This paper develops a microstructure-based numerical model to simulate the mechanical behavior of homogeneous coarse-grained (CG) and harmonic-structured (HS) Ti–6Al–4V under monotonic and cyclic simple shear loading conditions. This model incorporates a crystal plasticity model describing the deformation behavior of lamellar $$\alpha +\beta $$ colonies and a scale transition rule called ‘ $$\beta $$ -rule’ which enables to deal with the huge contrast between grain sizes in fine-grained and coarse-grained regions in HS Ti–6Al–4V. Besides, the numerical model can be used to consider the effects of microstructural features, such as the slip geometry for lamellar $$\alpha +\beta $$ colonies, length scale dependence of hardening, or anisotropic strength of the slip systems. The model is implemented into a finite element code (Cast3M) via a UMAT subroutine. The strengthening effect of harmonic structure design is studied based on the numerical results for HS Ti–6Al–4V and homogeneous CG Ti–6Al–4V. The simulation results are in good agreement with the experimental observations.

中文翻译：

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单调和循环剪切载荷下粗晶和谐波结构 Ti-6Al-4V 的三维微观结构晶体塑性模型

本文开发了一种基于微观结构的数值模型来模拟均匀粗晶 (CG) 和谐波结构 (HS) Ti-6Al-4V 在单调和循环简单剪切载荷条件下的力学行为。该模型结合了描述层状 $$\alpha +\beta $$ 菌落变形行为的晶体塑性模型和称为“$$\beta $$ -rule”的尺度转换规则，该规则能够处理晶粒尺寸之间的巨大差异在 HS Ti-6Al-4V 的细晶粒和粗晶粒区域。此外，数值模型可用于考虑微观结构特征的影响，例如层状 $$\alpha +\beta $$ 菌落的滑移几何形状、硬化的长度尺度依赖性或滑移系统的各向异性强度。该模型通过 UMAT 子程序实现为有限元代码 (Cast3M)。基于HS Ti-6Al-4V和均质CG Ti-6Al-4V的数值结果研究了谐波结构设计的强化效果。模拟结果与实验观察非常吻合。