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A long-pulse low-velocity gas gun with a gas buffer is used to induce impact damage in cast Composition B and hot pressed PBXN-5. To obtain different damage states, a range of projectile velocities are used by control-ling the launching pressure of gas gun. The stress history during impact loading is recorded. Various methods are used to characterize the damage state of impacted explosive samples. The microstructure is examined by use of scanning electronic microscopy (SEM) and polarized light microscopy (PLM). The densities and ultrasonic atten-uation are also measured. The results show that both Composition B and PBXN-5 exhibit some damage character-istics of brittle materials. However, due to the difference in compositions, PBXN-5 exhibits better resistance to impact loading than Composition B. 相似文献
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煤与瓦斯突出的二维模拟实验研究 总被引:14,自引:2,他引:14
介绍了自行设计、加工的模拟煤与瓦斯突出的二维实验装置及配套的压力数据自动采集处理系统。在二维模拟实验装置上做了一系列的实验。实验发现,煤样的破坏存在“开裂”和“突出”两类典型的破坏形式,破坏阵面的前沿以拉伸强间断的形式向外传播;煤体破坏的初期是轴对称的,而后则只在某一方向上向外扩展,而且破坏阵面的扩展速度是逐渐衰减的,不存在恒稳推进,在煤体破坏过程中,应力重新分布,并有4种不同的应力转移形式。这些结论对于认识煤与瓦斯突出的机理是十分有益的。 相似文献
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通过水中爆炸波对水泥试样的损伤破坏实验来模拟水力裂缝层内爆炸采油中激波使岩石损伤开裂的现象。结果表明,试样预制剖面上的裂纹分布可以近似代表其内部的裂纹分布规律。观察到了四个破坏区域:压实破坏区、压实损伤区、拉伸损伤区和拉伸破坏区,并对这些区域特征做了详细描述;利用冲击波的相关理论,对水泥试样损伤开裂的机理做了初步分析。研究发现,裂纹的起裂扩展与水泥试样的初始损伤有密切关系;并且裂纹的形状受炸药与水泥试样尺度比值以及炸药的安放位置等条件控制。最后通过对压实破坏区渗透率实验,发现压实破坏区也有较好的渗透性,这对层内爆炸采油技术的深入研究具有重要意义。 相似文献
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The damage properties of polymer bonded explosives under dynamic loading were studied by using ultrasonic evaluation. Explosive samples were damaged by a low-velocity gas gun at different impact velocities. Ultrasonic examination was carried out with a pulse through-transmission method. Spectra analyses were carried outby using fast Fourier transform. Characteristic ultrasonic parameters, including ultrasonic velocities, attenuation coefficients, spectra area and master frequency, were obtained. The correlation between the impact damage and ultrasonic parameters was analyzed. A damage coefficient D was defined by considering a combination of ultrasonic velocity and amplitude. The results show that ultrasonic parameters can be used to quantitatively assess the damage extent in impacted plastic bonded explosives. 相似文献