Study On Automotive Structural Optimization Based On Component Mode Synthesis

NVH performance of automobile seriously effects environment, therefore, thereare strict national standards for it. Also, with the advance of people’s environmentalprotection awareness and their requirements to comfort, the NVH performance of avehicle greatly affects its performance in market. And，the structure of vehicle directlyaffects its NVH performance，so，the optimization of structure can improve the NVHperformance, then the security and comfort. For vehicles or some other complexstructures, the key problem of optimization is efficiently analysis of their vibrationcharacteristics, because there are many reanalysis of vibration characteristics during theprocess of optimization. The paper uses the improved algorithms based on ComponentMode Synthesis with interface reduction to improve the efficiency of analysis ofvibration characteristics, and then improves reanalysis during the process ofoptimization to improve the efficiency further. Finally, uses the improved algorithms tooptimize the structure of Body in White of a car.Firstly, studies on the principles of Component Mode Synthesis and ComponentMode Synthesis with interface reduction, finds their disadvantages, and uses DMAPlanguage to achieve Component Mode Synthesis with interface reduction in Nastran.Secondly, according to the feature of Constraint Modes, filters them to improve theefficiency of transform from physical coordinates to modal coordinates.Thirdly, according to the meaning of the coupling terms in the matrix of interfacemass, filters them to improve the efficiency of solving for Characteristic ConstraintModes. Uses Body in White of a car to verify the effect of the algorithms that statedabove.Then, based on the algorithms above-mentioned, during the process of reanalysis,improves the algorithm to reduce the time consumed in reanalysis. Similarly, uses theBody in White to verify the effect of the algorithm.Finally, analyzes the vibration characteristics of the Body in White, finds itsproblems, and then constructs an optimal model, optimizes the structure of it with theimproved algorithms, compares the improved and unimproved algorithms.