Simulation Study On Failure Of Non-rivet Clinch-adhesive Joints Between Steel And Aluminum

In order to improve the fuel economy of the entire vehicle and reduce the weight of the vehicle body,replacing some steel structures with aluminum alloy to form a steel-aluminum hybrid structure can greatly reduce the quality of the entire vehicle,which has been widely used.Compared with welding,self-piercing riveting and other connection technologies,rivetless riveting has the advantages of not easily generating stress concentration and low cost and is suitable for the connection of dissimilar metal materials such as steel and aluminum,but its joint strength is relatively low.The introduction of adhesives into rivet-free rivet joints to form Clinch-adhesive Joints not only significantly improves the mechanical properties of the joints,but also effectively prevents electrochemical corrosion between dissimilar metals.It has received extensive attention and attention from automotive industry practitioners and scholars at home and abroad.At present,the research direction of scholars is mainly focused on analyzing the mechanical properties of Clinch-adhesive Joints and the optimization of the process parameters of joint forming.However,there are few studies on the local stress changes of joints during joint failure.The stress change law of the joint failure process can not only analyze the failure mechanism of the joint,but also predict the failure mode of the joint.The joints used in this article are bonded and cured before riveting.The failure of the steel-aluminum dissimilar material Clinch-adhesive Joint is studied as follows:Selection of steel,aluminum and adhesives for composite connection joints,and the VIC-3D non-contact strain gauge was used to perform tensile tests on tensile test pieces of 5754 aluminum alloy,Q235 steel and adhesive,and the mechanical properties of the material were obtained.The finite element model of steel and aluminum was established to verify the accuracy of the material parameters.The tensile test is performed on the steel-aluminum bonding test piece,and theload-displacement curve during the failure of the bonded joint is output,and the accuracy of the adhesive material parameters is verified by combining the single-pull simulation model of the steel-aluminum bonding test piece,It also confirms the simulation effect of cohesive force model on adhesive bonding and failure.Tensile tests are carried out under specific conditions such as drawing,shearing,and peeling by using a special fixture to hold the small test piece of the Clinch-adhesive Joint to obtain the failure form and mechanical performance parameters of the composite joint under various conditions.A detailed model of the composite connection joint under various working conditions is established to simulate the failure process of the composite connection joint.During the failure process,the local stress change rule and failure mechanism of the joint are analyzed,and the failure form of the joint is predicted.The solid solder joint element model and the SPR2 constrained element model are used to simulate the composite connection joint.A simplified model of the composite connection joint under the conditions of drawing,shearing and peeling is established,and the mechanical performance parameters output by the fine model are used to calibrate the simplified model Failure parameters.By comparing the simulation effects of the two simplified models,it is concluded that the SPR2 constraint element model can be used to simulate composite connection joints,and judge the connection state of the composite joints under conditions of drawing,shearing and peeling.The SPR2 constrained element model was applied to a composite beam to simulate a composite connection joint.The crush process of the composite beam was simulated.The crush process and energy absorption characteristics of the composite beam at different joint spacings were analyzed.