A study on chest injury mechanism and the effectiveness of a headform impact test for pedestrian chest protection from vehicle collisions
A study on chest injury mechanism and the effectiveness of a headform impact test for pedestrian chest protection from vehicle collisions
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DOI：
10.1016/j.ssci.2011.12.002
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发表时间：
2012-06
期刊：
影响因子：
6.1
通讯作者：
Yong Han;Jikuang Yang;K. Mizuno;Y. Matsui
中科院分区：
文献类型：
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作者：
Yong Han;Jikuang Yang;K. Mizuno;Y. Matsui
通过在车辆胸部接触区进行人头模型碰撞试验，研究不同正面形状客车碰撞中行人胸部的损伤机理，并考察局部结构刚度对胸部损伤风险的影响。使用三个经过验证的行人有限元（FE）模型进行了三次车辆与行人碰撞的模拟，三个行人高度分别为177（AM50th）、165和150 cm，三个FE车辆模型分别代表一辆箱式车辆、一辆微型车和一辆中型车。车辆模型的有效性进行了评估，通过比较人头模型的加速度对测量响应从人头模型的冲击试验。从胸廓的vonMises应力分布和胸部变形两个方面分析了胸部撞击的运动学和损伤机理。确定了前面板和发动机罩顶部的胸部接触位置与肋骨骨折的原因有关。肋骨骨折的风险是通过使用冯米塞斯应力分布预测。在前面板和发动机罩的胸部接触区域进行人头模型冲击试验，以检查行人胸部保护方面的安全性能。在单箱车辆与行人碰撞的模拟中，由于刚性挡风玻璃框架产生剪切力，胸部被高速的前部结构直接撞击并发生显著变形。人头模型的加速度与肋骨的挠度有关。胸廓偏转的损伤阈值（42mm）对应于人头模型的平均加速度68G。在微型车碰撞中，胸部与发动机罩顶面及后围板区域以低速碰撞，由于胸部与发动机罩顶面之间的接触力分布均匀，变形较小。此外，肋骨变形太小，无法桥接人头模型加速度与肋骨变形之间的关系。在中型车碰撞中，胸部的变形模式与微型车碰撞相似。胸部与发动机罩顶部低速碰撞，均匀变形。肋骨的偏转与人头模型冲击试验中测得的人头模型加速度有明显的相关性。车辆的正面形状对行人的胸部载荷有很大的影响，并且胸部变形取决于行人的尺寸和车辆的刚度。单箱乘用车造成胸部受伤的风险很高。人头模型冲击器测试可用于评估车辆前部结构的局部刚度。降低头部模型加速度是一种有效的措施，通过修改局部结构刚度的效果，为行人胸部保护特定形状的车辆。
This study was aimed at investigating the injury mechanism of pedestrian chests in collisions with passenger vehicles of various frontal shapes and examining the influence of the local structural stiffness on the chest injury risk by using the headform impact test at the chest contact area of the vehicle. Three simulations of vehicle to pedestrian collisions were conducted using three validated pedestrian finite element (FE) models of three pedestrian heights of 177 (AM50th), 165 and 150cm and three FE vehicles models representing a one-box vehicle, a minicar and a medium car. The validity of the vehicle models was evaluated by comparing the headform acceleration against the measured responses from headform impact tests. The chest impact kinematics and the injury mechanisms were analyzed in terms of the distribution of the von Mises stress of the ribcage and in terms of the chest deflections. The chest contact locations on the front panel and the bonnet top were identified in connection to the causation of rib fractures. The risk of rib fractures was predicted by using the von Mises stress distribution. The headform impact tests were carried out at the chest contact area on the front panel and bonnet to examine the safety performance with respect to pedestrian chest protection. In simulations of the one-box vehicle to pedestrian collisions, the chest was struck directly by the frontal structure at a high velocity and deformed substantially, since a shear force was generated by the stiff windshield frame. The acceleration of the headform was related to the rib deflections. The injury threshold of the ribcage deflection (42mm) corresponded to the headform average acceleration of 68G. In the minicar collision, the chest was struck with the bonnet top and cowl area at a low velocity, and the deformation was small due to the distributed contact force between the chest and the bonnet top. Besides, the ribcage deformation was too small for bridging a relation between the headform accelerations and rib deflections. In the medium car collision, the deformation mode of the chest was similar to that in the minicar collision. The chest collided with the bonnet top at a low velocity and deformed uniformly. The deflection of the ribs had an observable correlation with the headform accelerations measured in the headform impact tests. The frontal shape of a vehicle has a large influence on a pedestrian’s chest loadings, and the chest deformation depends on the size of the pedestrian and the stiffness of the vehicle. The one-box passenger vehicle causes a high chest injury risk. The headform impactor test can be utilized for the evaluation of the local stiffness of a vehicle’s frontal structure. The reduction of the headform acceleration is an effective measure for pedestrian chest protection for specific shapes of vehicles by efficacy in modifying the local structural stiffness.