Strength Optimization Of Aluminum And Magnesium Alloy Hybrid Clinch And Structure Adhesive Bonded Joint And Its Application On Auto Body

Auto body lightweight is an important way to realize energy saving and emissionreduction, aluminum and magnesium alloy is ideal lightweight car body material since theirspecific strength and stiffness, good impact resistance and damping. Traditional resistancespot welding have been unable to meet the demand of aluminum and magnesium alloybonding process because of various welding defects such as electrochemistry corrosion andwear. Hybrid joint mechanical clinch and adhesive bonded is one of the new connectiontechnology consisted of traditional mechanical clinch and new structural adhesive bondedtechnology. It combines strengths of good plasticity characteristics from mechanical clinchand excellent joint strength, fatigue resistance from structural adhesive bonded and it isspecially to connect dissimilar materials such as aluminum and magnesium alloy. It showsgreat potential in strength stiffness and energy absorption capacity of hybrid joint and will beapplied widely in car body of aluminum-magnesium in the future. Hybrid joint does notsimply combine mechanical clinch with adhesive bonded simply, complicated factors areinvolved in joint strength prediction, few studies have been reported. Therefore, it isnecessary to explore different element influencing strength of joint and carry out optimizationon hybrid joint, which will bring benefit in engineering.Taking mechanical performance of hybrid joint mechanical clinch and adhesivestructural bonded as the goal, multi-objective optimization analysis is introduced in to analysedifferent factors influencing the target, joint internal stress distribution joint stracture formsand typical joint strength are analysed in simulation and experiment ways for mechanicalclinch and adhesive bonded, respectively. It points out ways to improve joint strength formechanical clinch and adhesive bonded and provides a reference in connection technology inengineering practice for dissimilar materials. Based on cohesive zone model used to simulatefracture process of adhesive joint, finite element model is set up to analyse strengthperformance of hybrid joint and is verified by standard experiments of single-lap shearstrength and peel strength. Key factors is analysed responsible for two different strengths andcomparison is carried out between simple mechanical clinch and adhesive bonded connection method in joint strength stiffness and energy absorption capacity, which proves hybrid jointto be effective way of combining different kinds of materials. With support of the finiteelement model of hybrid joint, different factors of mold geometry and adhesive types areconsidered with multi-objective optimization method, producing the Pareto optimal solutionset with proper shear strength and peel strength and the validity of the solution set is verifiedusing finite element method.B pillar and threshold stringer is assembled through hybrid joint of mechanical clinchand adhesive bonded, side impact performance is taken as the analysis object to deal withdifferent joints of hybrid mechanical clinch and adhesive bonded. Conclusions carry out thathybrid joint has better performance in energy absorbion and passenger cabin deformationreduction, which implies great prospect in auto body structure of aluminum-magnesium.