Analysis of bolted assemblies in structural mechanics: modeling issues and simulation by domain decomposition methods
Résumé
Due to a high number of contact interactions, fine scale computations of bolted assemblies are generally too costly and hardly tractable within an optimization process. Thus, engineers often resort to simplified models for bolted joints. Moreover, advanced computational strategies, such as domain decomposition methods and parallel computing, may be necessary to handle such large size problems.
In the first part of this presentation, the motivations of parallel computing by domain decomposition methods (DDM) are first given. After a brief classification of DDM, the basics of the primal, dual and mixed approaches are described for linear elastic problems. The focus is made on the mixed approach that shares similar features with augmented Lagrangian formulation and provides a versatile framework to handle various interface behaviors such as frictional contact. Some industrial applications are presented to assess the robustness and the efficiency of mixed DDM to deal with complex assemblies.
In the second part of this talk, a simplified model for bolted joint is presented. FE connectors or user-elements are usually used or developed in FE commercial code by engineers as substitutes for bolts. In this work, a nonlinear FE connector with its identification methodology is proposed to model the behavior of a single-bolt joint. Developed in SAMCEF through a Fortran user-element subroutine, the performances of the proposed connector are illustrated through the example of a double lap bolted joint. In particular, it is shown that dissipated energies are in good agreement and that a significant gain in CPU time can be obtained compared with a full fine scale 3D computation.