Kemper Andrew R, Beeman Stephanie M, Madigan Michael L, Duma Stefan M
a Virginia Tech-Wake Forest University , Center for Injury Biomechanics , Blacksburg , Virginia.
Traffic Inj Prev. 2014;15 Suppl 1:S141-50. doi: 10.1080/15389588.2014.938323.
The purpose of this study was to investigate the effects of pre-impact bracing on the chest compression, reaction forces, and accelerations experienced by human occupants during low-speed frontal sled tests.
A total of twenty low-speed frontal sled tests, ten low severity (∼2.5g, Δv=5 kph) and ten medium severity (∼5g, Δv=10 kph), were performed on five 50th-percentile male human volunteers. Each volunteer was exposed to two impulses at each severity, one relaxed and the other braced prior to the impulse. A 59-channel chestband, aligned at the nipple line, was used to quantify the chest contour and anterior-posterior sternum deflection. Three-axis accelerometer cubes were attached to the sternum, 7th cervical vertebra, and sacrum of each subject. In addition, three linear accelerometers and a three-axis angular rate sensor were mounted to a metal mouthpiece worn by each subject. Seatbelt tension load cells were attached to the retractor, shoulder, and lap portions of the standard three-point driver-side seatbelt. In addition, multi-axis load cells were mounted to each interface between the subject and the test buck to quantify reaction forces.
For relaxed tests, the higher test severity resulted in significantly larger peak values for all resultant accelerations, all belt forces, and three resultant reaction forces (right foot, seatpan, and seatback). For braced tests, the higher test severity resulted in significantly larger peak values for all resultant accelerations, and two resultant reaction forces (right foot and seatpan). Bracing did not have a significant effect on the occupant accelerations during the low severity tests, but did result in a significant decrease in peak resultant sacrum linear acceleration during the medium severity tests. Bracing was also found to significantly reduce peak shoulder and retractor belt forces for both test severities, and peak lap belt force for the medium test severity. In contrast, bracing resulted in a significant increase in the peak resultant reaction force for the right foot and steering column at both test severities. Chest compression due to belt loading was observed for all relaxed subjects at both test severities, and was found to increase significantly with increasing severity. Conversely, chest compression due to belt loading was essentially eliminated during the braced tests for all but one subject, who sustained minor chest compression due to belt loading during the medium severity braced test.
Overall, the data from this study illustrate that muscle activation has a significant effect on the biomechanical response of human occupants in low-speed frontal impacts.
本研究旨在调查在低速正面雪橇试验中，撞击前支撑对人体乘员胸部压缩、反作用力和加速度的影响。
对五名第50百分位的男性志愿者进行了总共二十次低速正面雪橇试验，其中十次低严重度试验（约2.5g，速度变化量Δv = 5公里/小时）和十次中严重度试验（约5g，速度变化量Δv = 10公里/小时）。每位志愿者在每种严重度下接受两次冲击，一次是放松状态，另一次是在冲击前进行支撑。使用一条对齐乳头线的59通道胸带，来量化胸部轮廓和胸骨前后位移。在每个受试者的胸骨、第七颈椎和骶骨处附着三轴加速度计立方体。此外，在每个受试者佩戴的金属咬嘴处安装了三个线性加速度计和一个三轴角速率传感器。安全带张力负荷传感器附着在标准三点式驾驶员侧安全带的卷收器、肩部和腰部部分。此外，在受试者与试验台架的每个界面处安装了多轴负荷传感器，以量化反作用力。
对于放松状态下的试验，较高的试验严重度导致所有合成加速度、所有安全带力以及三个合成反作用力（右脚、座椅座面和座椅靠背）的峰值显著增大。对于支撑状态下的试验，较高的试验严重度导致所有合成加速度以及两个合成反作用力（右脚和座椅座面）的峰值显著增大。支撑在低严重度试验中对乘员加速度没有显著影响，但在中严重度试验中确实导致骶骨合成线性加速度峰值显著降低。还发现支撑在两种试验严重度下均能显著降低肩部和卷收器安全带力的峰值，以及中严重度试验下腰部安全带力的峰值。相比之下，支撑在两种试验严重度下均导致右脚和转向柱的合成反作用力峰值显著增大。在两种试验严重度下，所有放松状态的受试者均观察到因安全带加载导致的胸部压缩，且发现其随严重度增加而显著增大。相反，在支撑状态下的试验中，除一名受试者外，所有受试者因安全带加载导致的胸部压缩基本消除，该受试者在中严重度支撑试验中因安全带加载而受到轻微胸部压缩。
总体而言，本研究数据表明，肌肉激活对低速正面碰撞中人体乘员的生物力学响应具有显著影响。
