The Optimization Design Of Structural Acoustic Performance Based On Mode Shapes And Response Surface Method

Our environment has been contaminated seriously by noise pollution. With the development of modern industrial technology, the noise pollution has aggravated, which affects seriously on our health Structure-born noise is the major sources of noise. Optimization design of structural acoustic characteristics can provide quantitative and optimal approchs to reduce structural noise. Improvement of structural acoustic characteristics plays a leading role in the research of noise controllingIn the product design stage, the acoustic characteristics and competitiveness of products can be improved effectively by size optimization, shape optimization and topology optimization, using damping materials and sound-absorbing materials. This dissertation, sponsored by the project "Yue Sheng Program", the independent innovation capabilities of high-level car construction in China ("Zhong Qi Program") and the Science Fund of State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body (No.60870002), carries on a systemic research work on the optimization design of structural acoustic characteristics based on mode shapes. The proposed optimization design approachs proposed in this dissertation are applied to the improvement of the interior acoustic characteristics of "Zhong Qi Program" car.The main researches and innovative achievements in this dissertation include:(1) Aiming at the parameterized problem of complex structural shape, a structural shape optimization method is presented based on mode shape. The approach is applied to the improvement of structural acoustic performance. The effect of the shape parameters on the acoustic performance is studied. Based on the structural acoustic analysis, the optimization model of structural acoustic performance is established The structural acoustic optimization is studied under harmonic excitation. Numerical examples of geometric plate, complex surface and "Zhong Qi Program" car are presented, which show shat the structural noise is controlled effectively.(2) Aiming at the problem of optimum thickness distribution of damping materials, a thickness distribution optimization method is presented based on mode shapes. The approach is applied to improvement of acoustic performance of composite structures. The effect of the thickness distribution parameters on the acoustic performance is studied. Based on viscous elastic dynamic analysis of composite structures, structural acoustic analysis and optimization algorithm,the optimization model of acoustic performance of composite structures is established.The optimization problem of thickness distribution of unconstrained damping materials under constant damping materials is studied. Numerical examples of geometric plate and "Zhong Qi Program" car are presented, which show that the system loss factors and the utilization of damping material are improved and structural noise is controlled effectively.(3) Aiming at the problem of long time in solving structural acoustic optimization, response surface model is used to replace structural acoustic analysis of complex structures with a large degrees of freedom. The optimization model of structural acoustic performance is established by combing experiment design, RSM and optimization algorithm. The structural acoustic optimization is studied under harmonic excitation. Numerical examples of a sealed box and "Zhong Qi Program" car are presented, which show that the system loss factors and the utilization of damping material are improved and optimization of acoustic performance of complex structures is solved suitably.(4) Aiming at the uncertain problem of structural acoustic design parameters, reliability theory is introduced to structural acoustic optimization. The reliability optimization model of structural acoustic performance is established by combing RSM, structural acoustic analysis, reliability theory and optimization algorithm. Numerical example of sealed "Zhong Qi Program" car is presented, which shows that the requirements and goals of reliability design are satisfied and the reliability optimization of structural acoustic performance is solved suitably.In order to improve the structural acoustic performance, shape optimization, damping optimization, deterministic optimization and reliability optimization are discussed thoroughly in this dissertation. The parameterized models of structural shape and thickness distribution of damping materials are proposed based on mode shapes. Based on RSM, the optimization models of structural acoustic performance with certain and uncertain parameters are established. The research achievement has theoretical significance and application value, which provides an effective approach for the improvement of acoustic performance of industrial products, such as autos.