Conical-nosed Projectiles Research Articles

Perforation Characteristics of Metal Target plate subjected to PELE

Abstract The perforation tests of 45 # steel target plate and 2A12 aluminium alloy target plate by PELE (the Penetrator with Lateral Efficiency) were carried out in this paper to study the perforation failure characteristics of metal target plate. The macroscopic morphology of perforation on the target plate and the plug was observed, and the perforation wall was cut and polished to observe the distribution and trend of the cracks in the perforation wall by scanning electron microscopy (SEM) and metallographic microscopy. The magnitude and direction of the force produced by PELE on the target during penetration were calculated by numerical simulation. The experimental and numerical results show that, the perforation failure of metal target plate by PELE is different from the ductile perforation by conical-nosed projectile and the punching failure by flat-nosed projectile. The longitudinal cross section of the perforation is funnel-shaped and the shape of the plug is like a circular truncated cone. In the process of penetrating the target plate, the expansion of the filling causes the jacket to exert a force with a certain angle to the direction of projectile movement, which is the main reason for the funnel-shaped perforation and the circular truncated cone shaped plug.

Critical parameters for the penetration depth in cement-based materials subjected to small caliber non-deformable projectile impact

It has been recognized that the compressive strength alone cannot accurately describe the penetration depth in cement-based materials subjected to high-velocity non-deformable projectile impact. This paper provides an in-depth investigation with the aim to determine critical effective properties for the penetration depth in cement-based materials across a wide range of compositions and material properties against small caliber non-deformable projectile impact. Compressive strength, elastic modulus, effective hardness index, density, splitting tensile strength, and flexural toughness are considered in the investigation. Cement-based materials investigated include cement pastes, mortars, concretes, ultra-high performance concretes (UHPCs), and engineered cementitious composites (ECCs) with 28-day compressive strengths from 34.2 to 220.2 MPa and elastic moduli from 17.1 to 80.4 GPa. The penetration resistance was evaluated using 300 × 170 × 150 mm3 specimens subjected to the impact of conical-nosed projectiles with a diameter of 8.0 mm and a mass of about 7.8 g at velocities of about 400.0 m/s. Within the range of effective properties considered, the effective hardness index and elastic modulus have the most influence on the penetration depth, as these two parameters characterize the overall contributions of constituent components (e.g. aggregate and matrix). It is also found that UHPCs do not exhibit better impact resistance in terms of penetration depth, in comparison to high performance concretes (HPCs) with coarse aggregate.

Influence of metal layer distribution on the projectiles impact response of glass fiber reinforced aluminum laminates

The effect of the distribution of aluminum layer through the thickness of fiber metal laminates (FMLs) on their projectiles impact response is studied using high speed 3D digital image correlation technique (DIC). The FMLs consisting of aluminum alloy 2024-T3 sheets of thicknesses 0.3 mm, 0.4 mm, and 0.6 mm and glass fiber reinforced epoxy layers (two layers with each of 0° and 90°) were prepared by the hand layup process followed by vacuum bagging. The metallic layers are placed at different locations through the thickness of four different layups while keeping the total metal layer thickness constant. The hemispherical and conical nose projectiles of the same mass are impacted normal to the FMLs plate using nitrogen gas gun. The performance of the FMLs is evaluated using different parameters such as the deformation history, residual deformation and also the surface and internal damages. FML 4/3–0.3 in which the two adjacent composite layers with different fiber orientations separating by an aluminum layer exhibited the highest deformation with hemispherical projectile impact for the same impact energy level. The deformation was found to be lower and nearly same for the other three FMLs. This observation is also noticed in the case of drop weight impact (low velocity impact). The FML 2/1–0.6 in which the composite layers were stacked together exhibited a comparatively higher lateral spread of delamination and interlayer opening with hemispherical projectile impact when compared to FML 4/3–0.3, indicating that the lateral spread of damage within the FML can be decreased by distributing the aluminum layers in the FML. This is also observed in the case of drop weight impact.

Experimental Study of High-Velocity Projectile Impact Welding

The purpose of this study is to investigate the effect of various parameters on the welding process with high-velocity projectiles. For carrying out Impact Spot Welding tests, a single stage compressed gas gun impact test facility was used to launch flat- and conical-nosed projectiles within the velocity range from 100 to 150 m/s and performed. Different types of materials such as steel, copper, brass, and aluminum alloy were used. In the present experimental study, the steel plate with a thickness of 4 mm was considered as a back layer and the other plates made of copper, brass, and aluminum alloy were considered as front layers. Different gaps of 0.1, 0.2, and 0.5 mm were considered between the layers. The shape of the welded interface was studied by Scanning Electron Microscopy (SEM). The depth of penetration in the specimen and the kinetic energy of the projectiles were calculated. The experimental results showed that a complete bonding has occurred in the collision zone, especially in the central areas.

Conical nosed projectile perforation of polyethylene reinforced cross-ply laminates: Effect of fiber lateral displacement

Fiber lateral displacement refers to fibers being pushed aside transversely rather than being strained to tensile failure; a phenomenon that lowers the ballistic resistance of fabric composites. In this study, the effect of lateral displacement was examined for cross-ply laminates. Ballistic impact tests were performed on ultra-high molecular weight polyethylene (UHMWPE) cross-ply laminates of different thicknesses with a 90° or 60° conical-nosed projectile. Two types of laminates, HB26 and HB50 that contain the same fibers but different matrices, were tested. The number of fibers undergoing lateral displacement in each ply of perforated laminates was quantitatively determined and found to generally decrease from the impact surface to the rear surface of laminates. Following perforation by a projectile with 90° nose angle, fewer fibers lying in the projectile path failed in the weaker matrix HB50 laminate than in the stronger matrix HB26 laminate. On the other hand, the HB50 laminate exhibited a larger ballistic limit velocity than the HB26 laminate. For a projectile with 60° nose angle, more fibers failed during perforation of HB26 laminates but the ballistic limit was smaller than that of the 90° projectile. These contrary results demonstrate that for fibrous cross-ply laminates, the kinetic energy dissipated during projectile penetration is not proportional to the number of failed fibers and the ballistic resistance cannot be evaluated solely by the magnitude of lateral displacement. Localized direct tension along with membrane stretching, makes important contributions to fiber failure. The longer nose of the 60° projectile resulted in more extensive fiber breakage through this localized mechanism and thereby resulted in a smaller ballistic resistance than the 90° projectile.

High velocity impact response of carbon nanotubes-reinforced composite sandwich panels

Effect of adding carboxyl-modified multi-walled carbon nanotubes (COOH-MWCNTs) on the high velocity impact of sandwich panels with plywood core and two different facesheets, E-glass/epoxy and E-glass/ nylon 6, was investigated in this study. Facesheets were prepared with and without COOH-MWCNTs. Three different weight percentages of 0.3, 0.5, and 1 wt% of COOH-MWCNTs were used to reinforce epoxy and nylon 6 polymers. The sandwich panels’ estimated ballistic limit ( Vbl) and impact energy absorbed ( Eab) were determined by subjecting them to impact velocities in their ballistic limit range and above by conical nose projectile. It was found that the sandwich panels containing E-glass/ epoxy facesheets exhibited more energy absorption than those containing E-glass/nylon 6 facesheets. Moreover, the high velocity impact response of sandwich panels improved with the increase of COOH-MWCNT content. Besides, the damage area for different types of materials studied is presented, and it is observed that at a given impact velocity, the damage size on the rear facesheet of target around the point of impact decreases on addition of COOH-MWCNTs.

Ballistic impact behaviors of aluminum alloy sandwich panels with honeycomb cores: An experimental study

To study the protection property of aluminum alloy sandwich panels with honeycomb cores under the attack of bullets or debris, quasi-static perforation, and ballistic impact tests were conducted, in which the thicknesses of the face sheet and core were 0.5–2.0 and 12.7 mm, respectively, while projectiles with diameter 7.5 mm and impact velocity 50–220 m/s were employed. Based on the experiments, the influences of impact velocity, face sheet thickness, core density as well as the nose shape of the projectiles were investigated. The results showed that in the impact tests, the sandwich panels dissipated much more energy than those in quasi-static perforation tests, and the energy absorption and ballistic limit of the sandwich panels increased with the increase of impact velocity. The influence of face sheet thickness was more remarkable than the core density, which was due to the relative density of honeycomb is too small. Although the increase of core density could induce the increase of energy absorption, this effect is more effective for thinner face sheet. Moreover, under the same impact velocity about 200 m/s and face sheet thickness 1.0 mm, the ballistic limit for conical-nosed projectile is highest, while it is lowest for flat-nosed projectile.

Ballistic analysis of fiber metal laminates impacted by flat and conical impactors

In the present study, the ballistic limit of GLARE is investigated experimentally and numerically. Ballistic tests were conducted using one stage gas gun. In the experimental part, the ballistic limit of GLARE was determined. The effect of aluminum lamina thickness and the nose shape of projectile on the ballistic limit were also investigated. The experimental results show that the ballistic limit of GLARE impacted by a flat projectile is higher than in the case of a conical nose projectile, and that by decreasing the aluminum laminate thickness from 0.5mm to 0.3mm, the Specific Perforation Energy (SPE) is increased. In the numerical section, the penetration process was simulated using LS–DYNA software. The validation of the finite element model was done by experimental results. The effects of various involved parameters such as laminate thickness, mass and radii of impactor were also investigated. The numerical results prove the efficiency of GLARE over bare aluminum laminate with equal thickness, due to the lower deflection and higher SPE. Furthermore, the less the mass of the impactor or the greater the diameter of the flat projectile, the greater the ballistic limit of GLARE. Reasonable agreement is concluded between the numerical and experimental results.

Improvement in impact resistance performance of glass/epoxy composite through carbon nanotubes and silica nanoparticles

Experimental studies are presented on the high velocity impact behavior of nanomaterial dispersed resin viz laminates made using E-glass fabric with epoxy resin. The nanomaterials used are silica nanoparticles and carboxyl functionalized multi-walled carbon nanotube (COOH-MWCNT) for polymer matrix composites. The composites' ballistic limit ( Vbl) and impact energy absorbed ( Eab) were determined by subjecting the material to impact loading of 85, 100, and 112 m/s by conical nose projectile. It was found that the high velocity impact response of epoxy composites improved when a nanomaterial was used as reinforcement. COOH-MWCNTs reinforced composites exhibited better energy absorption than silica nanoparticles composites. Moreover, the damage pattern for different types of materials studied is presented. It is observed that the damage size on the target around the point of impact decreases on addition of nanoparticles especially COOH-MWCNTs. Quantitative data are presented for high velocity impact behavior of the seven types of specimens studied.

Petalling of a thin metal plate struck by a conical-nosed projectile

A theoretical study is presented herein on the petalling of a fully-clamped thin metal plate struck by a rigid conical-nosed projectile. It is assumed that the energy absorbed in the petalling process consists of two parts, one part is due to the local deformation during the hole formation and the other is from the global response such as bending and membrane stretching. Various energy absorbing mechanisms are delineated and an approximate equation for the ballistic limit is obtained. It transpires that the predictions from the present model are in good agreement with test data available when the sensitivity of the strain rate of the material is taken into account.

Modelling of projectile penetration using transparent soils

This paper presents a novel physical modelling method to study projectile penetration problems. The method employs a recently developed transparent synthetic soil made of oil-saturated fused quartz, which represents the macroscopic behaviour of silica sand. Digital image correlation (DIC, also known as particle image velocimetry (PIV)) techniques were employed to quantify the response of granular soils to high-speed penetration, non-intrusively. A conical nose projectile made of steel was accelerated into a transparent soil target at an impact velocity of 13.6 m/s. Visualisation of the soil deformation was made possible by means of a novel seeded plane within the transparent soil model. The complete penetration event was recorded using a high-speed digital camera. The captured images were analysed using DIC, and further analysis of displacement trajectories and strains were also carried out using in-house algorithms.

Ballistic Resistance of AA5083-H116 Aluminum Plates against Conical-Nose Steel Projectiles Impact

This paper evaluates the ballistic resistance of AA5083-H116 aluminum plates against conical-nose steel projectiles impact using Arbitrary Lagrange-Euler (ALE) finite element methods. The target material was modeled with the Johnson-Cook constitutive relation using 2D axisymmetric elements with ALE rezoning. Impact vs. residual velocity curves were constructed and the ballistic limit velocity was determined. It is found that the ballistic limits increase almost linearly with increasing plate thicknesses. The numerical results have been compared to available experimental results, and good agreement was in general obtained. The study shows that the ALE formulation works well for large deformation in ballistic penetration.

Reliability of RC shielded steel plates against the impact of sharp nose projectiles

Reinforced Concrete (RC) shielded steel plates are extensively employed in double wall containment structures. In such structures, RC shield surrounds the inner steel shell/plate, and inner steel shell/plate acts as a barrier against the release of radiations. Although a substantial research is available on impact studies of concrete, reinforced concrete and steel plates, the studies on RC-shielded steel plates are not widely available. Also how the uncertainties involved in the design parameters influence the reliability or safety of RC shielded steel plates is not very well known. In the present study, a simple experiment was designed to simulate a double-wall containment (i) to study the response of RC shielded steel plates against the impact of single (ogive) and double nose (bi-conical) shaped projectiles, and (ii) quantitatively evaluate how much safe the inner wall (steel plate) is under the impact of these projectiles. To achieve the above objectives, the study was carried out in two parts. In the first part, experiments were conducted by studying the impact resistance of RC shielded steel plates of 600 × 600 × 5 mm thickness against the impact of non-deforming projectiles of ogive and bi-conical nose shapes. The steel plate was placed at a clear distance of 75 mm from 60 mm thick RC slab. The specimens were tested at varying projectile impact velocities. Investigations were carried out to measure damage level in steel plate in terms of its deformation, fracture and perforation. In the second part, reliability analysis of all the tested concrete shielded steel plates was carried out using Monte Carlo Simulation technique for a range of impact velocities. The results of the reliability analysis were then used to relate the probability of failure with different scenarios of the failure of the specimens. The effect of RC shield thickness and steel plate thickness on the reliability of RC shielded steel plate against the impact of bi-conical and ogive nose projectiles were also studied on parametric basis. In order to use the available formulation on conical nose shape projectiles, the bi-conical nose was replaced by an equivalent conical nose for which a simple formula was derived. In order to validate this simplified attempt to suggest an equivalent conical nose, one of the tests with bi-conical nose projectile was repeated with the equivalent conical nose projectile. At a given striking velocity, the equivalent conical nose projectile produces a similar damage pattern and the same damage level in the RC shielded steel plate, as that of bi-conical nose projectile at the same impact velocity.

Numerical Simulations of the Perforation in Metal Plates with Different Conical-Nosed Projectiles

Numerical simulations with ABAQUS/Explicit into which Johnson-Cook constitutive relation is incorporated, are performed to study the perforation of Weldox 460E steel plates struck normally by conical-nosed projectiles with different cone angles. Different failure modes and perforation process are obtained. Numerical results are found to be in good agreement with available test data. It is revealed that with increasing cone angle, the failure modes of metal plates become to shear plugging from ductile hole enlargement, and the ballistic limits decrease with that. The conclusions are helpful for the design of protective structures.

Effect of Configuration and Target Span on the Ballistic Resistance

Numerical simulations were carried out wherein 20 mm diameter conical nosed projectiles were hit on Weldox 460 E steel targets of varying span and configuration in order to study the influence on the ballistic limit. The effect of configuration was studied with 12 mm thick monolithic and double layered in contact target (2 × 6 mm) of 500 mm span diameter whereas the influence of target span was investigated by varying the diameter of 12 mm thick monolithic target as 100, 200, 300, 400 and 500 mm. The monolithic targets were found to offer higher ballistic limit than that of the layered in-contact target. The ballistic limit was also found to be affected by the variation in span diameter; its value was found to be 199.5, 213.9, 220.7, 226.08 and 230 m/s for 100, 200, 300, 400 and 500 mm span diameter respectively.

Cylindrical Cavity Expansion Penetration Model for Concrete Targets with Shear Dilatancy

A dynamic cylindrical cavity expansion model is presented herein to predict the penetration of concrete targets subjected to impact by conical-nosed projectiles at normal incidence. It is assumed that cavity expansion in an infinite concrete target produces three response regions: elastic, cracked, and comminuted regions. To allow for compressibility or dilatancy of the material in the comminuted region, a dilatant-kinematic relation is introduced in this paper. A procedure is first given to calculate the radial stress at the cavity surface, and then, a numerical method is used to calculate the results of penetration with friction being taken into account. It transpires that the present model predictions are in reasonable agreement with the available experimental data.

Penetrating Resistance of the Laminated Composite with Stepwise Graded Foam

The present study focuses on the penetrating resistance of the laminated composite with stepwise graded foam target struck normally by conical-nosed projectiles. The dynamic cavity expansion theory is applied to formulate analytical model. Experimental results verify that this model on account of rigid-perfectly plastic-locking model is suitable for analyzing penetration depth of the projectile into a cellular target. The difference types of foam configurations, with identical areal density, were arranged according to the density of the respective foam. The penetrating process can be divided into 7 stages. Penetrating depth; the effect of mass density and the change of graded/layered core structures of the difference configurations are analyzed. It is found that composite target have a higher penetrating resistance than the monolithic foam material target of equal mass. The analytical results show great potential to reasonable structures for absorbing the dynamics energy and improving the overall penetrating resistance.

Penetration of Cone-Nose Projectile to the Laminated Composite Aluminum Alloy Foam Target

A theoretical study is presented herein on the penetration of the laminated composite aluminum alloy foam target struck normally by conical-nosed projectiles. Two layers were arranged according to the density of the respective foam; configuration 1 consisted of 10mm/semi-infinite continuous foams and configuration 2 consisted of 20mm/ semi-infinite continuous foams. The dynamic cavity expansion theory is applied to formulate analytical model. The penetrating process can be divided into 6 stages. The resistance equations during every stage are derived. Penetrating depth of projectile are analyzed. The effect of initial velocity, mass density of foam material and the thickness of the upper layered foam on the penetration resistance are investigated. It is found that composite target have a higher penetrating resistance than the monolithic foam material target of equal mass. The analytical results show that configuration 1 outperformed configuration 2 in regards to their penetrating resistance. The thickness of the upper layered foam within 5-20mm has significant influence on penetrating depth. The energy absorption capacity of the composite target material is evaluated.

Effect of projectile nose shape on the ballistic resistance of ductile targets

Abstract Three-dimensional numerical simulations were carried out to study the ballistic resistance of ductile targets subjected to normal impact by the projectiles. 12 mm thick Weldox 460 E steel targets were impacted by 20 mm diameter conical nosed projectiles and 1 mm thick 1100-H12 aluminum targets were impacted by 19 mm diameter ogive nosed projectiles. The internal nose angle of conical projectile was varied (33.4°–180°) and found to have significant effect on the ballistic limit of 12 mm thick Weldox 460 E steel target. Similarly, the caliber radius head (CRH) of ogive nosed projectile was varied (0–2.5) and found to have significant effect on the ballistic limit of 1 mm thick 1100-H12 aluminum target. The ballistic limit of 12 mm thick Weldox 460 E steel target increased almost linearly with the decrease in the projectile nose angle. While the ballistic limit of 1 mm thick 1100-H12 aluminum target increased as the CRH increased from 0 to 0.5 and with further increase in CRH to 1.0, 1.5, 2.0 and 2.5 its values were found to drop quite significantly. ABAQUS/Explicit finite element code was used to carry out the numerical simulations.

3D numerical simulations of sharp nosed projectile impact on ductile targets

Three-dimensional FE model is presented for perforation under normal and oblique impact of sharp nosed projectiles on single and layered ductile targets. Numerical simulations have been carried out to study the behavior of Weldox 460 E steel and 1100-H12 aluminum targets impacted by conical and ogive nosed steel projectiles respectively. Weldox 460 E steel targets of 12 mm thickness in single and double layered combination (2 × 6 mm) and 1100-H12 aluminum targets of 1 mm thickness in single and double layered combination (2 × 0.5 mm) impacted at 0°, 15° and 30° obliquity were considered for simulations. The results of monolithic and layered targets were compared for each angle of impact. Monolithic targets were found to have higher ballistic resistance than that of the layered in-contact targets of equivalent thickness. Failure of both the targets occurred through ductile hole enlargement. However, ogive nosed projectile failed 1 mm thick aluminum target through petal formation and conical nosed projectile failed 12 mm thick steel target through a circular or elliptical hole enclosed by a bulge at rear surface. The explicit algorithm of ABAQUS finite element code was used to carry out the numerical simulations. Various parameters which play critical role in numerical simulation such as element size and its aspect ratio have been studied.