The Constitutive Model And Application Of Ti-6AL-4V Material Based On YLD2000-2D Yield Criterion And Variable Elastic Modulus

In recent years,Ti-6Al-4V titanium alloy has been widely used in many fields because of its excellent material properties.However,the properties of Ti-6Al-4V titanium alloy are complex,which makes the common material constitutive model not applicable.It is difficult to accurately analyze the deformation process of Ti-6Al-4V titanium alloy in theoretical analysis or numerical simulation.In this paper,the change of elastic modulus of Ti-6Al-4V titanium alloy was studied.Based on the YLD2000-2D yield criterion and the mathematical model of variable modulus of elasticity,the constitutive model of Ti-6Al-4V titanium alloy was established,and applied to the numerical simulation of V-bending of Ti-6Al-4V titanium alloy plate,which was used to predict the springback of the material after forming,and achieved good results.The specific work of this paper is as follows:(1)The anisotropy of Ti-6Al-4V titanium alloy material was analyzed through uniaxial quasi-static tensile test and load-unloading experiment,and the change law of elastic modulus and plastic strain was studied.Based on the empirical formula of variable elastic modulus,the mathematical model of variable elastic modulus of Ti-6Al-4V titanium alloy was established.(2)Based on YLD2000-2D yield criterion and variable elastic modulus model,a constitutive model of Ti-6Al-4V titanium alloy material was established.And the corresponding constitutive relationship formula and elastic-plastic stiffness matrix were derived.(3)The fully implicit graph return algorithm was applied to the numerical derivation of the constitutive model,the writing of UMAT subroutine was completed.The user-defined constitutive model was successfully applied to ABAQUS,and the secondary development of material constitutive model of ABAQUS software was realized.(4)Three different constitutive models were used to simulate the springback of Ti-6Al-4V titanium alloy sheet in V-bending.And the effects of yield criterion and variable elastic modulus on springback prediction of Ti-6Al-4V titanium alloy sheet were studied.(5)Based on the experimental data and finite element simulation results,the springback prediction accuracy of three constitutive models was compared and analyzed.