Investigation Of Springbcak And Forming Limit Of 6061 Aluminum Alloy In Cold Stamping

With the rapid development of social economy,people's living standards have been improving and the development of the auto industry is unstoppable.However,due to the great increment of car ownership in global,exhaust pollution and the increase in carbon dioxide and other greenhouse gases gradually become serious problems which people have to face,which followed by the global shortage of oil resources,serious environmental pollution,frequent traffic accidents which caused heavy casualties,and so on and so forth.So the energy conservation and emissions reduction and safety problem become important issues which should urgently to be solved in automobile industry.By conducting a great deal of experimental research and theoretical analysis,researchers point out that the automotive lightweight is one of the important means to improve the fuel economy,save energy and safety of vehicle.In recent years,people began to look for alternative to traditional steel to achieve auto lightweight.It is found that the aluminum alloys possess the characteristics of high strength and low density.Thus aluminum alloys become more and more popular in auto industry.Now,two key problems in sheet metal stamping are springback and rupture,because the size of the final part shape is closely related to the size of the springback after forming,and the production of parts depend on good formability.For the reason of poor performance at room room temperature,the inevitable springback and rupture problem have become main barriers to aluminum alloy stamping technology.To control and reduce springback after sheet metal stamping forming,and to improve the sheet metal forming performance gradually become major work of researchers.This paper chooses the 6061 aluminum alloy-6061-T4 which is used most in auto industry as the research object.And it concentrates on the springback and rupture problems at room temperature.The main contents are as follows:1)Carry out fundamental test of 6061 aluminum alloy performance,and acquire basic parameters for building finite element material model;And results show the strain hardening index is low and the strength and elongation in 45° direction is better than other directions.2)By using self-designed clap,we have carried out the tensile-compression test of 6061 aluminum alloy,studied the 6061 aluminum alloy Bauschinger effect,and studied the decrease of young's modulus,and acquired corresponding parameters of Y-U hardening model.Based on the Ls-dyna software,this paper builds four different material models and then conducts the finite element analysis of tensile-compression test and compares the accuracy of four models on predicting the Bauschinger effect.3)Carry out 6061 aluminum alloy U-shaped parts stamping test and its finite element analysis.Compare the accuracy of the four kinds of material models in predicting the springback through comparing the springback angle.MAT125 is recommended to well predict the springback of 6061 aluminum alloy.4)Set up a DIC platform in material test machine by using existing device.Carry out a series of load tests of different strain paths and get the 6061 aluminum alloy FLD diagram at room temperature.Then analyze the load tests by finite element analysis and acquire two FLD diagrams for different hardening model.This paper conducts some research on springback and rupture of 6061 aluminum alloy,in order to provide guidance for its CAE analysis in actual production.