Development of Plastic Deformation Induced Crystalline Structure Analysis Code Based on Crystalline Restructuring Assey Theory

主要研究内容如下：1.利用扫描电子显微镜和电子背散射谱研究了面心立方单晶片在拉伸过程中，样品的尺寸和初始取向对塑性变形引起的晶体旋转和滑移带形成的影响。这有助于在微观实验观察的基础上建立弹塑性/结晶塑性有限元程序。提出了晶体塑性有限元模型的取向概率赋值方法，该方法可归结为非均匀材料模型。确定了取向，并将其分配给有限元积分点，这些积分点代表微晶，可以单独旋转。考虑到初始和演化的塑性各向异性，大量的有限元积分点被用来表示板材的织构。采用取向分布函数(ODF)分析方法研究了面心立方铝合金板材和体心立方板材的织构。测量的ODF结果清楚地显示了板材的织构，表现为取向纤维、骨架线和在欧拉角空间的择优取向，这可能与塑性各向异性有关。采用弹性/晶态粘塑性有限元程序对面心立方铝合金和体心立方钢板的成形性进行了评价。通过与实验的对比，验证了有限元模拟能够较好地预测应变局部化、耳塞和失效。

This Study can be summarized as follow ;1. Using SEM and EBSD observations were employed to study how the size and initial orientation of specimen effect the plastic deformation induced crystal rotation and slip band formation during tension tests of FCC single crystal sheets. It is helpful to establish an elastic/crystalline plasticity FE code based on microscopic experimental observation.2. The orientation probability assignment method for crystalline plasticity finite element (FE) modeling, which could be categorized as an inhomogenized material model, was newly proposed. The orientations were determined and assigned to FE integration points, which represent crystallites and can rotate individually. Huge numbers of FE integration points were employed to represent textures of the sheet metals for taking account of the initial and evolutional plastic anisotropy.3. The textures of FCC aluminum alloy and BCC steel sheets were investigated by using orientation distribution function (ODF) analyses. The measured ODF results revealed clearly textures of the sheets, featured by orientation fibers, skeleton lines and selected orientations in Euler angle space, which could be related to the plastic anisotro py.4. The formability of FCC aluminum alloy and BCC steel sheets were assessed by using the elastic/crystalline viscoplastic FE code. It was confirmed by comparison with experiment that Finite Element simulation could predict the strain localization, earing and failure with good accuracy.