A combined stress/energy-based criterion for mixed-mode fracture of laminated composites considering fiber bridging micromechanics

Abstract

A combined stress/energy-based (CSE) criterion is developed to predict mixed mode I/II fracture behavior in laminated composites by taking into account the effect of fiber bridging toughening. Following the proposed criterion, first, the absorbed energy resulting from fiber bridging micro-mechanisms is obtained and translated into a defined effective critical distance (i.e., the size of the crack tip micro-cracking zone). Then, the maximum principal stress is evaluated at the calculated effective critical distance around the crack tip to predict the onset of fracture. The CSE criterion is employed, along with other criteria, to predict experimental data reported in the literature on the onset of mixed mode I/II fracture in laminated composites and wood species (i.e. orthotropic composites). A higher correlation is found between the theoretical results predicted by the CSE criterion and the test data, as compared to other criteria. The stress-based formulation of the CSE criterion offers more computational simplicity as compared to the energy-based criteria while providing an acceptable accuracy and taking into account the effects of absorbed energy resulting from the micromechanical fiber bridging in the solution.