In the present study, damage initiation and growth in a polycrystalline aggregate are investigated. In this regard, an anisotropic continuum damage mechanics coupled with rate-dependent crystal plasticity theory is employed. Using a thermodynamically consistent procedure, a finite deformation formulation is derived. For this purpose, the damage tensor is incorporated in the crystal plasticity formulation for a cubic single crystal. The damage evolution is considered to be dependent on the history of damage, equivalent plastic strain, stress triaxiality, and Lode parameters. This material model is implemented in the commercial finite-element code Abaqus/Standard by developing a user material subroutine (UMAT). Using the available experimental tests of 316L single crystal in the literature, the crystal plasticity hardening and damage parameters are calibrated considering the stress–strain curve before and after necking, respectively. The damage sites in a single-phase polycrystalline aggregate are also considered using a polycrystalline model consisting of grains with random sizes and orientations. The results show that the damage arises at the grain boundaries and triple junctions. Moreover, growth of the damage mostly occurs in the grains with higher Schmid factor compared to the neighboring grains. The presented model manifests capacity for determination of damage initiation sites and damage evolution in polycrystalline models.

在本研究中，研究了多晶聚集体中的损伤引发和生长。在这方面，采用各向异性连续体损伤力学与速率依赖型晶体可塑性理论相结合。使用热力学一致的过程，得出有限变形公式。为此，将破坏张量并入用于立方单晶的晶体可塑性配方中。损坏的演变被认为取决于损坏的历史，等效塑性应变，应力三轴性和Lode参数。通过开发用户材料子例程（UMAT），可以在商业有限元代码Abaqus / Standard中实现该材料模型。使用文献中可用的316L单晶的实验测试，分别考虑颈缩前后的应力-应变曲线来校准晶体的可塑性硬化和损伤参数。还可以使用由具有随机尺寸和方向的晶粒组成的多晶模型来考虑单相多晶聚集体中的损伤部位。结果表明，损伤发生在晶界和三重结处。而且，与邻近的晶粒相比，损害的增长主要发生在具有施密德因子较高的晶粒中。提出的模型表明了在多晶模型中确定损伤起始位点和损伤演变的能力。还可以使用由具有随机尺寸和方向的晶粒组成的多晶模型来考虑单相多晶聚集体中的损伤部位。结果表明，损伤发生在晶界和三重结处。而且，与邻近的晶粒相比，损害的增长主要发生在具有施密德因子较高的晶粒中。提出的模型表明了在多晶模型中确定损伤起始位点和损伤演变的能力。还可以使用由具有随机尺寸和方向的晶粒组成的多晶模型来考虑单相多晶聚集体中的损伤部位。结果表明，损伤发生在晶界和三重结处。而且，与邻近的晶粒相比，损害的增长主要发生在具有施密德因子较高的晶粒中。提出的模型表明了在多晶模型中确定损伤起始位点和损伤演变的能力。