Bulletin of the American Physical Society
16th APS Topical Conference on Shock Compression of Condensed Matter
Volume 54, Number 8
Sunday–Friday, June 28–July 3 2009; Nashville, Tennessee
Session Y4: BL-2: Ballistics |
Hide Abstracts |
Chair: Dennis Orphal, IRA Room: Hermitage D |
Friday, July 3, 2009 8:00AM - 8:15AM |
Y4.00001: Effect of Nose Shape on Long Rod Penetration into Dry Sand Adam Collins, John Addiss, William Proud Flat and Ogive-3 nosed mild steel projectiles (10~mm diameter, 100~mm length) were fired at 200~m~s$^{-1}$ into the end face of cylindrically confined dry sand (100~mm diameter, 150~mm length). Projectiles were tracked through the sand using flash radiography and high speed photography. By seeding a horizontal plane of randomly dispersed lead shot ($<$~1.5~mm diameter) across the centre of the cylinder, the induced displacement field was mapped using Digital Speckle Radiography~(DSR). By imaging at successive time intervals, a temporal history of the penetration is generated. DSR reveals a cone of displacement emanating from the impact point in all cases, leaving areas unmoved during the early stages of penetration. The magnitude and extent of the displacement cone is observed to be greater in the flat nosed case. Initial rapid deceleration is seen in both nose cases, relaxing to an approximately steady velocity as the projectile reaches the end of the target. Ogive nosed projectiles suffer less deceleration, and perforate the target with greater speed than the flat nosed projectile. This combined behaviour is attributed to the flat nosed projectile transferring more energy to movement of sand, and hence experiencing more effective drag. [Preview Abstract] |
Friday, July 3, 2009 8:15AM - 8:30AM |
Y4.00002: Numerical Analysis on the Head-Shape Effect for Long-Rod Normally Penetrating Concrete Target Zhong-Cheng Mu, Wei Zhang, Zong-Sheng Cao The deep penetration of long rods into thick target has been the focus for many decades in the terminal ballistic. Especially the study on long rods penetrating concrete targets arouses more and more attention. But the investigations of the head-shape effect to the high velocity penetration of long rod are few. In this paper, the penetration process of long rod with different head-shapes is analyzed through a series of numerical simulations. The impact velocity from subsonic velocity on the order of 10$^{2}$ m/s to hypervelocity on the order of 10$^{3}$ m/s is used. The penetration target is high strength concrete. Numerical model of concrete target adopts typical dynamic concrete damage model-RHT. The model has shown promising results for prediction of penetration depth. The projectile material is 4340 steel, Johnson-Cook model is chosen. In all the simulations presented here the material properties of projectiles and targets doesn't change. The flat-head and the ogive-head projectile are chosen. The effect of the CRH of ogive-head projectile on penetration depth is analyzed. Difference and similarity are described by the time history of penetrating velocity, acceleration and the head deformation. [Preview Abstract] |
Friday, July 3, 2009 8:30AM - 9:00AM |
Y4.00003: Interface Defeat, Dwell and Penetration of Long Rods on Borosilicate Glass Targets Invited Speaker: We have been investigating the impact response of transparent materials during the last several years. We have conducted long-rod impact experiments into a borosilicate glass and measured penetration and rod consumption velocities as a function of impact velocity. We also measured the failure front velocity. At sufficiently low impact velocities, the glass target resists penetration, and there is dwell. In particular, if a copper buffer is placed over the glass to eliminate the impact shock, complete interface defeat can be observed for Bernoulli stresses of 7.3 GPa. In a few cases, dwell was observed at higher Bernoulli stresses, but then the rod began to penetrate the glass, at which point the Bernoulli stress dropped to $\sim $1 GPa. The paper will describe the experimental techniques and data, and summarize results and conclusions. [Preview Abstract] |
Friday, July 3, 2009 9:00AM - 9:15AM |
Y4.00004: Compression Behavior and Structure of a Borosilicate Glass under Static and Shock-wave Pressures to 49.1 GPa Murli Manghnani, Anwar Hushur, Toshimori Sekine, Jonathan Stebbins Using ultrasonic interferometry, and Brillouin and Raman scattering, we have determined the elastic moduli, compression behavior (volumetric strain), and structural changes (in Si-O-Si, B-O-B, B-O-Si bonds) of borosilicate glass under hydrostatic pressure to 19 GPa in diamond anvil cell. The elastic and vibrational properties of 4 post-shocked specimens of the same glass, recovered from peak pressures of 19.8, 31.3, 41.3 and 49.1 GPa, are also reported. Raman spectra for the samples shocked to 41.3 and 49.1 GPa are similar to those for the unshocked sample, suggesting that the irreversible density and structural changes are recoverable on following decompression. $^{11}$B NMR spectra for all four shocked specimens are similar, and indicate ratios of $^{III}$B to $^{IV}$B that are not greatly changed from the starting glass. [Preview Abstract] |
Friday, July 3, 2009 9:15AM - 9:30AM |
Y4.00005: Damage Evolution in Ballistic Impact of Glass Plates Stephan Bless, Rod Russell, Don Berry, Scott Levinson High-speed photographs were obtained from impact of .50-caliber fragment-simulating projectiles at 1100 m/s onto a 12 mm glass plate bonded with polyurethane to 28~mm of polycarbonate. Impact damage was compared to similar impacts on multi-glass-layer targets. Transitions from bundled radial cracks to fan cracks to radial cracks to dicing cracks occurred in both targets, but in the single-glass-layer target, a layer of glass remained adhered to the substrate. Initial damage spread was faster than the maximum crack speed, but fan and radial cracks grew at the crack speed in glass. The damage development is similar to that seen in edge-on-impact experiments reported over the past couple of years, and it is suggested that those experiments should be reinterpreted as showing impact-plate damage and not penetration phenomena. [Preview Abstract] |
Friday, July 3, 2009 9:30AM - 9:45AM |
Y4.00006: Experimental Results and a Simple Theory for the Early Deflection-Time History of a Ballistic Fabric Charles Anderson, Sidney Chocron A high-speed digital camera was used to observe the deflection-time history of a Kevlar$^{\mbox{{\textregistered}}}$ fabric to bullet impact. It was observed, as others have, that the deflecting fabric has the shape of a pyramid. The average apex angle of the pyramid was calculated from the digital images and was found to be constant with time for the first 50 to 70 microseconds. Using this information, a simple momentum transfer model is shown to capture the velocity-time history of fabric deflection until ply failure. As expected, once ply failure occurs, the model overpredicts deceleration of the bullet. [Preview Abstract] |
Friday, July 3, 2009 9:45AM - 10:00AM |
Y4.00007: The Effect of Aerodynamic Heating on Air Penetration by Shaped Charge Jets and Their Particles Joseph Backofen The goal of this paper is to present recent work modeling thermal coupling between shaped charge jets and their particles with air while it is being penetrated to form a crater that subsequently collapses back onto the jet. This work complements research published at International Symposia on Ballistics: 1) 1987 - Shaped Charge Jet Aerodynamics, Particulation and Blast Field Modeling; and 2) 2007 - Air Cratering by Eroding Shaped Charge Jets. The current work shows how and when a shaped charge jet's tip and jet particles are softened enough that they can erode in a hydrodynamic manner as modeled in these papers. This paper and its presentation includes models for heat transfer from shocked air as a function of jet velocity as well as heat flow within the jet or particle. The work is supported by an extensive bibliographic search including publications on meteors and ballistic missile re-entry vehicles. The modeling shows that a jet loses its strength to the depth required to justify hydrodynamic erosion when its velocity is above a specific velocity related to the shock properties of air and the jet material's properties. As a result, the portion of a jet's kinetic energy converted at the aerodynamic shock into heating transferred back onto the jet affects the energy deposited into the air through drag and ablation which in turn affect air crater expansion and subsequent collapse back onto the jet and its particles as shown in high-speed photography. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700