Aspects of mesh sensitivity for phenomenological damage models using small solid and large shell elements

Application-oriented simulations, such as automotive crash simulations, often utilize large shell elements to optimize computational efficiency. This study applies the crack band approach typically used for concrete materials to steel sheets. The aim was to examine this regularization method for different stress states with plane stress shell elements to reduce mesh sensitivity, in respect to element size as well as to element shape. Finite element simulations of four specimens covering the lower and mid triaxiality range were performed with LS-Dyna using small solid elements and large shell elements. For each specimen, the results of a finite element simulation performed with large shell elements were compared with results of a block of solid elements of equal dimensions. Each finite element solver uses different shell formulations, which can influence the exact results of the simulation. Nonetheless, the comparison provides insights into the expected behavior compared to the behavior resulting from shell simulations. The guidelines developed in this study were tested numerically for a tensile test with a spot weld by comparing differently discretized meshes. ... mehrThe results show that the characteristic length determined by the crack band approach improves shell element simulations compared to the conventionally calculated characteristic length. This approach accommodates various aspect ratios and arbitrarily shaped shell elements.