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A terminal ballistic analysis of the effects of 7.62 mm X 51 AP P80 rounds on inclined high-strength armor steel plates is the focus of the presented study. The findings of an instrumented ballistic testing combined with 3D advanced numerical simulations performed using the IMPETUS Afea® software yielded the conclusions. The experimental verification proved that slight differences in the pitch-andyaw angles of a projectile upon an impact caused different damage types to the projectile's core. The residual velocities predicted numerically were close to the experimental values and the calculated core deviations were in satisfactory agreement with the experimental results. An extended matrix of the core deviation angles with combinations of pitch-and-yaw upon impact angles was subsequently built on the basis of the numerical study. The presented experimental and numerical investigation examined thoroughly the influence of the initial pitch and yaw angles on the after-perforation projectile's performance. [ABSTRACT FROM AUTHOR]

In the present paper, the high velocity impact of 9mm soft lead projectile on 10mm and 30mm thick Eglass/ epoxy composites was studied using a 450 kV Flash X-ray radiography (FXR) system. The basic parameters of FXR imaging, such as effect of ratio of target to film (TF) and source to target (ST) distances and X-ray penetration thickness of the composite material were optimized based on clarity and the actual dimensions of the objects. The optimized parameters were used in the FXR imaging of the ballistic event of 9mm soft projectile on E-glass/epoxy composite. The real time deformation patterns of both the projectile and composite target during the ballistic impact were captured and studied at different time intervals. The notable failure modes of the 10mm thick target with time include fibre breakage, bulging on the back side, delamination, recovery of the bulging, reverse bulging and its recovery. However, with increase in thickness of the target to 30mm the only failure mechanism observed is the breaking of fibres. The ballistic impact event was also numerically simulated using commercially available LS-DYNA software. The numerically simulated deformation patterns of the projectile and target at different time intervals are closely matching with the corresponding radiographic images. [ABSTRACT FROM AUTHOR]

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Mechanisms of projectile defeat and ballistic resistance of thin targets impacted by tip-deformable conical projectiles have been discussed in the context of the influence of apex angle of the projectile. Transition in target local failure modes occurred as the projectile apex angle was altered. The effect on projectile deformation and ballistic properties has also been discussed. A brief discussion on projectile deformation mechanism and projectile defeat near ballistic limit velocities with supporting experimental evidence is included. Numerical simulation using ABAQUS/Explicit has been able to effectively predict the projectile deformation and associated target behavior. [ABSTRACT FROM AUTHOR]

In this article, the ballistic impact response of square clamped fiber–metal laminates and monolithic plates consisting of different aluminum alloys is investigated using the ANSYS LS-DYNA explicit nonlinear analysis software. The panels are subjected to central normal high velocity ballistic impact by a cylindrical projectile. The implemented finite element models have been validated by comparison with published experimental data concerning GLARE 5 and monolithic 2024-T3 aluminum plates. Using the validated models, the influence of the mechanical properties of the constituent aluminum alloy on the ballistic resistance of the fiber–metal laminates and the monolithic plates is studied. Apart from 2024-T3, the aluminum alloys 2024-T351, 2024-O, 6061-T6, 7039 and 7075-T6 are considered. It is found that the ballistic limits of the panels can be substantially affected by the constituent aluminum alloy. The 7075-T6 aluminum alloy offers the highest ballistic resistance whereas 2024-O aluminum alloy offers the lowest ballistic resistance. [ABSTRACT FROM AUTHOR]

In this paper, a modified laminated finite-element model based on subcell of unit cell and CDM material model was developed in nonlinear explicit finite-element code to investigate the dynamic response of 2D triaxial braided composite under ballistic impact of projectile. Six subcells, which were considered as laminate with different stacking sequences using solid elements, were employed to represent one unit cell of triaxial braided composites, therefore, the fiber-laying direction of braiding architecture is reproduced. In the prediction of the subcell model, an approximate round conical deformation area forms in the target and the failure modes are mainly longitudinal and transverse cracking due to tension. Compared with the continuum model, the subcell model is capable of analyzing the energy absorption of fiber in each direction. Although the failure modes are similar for both methods, the subcell model is more effective in prediction of impact wave propagation than the continuum model because it describes the fiber arrangement of triaxial braided composites. The developed subcell model will be an effective tool for the design process of carbon/epoxy composite fan casings. [ABSTRACT FROM AUTHOR]

This paper presents the computational-based ballistic limit of laminated metal panels comprised of high strength steel and aluminium alloy Al7075-T6 plate at different thickness combinations to necessitate the weight reduction of existing armour steel plate. The numerical models of monolithic configuration, double-layered configuration and triple-layered configuration were developed using a commercial explicit finite element code and were impacted by 7.62 mm armour piercing projectile at velocity range of 900 to 950 m/s. The ballistic performance of each configuration plate in terms of ballistic limit velocity, penetration process and permanent deformation was quantified and considered. It was found that the monolithic panel of high-strength steel has the best ballistic performance among all panels, yet it has not caused any weight reduction in existing armour plate. As the weight reduction was increased from 20-30%, the double-layered configuration panels became less resistance to ballistic impact where only at 20% and 23.2% of weight reduction panel could stop the 950m/s projectile. The triple-layered configuration panels with similar areal density performed much better where all panels subjected to 20-30% weight reductions successfully stopped the 950 m/s projectile. Thus, triple-layered configurations are interesting option in designing a protective structure without sacrificing the performance in achieving weight reduction. [ABSTRACT FROM AUTHOR]

This paper focuses on validating a numerical modelling of woven materials subjected to ballistic impact based on experimental data. Studied impact system is a 3D warp interlock fabric (4 layers of angle interlock – through the thickness) and FSP projectile (Fragment Simulating Projectile). Numerical prediction is compared with ballistic tests on data obtained from ultra-rapid camera in two typical impact cases: no perforation and perforation. Effect of deformation rate is investigated by using both mechanical properties of yarn in static and dynamic states for numerical modelling. The numerical model using dynamic parameters shows a better prediction of impact behaviour of the 3D woven fabric than the one using static parameters. [ABSTRACT FROM AUTHOR]

In this research effort, ballistic performance of a quenched and tempered steel was investigated. Low alloy steel was selected where austenization, quenching and finally tempering at 600°C were applied to it. Thereafter, the heat-treated steel was shot with armour piercing 7.62 mm calibre and the occurrence of failure, after the interaction between the projectile and the steel, was investigated. The shot was performed at zero degree (0°) obliquity with a projectile velocity of 830m/s. After the shot, microstructural and fractographical examinations were carried out on the sample taken from the perforated region using scanning electron microscopes to determine the matrix phase and secondary phases. It was observed that the steels had tempered martensitic-bainitic matrices after heat treatments; a crater was formed on the front side of the steel; deformed and transformed adiabatic shear bands had an effect on the crack formation and propagation in the matrix; and perforation mode of the steels was typical petalling. [ABSTRACT FROM AUTHOR]

Sandwiched hollow sphere structure may have the potential to provide better ballistic impact protection as compared with monolithic plate based on the same weight and impact area. In the previous study of a sandwiched hollow sphere structure by the authors, a novel unit cell was created as a basic building unit of the structure, the tumbling effect was observed for significant impact energy absorption, and the existence of an optimal yield stress or hardness was proved for maximizing the impact energy absorption. However, the impact energy absorption ability of the sandwiched hollow sphere structure may also relate to many other factors. In this study, the diameter relation between the incoming projectile and the spheres in the sandwich core, the projectile initial impact velocity, and the sphere arrangement in the sandwich core are examined. It is revealed that the first layer sphere diameter should be comparable to the diameter of the incoming projectile, the diameter of spheres in different layers in one sandwich core should either decrease or increase monotonically, and there exists a critical impacting speed, at which the sandwiched sphere structure is most effective for impact energy absorption, etc. All these findings make the sandwiched hollow sphere structure a promising new member to the passive armor family. [ABSTRACT FROM PUBLISHER]

Ballistic impact response of ceramic- composite armor, consisting of zirconia toughened alumina (ZTA) ceramic front and aramid laminated composite as backing, against 7.62 mm armor piercing (AP) projectiles has been studied. Two types of backing composite laminates i.e. Twaron-epoxy and Twaron-polypropylene (PP) of 10 mm and 15 mm thickness were used with a ceramic face of 4mm thick ZTA. The ceramic- faced and the stand alone composite laminates were subjected to ballistic impact of steel core 7.62 mm AP projectiles with varying impact velocities and their V50 ballistic limit (BLl) was determined. A sharp rise in BL was observed due to addition of ceramic front layer as compared to stand alone ones. The impact energy was absorbed during penetration primarily by fracture of ceramic, deformation and fracture of projectile and elastic-plastic deformation of flexible backing composite layer. The breaking of ceramic tiles were only limited to impact area and did not spread to whole surface and projectile shattering above BLl and blunting on impact below BLl was observed. The ceramic-faced composites showed higher BL with Twaron-PP as backing than Twaron-epoxy laminate of same thickness. This combination of ceramic-composite laminates exhibited better multi-hit resistance capability; ideal for light weight armor. [ABSTRACT FROM AUTHOR]

Abstract: The present study describes the ballistic impact behaviour of a high strength metastable near beta Ti alloy, β-CEZ in different microstructural conditions against 7.62 mm armour piercing projectiles. Ballistic trials were carried out on 10 mm thick β-CEZ and Ti–6Al–4V plates clamped with 50 mm thick 7017 Al alloy backing. The ballistic performance of different conditions was evaluated by measuring residual depth of penetration (DOP) in 50 mm thick Al-7017 alloy backing. In the present study, even though the β-CEZ titanium alloy in as-rolled and α + β solution treated + aged conditions had significantly higher strength and hardness compared to conventionally used Ti–6Al–4V, significant improvement in ballistic impact resistance was not observed. Post ballistic microstructural observation of crater cross section showed formation of adiabatic shear bands (ASBs) and ASB induced cracks in all conditions. As-rolled, α + β solution treated and aged conditions of β-CEZ alloy showed more ASBs, ASB induced cracks in comparison to Ti–6Al–4V. The β-solution treated and quenched condition of β-CEZ had less number of ASB and highest residual depth of penetration. In this study the ballistic results are discussed based on the post ballistic microstructural observations. [Copyright &y& Elsevier]

An analytical model is presented for the ballistic impact behavior of ceramic-composite armors. The model is based on wave theory and energy balance between the kinetic energy of the projectile and the energy absorbed by different mechanisms. The armor analyzed consists of front composite cover layer, ceramic plate, rubber layer and the composite backing plate. The projectile is cylindrical. The major damage and energy-absorbing mechanisms are compression of the target directly below the projectile, compression in the surrounding region around the point of impact, formation of ring cracks and radial cracks in the ceramic leading to tensile failure, shear plugging, pulverization of the ceramic, tension in the yarns, delamination and matrix cracking in the composite, bulge formation on the back face of the composite backing plate and friction between the target and the projectile. Projectile erosion and deformation are also considered. Kinetic energy, velocity and deceleration of the projectile, distance traveled by the projectile and the contact force are presented as a function of time. Ballistic limit velocity, contact duration and damage progression are also given. Further, solution procedure is presented for the study of ballistic impact behavior of ceramic-composite armors. Analytical predictions are validated with the experimental results. Finally, performance of a typical ceramic-composite armor is presented. [ABSTRACT FROM PUBLISHER]

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]

\As modern helmets have become quite capable of defeating the penetration capabilities of ballistic threats, Soldiers may experience head injuries due to blunt trauma caused by helmet back face deformation (BFD). Possible resulting injuries include skull fracture, hematoma, concussion, contusion, diffuse axonal injury, etc. Some of these injuries have been associated with traumatic brain injury. In order to assess potential injury mechanisms prior to fielding new helmets, we have developed a means to experimentally replicate and measure helmet BFD that can be correlated to injury criteria. In this study, helmet performance test methodology is developed using a digital image correlation (DIC) technique. DIC provides the capability to measure dynamic displacements, thereby providing the ability to calculate deformation, velocity, and acceleration rates. We have shown that digital image correlation is an experimentation technique that accurately captures BFD area and rate of deformation for impacts against combat helmets. We used the DIC data to calculate a new metric; the available energy that could potentially impact a Soldier's head. Our study shows that DIC data upholds the hypothesis that helmet BFD mechanically loads the skull similar to a direct impact from a less-than-lethal projectile or blunt object impact. The available energy obtained from DIC measurements was used to calculate the blunt criterion (BC) for helmet standoff distances of 12.7 mm (0.5 in) and 19.1 mm (0.75 in), which in turn can provide a prediction of the probability of abbreviated injury scale (AIS) levels and, in particular, skull fracture. DIC can be used to provide dynamic helmet performance data that will allow increased understanding of BFD and quantitative assessment and validation of helmet performance results. Knowledge of the conditions leading to head trauma obtained through DIC experimentation should enable the selection of new energy-absorbing materials for helmets; thus, allowing new helmet design candidate performances to be objectively evaluated. Test data and characterization of helmet response could then be used to achieve improved warfighter survivability. [ABSTRACT FROM AUTHOR]

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]

The present article deals with the development of a finite element modelling approach for the prediction of residual velocities of hard core ogival-nose projectiles following normal impact on mild steel target plates causing perforation. The impact velocities for the cases analysed are in the range 818-866.3 m/s. Assessment of finite element modelling and analysis includes a comprehensive mesh convergence study using shell elements for representing target plates and solid elements for jacketed projectiles with a copper sheath and a rigid core. Dynamic analyses were carried out with the explicit contact-impact LS-DYNA 970 solver. It has been shown that proper choice of element size and strain rate-based material modelling of target plate are crucial for obtaining test-based residual velocity. The present modelling procedure also leads to realistic representation of target plate failure and projectile sheath erosion during perforation, and confirms earlier observations that thermal effects are not significant for impact problems within the ordnance range. To the best of our knowledge, any aspect of projectile failure or degradation obtained in simulation has not been reported earlier in the literature. The validated simulation approach was applied to compute the ballistic limits and to study the effects of plate thickness and projectile diameter on residual velocity, and trends consistent with experimental data for similar situations were obtained. [ABSTRACT FROM AUTHOR]

The subject of this paper is to analyze the impact of projectiles against ceramic/metal armour using a simple one-dimensional mode. The model allows the calculation of the loss of projectile mass and its velocity, and gives the deflection of the backup material. This work also investigates the influence of grain size of the ceramic material on ballistic performance, which is very useful during selection of the best material for each application. Therefore, two formulations of the same ceramic material were produced. They had the same chemical composition, the same mechanical properties, but different grain size. The ballistic performances were compared measuring the maximum velocity each formulation was able to support, without perforation. [Copyright &y& Elsevier]

Work done previously on single-ply ballistic resistant fabric systems is now extended to double-ply systems. Experiments were carried out to investigate the impact phenomenon of double-ply systems that consists of Twaron® CT 716 fabric and projectiles of the following nose shapes: hemispherical, flat, ogival (CRH 2.5) and conical (half-angle of 30°). Results obtained revealed that the increase in energy absorption does not necessarily double when the ply number is increased to two. In fact, the ratio of energy absorbed in the double-ply system to that of the single-ply system varies with impact velocity and projectile geometry. At points corresponding to maximum energy absorption, the ratio for all projectile types scatters about an average of 2.1. The amount of deviation from this value depends on the mechanisms that lead to perforation. Failure mechanisms of a double-ply system are similar to those of a single-ply system, but the degree of damage of the impact and distal plies differs. [Copyright &y& Elsevier]

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.