变密度法在车身焊点布置拓扑优化中的应用

Application of Variable Density Method in Topology Combinatorial Optimization of Spot Weld Layout in Car Body-in-white

为探索焊点布置对乘用车车身振动特性的影响,将变密度拓扑优化法应用于车身焊点布置的设计中,改善乘用车车身共振问题。首先,确定影响车身低阶模态频率的关键部件,然后将车身结构进行分区,最后应用变密度法对车身关键部件的焊点进行分区拓扑优化。结合乘用车车身焊接工艺,以车身低频固有振动特性为优化目标,以车身焊点体积最少为约束条件,以焊点单元密度为设计变量,对车身结构焊点布置进行拓扑优化。经模态分析,结果表明拓扑优化后车身焊点数目缩减了2.38%,车身的一阶模态频率为27.53 Hz,提高了1.28 Hz。将变密度法应用于乘用车车身焊点布置拓扑优化设计,有助于确定车身焊点的最佳布局,减少结构共振的可能性。

For exploring vibration characteristics of car body-in-white susceptible to the influence of spot weld layout（ SWL）,a variable density topology combinatorial optimization method was applied to the SWL design,which would improve structural resonance problems. Firstly,the key principal components easy to effect low order modal frequency of car body-in-white were determined. Then an automotive body is partitioned into several different functional domains. Finally,the variable density analysis based topology optimization method was developed for optimal SWL design of car body-in-white. Combined with the welding process of car body-in-white,the topology optimization of SWL design was performed with inherent low frequency vibration characteristics as the optimization goal,the minimum volume of spot welds as boundary constrain and the material density as design variable. Modal analysis results showed that the number of spot weld after topology combinatorial optimization has reduced by2.38%,and the first-order modal frequency of car body-in-white is 27. 53 Hz,which is increased by 1. 28 Hz.Consequently the variable structure control based topology optimization method used in SWL design of car body-inwhite can determine the best layout of spot weld of car body-in-white and decrease the possibility of structural resonance in idle condition.