Design And Optimization Of Aluminum Alloy Body Joints For Passenger Cars

Aluminum alloy is an ideal lightweight material for vehicles.'Manuacturing 2025 in China' specifies that core technologies such as low-carbon and lightweight materials for automobiles should be mastered as soon as possible,and a complete industrial system from key components to complete vehicles should be built to promote the rapid development of the lightweight industry.The China Society of Automotive Engineering has proposed that by 2025,the average aluminum alloy consumption of China's automobile bicycles will reach 250kg.Aluminum alloy has the characteristics of low density,high strength,and strong forming ability,and can be widely used in automotive products;however,it also has low elastic modulus and unsatisfactory welding performance.The above problems may have a greater impact on the overall performance such as safety,stiffness and durability in the structural design of the aluminum alloy body of the passenger car,and urgently need to be solved by scientific methods.The main contents of this topic are as follows:First,mechanical testing and simulation of aluminum alloy connectors.Use MTS universal testing machine to carry out static tensile test of 6082-T6 material;Select three types of connectors that are widely used on passenger car bodies,including N-type,L-type,and H-type,carry out quasi-static three-point bending tests,and study the mechanical properties and deformation failure modes of the connectors;The finite element method is used to establish and verify the corresponding simulation model.The results show that the deformation forms of the three joints in the elastic stage are relatively similar,and all of them have different degrees of warpage separation in the plastic deformation stage;the difference between the simulation and the experiment is controlled within 10%,and the simulation accuracy is better guaranteed.Second,the safety research of aluminum alloy body rollover and stiffness calculation.Establish a finite element model of the aluminum alloy body of a passenger car,use LS-DYNA to carry out ECE R66 rollover safety simulation analysis,study the deformation characteristics of the aluminum alloy body during the rollover process,and analyze the energy absorption capacity and Failure form.In addition,the bending stiffness and torsional stiffness of the aluminum alloy car body were calculated,During the rollover process,each column of the current aluminum alloy car body frame intrudes into the occupant's living space,which cannot meet the safety requirements of ECE R66 rollover;During the rollover process,the deformation mode of the connector is similar to the deformation model of the three-point bending test.Therefore,the idea of optimizing the connector based on the three-point bending and bending finite element model is initially proposed.Third,multi-objective collaborative optimization of bus aluminum alloy body connectors The multi-objective collaborative optimization platform for establishing connectors using approximate method technology:In order to obtain the optimal energy absorption capacity and light weight at the same time,the optimal Latin hypercube,neural network and NSGA-?genetic algorithm are used in conjunction to perform multi-objective optimization on the above three connectors under three-point bending conditions.The optimization results show that the bending resistance,energy absorption and failure load of the connectors are greatly improved;The mass of the superstructure of the optimized aluminum alloy car body segment was reduced by 0.4%,the static bending stiffness was increased by 4.7%,and the torsional stiffness was increased by 3.0%.Therefore,it can be shown that the above method can effectively obtain a better collaborative optimization scheme.