关键词: 排气系统, 平均驱动自由度位移法, 哈默斯雷采样, 全局响应面法

Abstract: To improve the vibration performance of the exhaust system for a specific vehicle model, the Average Drive Degree Of Freedom Displacement method (ADDOFD) was firstly used to determine hook position of the exhaust system,followed by a vibration performance analysis. Static analysis revealed that the support reaction forces of the hangers exceeded durability design requirements,while dynamic analysis indicated that the dynamic reaction forces transmitted from the hangers to the vehicle body were excessively large. Therefore,the sum of the dynamic reaction forces of all hangers was selected as the first optimization objective,and the weighted sum of the normalized static displacements and support reaction forces at the lugs was defined as the second optimization objective.Using HyperStudy software,Hammersley sampling and Design Of Experiments (DOE) were conducted,followed by variable screening. Ultimately,the torsional stiffness in the RY and RZ directions of the flex pipe and the dynamic stiffness in the Z direction of five hangers were identified as design variables. A response surface model was constructed,and Global Response Search Method (GRSM) was employed to determine the optimal solutions for the dynamic stiffness of the flex pipe and the hangers. One set of optimal solutions was substituted into the finite element model of the exhaust system for analysis. The results showed all optimization objectives meet the vibration performance design requirements. A valuable reference was provided for the design of hanger positions,as well as the selection of stiffness for flex pipes and hangers in exhaust systems.

Key words: exhaust system, the Average Drive Degree Of Freedom Displacement method (ADDOFD), Hammersley sampling, Global Response Search Method (GRSM)