Thomas Cody J H, Dogan Fatih, Johnson Catherine E
Mining and Explosives Engineering Department, Missouri University of Science and Technology, Rolla, MO, United States.
Materials Science and Engineering Department, Missouri University of Science and Technology, Rolla, MO, United States.
Front Bioeng Biotechnol. 2024 Aug 30;12:1455324. doi: 10.3389/fbioe.2024.1455324. eCollection 2024.
Shock wave overpressure exposures can result in blast-induced traumatic brain injury (bTBI) in warfighters. Although combat helmets provide protection against blunt impacts, the protection against blast waves is limited due to the observed high overpressures occurring underneath the helmet. One route to enhance these helmets is by incorporating viscoelastic materials into the helmet designs, reducing pressures imposed on the head. This study aims to further investigate this mitigation technique against under-helmet overpressures by adding a viscoelastic liner to the inside of a combat helmet.
The liner's effectiveness was evaluated by exposing it to free-field blasts of Composition C-4 at overpressures ranging from 27.5 to 165 kPa (4 - 24 psi) and comparing shock waveform parameters to an unlined helmet. Blasts were conducted using an instrumented manikin equipped with and without a helmet and then with a helmet modified to incorporate a viscoelastic liner. Evaluation of blast exposure results focused on the waveform parameters of peak pressure, impulse and positive phase duration.
The results show that peak overpressure was higher when wearing a helmet compared to not wearing a helmet. However, the helmet with the viscoelastic liner reduced the average peak overpressures compared to the helmet alone. For the lowest overpressure tested, 27.5 kPa, the helmet liner decreased the overpressure on the top of the head by 37.6%, with reduction reaching 26% at the highest overpressure exposure of 165 kPa. Additionally, the inclusion of the viscoelastic material extended the shock waveforms' duration, reducing the rate the shock wave was applied to the head. The results of this study show the role a helmet and helmet design play in the level of blast exposure imposed on a wearer. The testing and evaluation of these materials hold promise for enhancing helmet design to better protect against bTBI.
冲击波超压暴露可导致战士发生爆炸所致创伤性脑损伤（bTBI）。尽管作战头盔能提供针对钝器撞击的防护，但由于观察到头盔下方会出现较高超压，其对冲击波的防护作用有限。增强这些头盔防护能力的一种途径是在头盔设计中加入粘弹性材料，以降低施加在头部的压力。本研究旨在通过在作战头盔内部添加粘弹性衬里，进一步研究这种减轻头盔下超压的技术。
通过将衬里暴露于压力范围为27.5至165千帕（4至24磅力/平方英寸）的C-4炸药自由场爆炸中，并将冲击波形参数与无衬里头盔进行比较，来评估衬里的有效性。使用配备和不配备头盔的仪器化人体模型进行爆炸试验，然后使用改装后加入粘弹性衬里的头盔进行试验。爆炸暴露结果的评估重点是峰值压力、冲量和正相持续时间等波形参数。
结果表明，与不戴头盔相比，戴头盔时的峰值超压更高。然而，与单独的头盔相比，带有粘弹性衬里的头盔降低了平均峰值超压。对于测试的最低超压27.5千帕，头盔衬里使头顶的超压降低了37.6%，在最高超压暴露165千帕时，降低幅度达到26%。此外，粘弹性材料的加入延长了冲击波形的持续时间，降低了冲击波作用于头部的速率。本研究结果表明了头盔及头盔设计在施加于佩戴者的爆炸暴露水平中所起的作用。这些材料的测试和评估有望改进头盔设计，以更好地预防bTBI。
