Energy-Based Cohesive Crack Propagation Modeling

This paper presents an energy-based approach for the finite-element modeling of mixed-mode cohesive crack propagation. This approach predicts the propagation of a quasistatic cohesive crack based on the principle of energy conservation. The crack propagation direction is assumed to be perpendicular to the direction of the maximum tensile principal stress at the cohesive crack tip. A generalized virtual crack-extension technique including the cohesive crack model is used to efficiently evaluate the crack propagation condition. The energy-based approach is both theoretically more fundamental and numerically more accurate than the commonly used strength-based cohesive crack modeling approach. A two-dimensional automatic mixed-mode discrete crack propagation modeling program has been developed that is capable of modeling both nonlinear and linear elastic crack propagation problems. The numerical efficiency and convergence behavior of the present approach are demonstrated through two example problems: a three-point bend beam and a single edge-notched shear beam.