标题： 多孔单晶的凝聚准则 显示英文标题

标题： A coalescence criterion for porous single crystals

摘要： 在延性材料中，可以在各种尺度上观察到孔隙，通常孔隙尺寸小于晶粒尺寸，导致多孔单晶材料。 已经识别并称为孔隙生长和孔隙聚结的两种多孔延性（单晶）材料的局部变形模式，后者以相邻孔隙之间的强相互作用为特征。 提出了一种用于具有周期性排列孔隙的多孔单晶材料的简单半解析聚结准则，该准则使用与各向同性材料推导出的准则相关的有效各向同性屈服应力。 还提出了聚结准则的扩展，以考虑相对于聚结平面的剪切。 有效屈服应力通过单晶变形的泰勒理论定义，并最终依赖于平均泰勒因子的计算。 可以考虑任意滑移系统集合。 通过与基于快速傅里叶变换的求解器进行的数值极限分析结果进行比较，评估了聚结准则。 对于包括不同滑移系统集合（面心立方、六方密堆）、晶体取向、孔隙形状和加载条件的各种配置，观察到了所提出的准则与数值结果之间良好的一致性。 在特定条件下描述了孔隙生长和孔隙聚结之间的竞争，强调了晶体取向和孔隙晶格以及它们之间相互作用的强烈影响。 显示英文摘要

摘要： Voids can be observed at various scales in ductile materials, frequently of sizes lower than the grain size, leading to porous single crystals materials. Two local deformation modes of porous ductile (single crystals) materials have been identified and referred to as void growth and void coalescence, the latter being characterized by strong interactions between neighboring voids. A simple semi-analytical coalescence criterion for porous single crystals with periodic arrangement of voids is proposed using effective isotropic yield stresses associated with a criterion derived for isotropic materials. An extension of the coalescence criterion is also proposed to account for shear with respect to the coalescence plane. Effective yield stresses are defined using Taylor theory of single crystal deformation, and rely ultimately on the computation of average Taylor factors. Arbitrary sets of slip systems can be considered. The coalescence criterion is assessed through comparisons to numerical limit analysis results performed using a Fast-Fourier-Transform based solver. A good agreement is observed between the proposed criterion and numerical results for various configurations including different sets of slip systems (Face-Centered-Cubic, Hexagonal-Close-Packed), crystal orientations, void shapes and loading conditions. The competition between void growth and void coalescence is described for specific conditions, emphasizing the strong influence of both crystal orientation and void lattice, as well as their interactions.