Occupant Kinematics during Moderate-to-High Speed Side Impacts: An Analysis of IIHS Crash Data over the Past Decade 2020-01-5165

The main objective of the present study was to examine trends in occupant kinematics during side impact testing in vehicle models over the past decade. Head, shoulder, torso, spine, and pelvis kinematic responses were analyzed for “near-side” driver and passenger test dummies in “moderate-to-high” speed side impacts for vehicle model years, MY2010-2020.

The Insurance Institute for Highway Safety (IIHS) side impact crash data was examined (N = 126). The test procedure involved a 50.0 km/h (31.1 mph) moving deformable barrier (MDB) impacting the sides of stationary vehicles. Instrumented 5th-percentile female SIDIIs dummies were positioned in the driver and left rear passenger seats. Occupant kinematic data, including head accelerations, Head Injury Criterion (HIC15), shoulder lateral deflections, torso deflections at thorax and abdominal ribs, spine accelerations at T1, T4, and T12, and pelvis accelerations were evaluated and compared to Injury Assessment Reference Values (IARVs). The “peak” and “time-to-peak” responses were compared across different vehicle model years. The effect of delta-V, vehicle MY, vehicle wheelbase size, and occupant seating position (front versus rear) on occupant kinematics was examined.

The vehicle lateral delta-Vs ranged from 15.9 to 34.5 km/h (9.9 to 21.4 mph). The MY2010-2013 demonstrated higher peak kinematic responses compared to the MY2018-2020, for the driver head resultant acceleration (56.7 ± 20.4 g and 46.4 ± 11.6 g, respectively), shoulder deflection (36.8 ± 10.1 mm and 29.8 ± 6.5 mm, respectively), torso average rib deflection (30.7 ± 9.2 mm and 28.4 ± 6.2 mm, respectively), spine T12 acceleration (63.4 ± 45.8 g and 45.2 ± 9.6 g, respectively), and pelvis acceleration (61.5 ± 44.4 g and 53.1 ± 14.1 g, respectively). A phase difference for onset of lateral acceleration existed for various body regions, with the pelvis and lower spine accelerating first (31.9-45.2 ms and 29.6-52.0 ms, respectively), followed by the torso and shoulder (34.4-57.5 ms and 38.2-58.9 ms, respectively), and finally the head (46.1-60.4 ms). The driver indicated statistically higher kinematic parameters than the left rear passenger, potentially due to higher vehicle crush in the driver compartment. Larger wheelbase vehicles showed statistically lower occupant responses than the smaller vehicles, due to lower changes in momentum.

The present study enhances the existing database of occupant kinematics in side impacts with an emphasis on “moderate-to-high” speed collisions. A reduction in occupant kinematics and risks for injury was observed in vehicle models over the past decade. This information provides further insight into injury mechanisms. The data also serves as a baseline for occupant mathematical modeling and enhancement of seat and restraint design.