Projectile impact

Investigations in the field of shoek eompression of solid materials were originally performed for military purposes. Speeimens sueh as armor were subjected to either projectile impact or explosive detonation, and the severity and character of the resulting damage constituted the experimental data (see, e.g., Helie, 1840). Investigations of this type continue today, and although they certainly have their place, they are now considered more as engineering experiments than scientific research, inasmuch as they do little to illuminate the basic physics and material properties which determine the results of shock-compression events. 

The complexity of the stress waves generated by explosive charges or projectile impact, and the appearance of relief waves that emanate from free sur-... 

Test data are available for two experiments at different impact velocities in this configuration. In one of the tests the projectile impact velocity was 1.54 km/s, while in the second the impact velocity was 2.10 km/s. This test was simulated with the WONDY [60] one-dimensional Lagrangian wave code, and Fig. 9.21 compares calculated and measured particle velocity histories at the sample/window interface for the two tests [61]. Other test parameters are listed at the top of each plot in the figure. 

Figure 9.23. Lagrangian calculation of projectile impact—setup.

Figure 9.25. Lagrangian calculation of projectile impact—grid in Fig. 9.24 after rezoning.

L.D. Bertholf et al.. Kinetic Energy Projectile Impact on Multi-Layered Targets Two-Dimensional Stress Wave Calculations, Prepared by Sandia National La-... 

G.R. Johnson, R.A. Stryk, and M.E. Nixon, Two- and Three-Dimensional Computational Approaches for Steel Projectiles Impacting Concrete Targets, Proc. Post-SM RT Seminar on Impact, Lausanne, Switzerland, 1987. 

Shock-wave loading of solids is normally accomplished by either projectile impact, such as produced by guns or by explosives. The shock heating and compression of solids covers a wide range of temperatures and densities. For example, the temperature may be as high as a few electron volts (1 eV =... 

Grosse et al, JACS 79, 6341-42(1957) (Initiation to deton of liquid oxygen-liquid methane solns) 21) K.E. Spells D.W. Woodhead, Nature 179, 251-52 (1957) (Initiation of deton by projectile impact)... 

Initiation by Bullet Impact is a special case of Initiation by Projectile Impact. See Bullet Tests in Vol 2, pp B332-340 and Vol 4, p D153 also under Projectile Impact below... 

Initiation by Projectile Impact is a complicated process which depends on a combination of shock initiation, impact initiation and hot fragment initiation effects. For fast projectile impact, shock initiation effects are predominant. With slow projectiles the initiation resembles Impact Initiation. Further complications are introduced if the impacting projectiles are hot a special case where the explosive is part of the projectile is the so-called Susan Test—see Barrier Tests Their Comparison with Shooting Tests in Vo 4, pp D145-147 and Detonation (and Explosion) Experimental Procedures in Vol 4, pp 333-335... 

Explosives Sensitivity Data. Card-gap and projectile sensitivity, data are presented by Watson (Ref 1) for a wide variety of expl compns tested at the USBurMines laboratories in more or less standard test geometries. The results of both tests are in good agreement in that they provide the same sensitivity ordering fbr different subclasses of expls. Least sensitive were homogeneous liquids that did not exhibit a tendency, to undergo low-velocity detonation, AN-FO (Ammonium Nitrate-Fuel Oil), and most cast military expls. Of intermediate sensitivity were pressed and powdered military expls, cast Pentolite, permissible and nonpetmissible water-based expls, and one commercial two-component expl. The most sensitive were permissible and nonpermissible Dynamites and expls susceptible to low-velocity detonations Refs I) R.W. Watson, 1 Card-Gap and Projectile Impact Sensitivity Measurements, A Compilation , USBurMines Information Circular 1C 8605(1973)... 

R,W.Lawrence J.E.Meyers, "Sensitiveness of High Explosives to Rifle Bui lets Experiment Station, Hercules Power Co, Wilmington, Del (1944) published as seen 1 in OSRD 3156(1944) 6)D.I.Hedrick, The Sensitivity to Projectile Impact of Explosives in Various Containers ,... 

Refs 1) Anon, Sensitivity of Explosives to Projectile Impact , OSRD 3156 (1944), Appendix A 2) D.P. MacDougall et al, Physical Testing of Explosives , OSRD 5745 (1945)... 

The Susan Sensitivity Test (Ref 7) is a projectile impact test with the projectile shown in Fig 1. The wt of expl in the projectile head is about 1 lb (0.45 kg). The target is armor-plate steel. The results of the tests are expressed in... 

On the other hand, when a projectile impacts on a fully confined expl charge, a variety of results are possible. Sometimes explns occur which are quite violent, but they are not detonations. The time to expln in these situations can be hundreds of microseconds, and confinement can have a marked effect on the results... 

Critical Energies in Cal/cm2 Calculated from Projectile Impact Data on Tetryl... 

Also propellant charges for rockets and guns have also been developed by compounding solid explosives such as nitramines (e.g. -> Cy-clonite) with plastics. Plastic explosives and plastic propellants are of interest, if low thermal and impact sensitivity is needed (- LOVA -> Armor Plate Impact Test -> Friction Sensitivity -> Heat Sensitivity - Impact Sensitivity -> Projectile Impact Sensitifity - Susan Test). 

The projectile impact sensitivity is the reaction of an explosive charge if hit by infantry projectiles. Impact safety is given if the charge does not fully explode at impact. The projectile impact sensitivity does not only depend on the type of explosive itself, but also on the nature of its confinement (metallic, plastic, thin-walled, or thick-walled). A single bullet impact by an ordinary or a hard steel cored projectile, or a machine gun burst, will create different reactions. 

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