Improve the convergence rate and robustness of finite elements simulations.
It is widely accepted that good convergence (or any convergence at all) is difficult to achieve in a progressive failure simulation of a composite structure. In fact, many progressive failure simulations terminate early, not due to global structural failure, but rather due to the inability of the finite element code to obtain a converged solution at a particular load step. Helius PFA significantly improves the overall convergence rate and robustness of progressive failure simulations of composite structures. Experienced users of ANSYS are no doubt familiar with the code's tendency to reduce (or cut-back) the time increment size when the code senses that convergence is difficult to achieve. However, when Helius PFA is used in conjunction with ANSYS to perform a progressive failure analysis, the increased robustness of the solution greatly diminishes the need for time incrementation reductions (or cut-backs). Thus, the analysis can be completed much faster than without. In order to take full advantage of the convergence characteristics, you must change some of the default settings that govern the nonlinear solution process used by ANSYS. These changes can be enacted using the NROPT, PRED, NSUBST, NEQIT, and CNVTOL commands. The specific data and options that are used with these commands will be discussed later (Nonlinear Solution Control Parameters with the GUI and Nonlinear Solution Control Parameters with a Text Editor).