Experimental study on the law of rupture of pig eardrum based on free-field explosion
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摘要: 听觉系统各组成部分的机械损伤是爆炸后造成听力损失的主要原因,强脉冲声致听觉损害风险准则仍然存在许多争议,例如:指标选择冲量还是超压峰值,正压持续时间是否重要等。本研究基于自由场实爆条件,设计并搭建了大动物爆炸致伤平台,探究了不同爆炸参数对鼓膜破裂的影响规律,并建立了基于自由场超压峰值和正压持续时间的鼓膜创伤量效关系。通过笔形压力传感器测量自由场超压,通过Friedlander公式拟合超压时程曲线,确定冲击波超压峰值和正压持续时间,并对时域中记录的波形进行归一化能量频谱分析,以确定冲击波在频域上的信号能量分布。对爆炸后的小型猪进行解剖,记录不同爆炸参数下鼓膜创伤程度。以超压峰值和正压持续时间为自变量,对实验数据进行二元逻辑回归分析,并给出鼓膜破裂风险曲线。研究发现,当自由场超压峰值低于170 kPa时,鼓膜无明显损伤;当自由场超压峰值高于237 kPa时,部分鼓膜出现不同程度的破裂和充血。距爆心越近,超压峰值越大,但鼓膜创伤的严重程度并未随之单调增加。在8.0 kg TNT当量的爆炸实验中,鼓膜破裂的严重程度随爆心距的减小呈现先提高再降低的趋势。通过对冲击波载荷特征的分析可知,距爆心越近,正压持续时间越短,高频段能量占比相对更大,小型猪鼓膜破裂的概率可能反而降低,此时仍然出现显著的听力损失和耳蜗损伤。鼓膜作为通过振动传递声信号的黏弹性薄膜结构,其动力学响应可能与载荷频率成分密切相关。除了超压峰值,冲击波波形频谱分布对鼓膜破裂程度影响显著。Abstract: Mechanical damage to components of the auditory system is the main cause of hearing loss after exposure to blast overpressure waves. There still exist some controversies in high level impulse sound damage risk criteria (DRC). For example, whether average energy or peak overpressure should be used as a main criterion, whether positive duration is important or not, etc. Based on the free-field air explosion, we designed and built a platform for studying blast injuries in large animals. We studied the effect of different explosion parameters on the rupture of the tympanic membrane (TM) and created a relationship between the probability of TM rupture and the dose of the blast wave in terms of peak overpressure and positive duration. The free-field overpressure time history was measured by a pen-shaped pressure sensor. The overpressure time-history curves were fitted by the modified Friedlander equation, thus the peak pressure and positive duration of the blast wave were determined. The impulse pressure energy spectra analysis was performed on the recorded waveforms to determine the signal energy distribution over the frequencies. The degrees of TM rupture of miniature pigs were recorded after dissection under different blast conditions. A two-variable logistic regression was performed on the resulting experimental data for TM rupture risk in terms of peak overpressure and positive duration. The study found that when peak overpressure was lower than 170 kPa, there was no obvious damage to the TM; when peak overpressure was greater than 237 kPa, some of the TMs ruptured or were congested with varying severity. As the distance from the explosion center became smaller, the peak pressure became larger, while the severity of TM damage did not increase monotonically. In the 8.0-kg-TNT equivalent explosion, the severity of TM rupture showed a tendency to increase and then decrease as the distance became smaller. Through the analysis of the blast wave characteristics, we found that the smaller the distance away from the center, the shorter the positive duration and the increase in the high-frequency component of the blast wave. The probability of TM rupture of miniature pigs may decrease, but significant hearing loss and inner ear damage still occur at this time. As a viscoelastic membrane structure that transmits sound through vibration, the dynamic response of the eardrum may be closely related to the frequency spectrum of loads. In addition to the peak pressure, the blast wave waveform may have a significant impact on the degree of TM rupture.
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Key words:
- free-field explosion /
- blast wave /
- tympanic membrane rupture /
- hearing loss /
- damage risk
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表 1 不同爆炸条件下鼓膜创伤率及小型猪致死率
Table 1. Eardum trauma ratios and mortality ratios of minipigs under different explosion conditions
炸药当量/kg 爆心距/m 超压峰值/kPa 正压持续时间/ms 创伤率/% 致死率/% 鼓膜破裂 鼓膜充血 鼓膜无损 1.9 1.8 511.59±30.68 1.40±0.15 25 25 50 0 2.6 169.97±4.19 2.80±0.01 0 0 100 0 3.2 96.30±1.38 4.65±0.14 0 0 100 0 8.0 2.6* 628.28 1.30 0 25 75 50 2.9 528.74 2.11 0 100 0 0 3.2 378.51±38.57 2.98±0.14 100 0 0 0 3.8 237.01±15.46 4.26±0.10 50 25 0 0 4.6 142.13±1.32 5.69±0.11 5.5 100.43 6.63 注:*8.0 kg TNT当量爆炸条件下距爆心2.6 m处的载荷数据由其他距离参数推算而得。 -
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