Search Results

An automotive body is made by joining over 500 components made from steel sheets. Since the joining locations for spot-welding are decided by the designer of each component, the number of spot-welding points tends to be either excessive or inadequate for the required automotive body stiffness. In this study, a topology method which is able to select effectively from design space was applied to optimization of spot-welding locations for vehicle stiffness performance by using a full vehicle model. Static stiffness using constraint of nodes cannot sufficiently express deformation during driving. Torsional deformation occurred in all parts of the body in the mode in which one point of the front bilateral suspension parts was forced and the other three points were constrained in the general static stiffness mode.

A new topology analysis method was developed to optimize part shapes and the configuration of automotive components. Only solid elements are used in the conventional topology optimization method. The key point of the new method is to embed solid elements in a model made of shell elements. In this study, stiffness optimizations were carried out for a simple cylindrical model, automotive floor model and full vehicle model. Specifically, optimized automotive components were a center tunnel, a side-sill and a joint linking a side-member and a cross-member, which are made of steel sheets and have rectangular cross sections. The results show that the newly-developed topology optimization method is valuable in the optimization of automotive components which are made of steel sheets and have rectangular cross sections.

Sheet hydro-forming was applied to hydro-form a door outer panel using different steel grades. The effect of mechanical properties and the forming conditions on panel properties such as thickness profile and cross-sectional shape accuracy were investigated by both experimental sheet hydro-forming and FEM forming analysis. 590MPa T.S. steel grade was successfully formed with improved dent resistance compared to the conventional 340MPa T.S. steel grade. On the other hand, the results of the FEM forming process analysis showed that the pre-forming conditions were important in controlling the fracture formation during forming and to improve dent resistance, which successfully led to the best forming condition.