Franklyn Melanie, Laing Sheridan
a Defence Science and Technology Group (DST Group) , Fishermans Bend , Melbourne , Victoria , Australia.
Traffic Inj Prev. 2016 Oct 2;17(7):750-7. doi: 10.1080/15389588.2016.1146946. Epub 2016 Jul 1.
Soldiers in military vehicles subjected to underbelly blasts can sustain traumatic head and neck injuries due to a head impact with the roof. The severity of head and neck trauma can be influenced by the amount of head clearance available to the occupant as well as factors such as wearing a military helmet or the presence of padding on the interior roof. The aim of the current study was to examine the interaction between a Hybrid III headform, the helmet system, and the interior roof of the vehicle under vertical loading.
Using a head impact machine and a Hybrid III headform, tests were conducted on a rigid steel plate in a number of different configurations and velocities to assess helmet shell and padding performance, to evaluate different vehicle roof padding materials, and to determine the relative injury mitigating contributions of both the helmet and the roof padding. The resultant translational head acceleration was measured and the head injury criterion (HIC) was calculated for each impact.
For impacts with a helmeted headform hitting the steel plate only, which represented a common scenario in an underbelly blast event, velocities of ≤6 m/s resulted in HIC values below the FMVSS 201U threshold of 1,000, and a velocity of 7 m/s resulted in HIC values well over the threshold. Roof padding was found to reduce the peak translational head acceleration and the HIC, with rigid IMPAXX foams performing better than semirigid ethylene vinyl acetate (EVA) foam. However, the head injury potential was reduced considerably more by wearing a helmet than by the addition of roof padding.
The results of this study provide initial quantitative findings that provide a better understanding of helmet-roof interactions in vertical impacts and the contributions of the military helmet and roof padding to mitigating head injury potential. Findings from this study will be used to inform further testing with the future aim of developing a new minimum head clearance standard for occupants of light armored vehicles.
乘坐军车的士兵在腹部遭受爆炸时，可能因头部撞击车顶而导致头部和颈部创伤。头部和颈部创伤的严重程度可能受乘车人员头部上方空间大小以及诸如佩戴军用头盔或车内顶部是否有衬垫等因素影响。本研究的目的是在垂直载荷下，研究混合III型头模、头盔系统和车辆内部车顶之间的相互作用。
使用头部撞击试验机和混合III型头模，在多种不同配置和速度下对一块刚性钢板进行测试，以评估头盔外壳和衬垫的性能，评估不同的车辆顶部衬垫材料，并确定头盔和车顶衬垫在减轻伤害方面的相对贡献。测量每次撞击产生的头部平移加速度，并计算头部损伤准则（HIC）。
对于仅戴头盔的头模撞击钢板的情况（这代表腹部爆炸事件中的常见场景），速度≤6米/秒时，HIC值低于联邦机动车安全标准201U规定的1000的阈值，而速度为7米/秒时，HIC值远超过该阈值。发现车顶衬垫可降低头部平移加速度峰值和HIC，刚性IMPAXX泡沫的性能优于半刚性乙烯-醋酸乙烯酯（EVA）泡沫。然而，佩戴头盔比增加车顶衬垫能更大程度地降低头部受伤风险。
本研究结果提供了初步的定量数据，有助于更好地理解垂直撞击时头盔与车顶的相互作用，以及军用头盔和车顶衬垫在减轻头部受伤风险方面的作用。本研究结果将用于指导进一步测试，未来目标是为轻型装甲车乘员制定新的最小头部空间标准。
