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Wu J.,South China University of Technology | Wu J.,Guangdong Key Laboratory for Automotive Engineering | Hao S.,South China University of Technology
Qiche Gongcheng/Automotive Engineering | Year: 2013

Taking the mount stiffness as design variables with the uncertainty of design variables and inertia parameters of powertrain described by both normally and uniformly distributed random variables respectively, a reliability optimization model for the natural characteristics of mounting system is established and both certainty optimization and reliability optimization are conducted respectively on the natural characteristics of a car powertrain mounting system. The results show that compared with certainty optimization, using reliability optimization though slightly lowers the decoupling rates in all directions of mounting system but can significantly enhance its reliability of decoupling layout and frequency allocation. Source


Wu J.,South China University of Technology | Wu J.,Guangdong Key Laboratory for Automotive Engineering | Zhou S.-N.,South China University of Technology
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2012

Due to measurement inaccuracy, installation errors and aging, the mount stiffness of a powertrain mounting system (PMS) is usually not deterministic, thus the frequencies and decoupling ratios of a PMS are also somewhat uncertain. Interval numbers were used to describe the uncertainties of the mount stiffness as well as the frequencies and decoupling ratios of a PMS in consideration of being easy to obtain the variation ranges of the mount stiffness without knowing the probability distribution of the stiffness. An improved interval truncation method for obtaining the variation ranges of frequencies and decoupling ratios was presented and its computational accuracy was verified. To improve the design robustness of frequencies and decoupling ratios, an interval optimization method was presented. The presented optimization method was applied to a PMS for maximizing decoupling ratios with frequency constraints. Optimization results show that the interval optimization can significantly increase the robustness of frequencies in roll and pitch directions. In contrast to the deterministic optimization, though the decoupling ratios in vertical and pitch directions decrease slightly, the interval optimization result can meet the decoupling layout requirement. Source


Wu J.,South China University of Technology | Wu J.,Guangdong Key Laboratory for Automotive Engineering | Shangguan W.,South China University of Technology | Shangguan W.,Guangdong Key Laboratory for Automotive Engineering | Pan X.,Ningbo Tuopu Vibro Acoustics Technology Inc.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2010

The dynamic properties of rubber materials are related to excitation amplitude and excitation frequency. Based on the overlay method of constitutive models, the hyperelastic-viscoelastic-plastoelastic constitutive model is built for characterizing the dynamic properties of rubber materials. The hyperelastic model is used to describe the elastic property of rubber materials, and the viscoelastic and plastoelastic models are used to characterize the frequency and amplitude dependency, respectively. Parameter identification method and the computational aspects of the frequency- and amplitude-dependent dynamic properties of the rubber isolators are investigated. The model parameters are identified by using the simple shear experimental data of rubber specimens. Based on the identified model parameters, the dynamic properties of a powertrain rubber mount are calculated by using the finite element analysis method and the calculated results agree well with the experimental data. It is shown that the presented model can predict the frequency- and amplitude-dependent dynamic properties of the rubber materials with little relative errors. Therefore, the presented method can be used for prediction and optimization design of the dynamic properties of rubber isolators. © 2010 Journal of Mechanical Engineering. Source


Wu J.,South China University of Technology | Wu J.,Guangdong Key Laboratory for Automotive Engineering | Jiang M.,South China University of Technology | Luo Y.,South China University of Technology | Luo Y.,Guangdong Key Laboratory for Automotive Engineering
Qiche Gongcheng/Automotive Engineering | Year: 2015

For improving the vibration performance of exhaust system in a passenger car, a FE model is built, on which the static and kinetics calculation, hanger location evaluation and the motion envelope calculation of exhaust system are conducted with Nastran code. Then a multi-objective optimization model for the vibration performance of exhaust system is set up and a simulation is performed with minimizing the peak vertical dynamic load and its standard deviation of hook and the static deformation and preload standard deviation of hangers as objective, the vibration isolation of hangers being not less than 20 dB as constraint, and the dynamic stiffness of hangers and corrugated pipes as design variables. The results show that the peak vertical dynamic load and its standard deviation of hook and the static deformation and preload standard deviation of hangers significantly reduce. The optimization method proposed is a valuable reference for controlling exhaust system vibration and improving its structural fatigue durability. © 2015, SAE-China. All right reserved. Source


Lin H.,South China University of Technology | Lin H.,Guangdong Key Laboratory for Automotive Engineering | Ding K.,South China University of Technology | Ding K.,Guangdong Key Laboratory for Automotive Engineering | And 2 more authors.
Chinese Journal of Mechanical Engineering (English Edition) | Year: 2010

As a discrete spectrum correction method, the Fourier transform (FT) continuous zoom analysis method is widely used in vibration signal analysis, but little effort had been made on this method's anti-noise performance. It is widely believed that the analysis accuracy of the method can be substantially improved by increasing the zoom multiple, however, with the zoom multiple increases, the frequency estimation accuracy may decline sometimes in practices. Aiming at the problems above, this paper analyzes the sources of frequency estimation error when a harmonic signal mixed with and without noise is processed using the FT continuous zoom analysis. According to the characteristics that the local maximum of the zoom spectrum may be wrongly selected when the signal is corrupted with noise, the number of wrongly selected spectrum lines is deduced under different signal-to-noise ratio and local zoom multiple, and then the maximum frequency estimation error is given accordingly. The validity of the presented analysis is confirmed by simulations results. The frequency estimation accuracy of this method will not improve any more under the influence of noise, and there is a best zoom multiple, when the zoom multiple is larger than the best zoom multiple; the maximum frequency estimation error will fluctuate back and forth. The best zoom multiple curves under different signal-to-noise ratios given provide a theoretical basis for the choice of the appropriate zoom multiples of the FT continuous zoom analysis method in engineering applications. © 2010 Chinese Journal of Mechanical Engineering. Source

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