Adaptive phase-field modeling of fracture in orthotropic composites

Abstract

An adaptive phase-field method is developed and applied to model fracture propagation in orthotropic composites. The proposed approach extends the work of Muixí et al. (2020) to orthotropic composites through following modifications: (a) elastic tensor is evaluated in the global coordinate system from a given engineering stiffness matrix in the principal material coordinates, (b) strain energy density is additively decomposed into fiber and matrix-dominated modes, and (c) a penalized second-order structural tensor is introduced in the phase-field equation facilitating preferential damage growth along the fiber orientation. The developed approach is validated through several benchmark examples and available experimental results.Several numerical failure experiments are conducted varying fiber orientation, adhesive layer thickness, shear modulus, and fracture toughness. A large increase in ductility and peak-load carrying capacity is observed for laminate configurations where the fibers are oriented such that the principal material coordinates and the global coordinates are aligned. An increase in the adhesive layer’s fracture toughness increases the macroscopic ductility and prevents catastrophic failure of laminate. The results of this study provide valuable insights into the failure mechanisms in orthotropic composites.