Combination of fracture and damage mechanics for numerical failure analysis

A new approach for the analysis of crack propagation in brittle materials is proposed\ which is based on a combination of fracture mechanics and continuum damage mechanics within the context of the _nite element method[ The approach combines the accuracy of singular crack!tip elements from fracture mechanics theories with the ~exibility of crack representation by softening zones in damage mechanics formulations[ A super element is constructed in which the typical elements are joined together[ The crack propagation is decided on either of two fracture criteria^ one criterion is based on the energy release rate or the J!integralthe other on the largest principal stress in the crack!tip region[ Contrary to many damage mechanics methods\ the combined fracture:damage approach is not sensitive to variations in the _nite element division[ Applications to situations of mixed!mode crack propagation in both two! and three!dimensional problems reveal that the calculated crack paths are independent of the element size and the element orientation and are accurate within one element from the theoretical "curvilinear# crack paths