Investigation of Potential Design and Performance Criteria for Booster Seats Through Volunteer and Dynamic Testing

Technical Report FinalThe purpose of this research was to explore candidate booster performance metrics that have the potential to identify less effective booster systems, since current FMVSS No. 213 booster performance requirements can be met without a booster. A combination of volunteer testing of belt fit and posture along with dynamic sled tests of booster seats was employed to achieve the project goals. Posture and belt fit were measured in 24 child volunteers 4 to 12 years old. Children were measured in three vehicles and three laboratory seating conditions selected to provide cushion lengths and belt geometries representing the range found in late model vehicle rear seats. Six different booster seats, as well as the no-booster condition, were evaluated. Test conditions were also evaluated using 6YO, 10YO, and small female anthropomorphic test devices (ATDs). Posture differences between children and ATDs were greater in the no-booster condition and the two lower backless boosters compared to the four boosters that raised the occupant by 75 mm or more, but the differences were not large enough to warrant recommendation of an alternate seating procedure. The shoulder belt tended to be closer to the ATD necks than those of child volunteers; the lap belt was always further below the ATD ASIS than the volunteer’s belt. To provide a more realistic test environment, dynamic testing was performed using a surrogate seat belt retractor on the most recent preliminary design update for the FMVSS No. 213 seat assembly. Eleven booster products were evaluated, as well as the no-booster condition, with six tests performed using the Hybrid III 10YO and 33 tests run with the Hybrid III 6YO. Possible metrics associated with good ATD kinematics (no submarining or rollout) were the difference between knee and head excursion, maximum torso angle, as well as lumbar MomentZ and ForceY. Tests with the surrogate retractor were as repeatable as testing with current FMVSS No. 213 conditions.National Highway Traffic Safety Administrationhttp://deepblue.lib.umich.edu/bitstream/2027.42/167692/2/UMTRI-2020-6.pdfDescription of UMTRI-2020-6.pdf : Technical Report Fina