Chest deflection, one of the chest injury indicators measured in crash testing, has been the subject of much discussion recently. Chest deflection can be measured with the Hybrid III dummy developed by GM.

Chest deflection during crash testing is determined not only by chest deflection characteristics, but also by belt position. So the dummy requires chest deflection characteristics with high biofidelity and characteristics which cause a seat belt to be positioned as it would be on a human body. Therefore, we concentrated our efforts on belt position and chest construction.

We found that the rib cage features of the Hybrid III dummy differed from a human body's, which adversely affected belt movement and belt position' This difference will skew the chest deflection measured from a belt restrained Hybrid III dummy in frontal collision tests. Therefore, we improved the Hybrid III rib cage design, especially the lower part design, to match that of the human body, and verified that this modification actually reduced the magnitude of these Problems.