Contact Modelling in Method of Influence Coefficient for Variation Simulation of Sheet Metal Assemblies

Abstract

Sheet metal assembly is a common manufacturing process for several products such as automobiles and airplanes. Since all manufacturing processes are affected by variation and products need to have a high geometric quality, geometry related production problems must be analyzed during early design phases. Often, the analysis is done by using FEA (Finite Element Analysis) to include the compliant behavior of the parts. There are many variables that affect the geometric quality and to include many of them in a FEA simulation is often very time-consuming. One way of performing the simulations relatively fast is to establish linear relationships between part deviation and assembly spring-back deviation by using Method of Influence Coefficient (MIC). However, one limitation with the method is that the method does not consider contact between the parts. This means that the parts are allowed to penetrate each other. In some cases when contact occurs, this method will not simulate the real behavior of the assembly. This paper presents a contact modeling technique that can be implemented in the MIC. The contact modeling procedure consists of a contact detection algorithm and a solution algorithm for finding the position of equilibrium. When implemented, the MIC still only requires two FEA calculations. This paper describes the steps in the contact algorithm and how it can be used in MIC, finally a case study is analyzed.