Impulsive Loading of Armour by High Explosive Squash Head Munition

Abstract

Results obtained by theoretical modelling studies involving classical stress-strain theories, duly validated by experimental investigation in understanding the mechanism of impulsive loading (scabbing) and blast under dynamic and static conditions, are discussed. This concept has been used in designing a high explosive squash head ammunition being effective in defeating monolithic armour. Efforts have been made to carry out an in-depth study in understanding the mechanism of scabbing under static and dynamic (live firing) conditions. For this purpose, a one-dimensional computer code has been used to predict the spread of explosive against time on the target. The simulations were carried out using a 2-D Lagrangian hydrodynamic code for scabbing effect. The blast effect that follows under static and dynamic conditions has also been studied. Blast parameters have been computed in terms of TNT equivalent and compared with experimental results. The events occurring during impulsive loading of 135 mm monolithic rolled homogenous armour have been illustrated.

A review of the integrity of metallic vehicle armour to projectile attack

“…the latter consisting of multiple small fragments of material, as opposed to a complete separation of a large fragment, the result of 'complete coalescence of the voids, leading to a clear opening inside the specimen' (p. 4). Deshpande et al 62 also found that the material tends to break up into as many as five pieces in the region close to the axis of the projectile, but with reduced damage closer to the sides, and this has the effect of maintaining material integrity (Figure 9). It was postulated that the phenomenon of multiple spallation occurs due to the interaction of multiple waves and their reflections.…”

“…Deshpande et al. 62 also found that the material tends to break up into as many as five pieces in the region close to the axis of the projectile, but with reduced damage closer to the sides, and this has the effect of maintaining material integrity (Figure 9). It was postulated that the phenomenon of multiple spallation occurs due to the interaction of multiple waves and their reflections.…”

“…This process continues deeper and deeper into the material until the stress waves and their interactions fade in magnitude below the critical material strength. 62…”

“…21 Even without full penetration of armour from an anti-tank weapon, spall fragments can be lethal to vehicle crews. Some armaments, such as high-explosive squash head (HESH) ammunition, 62 are designed specifically to maximise pressure waves and spall fragmentation, rather than for penetration of the armour. Spalling is also of interest in the design and protection of structures using cementitious materials, e.g.…”

“…This process continues deeper and deeper into the material until the stress waves and their interactions fade in magnitude below the critical material strength. 62

Figure 9.Schematic diagram, adapted from Deshpande et al., 62 showing how a greater amount of fragmentation occurs near the axis of the projectile, while a smaller amount of fragmentation away from this axis has the effect of maintaining the integrity of the material.

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