Non-censored rib fracture data during frontal PMHS sled tests

Assessment of Thoracic Response and Injury Risk Using the Hybrid III, THOR-M, and Post-Mortem Human Surrogates under Various Restraint Conditions in Full-Scale Frontal Sled Tests

A total of 20 full-scale frontal sled tests were conducted using the Hybrid III (HIII), THOR-M and post-mortem human surrogates (PMHSs) to evaluate the thoracic biofidelity of the HIII and THOR-M under various belted restraint conditions. Each surrogate was tested under three belted restraint conditions: knee bolster, knee bolster and steering wheel airbag, and knee bolster airbag and steering wheel airbag. In order to assess the relative biofidelity of each ATD, external thoracic deflections were quantitatively compared between the ATDs and PMHSs using an objective rating metric. The HIII had slightly higher biofidelity than the THOR-M for the external thoracic deflections. Specifically, the THOR-M lower chest was more compliant compared to the other surrogates. However, the THOR-M exhibited expansion of the lower chest opposite belt loading, which was also observed to some degree in the PMHSs. The efficacy of the current injury risk prediction instrumentation and criteria were also evaluated for each surrogate. The THOR-M and its proposed injury risk criteria predicted the injuries observed in the PMHS tests better than the HIII. The PMHS injury criteria over-predicted the amount of chest deflection necessary to produce a severe injury and, consequently, under-predicted injury risk. The results of this study indicate that further testing should be performed to evaluate the biofidelity of the THOR-M thorax under more conditions. Furthermore, current thoracic injury risk criteria, which were developed using censored data, may not be effective at predicting injuries for all restraints and experimental conditions.

Influence of the chest compression measurement method on assessment of restraint performance in side-impact crash scenarios

Side impact crashes contribute a significant number of fatal injuries (25% of road fatalities in the USA in 2016), with severe thoracic injuries diagnosed in 58% of front near-side impact occupants. Epidemiological data indicate that thoracic-only side airbags (tSABs) are not as effective as laboratory testing has suggested, and one of the reasons for this may be the use of surrogate-specific injury assessment methods, which are not directly transferable between Anthropometric Test Devices (ATDs) and Post-Mortem Human Surrogates (PMHSs). This study examines the effect of the thorax deformation measurement location and method on the predicted performance of seatbelts and tSABs in a side impact using a Human Body Model (HBM). The HBM was integrated in a vehicle and subjected to a Moving Deformable Barrier (MDB) impact at 61 km/h, with four restraint configurations: belted and unbelted, with and without a tSAB. Occupant response was assessed through chest band (CB) deformation, and as a change in distance between markers on the ribs. Multiple measurement locations in the HBM enabled direct comparison between the methods. The CB method indicated a 35% increase of chest compression due to tSAB; the rib-deflection (RD) method was not sensitive to the tSAB. The RD method predicted a 20% reduction of chest compression due to the seatbelt, but the CB-measured change was negligible. This study highlights the importance of measurement method on the response outcome and demonstrates that different outcomes may be predicted using a HBM for the same impact scenario, depending on the measurement method.

Effect of Chestbands on the Global and Local Response of the Human Thorax to Frontal Impact

The purpose of this study was to examine the effects of chestbands on both global and local thoracic response. A total of twenty-two frontal impacts were imposed on two post-mortem human surrogates, using a 23 kg pneumatic impactor. Impacts were at speeds of 0.8, 1.0, 1.5, and 2.0 m/s, and there were either 0, 1, or 2 chestbands on the subject. The baseline configuration of 0.8 m/s with zero chestbands was tested initially, then was repeated intermittently throughout testing. For each impact speed, the difference between response with and without chestbands was calculated. Results showed average changes of +0.79 mm in chest deflection, -0.42 N/mm in thoracic stiffness, and -96 µS in rib strain when chestbands were used, none of which were statistically significant (t test, p = 0.35, p = 0.42 and, p = 0.42, respectively). The results provide support for the commonly employed assumption that chestbands do not alter the response of the thorax in frontal impact.