Effect of the cross-sectional shape of hat-type cross-sections on crash resistance of an “S”-frame

This paper addresses a design aspect of a front side rail structure of an automobile body from the point of view of weight efficiency and crush energy absorption. Various orientations of the cross-section and ways of reinforcing the cross-section by an internal stiffening member are investigated. The specific energy absorption (i.e. energy absorption per unit weight) is taken as a measure of the performance of a structure. Also the advantages of reinforcing the side rail by means of aluminum foam filling are assessed. It is shown through extensive numerical simulation using nonlinear finite element code PAM–CRASH, that the model with a diagonally positioned internal stiffener and suitable triggering dents can absorb up to 200% more energy than the typical double-hat/double-cell profile member. At the same time there is a 3 fold increase in the specific energy absorption. By using the concept of aluminum foam-filling with 3 MPa foam, the specific energy absorption increases by a factor of 2.84.