Frontal-oblique impact sled tests of a rearward-facing child restraint system with and without a support leg

To quantify the head and neck injury metrics of an anthropometric test device (ATD) in a rearward-facing child restraint system (CRS), with and without a support leg, in frontal-oblique impacts.

Sled tests using the Federal Motor Vehicle Safety Standards (FMVSS) 213 frontal crash pulse (48 km/h, 23 g) were performed with a simulated Consumer Reports test buck, which comprised a test bench that mimics the rear outboard vehicle seat of a sport utility vehicle (SUV). The test bench was rigidised to increase durability for repeated testing and the seat springs and cushion were replaced every five tests. A force plate was mounted to the floor of the test buck directly in front of the test bench to measure support leg peak reaction force. The test buck was rotated 30° and 60° relative to the longitudinal axis of the sled deck to represent frontal-oblique impacts. The door surrogate from the FMVSS 213a side impact test was rigidly attached to the sled deck adjacent to the test bench. The 18-month-old Q-Series (Q1.5) ATD was seated in a rearward-facing infant CRS, which was attached to the test bench with either rigid lower anchors or a three-point seatbelt. The rearward-facing infant CRS was tested with and without a support leg. Conductive foil was attached to the upper edge of the door panel and a strip of conductive foil was attached to the top of the ATD head so that a voltage signal quantified contact with the door panel. A new CRS was used for each test. A repeat test was performed for each condition for a total of 16 tests.

Resultant linear head acceleration 3 ms clip; head injury criterion 15 ms (HIC15); peak neck tensile force; peak neck flexion moment; potential difference between the ATD head and the door panel; support leg peak reaction force.

The presence of a support leg significantly reduced head injury metrics (p < 0.001) and peak neck tensile force (p = 0.004) compared to tests without a support leg. Rigid lower anchors were associated with significant reductions in head injury metrics and peak neck flexion moment (p < 0.001) compared to tests that attached the CRS with the seatbelt. The 60° frontal-oblique tests had significantly elevated head injury metrics (p < 0.01) compared to the 30° frontal-oblique tests. No ATD head contact with the door was observed for 30° frontal-oblique tests. The ATD head contacted the door panel in the 60° frontal-oblique tests when the CRS was tested without the support leg. Average support leg peak reaction forces ranged from 2167 to 4160 N. The 30° frontal-oblique sled tests had significantly higher support leg peak reaction forces (p < 0.001) compared to the 60° frontal-oblique sled tests.

The findings of the current study add to the growing body of evidence regarding the protective benefits of CRS models with a support leg and rigid lower anchors.