Improved contact procedure for implicit finite element sheet forming simulation

To enhance the reliability and efficiency of implicit finite element (FE) sheet forming simulations, a contact search method consisting of a global search procedure and a newly developed local search procedure was formulated to work with the N‐CFS solution algorithm, described in the literature. The method enforces and searches for contact search along the mesh normal direction using an irregular triangular mesh‐patch tool description. To take into account sheet thickness in contact analysis for shell elements, the contact distance error was reformulated. These improvements were implemented into the implicit FE program SHEET‐3 and tested numerically with several forming problems. The results show that the contact algorithm for general tools, including sheet thickness, is as accurate and efficient as special closed‐form approaches using analytical tool descriptions. Taking the sheet thickness into account can make improvements in the solution, in terms of shapes and forces, depending on the details of the problem. Copyright © 2010 John Wiley & Sons, Ltd.