Peugeot and Renault vehicles sold in France between 1970 and 1977 were equipped with static 3-point seat belts for the front seating positions, with a load limiter located between the shoulder and the upper anchorage point.

The multidisciplinary study team of doctors and engineers from the Laboratory of Physiology and Biomechanics has analyeedo ver 7,000 accidented vehicles to date, involving approximately 13,000 occupants. Of the 2,281 belted occupants involved in frontal impacts, 427 were wearing a seat belt equipped with the load limiter, while 170 broke the load limiter either partly or completely.

For the three types of load limiter with which these vehicles are equipped, it was possible to relate the load sustained by the occupant at the shoulder level to the presence or not ofrib fractures due to the seat belt alone.

The importance of the age factor in the occurrence of rib fractures is studied first, since it is certain that the choice of maximum load tolerable by an occupant, and accordingly thoracic deflection is closely linked to age.

The paper then analyzes thoracic deflections in Hybrid III measured during simulations of real accidents in which the greatest forces were observed. Note that the planned simulations of real accidents were mentioned in the ISO Group in October 1987 (1), to allow valid determination of the thoracic deflection of Hybrid III.

Finally, for shoulder loads of the same order of magnitude, cadaver tests were performed to compare real accident victims with Hybrid III dummies with respect to the number of rib fractures and deflection values. As we shall see, characterization of the test subjects' bones is essential for a good understanding of the results obtained.