Search

Artillery designers are always searching for means of improving a gun’s external and internal ballistic properties and this resulted in both new theories surrounding gun construction based on the properties of materials and new methods of building guns capable of firing heavier projectiles to greater ranges. The concept of the accelerator gun sought to achieve the same result without the need for larger and heavier guns and reducing recoil through the use of multiple propellant charges fired sequentially, thus accelerating the projectile without the need for a single high-pressure discharge. It was a quest initiated in France, pursued in the United States and then adopted by a desperate Germany during the latter years of World War 2. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to investigate the ballistic performance of angle-interlock woven fabrics. Different fabric structures firstly have been compared to benchmark the ballistic performance of angle-interlock woven fabrics using the energy loss test. It has been shown that compared with other woven structures, angle-interlock woven fabric demonstrates low ballistic resistance as absorbing less impact energy. This is because angle-interlock woven fabric owns less interlacements than its counterparts. The interlacement plays an important role to help to transfer energy to the adjacent yarns: the more interlacements, the larger area the stress wave could propagate, and more projectile impact energy could be absorbed. After this systemic analysis of overall ballistic performance, more detailed parametric study of angle-interlock woven fabric is carried out. A group of 16 different structures have been tested and compared using the in-house firing range. The studies have revealed that the 3D angle-interlock woven fabric not only displays normal features of energy absorption mechanism, like yarn slippage, fibre fracture and cone formation, which 2D fabric usually demonstrates, but also shows the new property: the weaker gripping power on the constituent yarns. Besides, it also shows that the structural parameters of angle-interlock fabrics do not have a clear influence on the ballistic performance, due to the complicated factors which also have been theoretically explained from the four aspects: (a) the clamping state; (b) yarns hit by the projectile; (c) the impact angle of the projectile; (d) the impact velocity. [ABSTRACT FROM AUTHOR]

The use of carbon nanotubes in composite hard armor is discussed in this study. The processing techniques to make various armor composite panels consisting of Kevlar®29 woven fabric in an epoxy matrix and the subsequent V50 test results for both 44 caliber soft-point rounds and 30 caliber FSP (fragment simulated projectile) threats are presented. A 6.5% improvement in the V50 test results was found for a combination of 1.65 wt% loading of carbon nanotubes and 1.65 wt% loading of milled fibers. The failure mechanism of carbon nanotubes during the ballistic event is discussed through scanning electron microscope images of the panels after the failure. Raman Spectroscopy was also utilized to evaluate the residual strain in the Kevlar®29 fibers post shoot. The Raman Spectroscopy shows a Raman shift of 25 cm−1for the Kevlar®29 fiber utilized in the composite panel that had an enhancement in the V50 performance by using milled fiber and multi-walled carbon nanotubes. Evaluating both scenarios where an improvement was made and other panels without any improvement allows for understanding of how loading levels and synergistic effects between carbon nanotubes and milled fibers can further enhance ballistic performance. [ABSTRACT FROM AUTHOR]

E-glass/polyester composite and layered corrugated aluminium and aluminium foam core sandwich panels were projectile impact tested between 127 m/s and 190 m/s using a hardened steel sphere projectile. The corrugated aluminium cores, constructed from aluminium fin layers and aluminium interlayers and face sheets, exhibited relatively lower-plateau stresses and higher stress oscillations in the plateau region than aluminium foam cores. The applied brazing process resulted in reductions in the plateau stresses of the corrugated aluminium cores. The sandwich panels with 2- and 3-mm-thick composite face sheets and the epoxy-bonded corrugated aluminium sheet cores were perforated, while the sandwich panels with 5-mm-thick composite face sheets were penetrated in the projectile impact tests. On the other hand, the sandwich panels with aluminium foam cores were only penetrated. A simple comparison between the ballistic limits of the sandwich panels as a function of total weight revealed significant increases in the ballistic limits of the cores with the inclusion of composite face sheets. The determined higher impact resistance of the foam core sandwich panels was attributed to the relatively higher strength of the foam cores investigated and the ability to distribute the incident impulse to a relatively large area of the backing composite plate. [ABSTRACT FROM PUBLISHER]

This article deals with the perforation of ductile metal plates subjected to impact by flat-nosed projectiles at normal incidence. Generally speaking, ductile metal plates under impact by flat-ended missiles can fail either by global deformation combined with local shear rupture or by localized adiabatic shear plugging depending upon the geometrical and thermo-mechanical properties of both the targets and the projectiles. Modification is first made to the Bai-Johnson model for adiabatic shear plugging by taking account of strain rate effects using a thermo-viscoplastic constitutive equation instead of thermo-plastic material model and equations for the energy dissipated in the perforation process (perforation energy), the ballistic limit and the residual velocity are then obtained. Furthermore, a critical condition is obtained for differentiating localized adiabatic shear plugging from simple shear plugging failure with global deformations by comparing the modified Bai-Johnson model and the Wen-Jones model. It transpires that the present theoretical predictions are in good agreement with available experimental data in terms of the ballistic limits and the critical transition condition for the modes of plugging failure of ductile metal plates subjected to impact by flat-nosed missiles. It also transpires that the present model predicts well the residual velocities and the energies dissipated in the perforation process. [ABSTRACT FROM AUTHOR]

This study evaluates the energy absorption, perforation and damage evolution created by cylindrical projectile of different nose geometries in woven roving mat/epoxy laminates with 0.45° orientation. A series of ballistic impact tests have been carried out on the laminate with projectile nose geometries representing hemispherical, conical, and conical with round nose and truncated tip. A gas gun projectile launcher set-up was employed to impact the target at different speeds. The damage pattern, perforation mechanism and ballistic limit for each type of projectiles have been studied. Truncated-nose projectile shows the highest ballistic limit while sharp-nose shows the lowest. A quasi-static punch test was carried out on targets with projectiles of above-mentioned nose geometries to assess the damage evolution at a constant strain rate. The maximum load required to cause perforation during punch test was noted for hemispherical-nose projectile. An in-depth layerwise analysis was carried out to analyse the damage in each layer. [ABSTRACT FROM AUTHOR]

The article presents a study which defines a method used for evaluating the injury potential of less lethal projectiles on the thoracic region. The study uses accelerometers and pressure sensors to measure the skeletal dynamic deflection and the distribution of thoracic response in porcine models. Result shows that kinetic energy is not sufficient for the local skeletal response to the impact of two projectiles.