Artificial kinematics and simple stabilization of solid-shell elements occurring in highly constrained situations and applications in composite sheet forming simulation

Well-known problems which occur for mixed or underintegrated element formulations are artificial kinematics resp. numerical instabilities. These problems are also observed for 3D-shell elements as the so-called solid-shell elements especially when the loading leads to a homogeneous stress state. To prevent the elements from artificial kinematical failure a simple procedure is applied which allows to identify critical states. Then the non-necessary element modifications responsible for the numerical instabilities can be taken out.A special application for the solid-shell elements which includes strong constraining are sheet forming problems with high stretching and large local contact pressure especially for layered composite sheets which cannot be modeled with standard 2D-shells. In the second part some numerical examples for the simulation of the forming process for pasted composite sheets are shown.