正交各向异性韧性材料应力-应变关系

采用大变形弹塑性有限元方法分析了各向同性和正交各向异性韧性材料光滑圆棒拉伸试件的颈缩问题．首先给出了采用计算机模拟确定各向同性韧性材料真实应力-应变曲线的具体方法；对正交各向异性韧性材料的分析表明，颈缩截面呈椭圆形，其长短轴方向的等效塑性应变基本上均匀分布，与Bridgman假设一致；轴向拉伸载荷-位移曲线与其它两方向的各向异性参数关系不大．在此基础上，建议了一种确定正交各向异性韧性材料真实应力-应变曲线的方法．

ON THE STUDY OF STRESS VS. STRAIN OF DUCTILE ORTHOTROPIC ELASTIC-PLASTIC MATERIAL

Large deformation elastic-plastic necking finite element analysis of tensile bar was carried out for isotropic and orthotropic material. Practical method combined with finite element analysis to determinate the relation between stress and strain was developed. The numerical results of necking of orthotropic material showed that the equivalent plastic strain along the two directions which perpendicular to tensile axis is almost uniform, the conclusion is accord with Bridgman formula. The anisotropic parameter along the directions perpendicular to tensile axis has the little influence on the relation between load and displacement. Based on FEM results and analysis a simple method was suggested to obtain the true stress and strain curve of orthotropic material.