Gilchrist A, Mills N J
School of Metallurgy and Materials, University of Birmingham, UK.
Accid Anal Prev. 1996 Jul;28(4):525-35. doi: 10.1016/0001-4575(96)00030-9.
The side of the head is a frequent impact site for pedal cyclists, motorcyclists, and industrial workers. It is vulnerable to impact, yet many helmet standards do not have impact tests at the side of the helmet. Laboratory impact tests should reproduce the phenomena in real impacts, but usually they do not allow the headform to rotate, or ignore the effect of the neck on the motion of the head. The authors designed a linkage, simulating the flexibility of the neck, for use with anthropomorphic dummies in helmet testing. Impacts at the side of the helmet, normal to the helmet surface, were made with flat and hemispherical strikers. Head rotation during impacts caused the impact site to move, in some cases to below the level protected by the helmet. The peak angular head acceleration correlated with the peak linear accelerations. Neck flexibility means that helmets can protect the head from higher kinetic energy impacts than those specified in standards using immovable headforms or impact anvils. The load spreading efficiency of polypropylene foam, used in soft shell bicycle helmets, is better than that of polystyrene foam. The authors conclude that the side of the head can be protected by a suitable helmet design.
头部侧面是骑自行车的人、骑摩托车的人和产业工人经常受到撞击的部位。该部位易受撞击，但许多头盔标准并未对头盔侧面进行撞击测试。实验室撞击测试应重现实际撞击中的现象，但通常不允许头模旋转，或忽略颈部对头部运动的影响。作者设计了一种模拟颈部灵活性的连杆机构，用于头盔测试中的人体模型。使用平面和半球形撞锤对头盔侧面与头盔表面垂直的部位进行撞击。撞击过程中头部的旋转导致撞击部位移动，在某些情况下移动到头盔保护范围以下。头部角加速度峰值与线性加速度峰值相关。颈部的灵活性意味着，与使用固定头模或撞击砧座的标准相比，头盔能够保护头部免受更高动能撞击。软壳自行车头盔中使用的聚丙烯泡沫的载荷分散效率优于聚苯乙烯泡沫。作者得出结论，通过合适的头盔设计可以保护头部侧面。
