Abstract:

A theoretical derivation method was described for calculating the front structure’s length and section
force of a positive development vehicle to move structural worthiness design forward to the conceptual design
phase and to obtain desired deformation behaviors of front structures and an ideal impact pulse. A 3-step
equivalence crash pulse design method was used. The 3-steps were the crash-box deformation step, the front
member deformation step, and the rear member and dash intrusion step. The 3-step structure’s section forces
were derived by a 3-step pulse target which was set in the prophase The 3-step structure lengths were derived
ccording to the energy conservation principle. The method was validated by numerical simulation. The results
show that the front structure has an ideal behavior of axial deformation. Therefore, the method can provide the
critical design parameters effectively in the conceptual phase with the method being especially suit for a positive
developing vehicle.

Key words: passive safety, frontal structure, section force, length, positive development