车身焊装钢结构生产平台动力特性优化

The Dynamic Characteristics Optimization of Automotive Body Welding Workshop Steel Structure Platform

为研究某车身焊装车间钢结构生产平台吊点相关的动力特性,首先采用有限元法,建立其梁壳单元模型进行模态分析。其次,进行工作状态下的模态试验,运用功率谱法完成结构模态参数识别;经对比,计算和试验模态分析结果一致性较好,有限元模型精度较高。最后,为提升钢结构生产平台中吊点结构的低阶固有频率,采用改进的非支配排序遗传算法以结构质量和第1阶固有频率为目标函数进行多目标优化;优化后,第1阶固有频率上升114%,而质量仅增加0.6%,满足工程抗震要求。

In order to study the dynamic characteristics of steel structure joints in automotive body welding workshop,firstly,a finite element model consisted of beam and shell elements is built and a modal analysis is carried out.Secondly,the modal identification of joints is finished by power spectrum method with responses measured by acceleration sensors under operational state excitation.The comparison shows that the computational modal results are in good correlation with those of experimental model analysis and this validates the finite element model.Finally,a multi-objective optimization method,modified non-dominated sorting genetic algorithm(NSGA-Ⅱ),is introduced to improve the undesirable lower intrinsic frequencies of steel structure joints with total mass and first order intrinsic frequency served as objective functions.After optimization process,while the first order intrinsic frequency of steel structure joints is increased by 114%,the total mass of steel structure only increases by 0.6%,and the optimal case meets the seismic requirements of steel structure platform.