Multidisciplinary Design Optimization Of Vehicle Body Base On Crash Safety

With the widely application of the vehicle and the damage of traffic accidents, people has higher requirement of its crash safety, and the vehicle is as a contradiction of various performances conditions. The research for improving vehicle safety is a complex systematic-project, How to deal the restriction mechanism of the crash safety performance, lightweight performance, NVH (Noise, Vibration, Harshness) performance is a difficult problem. Multidisciplinary design optimization method provides a reasonable way to solve this problem.Firstly, the finite element model of an SUV is established, and the rationality of this finite element model is verified. According to company standards and national crash regulations, the performance parameters of strength, stiffness, modal characterstic, crash safety of the full vehicle and some components is calculated. According to the calculation results, the performances which could be improved will be optimal designed, and considering the interaction between the role in the various performances. Finally, on the premise of ensuring the crash safety, other performances are coordination controlled and some multidisciplinary optimizations will be made.Some vehicle body components are improved by the multidisciplinary design optimization method in this study as follows:(1) The thickness of the rear door’s components which have higher sensibility on rear door’s first natural frequency and weight is treated as the design variables. Trial sample is got through the experiment design method of optimal Latin hypercube and the multidisciplinary approximate models are established by using the response surface method. The surrogate models is then optimized by sequential quadratic programming. As a result, The first natural frequency of the rear door is obviously improved and the weight of the rear door don’t increase.(2) With TRIZ conflict resolution matrix theory as the foundation,the manufacturing technique and lightweight performance of door impact beam is improved in order to simplify the original three members of the door impact beam as a whole, and the type of collision beam is improved from tube to M-shaped cross-section. The material parameters of the M-shaped cross-section door impact beam is as the design variables.In order to improve the lightweight performance of door impact beam and collision energy absorbing property, with orthogonal experimental design method for the design of the sample data, using the response surface method to establish the multidisciplinary approximate model of lightweight performance and collision energy absorbing property. Ultimately by the genetic algorithm to get the optimal material program of door impact beam to significantly improve the collision energy absorbing property of door impact beam, in the case of quality does not increase. At last, the arrangement position of the door impact beam is optimized in order to raise the collision absorbing property again.(3) Hood collision energy absorption values, the first natural frequency and quality of the sensitivity, select the material thickness of the larger members of the three performance impact of design variables, orthogonal experimental design method for the design of the sample data, using the response surface method to establish the hood collision energy absorbing property, the first natural frequency and quality of multidisciplinary approximate model to improve door collision energy absorbing property of the optimization goals, to ensure that the NVH performance and lightweight performance constraints by genetic algorithm ultimately get the most Priority program material, significantly improve the hood collision energy absorption.Through the above improvements, the crash safety performance, lightweight performance, NVH performance of the vehicle get different degrees of improvement. The contradiction mechanism between the various vehicle performances is coordinated. The feasibility of the multidisciplinary design optimization applicated in vehicle body improvement is verified, and theoretical support is provided for the practical application in the vehicle body impromement in this study.