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Chen S.M.,Jilin University | Wang D.F.,Jilin University | Zan J.M.,State Key Laboratory of Vehicle NVH and Safety Technology
Mathematical Problems in Engineering | Year: 2011

In order to predict the interior noise of the automobile in the low and middle frequency band in the design and development stage, the hybrid FE-SEA model of an automobile was created using hybrid FE-SEA method. The modal density was calculated using analytical method and finite element method; the damping loss factors of the structural and acoustic cavity subsystems were also calculated with analytical method; the coupling loss factors between structure and structure, structure and acoustic cavity were both calculated. Four different kinds of excitations including road excitations, engine mount excitations, sound radiation excitations of the engine, and wind excitations are exerted on the body of automobile when the automobile is running on the road. All the excitations were calculated using virtual prototype technology, computational fluid dynamics (CFD), and experiments realized in the design and development stage. The interior noise of the automobile was predicted and verified at speed of 120km/h. The predicted and tested overall SPLs of the interior noise were 73.79 and 74.44dB(A) respectively. The comparison results also show that the prediction precision is satisfied, and the effectiveness and reliability of the hybrid FE-SEA model of the automobile is verified. © 2011 S. M. Chen et al. Source

Gao Y.-K.,Tongji University | Feng H.-X.,Tongji University | Ma F.-W.,Zhejiang Geely Automobile Institute Co. | Yang L.,Changan Auto Global R and nter | Yang L.,State Key Laboratory of Vehicle NVH and Safety Technology
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2013

Modal frequencies and modal shapes of a BIW (body-in-white) reflect the inherent characteristics of an automotive body. They have an important influence on the interior noise. The car cavity also has modal frequencies and modal shapes. Acoustic modal test of a car cavity for a domestic SUV was performed with LMS data acquisition system. Firstly, the response points' signals were gained with a microphone array, and then the acoustic modal frequencies and modal shapes were extracted with PolyMAX method. The comparison between the acoustic modal frequencies and the test modal frequencies of the BIW showed that the first and the second acoustic modes of the car cavity are strongly coupled with the fourth and the tenth structural modes of the BIW. Finally, acoustic-structure coulpled resonance was verified through tests during the vehicle running. It was indicated that there are several ways to change the local modes of the automotive structure, such as, increasing the thickness of the key components, adding damping layer in the roof and floor, and strengthening the roof with ribs and so on; these actions can destroy the strong coupling between the modes of the BIW and the acoustic modes of the car cavity, decrease the lower frequency boom in the automotive. Source

Zhuang T.,Jiangsu University | Zuo Y.Y.,Jiangsu University | Zuo Y.Y.,State Key Laboratory of Vehicle NVH and Safety Technology
Applied Mechanics and Materials | Year: 2014

This experiment collected sound signals of four different cars driving at different speeds on highway and replayed the noise samples with playback software HEAD Audio Recorder. The subjective evaluation tests were carried out with paired comparison method. Evaluating models between subjective evaluation and objective psychoacoustic parameters were established with SPSS analysis software. © (2014) Trans Tech Publications, Switzerland. Source

Fang J.,Tongji University | Gao Y.,Tongji University | Wang J.,Tongji University | Wang Y.,Changan Automobile Co. | Wang Y.,State Key Laboratory of Vehicle NVH and Safety Technology
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2012

The fierce competition within the automotive industry requires manufacturers to shorten their development time for a new body, and the CAE-based optimization techniques are arousing wide attention. Compared with traditional size optimization, shape optimization in engineering optimization has greater potential. As a result, mesh morphing technology is first introduced into shape optimization, and a metamodel-based multi-objective shape optimization methodology is presented. Mesh morphing technology is employed to define the shape variables which are then screened through sensitivity analysis. An optimal Latin hypercube sampling is utilized to generate uniformly distributed sample points for fitting the Kriging models with high accuracies. A multi-objective particle swarm algorithm is adopted to perform the optimization where the mass and bending stiffness are defined as the objective functions while maintaining other performance indicators. The conclusion can be drawn that the proposed methodology is used to perform the multi-objective optimization for body-in-white successfully, and engineers can handle the trade-off between the objectives for guiding the decision-making. Source

Liu X.,State Key Laboratory of Vehicle NVH and Safety Technology | Liu X.,Beihang University | Ren Z.,Beihang University | Wang H.,Beihang University | Shan Y.,Beihang University
Zhendong Ceshi Yu Zhenduan/Journal of Vibration, Measurement and Diagnosis | Year: 2013

Aimed at the squeal problem induced by friction between brake pair when vehicle brakes, a test bench for researching the noise of automotive disc brake is set up, and the experimental research on brake squeal is performed. The time history of some key parameters affecting brake squeal such as the rotational speed of brake disc, brake pressure, torque parameter, and the noise signal for brake squeal are tested. Based on these signals, the relations of the coefficient of friction between the brake disc and pads with the brake pressure, the temperature of surface of brake pair, rotational speed and time, are investigated for the specific initial speed. Time domain and frequency domain methods are used to analyze the sound pressure signal obtained from brake squeal, respectively, and the signal characteristics and spectral components are also researched. These efforts will be helpful for understanding and revealing the generation mechanism of automotive brake squeal. Source

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