Anisotropic Phase-Field Modeling of Crack Growth in Shape Memory Ceramics: Application to Zirconia

Shape memory ceramics (SMCs) are promising candidates for actuators in extreme environments such as high temperature and corrosive applications. Despite outstanding energy dissipation, compared to metallic shape memory materials, SMCs suffer from sudden brittle fracture. While the interaction of crack propagation and phase transformation in SMCs have been subject of several experimental and theoretical studies, mainly at macroscale, the fundamental understanding of the interaction of crack propagation dynamics with evolving martensitic transformation is poorly understood. In this work we use the phase field technique to fully couple the martensitic transformation to the variational formulation of brittle fracture. The model is parameterized for zirconia which experiences tetragonal to monoclinic transformation during crack propagation. For the mode I of fracture, opening mode, crack shows an unusual propagation path which indicates the effect of phase transformation on crack path. The model is efficiently capable of predicting the crack initiation as well as propagation. The results show the dramatic effect of phase transformation on fracture toughening and crack propagation path.