Thoracic response to shoulder belt loading: comparison of tabletop and frontal sled tests with PMHS

The recent refinement of high-rate optical tracking allows dramatically detailed thoracic deformation measurements to be taken during postmortem human subject (PMHS) sled tests. These data allow analysis of restraint belt geometry and the 3-dimensional thoracic deformations generated by belt impingement. One consequence of this new capability is a better understanding of complementary thoracic characterization experiments such as tabletop tests and how the thoracic response can be interpreted for applications involving more complex loading mechanisms.

This article reports a detailed evaluation of the timing, magnitude, and direction of the applied belt forces and the resulting thoracic deformations in 2 previously performed tests series involving frontal sled tests and tabletop belt-loading tests.

In the sled tests, the posteriorly directed component (SAE x) of the belt tension (F(B)) was F(Bx) = 0.70 F(B) at the shoulder but only F(Bx) = 0.14 F(B) where the belt engaged the anterolateral torso inferiorly. The corresponding components on the tabletop were F(Bx) = 0.60 F(B) (shoulder) and F(Bx) = 0.48 F(B) (lower).

When these components are cross-plotted with chest deflection, pronounced consequences of thoracic anterior wall deformation patterns due to flexion of the thoracic spine and the internal viscera's inertia can be seen in the effective thoracic stiffness. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.