Fragment Simulating Projectile Research Articles

MULTI-SCALE MODEL TO PREDICT THE BALLISTIC IMPACT BEHAVIOR OF MULTI-LAYER PLAIN-WOVEN FABRICS

This paper presents a multi-scale model that can predict the ballistic impact behavior of multi-layer plain-woven fabrics using the finite element method (FEM). Multi-layer fabrics of 30.5 × 30.5 cm, woven by high performance yarns Kevlar® 29 3000 denier, are impacted by a 0.3 fragment simulating projectile (FSP). Using a multi-scale approach, behavior of multi-layer fabrics subjected to different impact velocities is numerically analyzed. Ballistic limit of the fabric can also be predicted. The multi-scale model shows an effective gain of computation time in comparison with current mesoscopic ones. Computational results show a good agreement with experimental data.

Characterisation of explosive fragments injuring the neck

Penetrating explosive fragments are the most common cause of neck injuries sustained by UK service personnel deployed to Afghanistan. Analysis of these fragments will enable future ballistic protective materials to be tested with appropriate projectiles. However, only a small number of fragments excised from the neck have been available for analysis and they are potentially unrepresentative. We analysed computed tomograms (CTs) of 110 consecutive UK soldiers whose necks were wounded by explosive fragments. Fragments were classified according to shape, and their dimensions used to estimate volume and mass. These calculations were then compared with the actual measurements of the excised fragments using a general linear model. The 2 most common shapes were cylinders (52%) and spheres (21%). Known and estimated masses were not significantly different (p=0.64). A fragment-simulating projectile of 0.49g represented 85% of fragments retained in the neck. CT can accurately delineate the shape and mass of fragments, which increases the number from which the most appropriate simulated projectile can be designed. We think that this methodology should be applied to fragments retained in other parts of the body to enable broader recommendations to be made regarding the testing of ballistic materials used to protect service personnel.

An Experimental Study on the Ballistic Impact Behavior of Non-Filled Tank against Fragment Simulating Projectile (FSP)

This paper presents the ballistic impact study for the non-filled aluminum tank. The objective was to determine the ballistic limit for front tank wall and rear tank wall. The tank was impacted with fragment simulating projectile (FSP) with various velocities range from 239 m/s up to 556 m/s. The aluminum tank was 3 mm thick, 150 mm wide and 750 mm long. The ends of tank were closed with two Polymethyl methacrylate (PMMA) windows which fixed to the tank with four steel bars. The test was conducted at the Science and Technology Research Institute for Defense (STRIDE) Batu Arang, Selangor. The results showed that the ballistic limit for the front tank wall and rear tank wall was 257.7 m/s and 481 m/s, respectively.

Blast and Ballistic Resistance of Ultra-High Strength Steel

This paper investigates the blast and ballistic resistance of high strength steel XAR-450 with a tensile strength of about 1200 MPa. Compared to normal strength steel, this steel provides significant improvements in ultimate strength performance and can be designed with minimum weight, which are of increasing importance for use in the construction and defense industries. First, material properties of high strength steel are investigated to understand the protective capability and robustness of the proposed protective structures by utilizing the high strength steel plate to resist blast loading and high velocity impact. Both strain hardening and strain rate hardening of XAR-450 steel are investigated. Tensile Split Hopkinson Bar tests were performed to obtain the ultimate tensile strength at strain rates between 103s−1and 104s−1. Test results show noticeable increase of tensile strength of up to 40% with the increase of strain rate from static to 104s−1. Suitable rate-dependent constitutive models and parameters are proposed based on least-squares fitting with test data. The ductile fracture mechanics is also investigated. Thus these material parameters can be used for numerical analysis of protective structures subject to blast and impact. Finally, high velocity impact resistance of high strength steel XAR-450 against bullet and Fragment Simulating Projectile (FSP) were investigated experimentally and numerically. The blast resistance of the high strength XAR-450 steel plate is investigated by the comparison of blast field test result with the finite element analysis results.

Characterisation of explosively propelled fragments injuring the neck

Introduction: Penetrating explosive fragments are the most common cause of neck injury sustained by UK service personnel deployed to Afghanistan. Characterisation of these fragments enables testing of future ballistic protective materials with appropriate Fragment Simulating Projectiles (FSPs). However due to its relatively small surface area, the numbers of fragments excised from the neck is small and potentially unrepresentative.

Computed Tomography Can Improve the Selection of Fragment Simulating Projectiles From Which to Test Future Body Armor Materials

Ballistic protective materials used in body armor are tested with fragment simulating projectiles (FSPs). The type of FSP used has historically been made by choosing fragments representative of those produced by controlled explosions, which may not be representative of those fragments actually injuring soldiers. 75 cylindrical FSPs of three different sizes were fired into six euthanized pigs, imaged using computed tomography (CT) and the wound tracks dissected. Skin entry wound locations, as determined by surface-shaded CT, were compared to clinical photographs. FSP dimensions and depth of penetration derived from CT were compared to surgical dissection using a Mann-Whitney U test. Skin entry wound locations derived from CT were identical to that seen clinically. FSP dimensions were consistently 15% to 19% larger than the true measurements, reflecting the magnifying effect associated with metallic artifact. No statistical difference (p = 0.26) was found between depth of penetration measured radiologically compared to dissection when a projectile did not hit bone but there was a statistical difference when bone was hit (p < 0.05). CT has the potential to accurately ascertain values required to improve the selection of representative FSPs from which future ballistic protective materials are tested.

Perforation of fragment simulating projectiles into goat skin and muscle

IntroductionBallistic gelatin is the most common tissue simulant used to reproduce the penetration of projectiles into muscle but published data to support its use are primarily based on bullets, despite...

Experimental penetration of fragment simulating projectiles into porcine tissues compared with simulants

IntroductionBallistic gelatin is well validated in its ability to simulate the retardation of bullets into homogenous muscle. However the relationship is less clear for fragmentation projectiles and non-homogenous tissues as would truly be found in a human. Method0.16 g, 1.10 g and 2.84 g NATO standardised cylindrical Fragment Simulating Projectiles (FSPs) were fired at a range of velocities (112–1652 m s−1) into four body areas (thigh, abdomen, thorax or neck) of six pig cadavers as well as 20% gelatin. Cadavers were imaged by Computed Tomography (CT) scanning and FSP Depth of Penetration (DoP) ascertained through radiology followed by dissection by a forensic pathologist. Results106/149 (71%) FSPs were retained in tissues enabling DoP measurements and 43/149 (29%) exited the subjects. There was significantly less retardation of FSPs in the thorax and abdomen compared to gelatin but no difference in retardation in leg and neck tissue compared to gelatin. Although the gradient appeared identical for the 2.84 g FSP as well, there were insufficient FSPs retained in the neck and leg for meaningful analysis to be undertaken. DiscussionPorcine leg and neck muscle was demonstrated to be comparable to 20% ballistic gelatin in terms of retardation, validating the use of projectile penetration algorithms derived from this tissue simulant. The effect of pig skin was significant for the 0.16 g FSP, especially at lower velocities, and we would therefore suggest that specific algorithms for any future numerical injury models be based directly from animal data or validated skin simulants for this smaller sized FSP. Reproducing the retardation effects of FSPs in the thorax and abdomen using tissue simulants alone will be problematic due to the anatomical complexity as well as multiple tissue–air interfaces and we would recommend further research in this area.

Novel polymer‐ceramic composites for protection against ballistic fragments

AbstractFor the first time, internally reinforced aggregate polymer ceramic composites were evaluated against fragment simulating projectiles (FSPs) of various calibers to investigate their ballistic impact response. Samples were prepared by mechanically mixing B4C and cBN over a range of ratios and combinations with either thermosetting phenolic or epoxy resin and aramid pulp. Dry mixtures were then molded in a closed die using a heated platen press. The resulting tiles were then mounted as “strike faces” to an aramid backing material using an epoxy resin. Backed targets were tested in a fully instrumented firing range against 5.56 mm FSPs to test ballistic limit. A further series of tests using 7.62, 12.5, and 20 mm FSPs was conducted to examine round deformation across a range of fragments calibers. Round deformations were measured after impact and plotted against shot velocity. It was found that the polymer ceramic composite materials were effective round deformers and, like sintered ceramic strike faces, demonstrated improved ballistic performance at an equivalent areal density and impressive multihit capability. POLYM. COMPOS., 2012. © 2013 Society of Plastics Engineers

Ballistic performance of hybrid panels composed of unidirectional/woven fabrics

This paper examines the effect of the layering sequence of unidirectional (UD)/woven fabric hybrid panels on perforation resistance (V50) against a 5.56 mm fragment-simulating projectile and the blunt trauma resistance represented by the backface signature (BFS) caused by a .44 Magnum semi-jacketed hollow point projectile. Some of the woven fabric layers were impregnated with shear thickening fluid (STF) to modify their properties. When layers with a smaller in-plane constraint (neat woven fabric) were laminated behind layers with a larger in-plane constraint (UD or STF-impregnated woven fabric), an increase in perforation resistance was observed due to the decreased out-of-plane constraint. When the layering sequence was reversed, an increase in blunt trauma resistance (i.e. smaller BFS) was observed due to better coupling of yarn elongation in the frontal and rear layers.

Kinetic Dissipation in Ballistic Tests of Soft Body Armors

The objective of this study was to assess the amount of energy transferred to the backing material of oil-based clay (i.e. kinetic dissipation) in ballistic tests of soft body armor panels. To determine the relationship between penetration depth (or dent volume) and impact velocity (or energy), weight dropping test with a series of steel spheres was carried out at low impact velocities, and direct shooting with a 5.56 mm NATO fragment simulating projectile (FSP) was carried out at high impact velocities. At high and low impact velocities, the volume of the dent made in the oil-based clay was proportional to the velocity of the impactor. The change in dent volume per the change in impact velocity was found to be proportional to the 1.5th power of the mass of the impactor, while the energy absorption per unit dent volume increased linearly with the impact velocity. The relationship between trauma depth (or dent volume) and kinetic dissipation of a soft body armor panel subjected to a 9 mm bullet at 436 m/s is presented, where the trauma diameter approached that of a 1.043 kg steel ball.

Influence of the vacuum resin process, on the ballistic behaviour of lightweight armouring solutions

The armour of vehicles against conventional threats is mainly composed with steel or aluminium panels. Efficient heavy solutions exist, but the involved industries require new lightweight structures. Moreover, unconventional threats as IEDs (Improvised Explosive Devices) may cause severe damages on these structural and protective panel solutions. Thus, combination of aluminium or steel plates with textile composite structures used as a backing, leads to the mass reduction and better performance under delamination behaviour against these new threats. This paper is a part of a study dealing with the impact behaviour of three warp interlocks weaving structures under Fragment Simulating Projectile (FSP) impact. During this research, several parameters has being studied as the influence of the yarns insertions [1–4], the degradation of the yarns during the weaving process [5–7], and the influence of the resin rate on the ballistic behaviour. The resin rate inside composite materials is dependant on the final application. In ballistic protection, we need to control the resin rate in order to have a deformable structure in order to absorb the maximum of energy. However, with the warp interlocks weaving structure, the yarns insertions induce empty spaces between the yarns where the resin takes place without being evacuated. The resin rate inside the warp interlocks structures is in the most of cases less than 50%, which lead to have brittle and hard material during the impact. Contrary to interlocks structures, the existing protection based on prepreg structure have a high fibres ratio around 88% of weight. That leads to have the best ballistic properties during the impact and good deformability of the structure. The aim of this paper is to evaluate the influence of the resin rate on the ballistic results of the composites materials. For that, we have chosen two kinds of warp interlocks fabrics which were infused with epoxy resin following two processes. The first is a classical vacuum resin infusion; the second used a press in order to reach a resin ratio near to the existing protection. The existing protection is a prepreg structure with a fibre content of 88%. It has been revealed that a resin rate less than 35% inside the warp interlocks composite material leads to have equivalent ballistics performances than existing protection.

A Computational Investigation of the Multi-Hit Ballistic-Protection Performance of Laminated Transparent-armor Systems

Multi-hit ballistic-protection performance of a prototypical laminated glass/polycarbonate transparent armor is investigated using a series of transient nonlinear dynamics analyses of armor impact with a sequence of four M2AP full metal jacket (FMJ) armor-piercing bullets. All calculations were carried out using ABAQUS/Explicit commercial finite element program (ABAQUS Version 6.7, User Documentation, Dessault Systems, 2007), and the computational results obtained were compared to their experimental counterparts obtained by Dolan (Ballistic Transparent-armor Testing Using a Multi-hit Rifle Pattern, Bachelors, Thesis, Kettering University, December 2007). The comparison revealed that (a) The proposed computational procedure can reasonably well account for the observed multi-hit ballistic-protection performance of the laminated transparent armor; (b) The role of prior bullet hits in reducing armor’s ballistic-protection performance is clearly revealed; (c) The role of polycarbonate lamina in preventing glass fragments from entering the vehicle interior is clearly demonstrated; and (d) Experimentally observed inability of the transparent armor to defeat 0.50-caliber Fragment Simulating Projectiles (FSPs) is confirmed.

Modeling Fragment Simulating Projectile Penetration into Steel Plates Using Finite Elements and Meshfree Particles

Simulating fragment penetration into steel involves complicated modeling of severe behavior of the materials through multiple phases of response. Penetration of a fragment-like projectile was simulated using finite element (FE) and meshfree particle formulations. Extreme deformation and failure of the material during the penetration event were modeled with several approaches to evaluate each as to how well it represents the actual physics of the material and structural response. A steel Fragment Simulating Projectile (FSP) – designed to simulate a fragment of metal from a weapon casing – was simulated for normal impact into a flat square plate. A range of impact velocities was used to examine levels of exit velocity ranging from relatively small to one on the same level as the impact velocity. The numerical code EPIC, used for all the simulations presented herein, contains the element and particle formulations, as well as the explicit methodology and constitutive models needed to perform these simulations. These simulations were compared against experimental data, evaluating the damage caused to the projectile and the target plates, as well as comparing the residual velocity when the projectile perforated the target.

Modeling Fragment Simulating Projectile Penetration into Steel Plates Using Finite Elements and Meshfree Particles

Simulating fragment penetration into steel involves complicated modeling of severe behavior of the materials through multiple phases of response. Penetration of a fragment-like projectile was simulated using finite element (FE) and meshfree particle formulations. Extreme deformation and failure of the material during the penetration event were modeled with several approaches to evaluate each as to how well it represents the actual physics of the material and structural response. A steel Fragment Simulating Projectile (FSP) – designed to simulate a fragment of metal from a weapon casing – was simulated for normal impact into a flat square plate. A range of impact velocities was used to examine levels of exit velocity ranging from relatively small to one on the same level as the impact velocity. The numerical code EPIC, used for all the simulations presented herein, contains the element and particle formulations, as well as the explicit methodology and constitutive models needed to perform these simulations. These simulations were compared against experimental data, evaluating the damage caused to the projectile and the target plates, as well as comparing the residual velocity when the projectile perforated the target.

Finite element analysis for the evaluation of protective functions of helmets against ballistic impact

The ballistic impact of a human head model protected by a Personnel Armor System Ground Troops Kevlar® helmet is analysed using the finite element method. The emphasis is to examine the effect of the interior cushioning system as a shock absorber in mitigating ballistic impact to the head. The simulations of the frontal and side impacts of the full metal jacket (FMJ) and fragment-simulating projectile (FSP) were carried out using LS-DYNA. It was found that the Kevlar® helmet with its interior nylon and leather strap was able to defeat both the FMJ and FSP without the projectiles penetrating the helmet. However, the head injuries caused by the FMJ impact can be fatal due to the high stiffness of the interior strap. The bulge section at the side of the Kevlar® helmet had more room for deformation that resulted in less serious head injuries.

Comparing finite element and meshfree particle formulations for projectile penetration into fiber reinforced concrete

Penetration of a fragment-like projectile into Fiber Reinforced Concrete (FRC) was simulated using finite element (FE) and particle formulations. Extreme deformations and failure of the material during the penetration event were modeled with multiple approaches to evaluate how well each represented the actual physics of the penetration process and compared to experimental data. A Fragment Simulating Projectile(FSP) normally impacting a flat, square plate of FRC was modeled using two target thicknesses to examine the different levels of damage. The thinner plate was perforated by the FSP, while the thicker plate captured the FSP and only allowed penetration part way through the thickness. Full three dimensional simulations were performed, so the capability was present for non-symmetric FRC behavior and possible projectile rotation in all directions. These calculations assessed the ability of the finite element and particle formulations to calculate penetration response while assessing criteria necessary to perform the computations. The numerical code EPIC contains the element and particle formulations, as well as the explicit methodology and constitutive models, needed to perform these simulations.

Improving Ballistic Performance of Polyurethane Foam by Nanoparticle Reinforcement

We report improving ballistic performance of polyurethane foam by reinforcing it with nanoscaleTiO2particles. Particles were dispersed through a sonic cavitation process and the loading of particles was 3 wt% of the total polymer. Once foams were reinforced, sandwich panels were made and impacted with fragment simulating projectiles (FSPs) in a 1.5-inch gas gun. Projectile speed was set up to have complete penetration of the target in each experiment. Test results have indicated that sandwich with nanophased cores absorbed about 20% more kinetic energy than their neat counterpart. The corresponding increase in ballistic limit was around 12% over the neat control samples. The penetration phenomenon was also monitored using a high-speed camera. Analyses of digital images showed that FSP remained inside the nanophased sandwich for about 7 microseconds longer than that of a neat sandwich demonstrating improved energy absorption capability of the nanoparticle reinforced core. Failure modes for energy absorption have been investigated through a microscope and high-speed images.

Ballistic impact of a KEVLAR ® helmet: Experiment and simulations

This paper presents the results from experiments and AUTODYN-3D ® simulations on the ballistic impact of a KEVLAR ® helmet. In the experiment, spherical projectile (∼11.9 g), launched from a light gas gun, strikes the helmet with an impact velocity of 205 m/s. The interaction of the projectile with the KEVLAR ® helmet is captured using high-speed photography. This helmet-projectile interaction is compared with that obtained from the AUTODYN-3D ® simulation. Post-test damage photos from the experiments are also compared with those from the simulations. The response of the helmet from the simulations is consistent with those from the experiments. Also included in this paper are AUTODYN-3D ® simulations on two ballistics test standards for KEVLAR ® helmets. They are namely the NIJ-STD-0106.01 Type II and the V 50 requirement of the US military specification for Personal Armor System Ground Troops (PASGT) Helmet, MIL-H-44099A. For the simulation on MIL-H-44099A, a fragment-simulating projectile (FSP) strikes the helmet with an impact velocity of 610 m/s. The simulation revealed that an impact velocity above 610 m/s is required to perforate the KEVLAR ® helmet. For the simulation on NIJ-STD-0106.01 Type II helmet, the projectile is a 9 mm full-jacketed bullet with a striking velocity of 358 m/s. Results from the simulation show that the KEVLAR ® helmet is able to defeat a 9 mm full-jacketed bullet traveling at 358 m/s.

Ballistic-performance optimization of a hybrid carbon-nanotube/E-glass reinforced poly-vinyl-ester-epoxy-matrix composite armor

The material model for a multi-walled carbon nanotube (MWCNT) reinforced poly-vinyl-ester-epoxy matrix composite material (carbon nanotube reinforced composite mats, in the following) developed in our recent work (M. Grujicic et al. submitted), has been used in the present work within a transient non-linear dynamics analysis to carry out design optimization of a hybrid polymer-matrix composite armor for the ballistic performance with respect to the impact by a fragment simulating projectile (FSP). The armor is constructed from E-glass continuous-fiber poly-vinyl-ester-epoxy matrix composite laminas interlaced with the carbon nanotube reinforced composite mats. Different designs of the hybrid armor are obtained by varying the location and the thickness of the carbon nanotube reinforced composite mats. The results obtained indicate that at a fixed thickness of the armor, both the position and the thickness of the carbon nanotube reinforced composite mats affect the ballistic performance of the armor. Specifically, it is found that the best performance of the armor is obtained when thicker carbon nanotube reinforced composite mats are placed near the front armor face, the face which is struck by the projectile. The results obtained are rationalized using an analysis of the elastic wave reflection and transmission behavior at the lamina/met and laminate/air interfaces.