Prediction of Initiation and Growth of Cracks in Composites. A Coupled Stress and Energy Criterion of the Finite Fracture Mechanics

Computational methods developed to predict crack onset and growth are briefly reviewed first. Assuming crack advances by (possibly) finite steps, which is the basic assumption of Finite Fracture Mechanics (FFM), in opposite to the hypothesis of crack advance by infinitesimal steps adopted in classical Linear Elastic Fracture Mechanics (LEFM), the coupled stress and energy criterion requires that both stress and energy conditions are simultaneously fulfilled. A quite general formulation of the coupled stress and energy criterion of FFM is introduced. A few examples of applications of this coupled criterion to the prediction of damage initiation in form of cracks in composites are mentioned. Finally, a new formulation of this coupled criterion representing a generalization of LEFM is proposed.