Load Path Optimization and U* Structural Analysis for Passenger Car Compartments under Frontal Collision

A new concept, a parameter U*, is introduced to express load transfer in a structure. Two cases of U* analysis for a floor structure of a passenger compartment are examined. In the first case, three conditions of U* are introduced as objective functions, and GA structural optimization is applied. The emergent floor structure after the GA calculation has a unique shape in which a member connects the frontal part of an under-floor member and the rear part of a side-sill. In the second case, the U* values and the load paths in a floor structure under collision are calculated by use of PAM-CRASH. As the collision progresses, the under-floor member becomes the principal load path, and in the final stage of the collision the roll of the under-floor member becomes dominant.