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The aim of this research was to find vehicle characteristics including stiffness that is effective for compatibility performance. Compatibility is said to be affected by three factors: vehicle mass, geometry and stiffness (1, 2). Of these factors, stiffness has more flexibility at the design stage than vehicle mass and geometry which are limited by the vehicle application. However, the stiffness is assumed to have a conflict issue between the self-protection and the partner-protection (3). In this research, it was analyzed comprehensively how some defined factors such as stiffness, mass, crash stroke and other vehicle characteristics indices relate to each occupant injury rate of the case and its partner vehicle in the real-world accidents. Both “front-to-front” and “front-to-side” crash occupants were covered.

Development of anti-whiplash technology is one of the hottest issues in the automotive safety field because of the frequent occurrence of rear impact accidents. We analyzed the whiplash mechanism and conducted a study to seek the optimized seat characteristics with BioRID II and MADYMO simulations. A parameter study was made to construct a conceptual theory to decrease NIC, Neck Injury Criteria, with the MADYMO model. As a result of the study, head restraint position and seatback stiffness were found to affect dummy movement and injury values. Applying the NIC mechanism and the influential parameters to the MADYMO model, the optimized seat characteristics for whiplash prevention were obtained.

We have developed injection molding technologies consist of a new high-strength long-glass fiber reinforced polypropylene (PPLGF). They are key technologies of new modular design for substantial reductions of weight and cost, offering integrated functionality. The strength of injection molded parts are three times stronger than that of the conventional material. This technology makes it possible to replace parts from steel stamping and press molded glass-mat reinforced polypropylene. The front end and door modules of Atenza / Mazda6, Demio / Mazda2, RX-8 employs the module carriers using this material, resulting in dramatic weight and cost savings. (Fig. 1)

Driver fatality rate of a passenger vehicle is considerably high when struck on the side by an LTV (light truck and van). Aggressivity of LTVs, particularly in side crashes, needs to be reduced to improve this incompatible situation. Crash energy absorption share of a passenger car struck on the side by an LTV was measured through component tests. As a result, B-pillar of the struck passenger car was found to receive most of the crash energy intensively. This intensive energy triggered large B-pillar deformation. Computer simulation proved that B-pillar deformation was closely related to occupant injury. The key to mitigate the injury of side-struck car occupant, therefore, is to disperse crash energy to other structural parts than B-pillar. Front-end structures of LTVs that realize crash energy dispersion were designed and examined. The structures include (a) optimization of the vehicle height, and (b) adoption of a forward-extended sub-frame.

In the development of fuel tank systems, it is important to maintain fuel system integrity even if a car accident occurs. When a fuel tank undergoes a sudden change in velocity, the fuel starts to move and deforms the tank walls and baffle plates, and then the deformation changes the flow pattern of fuel. Because interaction of fuel with tank components is the main cause of fuel spillage upon crash, it is important to predict complex fluid-structure interaction responses at an early stage of crash safety development with a multiphysics simulation. Development of the multiphysics simulation technique was conducted stepwise by examining “fluid motion” and “tank deformation.” First, a sled test of a rigid-wall tank with observation window was conducted to evaluate the fluid motion inside the tank. A numerical model was developed based on an ALE (Arbitrary Lagrangian Eulerian) algorithm for the fluid and a Lagrangian algorithm for the structure.

Of the injuries sustained by belted rear occupants in a frontal collision event in Japan, the neck and the head are the regions of the body most likely to be injured, while children and female occupants are accounting for the highest rate of injuries. For the purpose of reducing rear seat occupant injuries, the occurrence mechanism of neck and head injuries is clarified by sled tests with the current rear seat belt system. When a high load is applied to the occupant via the seat belt, the occupant experiences sudden deceleration of the chest, resulting in a great relative velocity difference between the head and the chest. This causes injury to the occupant's neck and head. To reduce occupant injuries, therefore, it is important to minimize the relative velocity difference by control of belt load.