Study On Fracture Failure Behavior Of Extruded Aluminum Profiles

With the rapid development of the automotive industry,it has brought about serious energy shortages and environmental degradation.Therefore,the automotive industry must develop in the direction of energy conservation and environmental protection,and lightweight technology is one of the effective ways.Lightweight technologies such as new materials,new structures and new processes have promoted the rapid development of lightweight vehicles.Aluminum alloy materials have the characteristics of low density,high strength,corrosion resistance,good processability and recyclability,and are called the most potential lightweight materials.The extruded aluminum profile produced by the extrusion molding process has excellent mechanical properties and light weight effect,which brings new ideas for the design of automotive thin-walled structural parts.As a kind of thin-walled structure,extruded aluminum material will have fracture failure behavior in the case of automobile collision.Therefore,in order to study the fracture failure of extruded aluminum profiles in depth,this article has carried out a series of studies around the construction method of its constitutive model.The main contents are as follows:(1)Due to the extrusion molding,the material will be anisotropic,that is,it will show different mechanical properties in different directions.Therefore,using AA6063 extruded aluminum tube as the research object,the uniaxial tension tests in different directions(0 °,45 °,90 °)under quasi-static condition were established.The anisotropy of plastic behavior of aa6063 extruded aluminum tube was analyzed with DIC technology,and the stress-strain curves and the corresponding anisotropic parameter r values in each direction were obtained.The results show that the material has obvious anisotropy,and then the material parameters of the Barlat89 anisotropic yield criterion are determined.(2)The material test methods of extruded aluminum tube under multi-stress state were established,including uniaxial tension test,biaxial tension test,plane strain tension test and shear test.The specimens under each test were analyzed in detail,the shape and size of the related specimens were determined,and the corresponding test platform was improved and built.By using DIC technology to analyze the deformation process of the specimens,the fracture failure strain of the specimens under different stress states is obtained,and then the material parameters required for the DIEM fracture model are determined.(3)Through the axial compression test of extruded aluminum tube,the failure deformation mode,the change of crushing force and energy absorption are analyzed.A precise finite element model of axial crushing was established.Based on the material parameters obtained by the test,the Barlat89 yield criterion and the DIEM fracture model and the Mises yield criterion were used to conduct a simulation and comparative study on the mechanical response of the test.Comparing the simulation results with the test results,the results show that using the Barlat89 yield criterion and DIEM fracture model can well predict the load response and failure deformation mode in the test,and verify the accuracy of the test parameters and the established model.