Gan Rong Z, Leckness Kegan, Nakmali Don, Ji Xiao D
School of Aerospace and Mechanical Engineering, University of Oklahoma, 865 Asp Avenue, Norman, OK 73019.
Mil Med. 2018 Mar 1;183(suppl_1):245-251. doi: 10.1093/milmed/usx149.
Rupture of the eardrum or tympanic membrane (TM) is one of the most frequent injuries of the ear after blast exposure. To understand how the TM damage is related to blast wave direction, human cadaver ears were exposed to blast waves along three directions: vertical, horizontal, and front with respect to the head. Blast overpressure waveforms were recorded at the ear canal entrance (P0), near the TM (P1), and inside the middle ear (P2). Thirteen to fourteen cadaver ears were tested in each wave direction and the TM rupture thresholds were identified. Results show that blast wave direction affected the peak P1/P0 ratio, TM rupture threshold, and energy flux distribution over frequencies. The front wave resulted in lowest TM rupture threshold and the horizontal wave resulted in highest P1/P0 ratio. To investigate the mechanisms of TM injury in relation to blast wave direction, the recorded P1 waveforms were applied onto the surface of the TM in a three-dimensional finite element model of the human ear and distributions of the stress in TM were calculated. Modeling results indicate that the sensitivity of TM stress change with respect to P1 pressure (dσ/dP1) may characterize mechanical damage of the TM in relation to blast waves.
鼓膜破裂是爆炸暴露后最常见的耳部损伤之一。为了解鼓膜损伤与冲击波方向的关系，将人类尸体耳朵沿三个方向暴露于冲击波：相对于头部的垂直方向、水平方向和前方。在耳道入口（P0）、鼓膜附近（P1）和中耳内部（P2）记录冲击波超压波形。在每个波向测试了13至14只尸体耳朵，并确定了鼓膜破裂阈值。结果表明，冲击波方向影响峰值P1/P0比值、鼓膜破裂阈值以及频率上的能量通量分布。前向波导致最低的鼓膜破裂阈值，水平波导致最高的P1/P0比值。为研究与冲击波方向相关的鼓膜损伤机制，将记录的P1波形应用于人体耳朵三维有限元模型中的鼓膜表面，并计算鼓膜中的应力分布。建模结果表明，鼓膜应力变化相对于P1压力的敏感度（dσ/dP1）可能表征与冲击波相关的鼓膜机械损伤。
