ERROR ESTIMATION AND ADAPTIVITY IN ELASTOPLASTICITY

In this paper, a method is developed to control the parameters of a fi nite element computation for time-dependent material models. This meth od allows the user to obtain a prescribed accuracy with a computationa l cost as low as possible. To evaluate discretization errors, we use a global error measure in constitutive relation based on Drucker's ineq uality. This error includes, over the studied time interval, the error of the finite element model and the error of the algorithm being used . In order to master the size of the elements of the mesh and the leng th of the time inclements,an error estimator, which permits estimating the errors due to the time discretization, is proposed. These tools a re used to elaborate two procedures of adaptivity. Various examples fo r monotonous or non-monotonous loadings, for 2-D or axisymmetric probl ems, show the reliability of these procedures.