Dynamic effects of interaction of composite projectiles with targets
V. M. ZakharovCitation: AIP Conference Proceedings 1698, 040008 (2016); doi: 10.1063/1.4937844 View online: http://dx.doi.org/10.1063/1.4937844
View Table of Contents: http://scitation.aip.org/content/aip/proceeding/aipcp/1698?ver=pdfcov Published by the AIP Publishing
Articles you may be interested in
Reaction dynamics of 34-38Mg projectile with carbon target using Glauber model AIP Conf. Proc. 1675, 030093 (2015); 10.1063/1.4929309
Effect of projectile break-up on incomplete fusion reaction dynamics AIP Conf. Proc. 1524, 182 (2013); 10.1063/1.4801708
Effect of target composition on proton acceleration in ultraintense laser-thin foil interaction Phys. Plasmas 19, 093108 (2012); 10.1063/1.4750050
Failure of a Long‐Rod Projectile Obliquely Interacting with a Three‐Layer Target AIP Conf. Proc. 845, 1407 (2006); 10.1063/1.2263588
Projectile and Target Fragmentation in the Interaction of 12C and 27Al AIP Conf. Proc. 769, 1642 (2005); 10.1063/1.1945322
Dynamic Effects of Interaction of Composite Projectiles with
Targets
V.M. Zakharov
11Scientific Research Institute of Applied Mathematics and Mechanics of Tomsk State University,
36, Lenin Avenue, Tomsk, 634050, Russia
Corresponding author: [email protected]
Abstract. The process of high-speed impact of projectiles against targets of finite thickness is experimentally investigated. Medium-hard steel plates are used as targets. The objective of this research is to carry out a comparative analysis of dynamic effects of interaction of various types of projectiles with targets, such as characteristics of destruction of the target, the state of the projectile behind the target, and particularities of the after-penetration stream of fragments after the target has been pierced. The projectiles are made of composites on the basis of tungsten carbide obtained by caking and the SHS-technology. To compare effectiveness of composite projectiles steel projectiles are used. Their effectiveness was estimated in terms of the ballistic limit. High density projectiles obtained by means of the SHS-technology are shown to produce results comparable in terms of the ballistic limit with high-strength projectiles that contain tungsten received by caking.
INTRODUCTION
Research of high-speed interaction of projectiles against targets has shown that reserves required to increase effectiveness of steel projectiles are almost exhausted. Their further perfecting involves changing the design and applying high density materials.
Composites on the basis of tungsten and its compounds have been used widely as such materials. These are solid and heavy composites received by caking. In our case they are WCo and WNFe respectively. Materials containing compounds of tungsten and other high density metals are often used in designing projectiles [1-3].
For the purpose of obtaining composites uniting properties of WCo and WNFe alloys, a technology of the self-propagating high-temperature synthesis (SHS-technology) was used. The SHS-technology is more flexible than the technology of caking. It also allows receiving composites with various properties, in particular, to obtain materials with a different value of density, to change it over a wide range, and to vary initial components of the fusion mixture greatly, including in a nanodimensional state.
The first series of experiments with the mentioned projectiles from bearing steel BS15, alloys of WCo15, and SHS-composites was presented in the paper [4, 5]. These experiments resulted in the following: the projectiles under research demonstrated various dynamic effects of high-speed interaction with targets.
In particular, destruction of projectiles after penetrating the target had essential differences: the BS projectile at the velocity of impact V0 exceeding the ballistic limit (BL) of VBL by 1.33 times collapsed highly, its head destroyed
steadily, and the target was destroyed according to the scheme of “cutting a plug”.
Thus, the high-strength WCo-projectile broke friably into three parts that moved almost coaxially – the head, the centre, and the tail - and at V0 = 1.35VBL pierced the target forming a “plug” and splitting off.
The destruction of the target by the SHS13 projectile, its density = 13.29 g/cm3 at V
0 = 1.40VBL, was similar to
that by the WCo projectile, i.e. the “plug” and the splitting off were formed. However, destruction of the SHS13 projectile had an “explosive” character – an after-penetration stream of high space density particles was formed.
THE METHOD OF THE BALLISTIC EXPERIMENT
First experiments have shown that the SHS13 projectile yields to that made of WCo according to the value of the ballistic limit but shows advantage in terms of the after-penetration stream. Therefore, the synthesis of SHS composites, the density of which is higher than that of SHS13, represents practical interest. It would allow balancing values of the ballistic limit with that for the WCo projectile. The W-W2C composite combining high density of
metal tungsten and high hardness of the W2C carbide was used for this purpose. Cast composites W-W2C were
obtained as a result of combustion of the aluminothermal mix under the pressure of the noble gas [6]. The fractographic research [6] of the surface of breaks conducted with the help of a raster electron microscope demonstrated that depending on the content of carbon destruction mechanisms can be different: from extremely brittle destruction with high carbon content to emergence of sites of ductile fracture when the content of carbon decreases. In the composite used in our experiments brittle destruction prevailed.
The second series of experiments was carried out with projectiles for which cores with increased density of SHS17 were produced from the received high density composite W-W2C. After being molded all the surface of
cores was polished. The head of cores had a biconical shape. Cores were placed in a demountable glass that had a classical streamline shape with a diameter of 23 mm from an aluminum alloy of D16. The glass was supplied with the bottom obturating cone. Figure 1 illustrates the shape and the design of the studied projectiles.
FIGURE 1. Elements of the design and the type of assemblage of the studied projectiles
Table 1 demonstrates parameters of all projectiles used in the experiments. In Table 1 the HRC value is hardness of the core material according to Rockwell, Scale C.
TABLE 1.Parameters of equivalent projectiles
Parameters Projectiles
BS SHS13 WCo SHS17
Core diameter, mm 14.5 14.5 14.5 14.5
Core weight, g 93 93 93 93
Projectile weight, g 131 131 131 131
Core material Bearing steel BS15 SHS alloy WCo15 alloy SHS alloy
Density, g/sm3 7.96 13.29 14.50 17.07
Hardness HRC 40 … 64 ≥ 82 ≥ 87 65
040008-2
Experiments with the SHS17 projectile were conducted with the help of a smooth-bore powder ballistic installation, the caliber of which was 23 mm. The velocity of projectiles was measured by a muzzle inductive meter. Figure 2 represents photographs of the ballistic installation with an inductive meter of velocity of the launched projectiles.
FIGURE 2. The laboratory ballistic installation with a muzzle meter of velocity
Two apparatus RINA-3B/6 that run X-ray pulse shooting were recording projectiles approaching the target, their state and the design integrity at the point of penetrating, as well as the nature of deformation and destruction of the projectile plus scattering of fragments of the projectile and the target after being pierced. The velocity of fragments of the after-penetration stream (Vs) was determined. Steel plates were used as a target. Their thickness was 21.6 mm;
their hardness according to Brinell HB amounted to 302.
Experiments were carried out in the conditions of a normal impact when the vector of velocity to the surface of the target coincides with the long axis of the projectile and the normal.
Figure 3 represents roentgenograms of the process of penetration of the projectile into the target in different instants. They show operability of the design of the projectile and adequacy of the given method of experiment.
RESULTS OF BALLISTIC EXPERIMENTS
As a result of the experiments, values of the ballistic limit for the studied projectiles were determined. The values of the limit VBL for all the projectiles and the values of density of materials referred to the density of the WCo15
alloy are given in Table 2.
TABLE 2. Values of the ballistic limit VBL
Projectile Density ratio VBL, m/s (VBL / VBL of WCo projectile), %
BS 0.55 1,030 206
SHS13 0.92 610 122
WCo 1.00 500 100
(a) (b)
FIGURE 3. Roentgenograms of the process of penetration of the BS projectile into the target, where V0 = 1,098 m/s:
(a) – 30 microseconds, (b) – 50 microseconds from the beginning of the penetration
The data of the experiment showed that the increase of density of the SHS17 composite to the value of 17.07 g/cm3 exceeding the WCo15 density by 1.18 times already provides identical values of the ballistic limit.
Experiments enabled to prove that destruction of the target by SHS projectiles is followed by powerful splitting-off destruction. The experiments conducted at higher velocities of interaction show that when the impact velocity of SHS projectiles rises, the splitting-off destruction of the target enlarges.
Figure 4 represents photographs of rear destruction of the target at various velocities of impact. The sizes of diameters of the split-off (SO) plates DSO are given.
The conclusion of the experiment was the following: when increasing the velocity of interaction from 1.40 VBL to
2.09 VBL, i.e. by 1.5 times, the sizes of the split-off plates increase by 1.4 times in proportion. All split-off plates
have a perforation in the centre from the “plug” that came out and the head of the core of the projectile. Thereof split-off plates turn out to be not flat, but extended along the impact axis. Furthermore, when piercing the split-off plate - strong radial breaks appear. Then the split-off plate detaches from the target in the form of single petals. The quantity of petals is always odd, which is a consequence of quite a general regularity of asymmetry of a high-velocity impact [7, 8].
The abovementioned experiments designate that SHS projectiles bear an advantage over a high-strength WCo-projectile in case of split-off destruction and the structure of the after-penetration stream. As the SHS17 WCo-projectile gives the value of the ballistic limit that is equal to the WCo-projectile, the advantage of SHS projectiles of high density becomes considerable. In principle, the SHS-technology can make use of cheaper raw materials, and have lower power consumption in the conditions of mass production. So the advantage of the SHS-technology becomes even more essential.
The structure of the after-penetration stream clearly illustrates dynamic effects. In the case of the WCo projectile the bulk of the after-penetration stream consists of several large fragments of the projectile and several large petals of the split-off plate. The structure of the after-penetration stream of SHS projectiles is absolutely different. SHS projectiles are followed by a powerful after-penetration stream with a high space density of secondary particles consisting of quite small but high-velocity ones (those of the projectile) and small particles (those of the target) formed from cutting of the “plug” and breaking of split-off plates. Such “explosive” nature of destruction of the core behind the target is caused by its brittle state and the existence of various defects: micro impurities, defects of molding, and certain features of its microstructure. They play a role of stress raisers leading to intensive subdivision of material owing to a load-relief after the core exits at the rear of the target.
040008-4
FIGURE 5. After-penetration velocity of fragments
behind the target
(a) (b) (c)
FIGURE 4. Split-off destruction of the rear of the target, the SHS13 projectile:
(a) - V0 = 1.40 VBL, DSO = (33 × 42) mm, below – the largest fragments of the SHS13 core; (b) - V0 = 1.58 VBL,
DSO = (42 × 50) mm; (c) - V0 = 2.09 VBL, DSO = (45 × 58) mm
Large fragments - petals of the split-off plate - create a second more sluggish wave of the after-penetration stream. Totally these waves of the stream have high energy, a wider angle of scattering of particles, and, respectively, create a larger field of impact on objects behind the target.
Interpretation of roentgenograms revealed dependence of the average velocity of the front wave of the after-penetration stream of Vs.
Figure 5 illustrates experimental dependence of the relative after-penetration velocity Vs/V0 from the values
of V0 and VBL for the SHS17 projectile.
The graph lets us identify the loss of initial velocity of the projectile when it penetrates the target and to estimate the Vs value depending on V0 and VBL. So, to
ensure the average velocity of the stream of 0.5V0 the
CONCLUSION
Thus, SHS-composites the density of which is more than 17 g/cm3 show high performance at the impact. The
SHS-technology requires fewer technological operations and can be especially effective when items have complex shapes. The SHS-technology, in principle, gives an opportunity obtaining any shapes of items, to fill them with various inserts, cores, and absorbers, which increases its attractiveness in different fields of technology.
ACKNOWLEDGEMENT
The article is based on results received in 2015 due to realizing the Project No. 9.1.02.2015 within the framework of the Program “D.I. Mendeleev’s Scientific Fund of Tomsk State University”.
REFERENCES
1. G.B. Chernyak and K.B. Povarova, Tungsten in ammunition, edited by Doctor of Engineering, Prof., Corresponding Member of the Russian Academy of Missile and Ammunition Sciences I.N. Torgun (Federal State Unitary Enterprise “TsNIIHM”, Moscow, 2014), 360 p.
2. F.I. Grase, Int. J. Impact Engng 16, 419-433 (1995).
3. D.L. Orphal, R.R. Frazen, A.J. Piekutowski and M.J. Forrestal, Int. J. Impact Engng 18, 335-368 (1996). 4. S.A. Afanas’eva, N.N. Belov, Yu.A. Biryukov, V.V. Burkin, V.M. Zakharov, A.N. Ishchenko, A.V.
Skosyrskii, A.N. Tabachenko, I.E. Khorev and N.T. Yugov, J. of Engng Phys. and Therm. 1, 49-58 (2011). 5. S.A. Afanasyeva, N.N. Belov, Yu.A. Biryukov, V.V. Burkin, V.M. Zakharov, A.N. Ishchenko, A.V.
Skosyrsky, A.N. Tabachenko, I.E. Horev, and N.T. Yugov, “Research of the shock-wave phenomena in composites developed the help of nanotechnologies”, in Physics of shockwaves, combustions, detonations,
explosion, and nonequilibrium processes. The collective monograph edited by V.A. Levin, N.A. Fomin and
V.E. Fortov. Part 1. (Publishing and printing “The Institute of Heat-and-mass transfer” named after A.V. Lykov NAS of Belarus, Minsk, 2014), pp. 11-22.
6. A.N. Avramchik, N.K. Galchenko and L.G. Raskolenko, “Synthesis in the mode of combustion, research of structure, structure and property of cast W-W2C alloys”, in The Self-propagating high-temperature synthesis,
edited by Yu.M. Maximov (Publishing House of Tomsk State University, Tomsk, 1991), pp. 157-170. 7. I.E. Khorev, Letters in J. of Techn. Phys. 4, 71-75 (2005).
8. I.E. Khorev and V. M. Zakharov, “Asymmetry of destruction at high-speed interaction of metal bodies”, in The
Modern Issues of Science – the XXI century (Publishing House of Tambov Regional Institute of Training and
Career-enhancement of Education Specialists (TOIPKRO), Tambov, 2011), pp. 140-141.
040008-6
