Blunt impacts to the back of the torso can occur in vehicle crashes due to interaction with unrestrained occupants, or cargo in frontal crashes, or intrusion in rear crashes, for example. Six pendulum tests were conducted on the back of an instrumented 50th percentile male Hybrid III ATD (Anthropomorphic Test Device) to determine kinematic and biomechanical responses. The impact locations were centered with the top of a 15-cm diameter impactor at the T1 or at T6 level of the thoracic spine. The impact speed varied from 16 to 24 km/h.
Two 24 km/h tests were conducted at the T1 level and showed repeatability of setup and ATD responses. The 16 and 24 km/h tests at T1 and T6 were compared. Results indicated greater head rotation, neck extension moments and neck shear forces at T1 level impacts. For example, lower neck extension was 2.6 times and 3.8 times greater at T1 versus T6 impacts at 16 and 24 km/h, respectively.
A 24 km/h test at T1 was also conducted with a seatback attached to the ATD torso to assess the effect of padding. ATD biomechanical responses were lower with the seatback, except for upper neck extension; head acceleration was 30 g with the seatback and 95 g without it. Head and T1 velocities were similar with or without the seatback.
The ATD responses were compared with published PMHS (Post Mortem Human Subjects) responses. ATD biomechanical responses were greater overall due to a stiffer, more durable spine. Pendulum forces were over 15 kN higher with a shorter duration than in PMHS tests. The head-to-torso rotation was similar at 24 km/h. This study demonstrates that the Hybrid III ATD is a useful tool for assessing high energy occupant loading by the seat.
