Penetration of a coarse sand target by rigid projectiles

Abstract

This paper presents a theory for the normal rigid body penetration of particulate media. This theory consists of two separate force regimes divided by a critical velocity at which the transition between the two regimes takes place. Also included in this theory is sliding friction, separated into two different regimes, one for the nose and one for the shank.In order to verify this new penetration theory, a set of laboratory experiments was performed where 7075-T6 Aluminum projectiles were shot into coarse foundry sand. Utilizing the total penetration depth and impact velocity of each projectile in the test, along with known projectile geometry, analyses of the penetration events were completed. The results of these experiments and analyses, which confirm the required use of a friction coefficient on the shank, are reported.

Historical review of high strain rate and shock properties of ceramics relevant to their application in armour

“…[143][144][145][146][147][148] There also exists a large body of knowledge about the properties of soils and sands relevant to piledriving, some of which may be relevant to ballistic impact, [149][150][151][152] and also their high strain rate, [153][154][155][156] shock [157][158][159][160] and ballistic properties. 116,117,[161][162][163][164][165][166][167] It should be emphasised that sand (or comminuted ceramic) does not have zero strength because the grains can interlock. 168 Direct evidence for this in glass has been obtained using flash X-ray and high-speed photography: 169 a steel rod was seen to be strongly resisted by glass up for at least 40 ms despite the glass having been completely comminuted within about 5-6 ms.…”