Investigation On Formability Of Automotive Aluminum Alloy Based On DIC Method

With the development of automobile industry,research of automobile lightweightbecomes more and more popular.Because of the lower density and higher strength,aluminum alloy is regarded as ideal lighting material in automobile industry.Formability of 5000 series and 6000 series aluminum alloy are better than the other brands,and often used in forming body cover.In terms of material performance measurement,the traditional measurement of grid has a lot of problems.The emergence of the DIC method solves many problems that something cannot be measured and be difficult to measure.So the method of DIC is using to research the two material in this paper,it has great important meaning for the automobile industry.The Main research content is as follows:The basic mechanical properties of the two materials are studied by tensile test.The constitutive equation was fitted by the stress-strain curve,and using the DIC to measure the parameter of anisotropy index,the result shows the parameter is not instability.By the test of natural aging,the performance of the material becomes different from previous performance.FLD and Simulated formability of two material are studied.In the research of FLD,concentrated and dispersive instability of two material are obtained by the equipment of DIC,and according to theory of Hill48?Hill79 and Keeler,FLD has been forecasted and compared with result of test,and mathematical model of FLD has been built.Contrary to the key point FLD0,prediction formula of FLD0 is acquired by the wide plate tensile test.Next,the influenced parameter of expanding rate is researched,including thickness of the sample,method of making hole,shape of punch,direction of burr.New method of measuring the expanding rate is put forward based on equipment of DIC.Last,According to the crimping technology used on the automobile industry,new test method and parameter is put forward,and the pre-stretch of limit crimping is obtained by the test.The process of formability of car fender cover is simulated by using limit element simulation software-Dynaform.According to the two step of forming part which are stamping and crimping,the parameter included harden exponent,anisotropy index and yield stress has been changed,than the best sensitive parameter is obtained by the test for the material thinning.