DeMarco Alyssa L, Good Craig A, Chimich Dennis D, Bakal Jeff A, Siegmund Gunter P
MEA Forensic Engineers & Scientists, 11-11151 Horseshoe Way, Richmond, BC, V7A 4S5, Canada.
Collision Analysis, 43 Skyline Cres NE, Calgary, AB, T2K 5X2, Canada.
Ann Biomed Eng. 2017 Aug;45(8):1974-1984. doi: 10.1007/s10439-017-1842-4. Epub 2017 May 1.
Helmet manufacturers recommend replacing a bicycle helmet after an impact or after anywhere from 2 to 10 years of use. The goal of this study was to quantify the effect of helmet age on peak headform acceleration during impact attenuation testing of field-used bicycle helmets. Helmets were acquired by donation from consumers and retail stores, and were included in the study if they were free of impact-related damage, had a legible manufacture date label, and were certified to at least one helmet standard. Helmets (n = 770) spanning 0-26 years old were drop tested to measure peak linear headform acceleration during impacts to the right and left front regions of the helmets at two impact speeds (3.0 and 6.2 m/s). General linear mixed models were used to assess the effect of age and three covariates (helmet style, size and certification impact speed) on peak acceleration. Overall, age was related to either no difference or a statistically significant but small increase (≤0.76 g/year of helmet age) in peak headform acceleration. Extrapolated across 20 years, age-related differences were less than both style- (traditional vs. BMX) and size-related differences. The age-related differences were also less than the variability observed between different helmets after accounting for style, size and certification effects. These findings mean that bicycle helmets (up to 26-year-old traditional helmets and 13-year-old BMX helmets) do not lose their ability to attenuate impacts with age; however, other helmet features that may change with age were not evaluated in this study.
头盔制造商建议在头盔受到撞击后，或使用2至10年后更换自行车头盔。本研究的目的是量化头盔使用年限对实地使用的自行车头盔在冲击衰减测试中头模峰值加速度的影响。头盔通过消费者和零售店捐赠获得，如果没有与撞击相关的损坏、有清晰可读的生产日期标签且至少符合一项头盔标准，则纳入本研究。对770顶使用年限在0至26年的头盔进行了跌落测试，以测量在两种撞击速度（3.0和6.2米/秒）下头盔左右前部受到撞击时头模的峰值线性加速度。使用广义线性混合模型评估使用年限和三个协变量（头盔款式、尺寸和认证撞击速度）对峰值加速度的影响。总体而言，使用年限与头模峰值加速度无差异或有统计学意义但较小的增加（每年增加≤0.76g）相关。推算20年的数据，与使用年限相关的差异小于款式（传统头盔与小轮车头盔）和尺寸相关的差异。在考虑款式、尺寸和认证影响后，与使用年限相关的差异也小于不同头盔之间观察到的变异性。这些研究结果意味着自行车头盔（26年以内的传统头盔和13年以内的小轮车头盔）不会随着使用年限的增加而丧失缓冲撞击的能力；然而，本研究未评估其他可能随使用年限变化的头盔特性。
