Evaluating the influence of out-of-Position postures on the comparative frontal crash performance of harnessed restraints and booster seats for rear-seated 6-year-old occupants

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Abstract The primary objective of the forty-four sled tests was: how different sitting positions in two types of child restraints affect injury risk for rear-seated six-year-old occupants. A restrained Q6 anthropomorphic test device (ATD) was positioned in a Type E booster seat and a Type G harnessed restraint under baseline and naturalistic out-of-position postures, then subjected to frontal impacts on a deceleration sled in accordance with Australian Standard (AS/NZS 1754:2013). Data from head, neck, and chest sensors were recorded, while head and femur displacements were measured from high-speed video analysis. The maximum total head displacement (752 mm) across all tests occurred in the Type G harness under forward and lateral inboard leaning position. Compared with standard sitting position (or baseline), Type G harnessed restraint reduced chest deflection by 11–43.1% (3–11.7 mm) and resultant neck force by 8.3–25% (178.3–536.4 N) across forward, forward–lateral inboard, and forward–lateral outboard positions. However, these benefits were accompanied by increases in resultant chest acceleration (0–23.2% or 0–10.4 g) and HIC15 (1.8–37% or 16–326.6), along with the structural damage in 11 cases. Selecting between harnessed restraints and booster seats for children aged 4–8 is often challenging. While the Type G harness offers better chest and neck protection than the Type E booster, it can increase head injury risk and structural failures in out-of-position conditions. Harnesses may permit greater head displacement in frontal impacts, raising contact risks in vehicles with limited space. Therefore, restraint recommendations should account for misuse patterns, vehicle space constraints, and crash performance across seating postures. Description of the data and file structure Figures of the filtered biomechanical data according to SAE J211 filtering standards were collected in a folder. The name of this folder is “Figures of the Responses of submarining Tests”. Biomechanical pure data of this group of frontal sled tests were collected in a Microsoft Excel file (Performance_of_a_Harnessed_Restraint_and_a_Booster_Seat_in_Different_Sitting_Positions_Using_Q6 ATD_in_Frontal_Impact). To view the data, Microsoft Excel can be used to open the file. This is important to highlight that these data are pure. Each worksheet in the Excel file contains the recorded data of each channel related to each sled test. For example, the sheet named “Responses of sled test 39” contains recorded data from different sensors at several regions of the Q6 ATD related to the sled test 39. Each response of the Q6 ATD includes two columns. For example, “Head Acceleration in X direction or Head Gx” includes two columns: 'Time' and 'Acceleration '. The first row of each column contains the column title. For example, “Time” denotes the time history for a sled test, and “Q6 - Head acceleration Gx (x-axis)” denotes the head-acceleration trace in X-direction for a sled test. Additionally, to make individual responses easier to distinguish, each response is shown in a different color. Responses’ title of each worksheet are respectively listed below to help you find the response you want. Q6 - Head acceleration Gx (x-axis): Head acceleration of Q6 ATD in the X direction (g or m⁄s^2 ) Q6 - Head acceleration Gy (y-axis): Head acceleration of Q6 ATD in the Y direction (g or m⁄s^2 ) Q6 - Head acceleration Gz (z-axis): Head acceleration of Q6 ATD in the Z direction (g or m⁄s^2 ) Q6 - Head acceleration resultant: Head acceleration resultant of Q6 ATD (g or m⁄s^2 ) Q6 - Chest acceleration Gx (x-axis): Chest acceleration of Q6 ATD in the X direction (g or m⁄s^2 ) Q6 - Chest acceleration Gy (y-axis): Chest acceleration of Q6 ATD in the Y direction (g or m⁄s^2 ) Q6 - Chest acceleration Gz (z-axis): Chest acceleration of Q6 ATD in the Z direction (g or m⁄s^2 ) Q6 - Chest acceleration resultant: Chest acceleration resultant of Q6 ATD (g or m⁄s^2 ) Q6 - Chest deflection: Chest deflection of Q6 ATD (mm) Q6 - Neck force Fx (x-axis): Neck force of Q6 ATD in the X direction (N) Q6 - Neck force Fy (y-axis): Neck force of Q6 ATD in the Y direction (N) Q6 - Neck force Fz (z-axis): Neck force of Q6 ATD in the Z direction (N) Q6 - Neck force resultant: Neck force resultant of Q6 ATD (N) Q6 - Neck moment Mx (x-axis): Neck moment of Q6 ATD in the X direction (N.m) Q6 - Neck moment My (y-axis): Neck moment of Q6 ATD in the Y direction (N.m) Q6 - Neck moment Mz (z-axis): Neck moment of Q6 ATD in the Z direction (N.m) Q6 - Neck moment resultant: Neck moment resultant of Q6 ATD (N.m) Seat belt force: Shoulder belt force of 3-point seat belt (N) Sled acceleration: Acceleration of Sled-board in the X direction (g or m⁄s^2 )