Error estimation and adaptivity in explicit nonlinear finite element simulation of quasi-static problems

摘要

A program module for error estimation with application to nonlinear finite element (FE) analysis of shell structures is coupled with the adaptive solution procedure in the explicit FE code LS-DYNA. The error estimation module provides estimates of the local and global errors and element-level refinement indicators. Hence, selective refinement of the mesh in areas where the local error is relatively large compared with a user-defined tolerance is made possible. Furthermore, the relative global error is estimated giving a measure of the overall accuracy of the FE model. Projection-type error estimators based on the L-_2-norm of the stress vector and the accumulated plastic strain are sued to predict the discretization error by comparison of the FE solution with an improved C~o- continuous solution obtained by the SPR-method. There example problems including both material and geometric nonlinearities are provided. The numerical results show that the error estimates capture phenomena such as diffuse necking and local buckling, and given meshes with high resolution in areas with large deformations or high stress gradients.