Neck and Spinal Responses in the Reclined Large Omnidirectional Child Anthropomorphic Test Device with and without a Booster Seat during Far-Side Lateral Oblique Impacts

Objective The objective of this study was to examine the Large Omnidirectional Child (LODC) anthropomorphic test device (ATD) neck and spine responses in reclined seating configurations with and without a backless belt-positioning booster (BPB) in far-side lateral oblique impacts. Methods The LODC was seated on a production passenger seat with an integrated seatbelt and tested in nine lateral oblique impact (80° from frontal) sled tests (31.3 km/h). A condition with a nominal seatback angle (~25°) with a backless BPB and two conditions with reclined seatback angles (~45° and ~60°) with and without a BPB were compared. Each condition was repeated, except for the 60° without BPB. Peak upper neck tension force and lateral moment, T1, T6, and T12 lateral rotation, lumbar axial and lateral shear forces, and lumbar axial moment (Mz) were extracted. Results With noBPB, upper neck tension (45° noBPB: 2.0 ± 0.1 kN; 60° noBPB: 1.8 kN) and lateral moment (45° noBPB: 31.7 ± 2.3 Nm; 60° noBPB: 29.2 Nm) were greater than with the BPB in all seatback angles (25° BPB: 1.3 ± 0.04 kN; 21.6 ± 0.1 Nm; 45° BPB: 1.2 ± 0.1 kN, 22.5 ± 2.3 Nm; 60° BPB: 1.2 ± 0.03 kN, 17.6 ± 0.7 Nm). Thoracic spine rotation was smaller in reclined conditions with noBPB (41°–59°) than with BPB (63°–80°). Lumbar axial forces decreased with increasing seatback angle with the BPB (from 2.2 to 1.2 kN). Lumbar Mz showed increasing unbelted shoulder rotation toward the seatback with increasing seatback angle (from 29.8 to 37.8 Nm) with the BPB but not without. Discussion The presence of the BPB may improve neck and spine coupled motion during far-side lateral impacts. However, increased lumbar Mz with the BPB in recline seatbacks requires further understanding.