Ballistic limit

About: Ballistic limit is a research topic. Over the lifetime, 1326 publications have been published within this topic receiving 26641 citations.

The mechanics of penetration of projectiles into targets

Abstract: The present survey is concerned with the terminal ballistics aspects and the penetration mechanics viewpoint of the interaction of penetrators and targets. The latter are categorized as semi-infinite, thick, intermediate and thin. Initial velocity ranges are established for the partial purpose of separating physical effects in various regimes. Target damage mechanisms are described and the concept of a phase diagram distinguishing between the domains of embedment (or perforation) and ricochet is presented. Methods for describing or observing the process are indicated; these include empirical relations, analytical models for ballistic velocities based on rather simple damage mechanisms (primarily for targets, but in some instances for the striker), hypervelocity descriptions, numerical techniques and experimental methods. Projectile and target characteristics are described and the penetration into the targets is examined for the various thickness categories. Finally, some unsolved problems in this area are indicated that require further investigation.

Perforation resistance of five different high-strength steel plates subjected to small-arms projectiles

Abstract: 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 + 6 = 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.

Ballistic penetration of steel plates

Abstract: This paper presents a research programme in progress where the main objective is to study the behaviour of Weldox 460 E steel plates impacted by blunt-nosed cylindrical projectiles in the lower ordnance velocity regime. A compressed gas gun is used to carry out high-precision tests, and a digital high-speed camera system is used to photograph the penetration process. A coupled constitutive model of viscoplasticity and ductile damage is formulated and implemented into the non-linear finite element code LS-DYNA, and the material constants for the target plate are determined. The proposed model is applied in simulations of the plate penetration problem and the results are compared with test data. Good agreement between the numerical simulations and the experimental results is found for velocities well above the ballistic limit, while the ballistic limit itself is overestimated by approximately 10% in the numerical simulations.

Composite structures under ballistic impact

Abstract: In the present study, investigations on the ballistic impact behaviour of two-dimensional woven fabric composites has been presented. Ballistic impact behaviour of plain weave E-glass/epoxy and twill weave T300 carbon/epoxy composites has been compared. The analytical method presented is based on our earlier work. Different damage and energy absorbing mechanisms during ballistic impact have been identified. These are: cone formation on the back face of the target, tensile failure of primary yarns, deformation of secondary yarns, delamination, matrix cracking, shear plugging and friction during penetration. Analytical formulation has been presented for each energy absorbing mechanism. Energy absorbed during each time interval and the corresponding reduction in velocity of the projectile has been determined. The solution is based on the target material properties at high strain rate and the geometry and the projectile parameters. Using the analytical formulation, ballistic limit, contact duration at ballistic limit, surface radius of the cone formed and the radius of the damaged zone have been predicted for typical woven fabric composites.

Modelling of the energy absorption by polymer composites upon ballistic impact

Abstract: In this paper we report on the development of a simple model for calculating the energy absorption by polymer composites upon ballistic impact. Three major components were identified as contributing to the energy lost by the projectile during ballistic impact, namely the energy absorbed in tensile failure of the composite, the energy converted into elastic deformation of the composite and the energy converted into the kinetic energy of the moving portion of the composite. These three contributions are combined in the model to determine a value for the ballistic limit of the composite, V0. The required input parameters for the model were determined by a combination of physical characterisation (for the physical and mechanical properties of the composites and the characteristics of the projectile) and from high-speed photography (for the size of the deformed region and the cone velocity). As the failure event usually occurred between two of a relatively small number of frames from the high-speed camera, the model predicted a range for V0. This range of V0 was compared with experimentally determined values for three composite systems: woven Nylon-66 fibres in a 50:50 mixture of phenol formaldehyde resin and polyvinyl butyral resin, woven aramid fibres in a similar matrix and Dyneema UD66 (straight gel-spun polyethylene fibres laid in a 0/90 fibre arrangement in a thermoplastic matrix). In all cases, the experimentally measured values of V0 were found to lie within the range predicted by the model. The size of the deformed region, formed through shear deformation, on the back face of the composite was found to relate directly to the in-plane shear modulus of the material. Perhaps the most surprising result was that the dominant energy absorbing mechanism was found to be the kinetic energy of the moving portion of the composites.