Bulletin of the American Physical Society
2005 14th APS Topical Conference on Shock Compression of Condensed Matter
Sunday–Friday, July 31–August 5 2005; Baltimore, MD
Session K5: Inelastic Deformation IV: Penetration |
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Chair: Dennis Orphal, International Research Associates Room: Hyatt Regency Constellation F |
Tuesday, August 2, 2005 1:30PM - 1:45PM |
K5.00001: Failure of a Long-Rod Projectile Obliquely Interacting with a Three-Layer Target Sergey Zelepugin, Valerie Grigorjan, Nikolaj Dorokhov Results of experimental and numerical research of the interaction of a tungsten-alloy long rod projectile (L/D=20) with a three-layer target at an angle of 60$^{\circ}$ and with a velocity of 1600 m/s are presented. The material of the middle layer was an elastomer or reacting mixture in which shock-induced solid-state exothermic reaction can take place. Analysis of the data obtained shows that the character of failure of the projectile qualitatively depends on the material of the middle layer. For elastomer layer the bend and failure of the projectile on large fragments is prevailed, for the reacting mixture -- ``thermoshock'' in an interaction zone and then high-rate erosion failure of the projectile is observed. The protective properties of the target can be improved by an activation of the middle layer with an explosive. [Preview Abstract] |
Tuesday, August 2, 2005 1:45PM - 2:00PM |
K5.00002: DOP test evaluation of the ballistic performance of armor ceramics against long rod penetration Huang Fenglei, Zhang Liansheng A series of DOP tests with lateral confinement has been carried out and a linear relation between the residual penetration in RHA and the alumina thickness been obtained. The rod configuration and the initial transient impact are thought to be responsible for the gradual decrease of differential efficiency factor (DEF) with the increase of ceramic thickness in literature DOP tests. A new revised DEF definition is proposed to more accurately characterize the thick tile ceramic ballistic performance on a more physically based analysis. [Preview Abstract] |
Tuesday, August 2, 2005 2:00PM - 2:15PM |
K5.00003: Modeling of bullet penetration in explosively welded composite armor plate Vasant Joshi, Theodore Carney Normal impact of high-speed armor piercing bullet on titanium-steel composite has been investigated using smooth particle hydrodynamics (SPH) code. The objective is to understand the effects of multiple hits during the ballistic testing of explosively welded armor plates. These plates have significant micro-structural differences within the weld region, heat-affected zone and the base metal. The variances result in substantial ductility, hardness and strength differences, important criteria in determining the failure mode, specifically whether it occurs at the joint or within the virgin base metal. Several configurations of composite plates with different material combination had to be modeled. The results were used to modify the heat treatment process of explosively welded plates, making them more likely to survive multiple hits. [Preview Abstract] |
Tuesday, August 2, 2005 2:15PM - 2:30PM |
K5.00004: Mesoscale Modelling of the Response of Aluminas N.K. Bourne The response of polycrystalline ceramics to shock loading has been studied for the past thirty years. Yet formulation of continuum models describing this has proved difficult. In uniaxial strain loading, failure mechanisms have been noted that proceed from the impact face. Particular problems have come to light when attempting to describe penetration into materials where the rod appears to dwell on the target surface. It has become clear that operating mechanisms are not completely described and so the technique of mesoscale simulation has been applied to understand composite behaviour at the grain scale. The alumina chosen for study has been experimentally investigated using plate impact loading. The microstructure has been determined by sectioning and visualizing using transmission electron microscopy. This microstructure has been converted into an input file for computer simulation of the experimental impacts. A view of the mesoscale response is presented and the mechanisms operating are highlighted. A connection with the macroscopic response is made to illustrate the features of the continuum response that originate at the mesoscale. [Preview Abstract] |
Tuesday, August 2, 2005 2:30PM - 2:45PM |
K5.00005: Critical Plastic Strain as a Criterion for Failure in Ballistic Impact Experiments of U/Ti and Ti64 Alloys B. Herrmann, D. Shvarts, V. Favorsky, E. Zaretsky Strain localization and failure in U-0.75Ti and Ti-6Al-4V alloys were studied in symmetric (rod-on-rod) and reverse ballistic (disk-on-rod) impact experiments accompanied by VISAR monitoring of the lateral sample surface velocity. Softly-recovered samples were metallurgically examined, and numerical simulations of the experiments were performed with AUTODYN 2-D code. Satisfactory reproduction of both the measured velocity profiles and the results of the metallography examination of the damage produced by adiabatic shearing were obtained using the Steinberg-Cohran-Guinan-type constitutive equation, calibrated in preliminary planar impact experiments and the AUTODYN built-in erosion function. A good agreement was found between strain measured by using natural martensite (U/Ti) and texture (Ti64) markers and corresponding to the onset of adiabatic shearing (0.5 - 1.0) and the value of the critical plastic strain used in the simulations as a criterion for triggering the erosion function (0.6 for both alloys). In Ti64 the shearing is finalized by cracks developed at observed strain of 1.0 - 1.5 whereas in the U/Ti the shear strain reaches values of 30 - 60 and terminated by void growth and coalescence. [Preview Abstract] |
Tuesday, August 2, 2005 2:45PM - 3:00PM |
K5.00006: Taylor Anvil Impact Charles Anderson, Arthur Nicholls, Sidney Chocron G. I. Taylor showed that dynamic material properties could be deduced from the impact of a projectile against a rigid boundary [1]. The Taylor anvil test became very useful with the advent of numerical simulations [2], and has been used to infer material constitutive constants [3]. A new experimental facility has been developed to conduct Taylor anvil impacts for validating constitutive constants used in numerical simulations. A 37-mm diameter Hopkinson bar apparatus was adapted to conduct the Taylor anvil experiments. Techniques were developed to separate the sabot from the impacting projectile, yet maintain high-precision impact planarity. The anvil is made from Vascomax steel, and backed by a 1.82-m steel bar to provide inertial mass to the anvil and ensure deceleration of the projectile solely from elastic waves within the projectile. Ultra-high speed photography provides time-resolved data, while a digital imaging system was adapted to determine radial deformation as a function of length. Details of the experimental techniques, along with examples of experiments using 6061-T6, are discussed. Numerical simulations are used to complement the experimental results. [1] G. I. Taylor, Proc. R. Soc. A, 194, 289 (1948); [2] M. L. Wilkins {\&} M. W. Guinan, J. Appl. Phys., 44(3), 1200 (1973); [3] T. J. Holmquist {\&} G. R. Johnson, private communication. [Preview Abstract] |
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