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Gear rattle noise is one of the important characteristics of manual and dual-clutch transmission，it is generated by the impact of unloaded meshing gear pairs in the transmission due to engine torsional vibration. Based on a front-drive manual transmission and a five dynos drivetrain NVH test bench with high-speed sine wave generator function, this paper designs an experimental program suitable for transmission rattle noise. By driving dynamometer to simulate the torque fluctuation of real engine, the main research is to study the characteristics of the transmission rattle noise under different excitation amplitudes and different excitation frequencies, and the sensitivity of rattle noise under different gears, different oil temperatures, different excitation amplitudes and excitation frequencies is analyzed. Finally, the transmission maps of rattle noise in different gears can be obtained.

This research examined the focused design, elastic design, energy decoupling, and torque roll axis (TRA) decoupling methods for mount optimization design. Requiring some assumptions, these methods are invalid for some load conditions and constraints. The linearity assumption is advantageous and simplifies both design and optimization analysis, facilitating engineering applications. However, the linearity is rarely seen in real-world applications, and there is no practical method to directly measure the reaction forces in the three locally orthogonal directions, preventing validation of existing methods by experimental results. For nonlinear system identification, there are additional challenges such as unobservable internal variables and the uncertainty of measured data.

This paper presents a road classifier based on the system response with consideration of the tire enveloping. The aim is to provide an easily applicable yet accurate road classification approach for automotive engineers. For this purpose, tire enveloping effect is firstly modeled based on the flexible roller contact (FRC) theory, then transfer functions between road input and commonly used suspension responses i.e. the sprung mass acceleration, unsprung mass acceleration, and rattle space, are calculated for a quarter vehicle model. The influence of parameter variations, vehicle velocity, and measurement noise on transfer functions are comprehensively analyzed to derive the most suitable system response thereafter. In addition, this paper proposes a vehicle speed correction mechanism to further improve the classification accuracy under complex driving conditions.

The dynamic properties of disc rotor play important role in the NVH performance of a disc brake system. Disc rotor in general is a centrosymmetric structure. It has many repeated-root modes within the interested frequency range and they may have significant influence on squeal occurrence. A pair of repeated-root modes is in nature one vibration mode. However, in current complex eigenvalue analysis model and relevant analysis methods, repeated-root modes are processed separately. This may lead to contradictory result. This paper presents methods to deal with repeated-root modes in substructure modal composition (SMC) analysis to avoid the contradiction. Through curve-fitting technique, the modal shape coefficients of repeated-root modes are expressed in an identical formula. This formula is used in SMC analysis to obtain an integrated SMC value to represent the total influence of two repeated-root modes.

One of the major challenges in multiobjective, multidisciplinary design optimization (MDO) is the long computational time required in evaluating the new designs' performances. To shorten the cycle time of product design, a data mining-based strategy is developed to improve the efficiency of heuristic optimization algorithms. Based on the historical information of the optimization process, clustering and classification techniques are employed to identify and eliminate the low quality and repetitive designs before operating the time-consuming design evaluations. The proposed method improves design performances within the same computation budget. Two case studies, one mathematical benchmark problem and one vehicle side impact design problem, are conducted as demonstration.

Since their inception, the design of airbag sensing systems has continued to evolve. The evolution of air bag sensing system design has been rapid. Electromechanical sensors used in earlier front air bag applications have been replaced by multi-point electronic sensors used to discriminate collision mechanics for potential air bag deployment in front, side and rollover accidents. In addition to multipoint electronic sensors, advanced air bag systems incorporate a variety of state sensors such as seat belt use status, seat track location, and occupant size classification that are taken into consideration by air bag system algorithms and occupant protection deployment strategies. Electronic sensing systems have allowed for the advent of event data recorders (EDRs), which over the past decade, have provided increasingly more information related to air bag deployment events in the field.

Wiper noise generated in the wiping process is one of the main influence factors affecting the driving comfort. Since the dynamic contact pressure of the contact between a blade and a windshield glass is difficult to be measured, it is also difficult to predict the degree of the wiper noise. In this paper, in the view of the reversal noise problem of a passenger-vehicle windscreen wiper system, the system dynamic models of the both wipers on the sides of the driver and copilot were built as considering the blade deformation and the elastic contact between the blades and the windscreen glass, including the crank pivot, the four linkage mechanism, the wiper blades, the wiper arms and the windscreen glass. The motion of the wiper system and the pressure distributions between the blades and the windscreen glass were analyzed under the half-dry condition.

This paper provides an investigation to improve vehicle powertrain NVH performance via modification of excitation and radiation system of powertrain. First of all, considering different excitation mechanisms of the powertrain, the excitation forces are analyzed. The FEM/BEM coupled analysis and the acoustic transfer vector (ATV) calculation as well as panel contribution analysis are applied to investigating the acoustic characteristics of the powertrain. Then a hybrid approach which couples the transmission gear profile modification for attenuating gear system excitation and the transmission housing modification for reducing transmission housing noise radiation is proposed to improve powertrain NVH performance. Experiment validation is conducted in order to assess the modified results. The assessment shows that this hybrid approach can effectively predict and reduce powertrain noise and vibration.

Advanced high strength steels (AHSS) have been widely accepted as a material of choice in the automotive industry to balance overall vehicle weight and stringent vehicle crash test performance targets. Combined with efficient use of geometry and load paths through shape and topology optimization, AHSS has enabled vehicle manufacturers to obtain the highest possible ratings in safety evaluations by the Insurance Institute for Highway Safety (IIHS) and the National Highway Traffic Safety Administration (NHTSA). In this study, vehicle CAE side impact models were used to evaluate three side impact crash test conditions (IIHS side impact, NHTSA LINCAP and FMVSS 214 side pole) and the IIHS roof strength test condition and to identify several key components affecting the side impact test performance. HyperStudy® optimization software and LS-DYNA® nonlinear finite element software were utilized for shape and gauge optimization.

Analytical models (math or computer simulation models) are typically built on the basis of many assumptions and simplifications and hence model prediction could be inaccurate in intended applications. Model validation is thus critical to quantify and improve the degree of accuracy of these models. So far, little work considers model validation for various design configurations so that model prediction is accurate in the intended design space. Furthermore, there is a lack of effective approaches that can be used to quantify model accuracy considering different number of experimental data. To overcome these limitations, objective of this paper is to develop a model validation approach for various design configurations with a reference metric for model accuracy check considering different number of experimental data.

ACOUSTOMIZE™ is a new method of acoustic evaluation used for the purpose of understanding and optimizing NVH performance of vehicles. The following paper documents a case study of the ACOUSTOMIZE™ test methodology on a passenger car BIW. This study includes an analysis of noise flow through BIW locations, a comparison of noise sound levels through BIW cavities with and without a sound treatment package and a comparison of the original cavity sealing design package consisting of baffles, tapes and baggies to low density polyurethane NVH Foam. The results of the study show detection of complex BIW pass throughs that the body leakage test (BLT) was not able to find. In addition, the data shows improved noise reduction with the low density polyurethane foam versus the original cavity sealing design package.

Gear meshing noise is a common noise issue in manual transmission, its noise generation mechanism has been studied extensively [1, 2]. But most of time we have situations where multiple gear sets are connected in series and the noise and vibration behavior for a multi-stage gear can be quite different due to vibration inter-actions or interferences among multiple gear sets. In this paper, a two-stage gear driveline model was built using MSC ADAMS. Vibration order contents of a two-stage gear driveline were analyzed by both CAE simulation and theoretical calculations. In addition to gear meshing vibration orders of each gear set, the orders resulted from modulations between individual gear meshing and their harmonics were evident in the results. These special order contents were verified by experimental results, and also evidenced on transmission end of line tester results at transmission supplier GJT in Ganzhou, China.

A coupled vibro-acoustic of a compressor modeling process was demonstrated for predicting the acoustic radiation from a vibrating compressor structure based on dynamic response data. FEM based modal analysis of the compressor was performed and the result was compared with experimental data, for the purpose of validating the FE model. Modal based force response analysis was conducted to calculate the compressor's surface vibration velocity on radiating structure, using the load which caused by mechanical excitation as input data. In addition, due to the coolant had oscillating gas pressure, the gas pulsed load was also considered during the dynamic response analysis. The surface vibration velocity solution of the compressor provided the necessary boundary condition input into a finite element/boundary element acoustic code for predicting acoustic radiation.

This study demonstrates the use of pressure sensing technology to predict the crash severity of frontal impacts. It presents an investigation of the pressure change in the front structural elements (bumper, crush cans, rails) during crash events. A series of subsystem tests were conducted in the laboratory that represent a typical frontal crash development series and provided empirical data to support the analysis of the concept. The pressure signal energy at different sensor mounting locations was studied and design concepts were developed for amplifying the pressure signal. In addition, a pressure signal processing methodology was developed that relies on the analysis of the air flow behavior by normalizing and integrating the pressure changes. The processed signal from the pressure sensor is combined with the restraint control module (RCM) signals to define the crash severity, discriminate between the frontal crash modes and deploy the required restraint devices.

This paper first discusses the principles of how to identify whether a time series has chaotic characteristics, and explores a method of finding out the embedding dimension of a time series. Then Grassberger-Procaccia (G-P) algorithm is adopted to calculate correlative dimension. After the validity of G-P algorithm is confirmed using several traditional strange attractors, it is applied to calculate the fractal dimension of some vibration signals of an automotive transmission. This article presents how to apply chaos and fractal theories to diagnose the wearing of ball bearings in automotive transmissions based on the analysis of the transmission acceleration vibration signals. The results show that the vibration signals of automotive transmissions have fractal nature. There are certain correlations between a bearing's condition and the fractal dimension of its vibration signal.

Effects of DOF and subjective method on evaluations of ride quality on the Ford Vehicle Vibration Simulator were studied. Seat track vibrations from 6 vehicles were reproduced on the 6 DOF seat shaker in a DOE with pitch and roll as factors. These appeared in two evaluations of ride/shake; semantic scaling by 30 subjects of 6 vehicles, and paired comparisons by 16 of the subjects on 3 of the vehicles. Both methods found significant vehicle, pitch and roll effects. Order dependence was shown for semantic scaling. The less susceptible paired comparison method gave a different ordering, and is thus preferred.

In order to reduce the vibration energy transferred from engine to the chassis of a vehicle and improve the riding comfortability of the vehicle, a new semi-active controlled hydraulic mount is developed which could adjust the vibration isolating effect at wide frequency range. The dynamic characteristic of the new mount could be changed through adjusting the cross-sectional area of its inertia channel. The control strategy of the mount is based on a great deal of engine tests. Test results of the semi-active mount on an engine test bench show that it could optimize the isolation effect according to engine''s working condition.

Accessory belt “chirp” noise is a major quality issue in the automotive and truck industry. Chirp noise control is often achieved by very tight pulley alignment, a guideline being .33 degree maximum belt entry angle into each grooved pulley. Occasionally belts will chirp at pulleys where the system alignment is this good or better. This study offers an explanation for such occurrences. This is a study to see if fundament groove side sticking theory correlates with the belt entry angle, and how the coefficient of friction relates to this entry angle. The study combines theory with lab data. In summary, the study fundamentally links the coefficient of friction of the belt to the belt chirp noise phenomenon, and allows the projection of a belt's general tendency to chirp to be predicted by the measurement of belt coefficient of friction on a test stand.

Identification of the noise generating mechanisms of gravity action and vibrator stimulated sliding chutes has resulted in the development of practical and effective noise abatement treatments for both. In the case of gravity action chutes the application of foam-backed thin and narrow spring steel plates on the chute surface achieves the desired effect with noise reduction of 14 to 25 dB(A). With vibrator stimulated chutes progressive steps were taken to attenuate source noise, chute radiation noise and the non-productive component of the force vector from the vibrator, resulting in noise reduction of 25 to 30 dB(A).

Noise generating mechanisms connected with steel-blanking operation has been identified and their engineering treatments developed and tested. Use of rubber-metal laminates proved to be successful for cushioning impacts in kinematic pairs and joints. Use of plastic for the stripper plate construction was recommended. The “die stiffener” concept was developed to reduce main noise peak associated with punch breakthrough. Screening of the die cavity by a transparent curtain of overlapping PVC strips was shown to be effective. A pulse load simulator with adjustable load rate and amplitude has been developed to facilitate testing of presses.