Finite element-based phase-field simulation of interfacial damage in unidirectional composite under transverse tension

A finite element-based phase field method for modeling the complex failure mechanism of a unidirectional fiber composite under transverse tensile loading was developed. An interface layer with a finite width was incorporated between a fiber and the matrix to implement interfacial failure. Different processes such as onset of interfacial cracking and kinking, matrix cracking, and their interactions were modeled within a unified framework. The sensitivity of the onset of interfacial cracking to the fracture mode was assessed by incorporating a phenomenological model of the interface fracture toughness in the computational model. It was found that the onset of interfacial cracking involved a combination of cracking modes I and II over a finite incremental length. The single-fiber composite model was verified by comparing its predictions of the stress distribution along the interface and the critical stress at the onset of interfacial cracking with those from the analytical solutions. The effects of the stiffness and fracture properties of the constituents on the critical stress at the onset of interfacial cracking were also evaluated, as well as the effects of the interface width and the fiber radius. Finally, the validated model was applied to the fracture analysis of a multi-fiber composite. The complex failure mechanisms were found to agree well with experimental observations.