MEA Forensic Engineers & Scientists, 11-11151 Horseshoe Way, Richmond, BC, Canada V7A 4S5.
Accid Anal Prev. 2010 Nov;42(6):1778-84. doi: 10.1016/j.aap.2010.04.019. Epub 2010 May 31.
Helmets reduce the frequency and severity of head and brain injuries over a range of impact severities broader than those covered by the impact attenuation standards. Our goal was to document the impact attenuation performance of common helmet types over a wide range of impact speeds. Sixty-five drop tests were performed against the side of 10 different helmets onto a flat anvil at impact speeds of 0.9-10.1 m/s (energy=2-260J; equivalent drop heights of 0.04-5.2 m). Three non-approved beanie helmets performed poorly, with the worst helmet reaching a peak headform acceleration of 852g at 29J. Three full-face and one open-face helmet responded similarly from about 100g at 30J to between 292g and 344g at 256-260J. Three shorty style helmets responded like the full-face helmets up to 150J, above which varying degrees of foam densification appeared to occur. Impact restitution values varied from 0.19 to 0.46. A three-parameter model successfully captured the plateau and densification responses exhibited by the various helmets (R(2)=0.95-0.99). Helmet responses varied with foam thickness, foam material and possibly shell material, with the largest response differences consistent with either the presence/absence of a foam liner or the densification of the foam liner.
头盔在广泛的冲击强度范围内，降低了头部和脑部受伤的频率和严重程度，超出了冲击衰减标准所涵盖的范围。我们的目标是记录常见头盔类型在广泛的冲击速度下的冲击衰减性能。对 10 种不同头盔的侧面进行了 65 次跌落测试，冲击速度为 0.9-10.1 m/s（能量=2-260J；等效跌落高度为 0.04-5.2 m），落在一个平的砧座上。三个未经批准的无边便帽头盔表现不佳，最差的头盔在 29J 时达到了 852g 的峰值头部加速度。三个全脸头盔和一个开脸头盔的反应类似，在 30J 时约为 100g，在 256-260J 时在 292g 和 344g 之间。三个短款头盔在 150J 之前的反应与全脸头盔相似，超过这一范围，似乎发生了不同程度的泡沫密实化。冲击恢复值从 0.19 到 0.46 不等。一个三参数模型成功地捕捉到了各种头盔表现出的平台和密实化响应（R(2)=0.95-0.99）。头盔的响应随泡沫厚度、泡沫材料和可能的外壳材料而变化，最大的响应差异与泡沫衬垫的存在/不存在或泡沫衬垫的密实化一致。
