ADAPTIVE FEM COMPUTATION OF GEOMETRIC AND MATERIAL NONLINEARITIES WITH APPLICATION TO BRITTLE FAILURE

A model is presented for the dynamic finite element analysis of large- strain, high strain rate deformation behavior of materials. A total La grangian formulation is used in the derivation of discrete equations o f motion. Both an isochoric finite deformation plasticity model, inclu ding rate and temperature effects, for metals, and a multiple-plane mi crocracking model for ceramics are introduced. In addition, algorithms are presented for correcting finite element mesh distortion through m esh rezoning, optimization, and refinement. A surface-defined multibod y contact algorithm designed to handle large relative displacements be tween bodies, with addition for friction, is included. Extensions of t he mechanical contact to account for heat fluxes between sliding bodie s and the treatment of body interfaces with cohesive strength are pres ented within a unified framework. Two test examples are examined, simu lating a modified Taylor rod impact experiment, in which an aluminum a nvil strikes a confined or unconfined ceramic rod. Axial and radial ve locities are computed at the free end of the ceramic and at 30 mm from the impact surface, respectively. Comparisons with experimental trace s reveal that the simulations produce the same overall features observ ed in the experimental data. (C) 1998 Elsevier Science Ltd. All rights reserved.