Using beam element in finite element analysis of automotive structures in the event of crash may significantly reduces the number of elements required to model the structures. It may significantly reduces the computing time for nonlinear integration. More significantly, it takes less time to establish, post-process and modify the models and is therefore, suitable for upfront engineering and concept analysis at early design stages. Considerable studies on beam elements (1–4) have been conducted and many commercial and academic finite element codes (5–7) incorporated it in their libraries. These beam elements are mostly based on the traditional theory that considers the deformation due to yielding and large displacement. However, the buckling phenomenon in the thin-walled components is not reflected in the formulation and therefore, the element are not suitable for thin-walled beams which are quite common in vehicle structures.
In this study, a thin-walled beam element is developed to incorporate both the deformation due to material yielding and the deformation due to the buckling of the thin wall plates. The buckling characteristics of the plates is approximately and equivalently converted into the behavior of crush hinge. Like the conventional plastic hinges, the crush hinges are formulated into the finite beam element. The element buckling effect is reflected into the structural response.
The beam element is coded into a computer program. The major formulations of beam element, numerical integration schemes of dynamic analysis and contact loading are illustrated in the follow sections. The computer program is used to analyze vehicle structures and the examples are shown in this paper. It should be pointed out that due to the limitations of beam element it is not possible to consider local design features such as small holes and notches. In those cases approximation must be adopted in finite element modeling.