AN EFFICIENT FORMULATION OF INTEGRATION ALGORITHMS FOR ELASTOPLASTIC SHELL ANALYSIS BASED ON LAYERED FINITE-ELEMENT APPROACH

For geometrically and physically nonlinear analyses of shell structure s a computational model employing a Reissner-Mindlin type kinematic as sumption, a layered finite element approach and a closest-point projec tion return mapping algorithm, completely formulated in tensor notatio n is presented. As a result of a consistent linearization. a tangent m odulus is derived, expressed also in tensor components. The applied co nstitutive model includes a von Mises yield criterion and linear isotr opic as well as kinematic hardening. All stress deviator components ar e employed in the formulation. The material model is implemented into a four-noded isoparametric assumed strain finite element, which permit s the simulation of geometric nonlinear responses considering finite r otations. The proposed numerical concept is unconditionally stable and allows large time steps, as the numerical examples illustrate. Furthe r, the numerical simulations demonstrate the expected quadratic conver gence in a global iterative technique.