Measurement of the Contour and Deflection of Vehicle Seats for Comparison with the FMVSS 213 Dynamic Test Bench

Federal Motor Vehicle Safety Standard (FMVSS) 213 specifies a bench seat that is used in dynamic testing of child restraint systems. To assess the representativeness of the FMVSS 213 bench, data from 54 passenger cars, minivans, and SUVs were analyzed to quantify the side-view profile of the seat centerlines in second-row, outboard seats. SAE J826 H-point measurements were performed on all seats and on the FMVSS 213 bench. A landmark-based resampling method was used to obtain a meaningful average seat contour after aligning on H-point. Principal component analysis and regression were conducted to quantify the effects of seat cushion angle, cushion length, and back angle on the seat profile. When aligned on H-point, the cushion length and surface angles of the FMVSS 213 bench were similar to the mean contour, except that no seats were as flat as the bench profile. However, the FMVSS 213 bench was softer than 93 percent of the vehicle seats, as measured by the depth of penetration of the H-point machine. When the profiles were aligned on the undeflected seat cushion and seat back surfaces near the H-point, the FMVSS 213 bench was 30 mm longer than the mean seat profile.