Research On The Optimization Model Of Mechanical Properties Of Clinching Process And Its Adaptive Optimization System

With the development of the lightweight design,more and more lightweight materials are widely used.Generally,the weldability of these materials is poor,and it is difficult to join with the metallurgical bonding method.Fortunately,such materials usually have good plasticity.Depending on their plasticity and proper mechanical joining technology,the strong mechanical joint can be formed.The urgent problem of mechanical joining technology need to solve is the optimization of joint strength.The essence of strength optimization is to find a set of reasonable tools,which can be characterized by several parameters.Because of the complex combination and interaction between these parameters,the multi-parameters optimization of mechanical joining process has not been solved commendably.Hence,it is of far-reaching significance to propose a universal optimization theory and develop an adaptive optimization system.In order to achieve this goal,the paper takes the common mechanical joining technology as research object,and combines the theoretical mechanics,the numerical simulation,the intelligent optimization and the multi-disciplinary software collaborative technology to work as follows:(1)According to theoretical mechanics,the formulas for calculating the transverse and longitudinal strength of joint are derived.The optimization model of joint strength is developed by analyzing these formulas.In order to get the feature parameters of joint,the automatic extraction formula of joint feature parameters are established.(2)Genetic algorithm is used to solve the optimization model,in which a real-time,dynamic and multidisciplinary software collaborative simulation strategy is used to build the response relationship between design indicators and design variables,and the response surface method was discarded to ensure accuracy.In addition,the graphical user interface(GUI)is developed.The automatic optimization of joint strength is very convenient by using this GUI.(3)The sheet thickness of 0.8mm-0.8mm,0.8mm-1.2mm,1.2mm-0.8mm,1.2mm-1.2mm is used to study the optimization process of joining process.By analyzing the shape and strength evolution of joints,the laws are obtained as follows:1)For the traditional clinching process,the existence of the lower die groove makes the mechanical property of the joint better,and the groove profile should be contacted with the sheet profile to obtain the best joint strength.The optimization results of the four initial shapes based on the Bezier Curve show that,for the traditional clinching process,the groove profile of right corner of the die should be arc.In practice,if the requirement of the high joint strength is not necessary,the groove of the die is not in contact with the profile of the sheet in order to simplify the die structure.2)By comparing the strength evolution curves with different thickness of different processes,it can be seen that,for all joining process,the greater the sum of the thickness the higher the joint strength in a certain range.In addition,for traditional clinching process,when the sum of thickness is equal,the higher the thickness of the upper sheet is,the higher the joint strength is.For flat hole-clinching process,the lower the thickness of the upper sheet,the higher the joint strength.Flat clinching process is not sensitive to the distribution of the thickness of the upper and lower sheet.3)The optimization results show that the adaptive optimization system has excellent performance and a great degree of intelligence.The system can evolve the joining process based on the survival of the fittest and finally obtain the global optimal joining process and joint shape.