A Mechanics Approach to Projectile Penetration (original) (raw)
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An investigation of oblique perforation of metallic plates by projectiles
Experimental Mechanics, 1977
SECURITY CLASSIFICATION OF THIS PAGV (1 *en k)*t& Enteri j) ____-___ REPORT DOCUMENTATION P AGE eREf IOSRUTI OR BFREAD INSTRUCTIONS I. REPORT NUMBER 2. GOVT ACCESSION NO. I. RECIPIENT'S CATALOG NUMBER AFO P-T.7 7-N OR *0. AOSTRACT (47"fifte an orev ie It moina.. y and Idon#ItV by' bloc% nL-MbiSf) 1473 EITI'ON oFa MOv*S O65QLITZ UNCLASSIFIED I SECURITY CLASSIVICATION OF TYiS PAGE t'l)I g tta En¢el4 UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGrE(h.n A&ft4'.d) developed previously by theautors for the case of normal perforation was modified to include the effects of the angle of impact. The experimental observtions for the present test conditions indicate that the only essential modification to the analysis is the use of the total projectile path as the effective target plate thickness. The comparison of the results shows reasonably good agreement between experiments and theory.
International Journal of Impact Engineering, 2004
The effect of target strength on the perforation of steel plates is studied. Three structural steels are considered: Weldox 460 E, Weldox 700 E and Weldox 900 E. The effects of strain hardening, strain rate hardening, temperature softening and stress triaxiality on material strength and ductility are determined for these steel alloys by conducting three types of tensile tests: quasi-static tests with smooth and notched specimens, quasi-static tests at elevated temperatures and dynamic tests over a wide range of strain rates. The test data are used to determine material constants for the three different steels in a slightly modified version of the Johnson-Cook constitutive equation and fracture criterion. Using these three steel alloys, perforation tests are carried out on 12 mm-thick plates with blunt-, conical-and ogivalnosed projectiles. A compressed gas gun was used to launch projectiles within the velocity range from 150 to 350 m/s. The initial and residual velocities of the projectile were measured, while the perforation process was captured using a digital high-speed camera system. Based on the test data the ballistic limit velocity was obtained for the three steels for the different nose shapes. The experimental results indicate that for perforation with blunt projectiles the ballistic limit velocity decreases for increasing strength, while the opposite trend is found in tests with conical and ogival projectiles. The tests on Weldox 700 E and Weldox 900 E targets with conical-nosed projectiles resulted in shattering of the projectile nose tip during penetration. Finally, numerical simulations of some of the experimental tests are carried out using the non-linear finite element code LS-DYNA. It is found that the numerical code is able to describe the physical mechanisms in the perforation events with good accuracy. However, the experimental trend of a decrease in ballistic limit with an increase in target strength for blunt projectiles is not obtained with the numerical models used in this study.
Numerical analysis of the penetration process of a 30mm armor-piercing projectile
Vojnotehnicki glasnik
Introduction/purpose: Thin plates made of high-strength steel are frequently used both in civil and military ballistic protection systems. In order to choose an appropriate type of alloy, it is necessary to fulfil a number of criteria, such as the condition of use, the desired ballistic performance, weight, dimensions, and price. This paper presents a numerical analysis of the penetration of a 30mm armor-piercing projectile with a velocity of 750m/s into steel alloy Weldox 460 plates of different thicknesses at a distance of 1000m . Methods: The analysis has been performed using numerical methods and finite element modeling to calculate stresses and deformation caused by the penetration effect. For defining material characteristics, the Johnson-Cook material model and the fracture of materials model have been used. In this paper, the software packages FEMAP and LS Dyna have been used for defining models and performing numerical calculations. Results: The results of the performed num...
Coupled numerical-experimental study of an armour perforation by the armour-piercing projectiles
Computational Methods and Experimental Measurements XV, 2011
This paper concerns an analysis of target penetration by a selected armourpiercing (AP) projectile: 7.62x54R with steel core. Numerical and experimental research was carried out. The aim of this work was a comparison of the results obtained in real conditions of ballistic test and computer simulation. In this study, two three-dimensional targets and the core of the projectile were built. The structure of the projectile is complex, but steel core plays the main role in the perforation process. Then the numerical model of the projectile was reduced to describe only steel core dynamics. The 3D Element Free Galerkin method is applied to solve the problem under consideration. The algorithm implemented in the Ls-Dyna code was used. Space discretization of the analyzed problem was prepared by means of the HyperWorks Software (HyperMesh module). The total amount of the elements reaches 500 000 in this model. The Johnson-Cook constitutive model is applied to describe the behaviour of the metallic parts: steel layers and the projectile's core. The experimental results were obtained using a high speed video-camera. The target penetrations by the projectile were recorded. The processing of the data obtained from a high speed camera was carried out by means of the TEMA Software. In this paper, a good correlation between the numerical and experimental results was obtained. A lot of interesting mechanical effects observed during the experiment were analyzed.
Penetration of Metallic Plates by Kinetic Energy Projectiles
Ballistic resistance of steel targets is important due to its common applications to the safety of personnel, shelters for arms and military vehicles. Although advanced lightweight composite based armors are available, metal based materials in militarily applications are often used to provide ballistic protection at a relatively low cost due to its widespread usage in vehicle structure. Production, reproduction, and forming of metal based armors are relatively easy comparing other types of composite armors. This study concerns behavior of metallic plates during projectile penetration. Investigations are made for different metallic materials having varying thicknesses. Scope of the work also includes different orientation of single and multiple metallic plates. Impact cases are investigated for differently angled and spaced plates. All cases are investigated for correlation between projectile masses, velocities, plate orientation and kinetic energy absorption behaviors. Residual velo...
There is an urgent need to develop light-weight protective structures with a sufficient protection to prevent the damage occurring during extreme loading events such as blast and ballistic impacts. This study is a part of ongoing research to develop light weight amour materials which can sustain under those severe conditions. Numerical modelling with explicit finite element code LS-DYNA has performed with realistic geometries. Ballistic protection class BR7 in European norm EN 1063 considered, thus penetration of different shaped projectiles through thick steel plates was examined. Since the geometries and materials of the projectiles have a very significant influence on the outcome of this research detail modelling of the projectiles was performed. For the purpose of this paper, perforation mechanism of 7.62mm APM2 bullet through 6mm thick Weldox 460E high strength structural steel plate was examined. Largrangian methods combined with Johnson-Cook material model available in the LS-DYNA were used for the numerical simulations. Finally the ballistic limit curve for the 6mm thick Weldox 460E plate perforated by APM2 bullet was obtained. Results were compared with the analytical models.
International Journal of Impact Engineering, 2009
Thin plates of high-strength steel are frequently being used both in civil and military ballistic protection systems. The choice of alloy is then a function of application, ballistic performance, weight and price. In this study the perforation resistance of five different high-strength steels has been determined and compared against each other. The considered alloys are Weldox 500E, Weldox 700E, Hardox 400, Domex Protect 500 and Armox 560T. The yield stress for Armox 560T is about three times the yield stress for Weldox 500E, while the opposite yields for the ductility. To certify the perforation resistance of the various targets, two different ballistic protection classes according to the European norm EN1063 have been considered. These are BR6 (7.62 mm Ball ammunition) and BR7 (7.62 mm AP ammunition), where the impact velocity of the bullet is about 830 m/s in both. Perforation tests have been carried out using adjusted ammunition to determine the ballistic limit of the various steels. In the tests, a target thickness of 6 mm and 6 þ 6 ¼ 12 mm was used for protection class BR6 and BR7, respectively. A material test programme was conducted for all steels to calibrate a modified Johnson-Cook constitutive relation and the Cockcroft-Latham fracture criterion, while material data for the bullets mainly were taken from the literature. Finally, results from 2D non-linear FE simulations with detailed models of the bullets are presented and the different findings are compared against each other. As will be shown, good agreement between the FE simulations and experimental data for the AP bullets is in general obtained, while it was difficult to get reliable FE results using the Lagrangian formulation of LS-DYNA for the soft core Ball bullet.
Numerical studies on perforation of multi-layered targets by hemispherical-nosed projectiles
In the present work, the ballistic performance of monolithic, in-contact and spaced type layered configurations of aluminium 1100 plates impacted by hemispherical-nosed projectiles was investigated. Numerical simulations were carried out to study the failure modes and ballistic performance of Al 1100 targets subjected to normal and oblique impact (0 0 ,15 0 and 30 0 ) of hemispherical-nosed projectiles. The explicit Autodyn FEM code was employed to carry out the numerical simulations. A study has been undertaken to assess the effect of element size and its aspect ratio in numerical simulations. The ballistic performance of monolithic target was found to be better at higher velocities than in-contact type target plates. The ballistic resistance of spaced type targets was observed to be less due to small contact force between layers. The reduction of spacing from 5mm to 1mm between the layers improved the ballistic resistance substantially due to large interaction force. It was concluded that obliquity effect in this study had significant influence on the response of target. At each angle of impact the ballistic resistance of monolithic target was found slightly better than that of other configurations.The variation in the deformation of target plates with radial distance from the center of the plate is also presented. At each radial distance of from the center of the plate for in-contact target plates, the deformation of target was found to be higher as compared to spaced target plates.