An evaluation method of macroscopic yield strength for polycrystalline metals subjected to plastic forming by micro-macro decoupling analysis

We introduce a method of predicting macroscopic yield strength of polycrystalline metals subjected to plastic forming by applying the micro-macro decoupling analysis method. The macroscopic plastic forming problem is assumed to be a three-stage forming process and is simulated with a single finite element in this study. At the same time, a polycrystalline aggregate composed of several crystal grains is adopted as a microstructure and is regarded as a numerical specimen for numerical material tests based on the homogenization theory. After simulating the macro-scale forming process with macroscopic approximate constitutive model, we apply the resulting macroscopic deformation histories to the microstrcutre to obtain the numerical specimen that enables us to evaluate the post-forming yield strengths. By performing the equivalent micro-macro coupling analysis and comparing the results with those by the coupling method, we demonstrate the capability of the proposed method in predicting the anisotropy in the macroscopic yield strength.