Elastoplastic dynamic analysis with hybrid stress elements

The stress model of the hybrid 7nite element formulation is applied to the solution of dynamic elastoplastic structural problems. The stress 7eld is approximated in the domain of the elements and the displacements on its boundary. The displacement, velocity and acceleration approximations in the domain of the element are implicit, in the sense that they result from a combination of the stress estimate with the time integration procedure that ensures that the equilibrium condition is locally satis7ed. The 7nite elements are subdivided in plastic cells where a gradient dependent model is implemented using a hybrid formulation based on the approximation of the plastic parameter and the plastic radiation 7elds in the domain and on the boundary of the plastic cells, respectively. Generalized variables associated with orthogonal and naturally hierarchical bases are used. The resulting solving systems are symmetric, sparse, p-adaptive and well suited to parallel processing. The performance of the element is assessed using a representative set of testing problems