Compression-based injury variables from chestbands in far-side impact THOR sled tests

Abstract

Objective: This study seeks to determine compression (C_max) and compression-related injury variables (velocity and viscous injury criterion: V_max and VC_max) from chestband data in pure lateral and oblique far-side impact sled tests.

Methods: The 3-point belt–restrained mid-sized male Test Device for Human Occupant Restraint (THOR) dummy was placed on a buck and subjected to side impacts with and without center-mounted airbags. The change in velocity was 8.3 m/s for all conditions. Two chestbands were routed around the outer circumference of the THOR at the levels of the third and sixth ribs. Maximum chest deflections were computed using strain gauge signals from the chestbands and their temporal contours. Three methods were used to determine deflection metrics. The first method paralleled methods used in previously published human cadaver studies; the second method used the actual anchor point location and actual alignment of the dummy’s internal sensors; and the third method used the anchor location of the internal sensor but determined the sensor’s locations on the contour confining to the aspect of the sensor. These 3 approaches are abbreviated as the SD, ID, and TD variables. The injury variables C_max, V_max, and VC_max were determined according to accepted procedures. Their peak magnitudes were extracted and an evaluation of their accuracy was made based on the SD method.

Results: The average SD-based C_max magnitudes for the upper and lower chest levels were 0.12 and 0.17 m/s, the V_max magnitudes were 5.3 and 1.8 m/s, and the VC_max magnitudes were 0.24 and 0.15 m/s, respectively. Other data are given for all variables at the 2 levels of the thorax in the body of this paper. The ID-based peak variables were the lowest, and this observation was true regardless of the aspect, right or left side. In contrast, the SD method produced the greatest magnitudes of the variables. The VC_max variable had the greatest normalized difference among all 3 injury variables.

Conclusions: Though the present study is limited in scope, the predetermined placement of the internal sensors in the THOR dummy underpredicted chest deflection-related injury variables, and the viscous criterion was the least reliable variable in these lateral and oblique far-side impact sled tests.

Keywords:

• Side impact
• biomechanics
• injury metrics
• viscous criteria
• chest deflection
• anthropomorphic device

Additional information

Funding

This study was supported by the U.S. Department of Transportation DTNH22-13-D-00290L; the School of Mechanical and Building Science, VIT University, Chennai Campus, India; the Zablocki VA Medical Center, Milwaukee, Wisconsin; the Center for NeuroTrauma Research (CNTR) from the Department of Neurosurgery, Medical College of Wisconsin; and the U.S. Department of Defense, Medical Research and Materiel Command, Grant W81XWH-161-0010.