Human tolerance to knee, chest, and head impacts based upon skeletal fracture of cadavers is reported. The results are based upon unrestrained cadaver impacts in a normal seated position in simulated frontal force accidents at velocities between 10 and 20 mph and stopping distances of 6-8 in.

The head target was covered with 15/16 in. of padding. No skull or facial fractures were observed at loads up to 2640 lb. Extensive facial fractures and a linear skull fracture occurred during the application of the maximum head force of 4350 lb.

The chest target was 6 in. in diameter with 15/16 in.of padding. The padding was rolled over the edge of the target to minimize localized high force areas on the ribs. A 1/8 in. diameter rod was inserted through the chest and fastened through a ball joint and flange to the soft tissue at the sternum. Deflection of the chest was determined by measuring the distance between the back of the cadaver and the end of the probe from the high-speed motion pictures. Four rib fractures were observed at 1340 lb and extensive fractures were observed at 1850 lb. The maximum chest deflection was 2.25 in. at 1545 lb.

The knee targets were padded with 1-7/16 in. of padding. No fractures were observed at forces up to 1970 lb