EXPLICIT DYNAMICS SIMULATIONS OF ELASTOPLASTIC AND BRITTLE FAILURE OF THIN SHELL STRUCTURES

Fracture propagation in elastoplastic shell structures, due to impact or cutting, is conveniently simulated using explicit finite element approaches, in view of the high nonlinearity of the problem. Solid-shell elements are usually preferred for the discretization in the presence of complex material behavior and degradation phenomena such as delamination, since they allow for a correct representation of the thickness geometry. Solid-shell elements require time consuming corrections to the element kinematics to avoid locking. Reduced integration with hourglass stabilization is used to reduce the computational cost. New "directional" cohesive interface elements are used to account for the interaction with a sharp blade in cutting problems. The element small thickness leads to very high eigenfrequencies, which imply very small stable time-steps. A new selective mass scaling technique is used to increase the time-step without affecting accuracy.