The purpose of this study was to evaluate the thoracic responses of the
50th-percenitle male Hybrid III, THOR, and post mortem human surrogates (PMHS)
in the rear seat during frontal sled tests using conventional and advanced
restraints in multiple vehicle environments. Twenty-one sled tests were
conducted using the Hybrid III and THOR in seven vehicle bucks, and 12 PMHS sled
tests were performed using four vehicle bucks. Trends in chest deflections
between vehicles and restraint conditions were compared between surrogates. The
Hybrid III and THOR thoracic injury risk predictions were compared to the
thoracic skeletal damage observed during the PMHS tests. The Hybrid III chest
deflections were statistically significantly greater for vehicles equipped with
conventional restraints compared to those equipped with advanced restraints. The
THOR chest deflections generally followed this trend, but the differences
between restraint types were not statistically significant. Hence, the THOR
thoracic response and injury predictions might be less sensitive to the presence
of advanced restraints. The PMHS sustained lower chest deflections and less
damage, on average for the vehicles equipped with advanced restraints. However,
this outcome was confounded by PMHS variability, the effect of submarining on
thoracic response, and other design differences between vehicles, leading to no
statistically significant difference in chest deflection between vehicles with
and without advanced restraints. All PMHS sustained at least nine rib fractures
regardless of restraint condition, so it was difficult to assess the accuracy of
the THOR and Hybrid III injury risk predictions. However, both ATDs accurately
predicted a high injury risk for the vehicle that resulted in the most severe
PMHS damage. These results support previous studies that suggest the
implementation of advanced restraints may reduce injury risk in the rear seat.
However, the results also suggest that other vehicle characteristics, apart from
restraint type, influence thoracic injury outcomes in the rear seat.