Establishment And Application Of Constitutive Model Based On Anisotropic Mixed Hardening

In the numerical simulation of sheet stamping,the accuracy of numerical simulation is deeply influenced by the constitutive model.As the shape of stamping parts becomes more and more complex,the non-uniformity of deformation of each part is enhanced,and repeated or cyclic loading may occur in the local deformation area,whether the forming effect of materials under complex loading conditions in different deformation areas can be accurately reflected by the constitutive model has become a research hotspot in the field of stamping.Considering the directional characteristics,Bauschinger effect and work hardening characteristics of sheet during loading,a new material constitutive relation with more accuracy and applicability is established,which is of great significance to improve the accuracy of numerical simulation of sheet stamping.Based on the elastic-plastic constitutive theory,a materials elastic-plastic constitutive model that satisfies the characteristics of anisotropic yield and mixed hardening is established with Hill48 anisotropic yield criterion,Voce isotropic hardening model and Armstrong-Frederic non-linear kinematic hardening model,the elastic-plastic matrix formula is derived,the user material subroutine of ABAQUS is compiled with FORTRAN assembly language,and the numerical simulation of the constitutive model is completed.The cyclic deformation stress-strain curves of DC54D+ZF,B170P1,B210P1 and DP590 sheets are obtained through the sheet cyclic tension-compression experimental system.The material parameters of the constitutive model under tension and compression deformation conditions are determined by using the universal global optimization algorithm.The applicability of the constitutive model for cyclic tension-compression and cyclic deformation through drawing of four sheets are analyzed by using ABAQUS.The accuracy and applicability of the constitutive model are verified by comparing the calculations of the isotropic yield and mixed hardening constitutive model of ABAQUS and the experimental results.Optimizing regression constitutive model parameters based on cyclic tensile-compressive experimental curves of materials is an effective method to improve the accuracy of numerical simulation analysis.Finally,the constitutive model is applied to the numerical simulation analysis of deep drawing of cone-box shaped part,which improves the calculation accuracy significantly.The error between the calculated thickness of shaped part and the experimental results is less than 3.60%,which shows that the established constitutive model has good calculation accuracy,and the feasibility of applying the constitutive model to practical production problems is verified.