Cooper G J, Townend D J, Cater S R, Pearce B P
Medical Division, Chemical Defence Establishment, Porton, Salisbury, U.K.
J Biomech. 1991;24(5):273-85. doi: 10.1016/0021-9290(91)90346-o.
Materials have been applied to the thoracic wall of anaesthetised experimental animals exposed to blast overpressure to investigate the coupling of direct stress waves into the thorax and the relative contribution of compressive stress waves and gross thoracic compression to lung injury. The ultimate purpose of the work is to develop effective personal protection from the primary effects of blast overpressure--efficient protection can only be achieved if the injury mechanism is identified and characterized. Foam materials acted as acoustic couplers and resulted in a significant augmentation of the visceral injury; decoupling and elimination of injury were achieved by application of a high acoustic impedance layer on top of the foam. In vitro experiments studying stress wave transmission from air through various layers into an anechoic water chamber showed a significant increase in power transmitted by the foams, principally at high frequencies. Material such as copper or resin bonded Kevlar incorporated as a facing upon the foam achieved substantial decoupling at high frequencies--low frequency transmission was largely unaffected. An acoustic transmission model replicated the coupling of the blast waves into the anechoic water chamber. The studies suggest that direct transmission of stress waves plays a dominant role in lung parenchymal injury from blast loading and that gross thoracic compression is not the primary injury mechanism. Acoustic decoupling principles may therefore be employed to reduce the direct stress coupled into the body and thus reduce the severity of lung injury--the most simple decoupler is a high acoustic impedance material as a facing upon a foam, but decoupling layers may be optimized using acoustic transmission models. Conventional impacts producing high body wall velocities will also lead to stress wave generation and transmission--stress wave effects may dominate the visceral response to the impact with direct compression and shear contributing little to the aetiology of the injury.
材料已应用于暴露于爆炸超压的麻醉实验动物的胸壁，以研究直接应力波与胸部的耦合以及压缩应力波和胸廓整体压缩对肺损伤的相对贡献。这项工作的最终目的是开发有效的个人防护措施以抵御爆炸超压的主要影响——只有确定并表征损伤机制，才能实现有效的防护。泡沫材料起到了声耦合器的作用，导致内脏损伤显著增加；通过在泡沫顶部施加高声阻抗层实现了解耦和损伤消除。体外实验研究了应力波从空气通过各种层传输到消声水腔的情况，结果表明泡沫传输的功率显著增加，主要是在高频时。诸如铜或树脂粘结凯夫拉尔等材料作为泡沫表面的覆层，在高频时实现了显著的解耦——低频传输基本不受影响。一个声传输模型再现了爆炸波与消声水腔的耦合。这些研究表明，应力波的直接传输在爆炸载荷导致的肺实质损伤中起主导作用，而胸廓整体压缩不是主要的损伤机制。因此，可以采用声解耦原理来减少耦合到身体的直接应力，从而降低肺损伤的严重程度——最简单的解耦器是在泡沫表面覆以高声阻抗材料，但可以使用声传输模型来优化解耦层。产生高体壁速度的传统撞击也会导致应力波的产生和传输——应力波效应可能在对内撞击的内脏反应中占主导，而直接压缩和剪切对损伤病因的贡献很小。
