EFFICIENT ITERATIVE SOLUTION OF CONSTRAINED FINITE-ELEMENT ANALYSES

This contribution describes how iterative solvers can meet specific re quirements of industrial FE analyses, focusing on the case frequently met where the unknowns are subject to linear equality constraints. Sta ndard iterative methods designed to deal with that kind of problem suf fer from a significant overhead with respect to the CPU times involved in the solution of unconstrained problems, whereas the performance of direct solvers traditionally used is not affected. Here we propose a subspace projection method that allows the use of any iterative scheme able to solve the unconstrained problem, with the same preconditioner . We also highlight that there is no loss of efficiency due to the pre sence of linear constraints. (C) 1998 Elsevier Science S.A. All rights reserved.