The objective of this paper is to examine a stiffer passenger compartment for a frontal collision impact force, and a more efficient front end structure of the vehicle body for absorption of the impact energy.

For design of the former, a sizing optimization analysis based on the fully stressed design is applied to determine the properties of the members that constitute the compartment. In this calculation, the balance between the strength of the floor side member and the impact force is reviewed.

For design of the latter, impact energy absorption efficiency is increased by "hybrid" members composed of steel and fiber reinforced plastic (FRP) composite materials. The relationship between the energy absorption characteristics and fiber distribution angle is determined by collapse tests using simple specimens made of steel tubes with FRP adhered to their inner surfaces. To evaluate the effect of energy management based on these preliminary tests, a dynamic collision test is conducted with the front end structure consisting of hybrid members.