Dislocation based Gradient Plasticity Theory

本项目旨在将通过第一个资助期开发的小应变梯度晶体塑性框架扩展到大变形。与小应变框架类似，大应变框架随后与包含位错输运项的cdd理论耦合。通过这种方法，将梯度晶体塑性理论与CDD联系起来，从而在本构上关闭后者。这种扩展类型的梯度理论有望在由尺寸依赖的体行为和晶界效应引起的寡晶中再现尺寸效应。此外，第二阶段旨在通过引入塑性晶界项（如抗塑性流动阻力）对晶界取向和相邻晶粒的晶体取向的取向依赖，扩展已开发的弹塑性晶界模型。在这里，还计划了已开发的有限变形弹塑性晶界模型的几何非线性有效扩展。通过将模拟结果与实验（微梁的弯曲，细线的扭转，拉伸测试）以及基准模拟（例如来自DDD）进行比较，可以实现各种各样的应用。

This project aims at the extension of the small strain gradient crystal plasticity framework, which has been developed through the first funding period, to large deformations. Similar to the smallstrain framework, the large-strain framework is then coupled to CDD-theory which incorporates dislocation transport terms. By such an approach a gradient crystal plasticity theory is linked to CDD thereby closing the latter constitutively. This extended type of gradient theory is expected to reproduce size effects in oligocrystals induced by both a size-dependent bulk behavior and grain boundary effects. Additionally, the second period aims at extension of the developed elastic-plastic grain boundary model by introducing an orientation dependence of the plastic grain boundary terms (like the resistance against plastic flow) on e.g. the orientation of the grain boundary and the crystal orientations of the adjacent grains. Here, also a geometrically nonlinear efficient extension of the developed elastic-plastic grain boundary model for finite deformations is planned. A broad variety of applications is intended by comparing the simulation results to experiments (bending of micro-beams, torsion of thin wires, tensile tests) as well as benchmark simulations, e.g. from DDD.