Effects of Cut Boundary Location on Finite Element Submodels With Contacts

Submodeling is a method used in Finite Element Modeling in order to evaluate features of interest, such as fillets or contact interfaces at a reduced cost. Submodeling can be done by creating a full-structure, coarse-mesh, “global” model and solving it. Once the solutions for this model are solved, a model just of the feature of interest, or “submodel”, can be solved using boundary conditions estimated based on global model results. The location of the submodel boundary has large effects on the accuracy of the solution and has been examined by the authors previously, but not for models with contact interfaces. This work uses the submodeling procedure on a model with two cantilever beams sandwiched together with a bolt close to the free end (dubbed “sandwich beam”). Numerous models are produced with different submodel boundary locations in order to better understand how those locations affect the solutions of a model with contact interfaces. The maximum contact pressure was the main metric used to examine the effects and the feature of interest was the bolt. In previous works, it was determined that the global model mesh size and submodel boundary locations are the main sources of error in submodeling [15]. From this work, it was concluded that the inaccuracies of the global model mesh size are magnified when the submodel mesh is too close to the feature of interest. Furthermore, contact pressure tends to be overestimated as the submodel is refined, but it tends to converge as the global model is converged. This work also demonstrated that errors in global model solution (due to meshing) are mitigated when the entire feature of interest is included in the submodel and the submodel boundary locations are far enough away from that feature.