Viano David C
ProBiomechanics LLC, Bloomfield Hills, Michigan.
Traffic Inj Prev. 2023;24(3):189-195. doi: 10.1080/15389588.2022.2138709. Epub 2022 Oct 28.
Rear-impact restraint guidelines have not developed to the same degree as for frontal crashes. This study provides criteria for favorable occupant kinematics in rear impacts.
Rear criteria were developed as an extension of Adomeit and Heger (1975) and Adomeit (1977) motion sequence criteria (MSC) for favorable occupant kinematics in frontal crashes. In this study, occupant kinematics in rear sled tests were studied to develop motion sequence criteria for favorable and unfavorable occupant kinematics in rear impacts with containment of the hip on the seat and no ramping up the seatback.
Rear MSC limit the angle of the torso (α) rearward of vertical to less than the critical angle (α) for ramping up the seatback and H-pt displacement rearward and downward, so z < z, where z is the initial height of the H-pt. The lateral displacement of the occupant is limited to less than the critical lateral displacement y, where the head becomes unsupported by the head restraint or the chest by the seatback. The rear MSC contain the pelvis on the seat and provide uniform support of the torso, head and neck. Most front seats in production provide reasonably favorable occupant kinematics in rear impacts up to 40 km/h (25 mph) delta V with the 50 Hybrid III. Kinematics become unfavorable in testing at higher severities and with heavier occupants. The amount of energy that the seat needs to transfer to the occupant in a rear impact depends on the delta V (ΔV or change in velocity) of the vehicle and the mass of the occupant (m) among other variables. The seat provides an interface with the occupant and transfers energy (E), which can be approximated by E = ½0.7m(ΔV) using 70% of the occupant mass (m) and delta V. Rear MSC provide performance guidelines to advance seat designs with favorable occupant kinematics at higher energy transfer levels in rear impacts. Sled testing at 40 km/h (25 mph) involves an energy transfer of 3,421 J with the 50 Hybrid III generally gives favorable kinematics. A 56.3 km/h (35 mph) test involves 6,704 J, double the energy transfer and often unfavorable kinematics. A target energy needs to be set, and there are practical limits because the energy transfer is 12,858 J with a 150 kg (330 lb) occupant in a 56.3 km/h (35 mph) delta V rear crash.
Rear motion sequence criteria (MSC) define favorable kinematics in rear impacts. MSC complement the assessment of biomechanical responses in sled and crash testing to ensure an overall evaluation of occupant restraint in rear impacts.
后碰撞约束指南的发展程度不及正面碰撞。本研究为后碰撞中有利的乘员运动学提供了标准。
后碰撞标准是作为阿多梅特和黑格（1975年）以及阿多梅特（1977年）正面碰撞中有利乘员运动学的运动序列标准（MSC）的扩展而制定的。在本研究中，对后滑橇试验中的乘员运动学进行了研究，以制定后碰撞中有利和不利乘员运动学的运动序列标准，同时使臀部保持在座椅上且座椅靠背不向上倾斜。
后碰撞MSC将躯干相对于垂直方向向后的角度（α）限制在小于座椅靠背向上倾斜的临界角度（α）以及H点向后和向下的位移，因此z < z，其中z是H点的初始高度。乘员的横向位移被限制在小于临界横向位移y，此时头部不再受到头枕支撑或胸部不再受到座椅靠背支撑。后碰撞MSC使骨盆保持在座椅上，并为躯干、头部和颈部提供均匀支撑。大多数量产的前排座椅在与50百分位混合III型假人进行高达40公里/小时（25英里/小时）速度变化的后碰撞中能提供合理有利的乘员运动学。在更高的碰撞严重程度和较重的乘员测试中，运动学变得不利。在后部碰撞中，座椅需要传递给乘员的能量大小取决于车辆的速度变化（ΔV）和乘员质量（m）等其他变量。座椅为乘员提供了一个界面并传递能量（E），对于70%的乘员质量（m）和速度变化，可以近似为E = ½ * 0.7 * m(ΔV)。后碰撞MSC提供了性能指南，以推进在更高能量传递水平的后碰撞中具有有利乘员运动学的座椅设计。在40公里/小时（25英里/小时）的滑橇试验中，与50百分位混合III型假人进行试验涉及的能量传递为3421焦耳，通常会产生有利的运动学。56.3公里/小时（35英里/小时）的试验涉及6704焦耳，能量传递翻倍且运动学通常不利。需要设定一个目标能量，并且存在实际限制，因为在56.3公里/小时（35英里/小时）速度变化的后碰撞中，对于150公斤（330磅）的乘员，能量传递为12858焦耳。
后碰撞运动序列标准（MSC）定义了后碰撞中有利的运动学。MSC补充了滑橇试验和碰撞试验中生物力学响应的评估，以确保对后碰撞中乘员约束进行全面评估。
