A comparison in terms of accuracy and efficiency between a MBS dynamic formulation with stress analysis and a non-linear FEA code

To perform the mechanical design of a machine through computer-aided techniques, at least three main di8erent products should be used: a CAD software, to model the parts of the machine; a MBS program, to analyse the kinematics and dynamics of the whole system; and a FEA code, to determine the level of stress and strain su8ered by each component. If it is true that CAD software is usually well connected with the two other tools, the same does not happen in what respects to FEA–MBS interfaces. Moreover, since both the large-amplitude motion and the elastic deformation are coupled, they cannot be solved separately, and the usual practice consisting of ;rst analysing the machine motion assuming rigid bodies, and then calculating stresses under the loads previously generated, is just an approximation. In order to provide mechanical designers with a tool which makes easier and shorter the design-cycle, this paper presents a comparison between the two options that are currently available to address the mentioned problem: a dynamic MBS formulation which simultaneously solves motion and performs stress analysis by considering >exible bodies; and a non-linear module of a FEA code, which takes into account large displacements and ;nite rotations. The comparison is carried out in terms of accuracy and e)ciency through four examples. The results lead to the conclusion that, for similar accuracy, the ;rst method is largely more e)cient. Therefore, the interest of developing MBS commercial codes which integrate motion calculation and stress analysis through the mentioned approach is envisioned, as long as they would provide faster solutions