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The injuries sustained by elderly car occupants in traffic accidents are usually more severe than those of younger occupants. Accident statistics data show that injuries to elderly occupants frequently occur in the chest. Belted drivers and front seat passengers in cars involved in frontal collisions were investigated using detailed data on traffic accidents in Japan. From a total of 246 vehicle occupants, the total number of injuries among the 167 occupants listed as injured was 462. Most of the injuries to the chest were minor ones such as skin abrasions or contusions. However, 21 occupants sustained rib fractures and 7 persons even sustained internal organ injuries. Younger occupants appeared not to sustain rib fractures even in higher impact collisions. Conversely, elderly occupants frequently experienced rib fractures near the seat belt line even under lower impact severity.

This paper describes the collapse characteristics of thin-walled curved beams with closed-hat section under axial compression load. Static and dynamic collapsing tests have been carried out on beams different in section size, curved angle, thickness and yield point. We clarify the influences of the initial bending curvature of beam axis, size of section and gauge of metal sheets on the gloval deformation mode, local buckling mode and load-deformation curve from the test results. These results of collapsing tests provide the necessary feedback for the structural components design and aid in the verification of analytical predictive techniques.

The airbag pressure waveform is the basis of the occupant restraint provided by an airbag and greatly influences the level of restraint performance achieved. The characteristics of the gas flowing into and out from the bag were analyzed experimentally and theoretically in order to make clear the factors determining the airbag pressure waveform when the bag was inflated in isolation. The results clarified the mechanism by which different factors affect the bag pressure waveform, including the gas flow characteristics from an inflator into an airbag, gas exhaust characteristics from a bag vent and various bag specifications such as volume. A simple numerical analysis model and an experimental model were prepared to analyze the relationship between the bag pressure waveform and occupant restraint performance. Analyses carried out with these models revealed the relationship between the airbag pressure waveform and deceleration of an impactor corresponding to the occupant.

In order to efficiently employ the MVMA-2D, i.e. 2-dimensional occupant movement simulation, the relation between the accuracy of the input data and the results of the simulation is examined. Moreover, the correlation of seatbelt characteristics to the movement and injury level of a dummy constrained by a 3-point seatbelt is investigated quatitatively. Many input data items in analytical simulation, such as geometric conditions and load-deflection conditions are often only rough estimates because of the lack of experimental verification. In particular, since input data on the 3- point seatbelt model to the MVMA-2D has contained many hypotheses due to it's complicated mechanism, the mechanism is clarified experimentally to improve the initial data on the characteristics of the seatbelt and initial dummy location.