动态冲击下泡沫能量吸收对头盔防护性能的影响

Effect of foam energy absorption on protective performance of helmet under dynamic loadings

为摩托车头盔的安全性设计,需要研究在冲击载荷下内衬泡沫的能量吸收能力对摩托车头盔防护性能的影响。该文建立了有限元数值分析头盔模型,依据欧洲经济委员会(ECE)的法规ECE R22.05的动态测试方法,验证该模型的有效性。改变头盔不同测试点下的泡沫密度,进行了12个跌落的仿真试验。结果表明:在头盔的前部、冠部和后部测试点区泡沫密度由40 kg/m3增加到80 kg/m^3时,泡沫的能量吸收能力逐渐增大,头部冲击能量衰减得更快,导致3个测试点头部颅骨骨折的风险从25%、55%、39%分别增大至53%、96%、96%。头盔右侧部测试点区域下的泡沫密度与颅骨骨折风险没有显著的关系。因而,头盔的安全性设计应同时兼顾内衬泡沫密度与尺寸。

For the safety design of motorcycle helmet,it is necessary to study the influence of the energy absorption capacity of the liner foam under the impact load on the protective performance of the motorcycle helmet.A finite element model of the helmet was established and the effectiveness of the model was verified according to the drop test in the regulation ECE R22.05by the Economic Commission for European.Twelve drop test simulations were performed by changing the foam density corresponding to different test points.The results show that when the foam density increases at the test points of front,crown,and rear from40kg/m3to80kg/m3,the energy absorption capacity of the foam increases,which makes the impact energy of the head decay faster.The risk of skull fracture at the three test points increases from25%,55%,and39%to53%,96%,and96%,respectively.However,there is not clear evidence of the relation between the skull fracture risk and foam density at the right lateral area of the helmet.Therefore,the safety design of the helmet should take into account both the density and size of the liner foam.