论文标题
使用基于脱位密度的应变梯度可塑性框架对定向硬化和内在尺寸效应进行建模
Modeling directional hardening and intrinsic size effects using a dislocation density-based strain gradient plasticity framework
论文作者
论文摘要
这项工作提出了一个基于脱位密度的应变梯度$ J_2 $可塑性框架，该框架使用较低阶，泰勒硬化的背心模型模拟了由于几何必要的脱位（GND）而引起的强度贡献。引入了各向异性因子，以在这个$ J_2 $可塑性框架中晶粒之间的差分硬化。为有限变形可塑性模型的时间集成，实现了隐式数值算法。该框架首先用于预测由于GND引起的循环载荷过程中的后退压力而导致的定向硬化。研究了变形轮廓，以了解导致方向硬化的子结构属性。然后，该框架用于预测聚生物集合的固有的，晶粒尺寸依赖性的增强。证明具有不同晶粒尺寸的模拟的模型预测与Hall-Petch效应以及Ashby的硬化模型相一致。
This work proposes a dislocation density-based strain gradient $J_2$ plasticity framework that models the strength contribution due to Geometrically Necessary Dislocations (GNDs) using a lower order, Taylor hardening backstress model. An anisotropy factor is introduced to phenomenologically represent the differential hardening between grains in this $J_2$ plasticity framework. An implicit numerical algorithm is implemented for the time integration of the finite deformation plasticity model. The framework is first used to predict directional hardening due to the GND-induced backstress during cyclic loading. Deformation contours are studied to understand the substructure attributes contributing to directional hardening. The framework is then used to predict the intrinsic, grain size-dependent strengthening of polygrain ensembles. Model predictions of simulations with different grain sizes are shown to agree with the Hall-Petch effect and also with Ashby's model of hardening due to GNDs in polygrain ensembles.
