Enhancing Robustness in Finite‐Strain Crystal Plasticity: An Interior Point Method With Sequential Rotation Updates

ABSTRACT Crystal plasticity simulations offer insights into the anisotropic deformation of polycrystalline materials such as metals and alloys. However, rate‐independent crystal plasticity models encounter the Taylor ambiguity, where the active slip systems and plastic slip magnitudes are not uniquely defined, posing well‐known numerical challenges [1]. Interior point methods, which smooth the problem via a barrier term, have recently emerged as a promising strategy for both small‐strain [2, 3] and large‐strain [4, 5] crystal plasticity frameworks. This contribution presents a finite‐strain crystal plasticity model based on an interior point [2, 3]. Distinctly from existing large‐strain IPM implementations, our approach incorporates sequential updates for slip system rotations, which are held constant during intermediate interior point iterations, significantly enhancing algorithmic robustness. The method is evaluated at the material point level for several test cases, and its predictions are shown to be consistent with established results from various crystal plasticity algorithms in the literature, such as those based on an augmented Lagrange method.