Effect of naturalistic seating postures and seatbelt routing on booster-seated Q6 ATD kinematics and kinetics in frontal impacts

•Reference posture captures responses exhibited by the leaning forward and leaning inboard postures i.e. the values for kinetic metrics for the reference posture were generally higher than the leaning forward or leaning inboard posture.•Reference posture was not able to capture the higher head excursions observed in the forward-leaning postures.•Static belt fit on booster seats was shown to affect their dynamic crash test performance.•The booster seat with more inboard shoulder belt, more inferior lap belt, and larger gap size (Booster A) resulted in relatively favorable kinematics and kinetics when compared to the booster with a more outboard shoulder belt, more superior lap belt, and smaller gap size (Booster B). Test protocols evaluate restraint performance with pediatric ATDs placed in an ideal seating posture. However, real-world evidence suggests that ideal test conditions do not always reflect actual occupant positions. Prior studies have also shown that booster seat designs affect the position of the seatbelt around the child. Occupants in naturalistic seating postures, coupled with potentially unfavorable seatbelt positions, could result in adverse kinematics and kinetics in a crash. Therefore, the aim of this study was to quantify the effect of different naturalistic seating postures on the response of the Q6 ATD restrained on boosters with varying initial static belt fit in a frontal impact. The Q6 ATD was positioned on two booster seats of similar design but varying static belt fit metrics in three seating postures: reference, leaning forward, and leaning inboard. These booster seats were chosen from extensive belt fit studies on human volunteers and ATDs, and were defined as follows:•Booster A: more inboard shoulder belt position, more inferior lap belt position, larger gap size.•Booster B: more outboard shoulder belt position, more superior lap belt position, smaller gap size.The booster-seated ATD was restrained on the simulated Consumer Reports test buck (2010 Ford Flex 2nd row seat) with a front blocker plate using a 3-point lap-shoulder belt with a retractor and pretensioner. The sled environment was subjected to the FMVSS 213 frontal impact pulse, and each booster and seating posture was evaluated twice (n = 12 sled tests). Kinematic and kinetic measures were recorded. A linear regression analysis was conducted across postures on each booster. Further, a paired t-test analysis was conducted across booster seats for each seating posture.