Abstract A numerical investigation of wedge indentation, with a nearly flat indenter, into a monazite (LaPO4) single crystal is carried out to obtain the asymptotic field solution associated with the moving contact point singularities. The crystal orientation is such that plane strain conditions prevail, under the assumption of small scale yielding, as out-of-plane deformations are eliminated due to out-of-plane mirror symmetry of the crystal, specimen and loading state. The plastic deformation in such a 2D study can be described in terms of effective in-plane slip systems comprised of crystallographic slip systems with equal and opposite out-of-plane deformation and rotation. The numerical simulations are conducted within a framework specialized for self-similar problems and adopts a visco-plastic single crystal material model. The detailed numerical investigation of the monazite single crystal reveals that the effective slip systems lead to a non-symmetric in-plane deformation field, which is consistent with the absence of in-plane mirror symmetries of the crystal. Interestingly, the non-symmetric deformation field results in one contact point singularity travelling at a greater speed than the other. The deformation near the moving contact point singularities are found to be divided into two angular sectors separated by a boundary of glide shear type. The slip rates on the individual systems reveal that one slip system dominates at both contact points, whereas the other slip system shows negligible activity. Thus, only one slip system gives rise to a discontinuity in the slip rate field.

中文翻译：

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单晶独居石的楔形压痕：数值研究

摘要 对独居石 (LaPO4) 单晶楔形压痕进行数值研究，获得了与移动接触点奇点相关的渐近场解。晶体取向使得平面应变条件占优势，在小规模屈服的假设下，由于晶体、试样和加载状态的平面外镜面对称，平面外变形被消除。这种二维研究中的塑性变形可以用有效的面内滑移系统来描述，该滑移系统由具有相等和相反的面外变形和旋转的晶体滑移系统组成。数值模拟在专门用于自相似问题的框架内进行，并采用粘塑性单晶材料模型。对独居石单晶的详细数值研究表明，有效的滑移系统导致非对称的面内变形场，这与晶体没有面内镜像对称性是一致的。有趣的是，非对称变形场导致一个接触点奇点以比另一个更快的速度移动。发现移动接触点奇点附近的变形被分成两个角扇区，由滑移剪切类型的边界隔开。单个系统的滑移率表明一个滑移系统在两个接触点占主导地位，而另一个滑移系统显示出可忽略不计的活动。因此，只有一个滑移系统会导致滑移率场的不连续性。