AN EXPLICIT DYNAMICS APPROACH TO THE SIMULATION OF CRACK PROPAGATION IN THIN SHELLS USING REDUCED INTEGRATION SOLID-SHELL ELEMENTS

Fracture propagation in laminated shell structures, due to impact or cutting, is a highly nonlinear problem which is more conveniently simulated using explicit finite element approaches. Solid-shell elements are better suited for the discretization in the presence of complex material behavior and delamination, since they allow for a correct representation of the through the thickness stress. In the presence of cutting problems with sharp blades, classi- cal crack-propagation approaches based on cohesive interfaces may prove inadequate. New “directional” cohesive interface elements are here proposed to account for the interaction with the cutter edge. The element small thickness leads to very high eigenfrequencies, which imply overly small stable time-steps. A new selective mass scaling technique is here proposed to increase the time-step without affecting accuracy.