To reduce the amount of casualties in traffic accidents that involve various types of vehicles, the improvement of compatibility performance is important. In case of accidents, there are mismatches between colliding vehicles, which are in structural geometry, vehicle frontal stiffness and so on. For improving compatibility, helping minimize these mismatch issues as the first step. The concept investigated in this research study, has three aspects. The first one is “Multi load path including mechanical parts”. To ensure good interaction between colliding vehicles under existing mismatch of structure parts, it is effective to make use of mechanical parts as ‘a substitute’ load path, such as an engine with transmission or tire. The second is “To increase the amount of energy absorption (EA) of front body parts”. The third is “Sufficient stiffness of the passenger compartment”. To crush the front body parts for attaining additional EA, a proper stiffness of the passenger compartment is the prerequisite.

For improving compatibility, to satisfy above three items simultaneously is effective. According to the results of crash analysis, the concept for improving compatibility is investigated. Then structures applied for this concept are studied from the viewpoint of load flow and energy absorption, mainly by conducting CAE simulation. The improved structures were subsequently tested using actual vehicles for verification and the effectiveness of the concept is confirmed.