A modal approach to linear fracture mechanics for dynamic loading at low frequency

In this paper, a modal approach to fracture mechanics for dynamic loading is proposed. This approach is based on the linear recombination of modal stress intensity factors. The modal stress intensity factors may be computed either from a classical crack-tip-opening-displacement method or by an energy method that is detailed in this paper. The energy method is based on a bilinear form stemming from the energy release rate quadratic form and it turns out to be very satisfactory—compared to other methods—in a large range of frequencies, up to moderate frequencies. The accuracy of the modal approach to fracture mechanics is discussed through several examples and demonstrated in an industrial application.