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Abstract
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Containment vessels have been widely used to contain the blast effects in both civil and military applications. As the vessel offers a containment boundary to the internal blast of high explosive (HE), the actual blast loading applied on the inner surface of the vessel may be influenced by the elastic response of the multiple-use containment vessels. In order to predict the dynamic behaviour of a containment vessel, it is necessary to understand the interactive mechanisms between the internal blast loading and the elastic response of the containment vessel.
It has been widely accepted that the blast loading in a containment vessel consists of two distinct phases, i.e. a transient impulsive pressure loading phase and a long-term quasi-static pressure loading phase. After the detonation of high explosives, a shock wave propagates outward from high explosives and strikes the vessel wall, imparting a transient impulsive pressure loading. The first shock wave is followed by a long-term multiple reflections of the shock wave between the centre and the wall of the vessel to build-up a uniformly distributed pressure. As the first shock wave carries most impulse of the blast loading, it has been considered as the primary-shock loading in the design of containment vessels.
The interactive mechanisms between internal blast loading and dynamic elastic response of spherical containment vessels are studied in this paper. The blast loading history in containment vessels can be divided into three periods, i.e. the primary-shock period, the shock-reflection period and the pressure-oscillation period. It is shown that the initial response of the containment vessel depends on both the impulse and the shape of the primary-shock depending on the ratio of the loading period to the breathing mode period. However, during the shock-reflection period, the response of the containment vessel can be coupled with the reflected shock waves in the vessel, especially when the dominant frequency of reflected shock waves is close to the breathing mode frequency of the vessel. During the pressure-oscillation period, the dynamic loading is mainly the oscillation of the internal pressure due to the oscillatory volume change of the vessel, which couples dissipatedly with the vibration of the vessel leading to reduced vibration amplitudes. The effects of the influential non-dimensional parameters on the resonant interaction in shock-reflection period are discussed, based on which guidelines are recommended for avoiding the strain growth in the shock-reflection period in the design of spherical containment vessels. |