Abstract
Vehicles with S-frames tend to distort the S-parts and does not maintain the occupant safety space during a frontal collision. Merely reinforcing the occupant space is not a good solution since it adds to the vehicle weight. The most important factor is a design for lightweight S-frames in which the front parts can absorb maximum collision energy in spite of minimum deformation of S-parts. We investigated characteristics of various cross-sectional configurations in the front part of the S-frame by means of dynamic crash tests and the lightweight structure of the S-part by means of CAE. Finally, we verified by vehicle crash tests the performance of the S-frames which these studies developed.