Development of 3D Damage Mechanics-Based Model for Predicting Fiber Orientation-Influenced Crack Propagation in Unidirectional Lamina

Abstract This study develops and validates a three-dimensional continuum damage mechanics (CDM) model to predict crack paths in a lamina, focusing on the influence of fiber orientation on crack propagation. Utilizing 3D Hashin’s failure theory and a stiffness degradation law based on equivalent strain and stress concepts, the model assesses damage onset and progression, respectively. The key contribution is providing a clear approach for orthotropic material 3D patch tests, addressing constitutive responses and specific failure modes, an area lacking in current literature. These patch tests, executed in ABAQUS with a user material subroutine (VUMAT), were verified by varying fiber orientations in unidirectional laminae. Results show model responses within a 2% margin of error, with consistent crack propagation along the fiber-matrix interface for different orientations. The numerical results are validated against available experimental results, accurately predicting crack paths influenced by fiber orientation. This framework will be applied to study machining-induced failures in 3D laminates.