F. Brun-Cassan

Comparison of Experimental Car-Pedestrian Collisions Performed with Various Modified Side-Impact Dummies and Cadavers

Experimental car-pedestrian collisions were performed with a modified PART 572 dummy and cadavers; they involved some reconstructions of real accidents. These collisions brought to light the differences between the kinematics and the impact responses when dummy and human subject are compared under identical and realistic test conditions to simulate a pedestrian struck sideways. These differences are mainly due to the overall relative stiffness of the PART 572 dummy when compared to cadavers. Same-type collisions were therefore carried out again with other dummies which were designed so as to simulate human response in lateral impact better; thus they were also assumed to display better kinematics as pedestrians. APROD and ONSER dummies were used; when compared to PART 572, their flexibility and deformation capabilities are greater, in particular as regards their thoraxes and shoulders.

Reconstruction of actual car-pedestrian collisions with dummy and cadavers

Car-pedestrian accidents were selected with reference to criteria like relevance in terms of injury severities, representativity and reproducibility, aiming for as accurate as possible reconstructions by dummy and cadaver tests. Parameters necessary for performance of these reconstructions were evaluated from the data of accident investigation teams. Preliminary tests were performed by research departments of automobile manufacturers to check the estimated conditions of these accidents before performing their reconstructions. A particular aim was to obtain insights into the mechanisms leading to injuries in pedestrian accidents; more generally, reconstructing actual accidents is a privileged approach to determine human tolerance limits and the corresponding protection criteria on dummies; the injuries resulting from the actual accidents are consequently compared with the data measured on dummies and cadavers in the reconstruction experiments. Conclusions are also related to the methodology of such reconstructions.

FROM THREE-YEARS-OLD TO ADULT SIZE--HOW TO ENSURE CHILD PROTECTION IN AUTOMOBILE ACCIDENTS

Safety of children as car occupants raises a specific problem: it is necessary to take into account two factors which are particular to them: their very fast growth and their behavior, which corresponds to a need for movement. An analysis of statistical and accidentological data points to the fact that whereas traffic accidents account for 25% of adult deaths, they account for nearly 50% of deaths for children (all kinds of road-users). Measures were adopted in France; such as the obligation for children of less than 10-years-old to travel on rear seats of cars and the definition of an homologation procedure for children restraint devices, with the aim of limiting the consequences of these accidents. The most common restraint devices look like little individual seats and are designed to protect young children (less than 3-years-old). Recently, new restraint devices, called cushions, were developed. They are designed for children of over 3 and they can be used almost up to small adult sizes. They enable some improvements in the location of the adult belt on the childs body; thus, improving safety. Several cushions were submitted to simulated frontal collisions, by using them in a car body fixed to a sled; the impact severity was similar to that encountered in some European restraint system certification tests. These runs brought to light the dynamic response obtained with these cushions and their efficiency, as regards the restraint of child dummies. From these results and with the help of an anthropometric survey concerning the heights of children between 3 and 10 years old, cushion shapes were defined, to be used simultaneously with a 3-pt-belt. This cushion was tested with the 3-year and 6-year child dummies and proved to be very efficient as regards safety; it also appears suitable from the standpoint of comfort.

INFLUENCE OF THE TYPE OF THORACIC PROTECTION CRITERIA USED IN SIDE IMPACTS ON THE CHOICE OF THORAX MODEL AND INTERIOR FITTINGS

Protection criteria aside from deflection are defined on the basis of measurement functions taken at various but unique points on the thorax (rib, spinal column); these functions may also use two points (two ribs, for example) which results in deflection intervening as a criterion. The conditions imposed by these criteria result in different requirements for vehicle wall conditions and thorax model construction. Mathematical modeling of the vehicle wall-thorax collision is performed in order to compare possible criteria on this basis. Concurrently, a statistical analysis performed on a sampling of side impacts occurring with human subjects permits injury severity to be expressed by means of several functions whose predictive qualities are unequal. These functions include deflection, and their literal expression takes into account the state of the subjects bone structure. The criteria produced by these predictive functions are used in the preceding mathematical model. The possibility of optionally using different criteria is discussed.