Topology Optimization For Spot-weld Of Vehicle Door Based On Static Stiffness And Modal

The vehicle door is an important part of the vehicle,and it has an important influence on the comfort and safety of the vehicle.The main parts of the door are connected together by spot weld;the number and layout of the spot weld have an important influence on the performance of the vehicle door.Considering the static-dynamic performance of the vehicle door,the multi-objective optimization of the spot weld was carried out.The main research contents include:(1)Analysis of structure of vehicle door and establishment of finite element model.Structure of vehicle door was analyzed and three kinds element types(ACM2,CWELD and BER2)were used as the spot weld model,and the modal frequency value of the vehicle door was analyzed.Furthermore,through the comparison result from the experiment and the simulation,the more accurate element type was selected as spot weld.(2)Analysis of static stiffness and modal of vehicle door.The vertical stiffness,lateral stiffness,torsional stiffness and modal frequency of the door were calculated,based on the finite element model of vehicle door.The stiffness value,modal frequency and modal shapes were obtained through solving.(3)Mathematical modeling of multi-objective optimization for spot-weld of vehicle door.A mathematical model was established for the optimization of the single condition and modal frequency of the vehicle door,based on variable density method.Multi-objective topology optimization model for spot-weld of the vehicle door was established by using compromising programming.(4)Static-Dynamic multi-objective topology optimization for spot weld of the vehicle door.Firstly,the single case topology optimization was used to obtain the maximum flexibility,the minimum flexibility as well as the maximum modal frequency and the minimum modal frequency.Secondly,through reasonable evaluation of the importance of the objective function,the weight comparison matrix was established,and the weight value of the objective function was obtained.Thirdly,in order to obtain a more reasonable optimization results,two kinds of volume fractions were applied to optimize the spot weld.Finally,the comparion results from the static and modal performance of the vehicle door before and after optimization,a more reasonable volume fraction was obtained,and the feasibility of the optimization were verified.The results showed that the number of spot weld was reduced by 14.1%,without affecting the static and dynamic performances,through the multi-objective topology optimization.