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It seems scarcely credible that thin polymer fibers, bound together in resin, can stop projectiles ranging from a hand-gun bullet to a high-power rifle round, but they can and have done so, saving many lives in the process. Composite body armor protects a wide range of civilians from security guards to police officers and from bailiffs to VIPs. [ABSTRACT FROM AUTHOR]

The paper deals with a possibility of the local repairing of damaged composite armours. The proposed repairs can be performed directly in the field, allowing thus to recover the full ballistic protection in a short time. Several solutions (temporary or permanent) were designed and tested both experimentally and using numerical simulations. Overlapping of the damaged area with patch from armour steel after filling the hole with ceramic balls showed to be optimal as a temporary repair. The calculation clearly showed that the depth of penetration of the projectile is reduced in all cases of designed permanent repairs in comparison to original armour configuration. The experiments confirmed supposed enhancing of ballistic resistance, but only some repair techniques met the requirements of multi-hit testing. However, the reason of failure after multi-hit could be clearly explained with the help of used numerical simulations. [ABSTRACT FROM AUTHOR]

The capability of conventional air gun lead pellets (diabolo pellets) to cause severe injuries or fatalities even at low kinetic energy levels is well documented in medical literature. Modern composite hunting pellets, usually a metal core (made of steel, lead, zinc, or a zinc and aluminum alloy) encased in a plastic sleeve, are of special forensic and traumatological interest. These projectiles are advertised by the manufacturers to discharge at higher velocities than conventional air gun pellets, thus generating very high tissue-penetrating capabilities. Lack of experimental data on these uncommon air gun projectiles induced this work. Ballistic parameters of 12 different caliber .177 (4.5 mm) composite pellets, discharged from two spring-piston air guns (Weihrauch HW 35, Webley CUB) and three pneumatic air guns (Walther LGR, Walther LG400, Walther LP300), were investigated using a ballistic speed measurement system and compared to a conventional diabolo pellet (RWS Meisterkugel) as reference projectile. Although overall results were inconsistent, for some projectile-weapon combinations (particularly spring-piston air guns), a significant change of the kinetic energy (−53 up to +48 %) to the reference projectile was observed. The data provided in this work may serve as a basis for forensic investigation as well as traumatological diagnosis and treatment of injuries caused by these uncommon projectiles. [ABSTRACT FROM AUTHOR]

Abstract: The spherical cavity expansion theory is applied. Considered are the effects of the resistance of the projectile nose and the friction of the projectile shank on the penetration depths and residual velocities of the projectiles. By progressively increasing the depth of penetration into double-layered composite targets, we adopted numerical calculation manner to develop the analytical model that determined the residual velocities, ballistic limit velocities, and penetration depths of the ogival nose projectiles during normal impact with double-layered composite targets of varying thicknesses. We also used NATO 0.30″ armor piercing (AP) bullets to strike double-layered composite targets made from 6061-T651 aluminum, 5083-H116 aluminum, polycarbonate (PC), and polymethylmethacrylate (PMMA) plates for the ballistic tests. The analytical model predictions show well agreement with experimental results from Dey et al. (Int. J. Solids Struct. 44 (2007) 6701–6723.), Børvik et al. (Proceedings of the SEM Annual Conference, 2009), and the present ballistic tests. [Copyright &y& Elsevier]

Abstract: This paper presents a ballistic impact simulation of an armour-piercing projectile in hybrid ceramic/fiber reinforced composite armour. The armour is composed by an alumina plate and an ultra high molecular weight polyethylene composite. In order to model the armour behavior three different constitutive models were formulated and implemented into ABAQUS/Explicit finite element code. Comparisons between numerical predictions and experimental results in terms of damage shape/extent and V50 are also presented and discussed in the paper. [Copyright &y& Elsevier]

Abstract: In this paper, based on LS-Dyna code, a new finite element (FE) simulation of the ballistic perforation of the ceramic/composite targets, which impacted by cylindrical tungsten projectiles, has been presented. Research on this method has been conducted by a few research groups in recent years. The ceramic material, which is the front plate, has been made of Alumina 99.5% and composite back-up plate composed of Twaron fibers. The 2-dimensional (2D), axi-symmetric, dynamic-explicit, Lagrangian model has been considered in this simulation. The Johnson–Cook, Johnson–Holmquist and Composite-Damage materials behaviors have been used for projectile, ceramic and composite materials respectively. The brittle fracture and fragmentation of ceramic conoid, the failure criteria based on fracture of fibers or matrixes of composite materials and erosion or flattening of projectile during perforation have been considered. The residual velocity and perforation time has been obtained and compared with the available analytical models. The results show that when the ceramic is impacted by a projectile, a fragmented ceramic conoid breaks from ceramic tile and the semi-angle of ceramic conoid with increasing initial velocity decreases. Furthermore, the dishing of composite layers at high impact velocities and the delamination of layers near the ballistic limit velocity decrease. [Copyright &y& Elsevier]

The interaction between a projectile and metal-matrix composites (MMCs) was investigated in terms of macro cracking, petalling and particularly grain deformation of a matrix alloy at the hole section caused by the projectile at high velocity impact. Metal matrix composites were manufactured by squeeze casting using Al alloys reinforced with Al2O3 or SiC. Additionally, laminated composites with SiC particles and back side supported by Kevlar 49® were manufactured and their ballistic behavior tested. The composite and unreinforced Al alloy targets were subjected to ballistic impact with an armor piercing projectile of 7.62mm caliber at a speed in the range of 770-800 m/s. The macro examination focused on cracking and petalling after impact. The investigation of grain deformations of matrix alloy was conducted by light microscopy in the hole section created by the projectile. The hole section created by the projectile had different profiles. Around the hole sections, different grain deformation rates in different directions took place for reinforced and unreinforced Al alloys. Strong friction took place between the projectile and hole surface and the velocity of the projectile was decreased suddenly in the hole as it met the reinforcement particles in the composite body. These led to deformations of the projectile surface and grain surrounding the reinforcement. In the case of laminate composites, the laminates were fractured and deformed in the direction of projectile movement [ABSTRACT FROM AUTHOR]

Abstract: In the present work, a material model development approach and transient non-linear dynamics simulations of the projectile/armor interactions are employed to explore the role of multi-walled carbon-nanotube (MWCNT) reinforcements in improving the ballistic-protection performance of poly-vinyl-ester-epoxy matrix (PVEE)/E-glass fiber matrix reinforced laminate armor. Two different architectures of the composite-laminate armor are considered: (a) a hybrid armor consisting of a 100μm-thick high MWCNT-content PVEE-matrix MWCNT-reinforced lamina sandwiched between two PVEE-matrix/E-glass mat reinforced laminas and (b) a monolithic E-glass mat reinforced composite laminate with a low MWCNT-content MWCNT-doped PVEE-matrix. The projectile/armor interaction simulation results show that both armor architectures yield a minimal (∼6%) increase in the ballistic-protection as measured by the armor V50, a velocity at which the probability of armor penetration by a given fragment is 50%. The results obtained are rationalized using a simple analysis of the effect of MWCNTs on the in-plane and the through-the-thickness properties of the armor. [Copyright &y& Elsevier]

Abstract: In this research an armor material with constant thickness has been studied. The armor consists of two layers: one is a boron carbide ceramic and the other is Kevlar 49 fiber composite material. By using Ansys/Lsdyna software, the ballistic limit velocity of this armor has been obtained and the Heterington equation (optimum thickness of layers) has been verified for constant thickness of the armor. In this research, mechanical properties of Kevlar 49 under different strain rates are utilized and showed that consideration of the strain rate is very important for the simulation of penetration process. Results from the model have confirmed the validity of the Chocron–Galvez analytical model. Moreover, the projectile velocity prediction, especially at high velocity, shows a good agreement with numerical simulations. Finally, normal and oblique impacts of projectile to armor have been simulated and compared. The results show that the ballistic limit velocity of armor increases under oblique impact conditions. [Copyright &y& Elsevier]

Abstract: This paper examines the penetration and perforation of fibre-reinforced plastic (FRP) laminates struck by rigid projectiles with different nose shapes within a wide range of impact conditions using ABAQUS/Explicit code. It is assumed that the FRP laminate target response can be represented by a velocity dependent forcing function which eliminates discretizing the target as well as the need for a complex contact algorithm. The forcing function is then applied to the surface of the projectiles as boundary conditions in the numerical model. With this combined analytical and computational technique we can obtain the depth of penetration, residual velocity, ballistic limit, transient response in terms of time-histories of displacement/penetration, velocity and deceleration of the projectile. It is shown that the model predictions are in good correlation with available experimental data. [Copyright &y& Elsevier]

The nondelamination characteristics of three-dimensional (3-D) braided composites under ballistic impact makes them possess considerable potential in ballistic protection applications. However, there are only a few references concerning the calculation of ballistic properties of these composites, and all are based on the continuum assumption of composite materials. In this paper, a refined quasi-microstructure model constructed with crossed inclined laminae of the same braided yarn with the same diameter and fiber volume fraction as in the 3-D braided composite at the actual microstructure level is established to analyze the ballistic penetration of 3-D braided composites target by a rigid projectile. The calculated results of the finite element analysis (FEA) are conservative to estimate the penetration resistance of the composite. From the acceleration-time history of the projectile and the damage morphology of the 3-D braided composite in FEA, it is indicated that the refined quasi-microstructure model can approximately simulate the real ballistic impact damage of these composites. The original ideas of this refined quasi-microstructure model are the scheme of decomposing the 3-D braided composite with the inclined lamina at its actual microstructure level and the adoption of constitutive equations of the reinforced fibers at a high strain rate. This model can also be extended to calculate the ballistic penetration of other 3-D textile preform-reinforced composites by rigid projectiles. [ABSTRACT FROM AUTHOR]