estimation of reverberation times. Some new definitions such as the T-F noise reduction and frequency weighted time history are defined by taking the advantage of unique capabilities of the AWT. Possible automotive applications of these new concepts are briefly discussed.
2007-05-15
Technical Paper
2007-01-2228
Tao Peng, Teik C. Lim
High speed, precision geared rotor systems are often plagued by excessive vibration and noise problems. The response that is primarily excited by gear transmission error is actually coupled to the large displacement rotational motion of the driveline system. Classical pure vibration model assumes that the system oscillates about its mean position without coupling to the large displacement motion. To improve on this approach and understanding of the influences of the dynamic coupling, a coupled multi-body dynamic and vibration simulation model is proposed. Even though the focus is on hypoid geared rotor system, the model is more general since hypoid and bevel gears have more complicated geometry and time and spatial-varying characteristics compared to parallel axis gears.
2007-05-15
Technical Paper
2007-01-2243
Jun Wang, Teik C. Lim, Mingfeng Li
A general time-varying nonlinear dynamic model of a hypoid gear pair for rear axle applications is proposed. The dynamic model considers time-varying mesh position, line of action, mesh stiffness, mesh damping and backlash nonlinearity. Based on the model, dynamic analysis is conducted to study the effect of mean load, mesh damping and mesh parameter variations on dynamic mesh force response and the interaction between them and backlash nonlinearity. Numerous nonlinear phenomena such as tooth impacts and jump discontinuities are revealed by computational results.
2016-03-14
Journal Article
2016-01-9108
Ji Xu, Guohua Sun, Tao Feng, Mingfeng Li, Teik Lim
Abstract Active noise control systems have been gaining popularity in the last couple of decades, due to the deficiencies in passive noise abatement techniques. In the future, a novel combination of passive and active noise control techniques may be applied more widely, to better control the interior sound quality of vehicles. In order to maximize the effectiveness of this combined approach, smarter algorithms will be needed for active noise control systems. These algorithms will have to be computationally efficient, with high stability and convergence rates. This will be necessary in order to accurately predict and control the interior noise response of a vehicle. In this study, a critical review of the filtered-x least mean square (FXLMS) algorithm and several other newly proposed algorithms for the active control of vehicle powertrain noise, is performed. The analysis examines the salient features of each algorithm, and compares their system performance.
2011-11-07
Technical Paper
2011-22-0003
Jeffrey T. Somers, Bradley Granderson, John W. Melvin, Ala Tabiei, Charles Lawrence, Alan Feiveson, Michael Gernhardt, Robert Ploutz-Snyder, John Patalak
NASA is developing a new crewed vehicle and desires a lower risk of injury compared to automotive or commercial aviation. Through an agreement with the National Association of Stock Car Auto Racing, Inc. (NASCAR®), an analysis of NASCAR impacts was performed to develop new injury assessment reference values (IARV) that may be more relevant to NASA's context of vehicle landing operations. Head IARVs associated with race car impacts were investigated by analyzing all NASCAR recorded impact data for the 2002-2008 race seasons. From the 4015 impact files, 274 impacts were selected for numerical simulation using a custom NASCAR restraint system and Hybrid III 50th percentile male Finite Element Model (FEM) in LS-DYNA. Head injury occurred in 27 of the 274 selected impacts, and all of the head injuries were mild concussions with or without brief loss of consciousness. The 247 noninjury impacts selected were representative of the range of crash dynamics present in the total set of impacts.
2017-06-05
Journal Article
2017-01-1902
Guan Qiao, Geng Liu, Zhenghong Shi, Yawen Wang, Shangjun Ma, Teik Lim
Abstract Actuator and roller screw mechanism are key components of electromechanical brake (EMB) system in automotive and aerospace industry. The inverted planetary roller screw mechanism (IPRSM) is particularly competitive due to its high load-carrying capacity and small assembly size. For such systems, friction characteristic and friction torque generated from rolling/sliding contacts can be an important factor that affects the dynamic performance as well as vibration behavior. This paper investigates the modeling and simulation of the EMB system in early design stage with special attention to friction torque modelling of IPRSM. Firstly, a step-by-step system model development is established, which includes the controller, servo motor, planetary gear train and roller screw mechanism to describe the dynamic behavior of the EMB system.
2015-06-15
Journal Article
2015-01-2173
Srikumar C Gopalakrishnan, Teik Lim
Abstract Modeling of elastohydrodynamic lubrication phenomena for the spiral bevel gears is performed in the present study. The damping and the friction coefficient generated from the lubricated contact area will have profound effects on the dynamics of spiral bevel gears. Thus the damping value generated from this friction model will be time varying. This makes the use of constant and empirical damping value in the dynamics of spiral bevel gears questionable. The input geometric and kinematic data required for the elastohydrodynamic lubrication (EHL) simulations are obtained using Tooth Contact Analysis. A full numerical elastohydrodynamic lubrication simulations are carried out using asymmetric integrated control volume (AICV) algorithm to compute the contact pressures. The fast Fourier transform is used to calculate the elastic deformations on the gear surfaces due to contact load.
2015-06-15
Technical Paper
2015-01-2181
Dong Guo, Yawen Wang, Teik Lim, Peng Yi
Abstract A combined lumped parameter, finite element (FE) and boundary element (BE) model is developed to predict the whine noise from rear axle. The hypoid geared rotor system, including the gear pair, shafts, bearings, engine and load, is represented by a lumped parameter model, in which the dynamic coupling between the engaging gear pair is represented by a gear mesh model condensed from the loaded tooth contact analysis results. The lumped parameter model gives the dynamic bearing forces, and the noise radiated by the gearbox housing vibration due to the dynamic bearing force excitations is calculated using a coupled FE-BE approach. Based on the predicted noise, a new procedure is proposed to tune basic rear axle design parameters for better sound quality purpose. To illustrate the salient features of the proposed method, the whine noise from an example rear axle is predicted and tuned.
2015-06-15
Journal Article
2015-01-2182
Yawen Wang, Junyi Yang, Xuan Li, Guohua Sun, Teik Lim
Abstract Due to the design of lightweight, high speed driveline system, the coupled bending and torsional vibration and rotordynamics must be considered to predict vibratory responses more realistically. In the current analysis, a lumped parameter model of the propeller shaft is developed with Timoshenko beam elements, which includes the effect of rotary inertia and shear deformation. The propeller shaft model is then coupled with a hypoid gear pair representation using the component mode synthesis approach. In the proposed formulation, the gyroscopic effect of both the gear and propeller shaft is considered. The simulation results show that the interaction between gear gyroscopic effect and propeller shaft bending flexibility has considerable influence on the gear dynamic mesh responses around bending resonances, whereas the torsional modes still dominate in the overall frequency spectrum.
2015-06-15
Journal Article
2015-01-2217
Guohua Sun, Tao Feng, JI Xu, Mingfeng Li, Teik Lim
Abstract Current powertrain active noise control (ANC) systems are not sufficient enough to track the fast engine speed variations, and yield consistent convergence speeds for individual engine order such that a balanced noise reduction performance can be achieved over a broad frequency range. This is because most of these ANC systems are configured with the standard filtered-x least mean squares (FxLMS) algorithm, which has an inherent limitation in the frequency-dependent convergence behavior due to the existence of secondary path model (electro-acoustic path from the input of control loudspeaker to the output of monitoring error microphone) in the reference signal path. In this paper, an overview is given first to compare several recently modified FxLMS algorithms to improve the convergence speed for harmonic responses such as eigenvalue equalization FxLMS (EE-FXLMS) and normalized reference LMS (NX-LMS) algorithms.
2015-06-15
Journal Article
2015-01-2220
Ji Xu, Guohua Sun, Tao Feng, Mingfeng Li, Teik Lim
Abstract This paper describes an active sound tuning (AST) system for vehicle powertrain response. Instead of simply aiming to attenuate cabin interior noise, AST system is capable of reshaping the powertrain response based on predetermined vehicle sound quality criteria. However, conventional AST systems cannot yield a balanced result over the broad frequency range when applied to powertrain noise. It is due to the fact that existing systems are typically configured with the filtered-x least mean square (FXLMS) algorithm or its modified versions, which has inherent frequency dependent convergence behavior due to large dynamic range of secondary path (the electro-acoustic path from the control speaker to the error microphone). Therefore, fast convergence can only be reached at the resonant frequencies.
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