Responses of the THOR in Oblique Sled Impacts: Focus on Chest Deflection 2020-01-0522
The National Highway Traffic Safety Administration (NHTSA) published a Request for Comments (RFC) on proposed changes to the New Car Assessment Program (NCAP) in 2015 and 2017. One potential change was the introduction of a frontal Oblique Impact (OI) crash test. The Test device for Human Occupant Restraint (THOR) in the front left seat was used in the proposed OI test. The motivations behind the current study were a) determine if OI sled tests can be simplified, b) study the sensitivity of the THOR chest deflection to the shoulder belt layout in OI and c) assess the NHTSA-proposed THOR thoracic injury risk curves.
In the current study, eleven oblique sled impact tests were conducted. The environment was representative of a generic mid-sized sedan. The buck was mounted on a rigid plate that allowed the pre-test rotation of the buck relative to the sled axis. A generic mid-sized OI pulse was used. The pulse was applied in the longitudinal direction of the sled. The THOR was seated in the driver seat and was restrained with a 3-point belt, a driver airbag (DAB) and a knee airbag (KAB). The belt had a 4-2.5 kN digressive shoulder load limit (LL), a retractor pre-tensioner (RPT) and an anchor pre-tensioner (APT). Out of the four IR-TRACC locations, the upper right (UR) yielded the maximum chest deflection in all tests. Responses of the other body regions were also reported. Neither the presence of side structure nor the position of the D-ring had significant effect on the THOR responses.
In addition, four tests with the THOR and two tests with the Hybrid III 50th male (HIII-50M) dummies seated on a rigid seat were conducted. The two dummies were restrained with the same 3-point belt used in the sled tests. In those tests, no pulse was applied and only the PTs were fired. Like the sled tests, the APT was fired 5 ms after the RPT. In the THOR tests, the UR yielded the maximum chest deflection out of the four locations. The average chest deflection of the four tests was 16.8 mm. Whereas, the average of the chest pot deflection of the HIII-50M was 10.9 mm.