Design Analysis and Behavior of a Variety of As-Formed Mild and High Strength Steel Sheet Materials in Large Deflection Bending

To develop design and application guidelines for a range of mild, high strength and dual phase steels with as received yields ranging from 27.5 to 108.4 ksi, a bending study was conducted for a series of capped hat section rails simulating vehicle underbody rail components. The combined effects of forming, die bias, section geometry and as received material yield strength are evaluated by assessing their effect on bending performance. Two material thicknesses are utilized to evaluate material performance. A third intermediate material gage is used to determine the combined effects of theoretical stiffness and yield strength increase and gage reduction.

The bending data is analyzed to determine actual test component stiffness, peak load capability, overall test component deflection, concentrated load effects and buckling effects for the various materials and section configurations fabricated. Probable NVH interactions and their effects are briefly discussed. An attempt is also made to identify HSS material and forming characteristics which contribute to buckling behavior.