Projectile

About: Projectile is a research topic. Over the lifetime, 13047 publications have been published within this topic receiving 115563 citations.

Ballistic Impact Behavior of Thick Composites: Analytical Formulation

Abstract: Structures undergo different loading conditions during their service life. Impact is one of the typical cases of loading. In this study, an analytical method is presented for the prediction of ballistic impact behavior of thick composites based on wave theory and energy balance between the projectile and the target. For thick composites the wave propagation along the thickness direction is also considered. During the ballistic impact event, energy transfer takes place from the projectile to the target. As the energy is absorbed by different mechanisms, kinetic energy and velocity of the projectile decrease. Different damage and energy-absorbing mechanisms for a typical woven fabric composite are compression of the target directly below the projectile, possible reverse bulge formation on the front face, compression in the surrounding region of the impacted zone, tension in the yarns, shear plugging, bulge formation on the back face, delamination and matrix cracking, friction between the target and the projectile, and heat generation caused by impact. Based on the analytical method presented, typical results are generated and compared with the experimental values. Nomenclature A = cross-sectional area of the projectile Aql = quasi-lemniscate area reduction factor Ay = cross-sectional area of the yarn d = diameter of the projectile dci = deceleration of the projectile during a given time interval E = energy Ebb = energy absorbed due to bulge formation on the back face of the target Ecf = energy absorbed due to compression of the target directly below the projectile Ecsy = energy absorbed due to compression of yarns in the surrounding region of the impacted zone: region 2 Edl = energy absorbed due to delamination Efr = energy absorbed due to friction Ehg = energy absorbed due to heat generated Emc = energy absorbed due to matrix cracking Emt = energy absorbed by matrix cracking per unit volume Erb = energy absorbed due to reverse bulge formation on the front face of the target Esp = energy absorbed due to shear plugging of the yarns Etf = energy absorbed due to tension in the yarns in a layer ETOTAL = total kinetic energy lost by the projectile F = total force/contact force Fc = compressive force Fi = inertial force GIIcd = critical strain energy release rate in mode II h = thickness of the target hl = thickness of each layer hlc = thickness of a layer after compression h p = length of the plug K = numerical constant (depends on the shape of the projectile)

Kinematic Method for Determination of Accelerator Beam Energies

Abstract: A method for determination of accelerator beam energies using hybrid targets is described. A target consisting of a homogeneous mixture of reference nuclei having well‐known excited states and projectile nuclei is used. Determination of the ``crossover'' angle at which recoil projectile particles and inelastically scattered particles from reference nuclei produce equal pulse heights is shown to provide a beam energy measurement. No special apparatus is required. The method is applicable over a wide range of energies. An alternative related measurement using other hybrid targets is discussed briefly.

Initiation of detonation by conical projectiles

Abstract: Initiation of detonation by a hypersonic conical projectile launched into a combustible gas mixture is investigated. From analytic considerations of the flowfield, energetic and kinetic limits are proposed to predict the conditions required to initiate an oblique detonation wave in the mixture. To experimentally investigate these limits, projectiles with cone half angles varying from 15° to 60° were launched into a stoichiometric mixture of hydrogen/oxygen with 70% argon dilution at initial pressure between 10 and 200 kPa. The projectiles were launched from a combustion-driven gas gun at velocities as great as 2.5 km/s (corresponding to 150% of the Chapman Jouguet velocity). Pictures of the flowfields generated by the projectiles were taken via schlieren photography. Five combustion regimes could be observed about the projectile ranging from a prompt and delayed oblique detonation wave formation, combustion instabilities, a wave splitting, and an inert shock wave. The two theoretical limits provide a means to interpret the observed flowfield regimes and are in satisfactory agreement with the experimental results.

An Investigation of Oblique Perforation of Metallic Plates by Projectiles

Abstract: An experimental and analytical study was performed on the mechanics of oblique perforation of metallic plates by projectiles. The purpose was to determine the dependence of the velocity drop on the angle of impact for prescribed mechanical and physical properties of the projectile and the target plate. The ballistic experiments were carried out with 0.22-in.-caliber lead bullets on target plates of commercially pure aluminum and an aluminum alloy which ranged from 2.0 to 6.0 mm in thickness. Transient measurements were taken which included high-speed photographs of the perforation process. The theoretical model that had been developed previously by the authors for the case of normal perforation was modified to include the effects of the angle of impact. The experimental observations for the present test conditions indicate that the main modification to the analysis is the use of the total projectile path as the effective target-plate thickness. Reasonably good agreement between the experimental and theoretical results was obtained.