Mechanical Mechanisms and Simulation of Blast Wave Protection

Abstract

A typical blast wave as an effective duration of 2–10 ms, and the features of a shock wave in a free field are illustrated in Fig. 1. When explosives or other explosive substances explode, immense energy is generated. When materials are compressed by the impact, compression wave is formed, which quickly spread and propagate in all directions, thereby creating drastic damage to surrounding materials and abruptly elevating pressure to the point of overpressure. A non-linear shock wave includes a discontinuous overpressure front, and pressure, density, and temperature behind the front usually decline according to an index until reaching negative pressure. Thereafter the figures gradually return to baseline, followed by a vacuum phase (cavitation), which then swiftly spread and propagate in all directions, thereby creating drastic damage to surrounding medium. The peak overpressure of a blast wave is related to the quantity of explosives, surrounding environment conditions, and other factors. Structures and solids are subjected to loads that may include many cycles comprised of such periodic overpressures and cavitation. Once a vertical shock wave (particle velocity parallel to wave velocity) hits a solid structure, without a doubt it would create some kind of shear (non-zero part of particle velocity perpendicular to wave velocity). In various isotropic materials, this kind of composite force is easy to dissipate. However, in various anisotropic materials, stress wave would create many qualitatively different transformations, which increase the difficulty of predicting responses in such solids. At the same time, in this kind of material, new mechanisms (dissipation, resonance, etc.) may be introduced to effectively defend against stress waves.