No abstract

1349As most fractures of ductile materials in metal forming processes occurred due to the results of evolution of internal damage -void nucleation, growth and coalescence. In this paper, an approximate yield criterion for voided (porous) anisotropic ductile materials is developed. The proposed approximate yield function is based on Gurson's yield function in conjunction with the Hosford's non-quadratic anisotropic yield criterion in order to consider the characteristic of anisotropic properties of matrix material. The associated flow rules are presented and the laws governing void growth with strain are derived. Using the proposed model void growth of an anisotropic sheet under biaxial tensile loading and its effect on sheet metal formability are investigated. The yield surface of voided anisotropic sheet and void growth with strain are predicted and compared with the experimental results.

In this study, in order to analyze deformation mechanism in rolling process and predict its yield surface finite element polycrystal model (FEPM) has been developed. Also numerical simulations for deep drawing process of AZ31 magnesium sheet were conducted at elevated temperature. Numerical simulation results for rolling process were compared with experiments of pole figure. For yield surface, the results indicated shift of yield surface along the biaxial strain direction denoting Bauschinger effect and strong anisotropic which is advantageous to deep drawing. Simulation results for limiting drawing ration (LDR) in cup drawing simulation agreed well with experimental observations.