Projectile Diameter Research Articles

Effects of electron beam irradiation on hypervelocity impact behavior of carbon fiber reinforced plastic plates

The effects of electron beam irradiation were examined on perforation holes and fragments from quasi-isotropic carbon fiber reinforced plastic plates (CFRP plates). CFRP plates with a total dose up to 60 MGy of electron beam irradiation were prepared for hypervelocity impact experiments. The perforation holes of CFRP plates in the hypervelocity impact experiments were decreased with electron beam irradiation when aluminum alloy spherical projectiles (2017-T4) of diameter of 1 mm struck at an impact velocity of 5 km/s. However, a slight reduction in the size of the perforation hole was observed at 2 km/s. Fragments ejected from CFRP plates were examined after collection from the impact side and rear side of the targets. The cumulative number distributions of fragment length and aspect ratio were compared among specimens with different total doses.

Application of meshless methods to modeling of pistol bullets

The paper presents an analysis of applicability of two meshless methods to the modeling of pistol bullets on the example of a 9 mm Parabellum. The studies included the following methods: SPH and SPG. The results of computer simulations were confronted with ballistic test results in terms of shape-dimensional compliance of the deformed projectile. The relative error of the projectile diameter was 15 and 17% for the SPG and SPH methods, respectively. The deformation form for the SPH method deviated from the ballistic test results, while the SPG method faithfully reproduced the shape of the deformed projectile. Keywords: mechanical engineering, impact simulation, pistol bullet, SPH, SPG

Effects of spinning on residual velocity of ogive-nosed projectile undergoing ordnance velocity impact

In the present article, finite element analysis (FEA) based simulation on the study of the impact of projectiles having ogive nose shape has been made using ANSYS explicit dynamics. The effects of spinning on the residual velocity of ogive nosed projectile undergoing ordnance velocity impact have been presented. The variations of residual velocity due to different projectile materials and target plate thickness have been evaluated when the projectile is impacted by translational and spinning velocity. The target plates and ogive nosed projectile of a given material are discretized, and a rigorous error and convergence study has been made. Subsequently, the residual velocity of the considered model is evaluated by numerical techniques based on FEA. The results with the optimized meshed model are compared with the analytical results using the penetration theory and found that the results are well compared. Parametric study of the residual velocity has been made with varied ogive nosed materials and target plate thickness when the ogive nosed projectile undergoing ordnance velocity impact. Based on the numerical results, it has been found that the ogive nose projectile having tungsten alloy material is more effective undergoing ordnance velocity impact compared to steel 4340 material. For a given target plate thickness, spinning velocity, and impact velocity, the residual velocity is about 3 percent higher for the projectile made up of tungsten alloy compared to the steel 4340. The effects of the target plate thickness on the residual velocity of the ogive nose projectile do not seem to have much significant effects. It may be due to the simple reason that the ratio of the target plate thickness to projectile diameter is remaining within the intermediate range, i.e. within 1 and 10.

Failure investigation on high velocity impact deformation of boron carbide (B4C) reinforced fiber metal laminates of titanium / glass fiber reinforced polymer

High velocity ballistic impact deformation behaviour of Titanium/GFRP Fiber Metal Laminates (FML) has been explored. Both single and multiple projectiles impact conditions were considered. Ti/GFRP FML targets were fabricated with addition of 5% and 10% weight percentage of boron carbide (B4C) particles. Mechanical properties of Ti/GFRP FML targets were determined as per ASTM standards. High velocity ballistic experiments were conducted using Armour Piercing Projectile (APP) of diameter 7.62 mm and velocity ranging between 350 and 450 m/s. Depth of penetration of the projectile into the target was measured. The deformation behaviour of Ti/GFRP targets with and without the presence of ceramic powder (B4C) was investigated. “Ductile hole growth” failure mode was observed for pure GFRP target when subjected to single projectile impact whereas “plugging” failure mode was noted for Ti/GFRP targets. The presence of B4C (5% by weight) particles has significantly improved the ballistic resistance of the Ti/GFRP FML target by offering frictional resistance to the projectile penetration. Further addition (10% by weight) of B4C has reduced the ballistic performance due to agglomeration. None of the targets showed ‘brittle cracking’ or ‘fragmentation’ failures. When compared to the published results of Aluminium (Al 1100/GFRP and Al 6061/GFRP) FMLs, Ti/GFRP FML showed lesser DoP which increases its potential application to aerospace industry.

Assessing event magnitude and target water depth for marine-target impacts: Ocean resurge deposits in the Chicxulub M0077A drill core compared

The rim wall of water formed from even a modestly-sized marine impact may be kilometers in height. Although modeling has shown that this wave swiftly breaks and relatively rapidly loses energy during outwards travel from the impact site, the portion of the rim wall that collapses inwards may generate a resurge flow with tremendous transport energy. Here we compare the deposits generated by this ocean resurge inside one of the largest marine-target craters on Earth, the 200-km wide Chicxulub crater, Yucatán Peninsula, México, with resurge deposits (breccias) in eight drill cores from five other marine-target craters in Sweden and the United States. Examination of the wide range of cored locations within the craters, and target water depths (H) relative to modeled projectile diameters (d) reveal a high correlation between location, average clast frequency (〈N〉), and d/H from which any of the four variables can be obtained. The relationship shown here may provide an important tool for diagnosing marine impact cratering processes where there is limited understanding of crater size and/or paleobathymetry.

Projectile oblique impact on granular media: penetration depth and dynamic process

The motion of a projectile oblique impacting sand bed with deep penetration was captured in experiment. Penetration depth, velocity and acceleration of the projectile were analyzed in terms of kinematic data. Horizontal and vertical penetration depths were measured under a series of impact angles, impact velocities and projectile diameters, and the collapsed curves were obtained. Specifically, an impact drag force model was assumed, which consists of an inertial term, a linear viscosity term, a linear static term, and a constant term. Then, we confirmed the terms related with velocities for both horizontal and vertical direction at the fixed depth-dependent term and obtained the linear depth-dependent static force at certain velocities. It demonstrated that viscous drag force is significant in deep penetration cases (vertical penetration depths are larger than the diameter of projectiles), but it can be neglected in shallow penetration cases. The generalized phenomenological resistance force model were proposed, which can predict the motion of projectile and resistance force exerted on the projectile by the granular medium at oblique impact cases.

A numerical investigation on low velocity impact response of polymer-based nanocomposite plates containing multiscale reinforcements

The hybridization of carbon fibers (CFs) with carbon nanotubes (CNTs) is a new way of improving the mechanical and physical performances of composite materials. The aim of this work is to evaluate the low velocity impact response of polymer-based hybrid composite plates reinforced by the chopped CFs and CNTs using finite element method (FEM). A nested micromechanical FEM considering interphase region created by the non-bonded van der Waals interactions between the CNTs and polymer is developed for predicting the mechanical properties of hybrid composites. The predictions of the proposed numerical model are compared with the results of experiment and other numerical methods. It is demonstrated that adding a small amount of CNTs into the chopped CF-reinforced polymer composites can increase the contact force and decrease the center deflection of hybrid composite plates. The influences of volume fractions of CF and CNT, thickness and elastic modulus of interphase region, diameter and initial velocity of projectile, dimensions and boundary conditions of plate on the dynamic response of hybrid composite structures are discussed.

Analytical investigation on deformation of PELE projectile and opening damage to concrete target

A penetrator with enhanced lateral effects (PELE), which is a particular thin-walled structure, is characterized by a low-density filling material surrounded by a high-density jacket material. When the PELE projectile penetrates a concrete target, the target is destroyed by its thin-walled jacket to a large opening. An analytical model describing deformation mode of the jacket during the penetration process is presented. Due to opening diameter of target plate is larger than projectile diameter under condition of a thin concrete target, a relationship between opening diameter of target plate and projectile diameter, based on existing experimental results of ridge projectile penetrating thin concrete target, is formulated. The relationship combined with the analytical model is used to predict opening diameter of concrete target. A quantitative comparison between the jacket deformation mode obtained from analytical results and experimental results is made to validate the accuracy of the analytical model proposed. As a result, the analytical results exhibit good correlation with experimental observations in terms of the opening diameter of target plate and the deformation mode of projectile jacket. In addition, the influence mechanism of three factors (jacket strength, impact velocity, and target thickness) on the opening diameter is analyzed. The jacket strength affects the opening diameter by changing the plastic limit bending moment of the jacket. Even though the impact velocity affects the opening diameter by changing the interaction force between the jacket and the target, it is equivalent to indirectly changing the jacket strength. However, the target thickness affects the opening diameter by changing the penetration time.

Estimation of the energy of detonation initiation in a hydrogen-oxygen mixture by a high-velocity projectile

The paper presents the results of a numerical study of the initiation of oblique detonation modes by a high velocity projectile moving in an argon-diluted hydrogen-oxygen mixture. The simulation of oblique detonation wave modes showed that calculated and experimental flow patterns agree. The calculated detonation cell size agreed with experimental data. For the initial pressure Pst = 121 kPa and Pst = 141 a series of calculations were carried out for a different projectile diameters. The detonation initiation energy was estimated, and the results were compared with theoretical models

Dual targets identification method for circular array photoelectric detection system

Aiming at the problem of vertical target coordinate measurement when two projectors were touching the target at the same time, a two-target identification method of circular array photoelectric detection system was proposed. A circular detection array was formed by using photodetectors, and three fan-shaped linear lasers with all luminescence angles of 60° were uniformly arranged on circular detection array to form a detection light curtain. When the two projectiles passed through detection light screen at the same time, six projectiles would be generated on the circular detection array. The central position of the six projectiles would be identified through the signal processing circuit. Finally, the target coordinates of two projectiles would be calculated by system projectile hitting coordinate measurement formula. On the basis of the theory of system measurement, the coordinate measurement model of the projectile hitting target was established, and the coordinate measurement error was analyzed and simulated. The simulation results show that the maximum standard deviation of the X coordinate measurement error is 2.7 mm and the maximum standard deviation of the Y coordinate measurement error is 0.6 mm when the target surface is 1 m×1 m. The experimental results show that the standard deviation of X coordinate measurement error is 2.22 mm and Y coordinate measurement error is 1.98 mm when the target surface is 1 m×1 m. Therefore, the system proposed can effectively measure the target coordinates of double projectors with a projectile diameter of 4.5 mm or above.

Impact response of composite laminates based on epoxy and glass fibre

Initially, the behavior of the glass fibre reinforced epoxy (GF/Epoxy) composites under low velocity impact loading was investigated experimentally. The experimental data were then compared with the corresponding numerical results to validate a number of finite element models. Here, simulations were developed, using ABAQUS/Explicit software, to predict the response of these composite laminates under impact loading. The composite plates were modelled using Hashin failure criteria. The result showed that the developed FE models were correlated well with data obtained experimentally. The influence of parameters, i.e. impact energy, indentor diameter and impact velocity on the behavior of GF/Epoxy plates were then investigated numerically. The results have shown that the values of peak force and absorbed energy increase with the impact energy. Increasing the projectile diameter leads to increase the values of peak force, maximum displacement, duration time and perforation energy. It has also shown that the peak forces show no dependency on the impact velocity and the values of absorbed energy values show a noticed reduction as the impact velocity increases.

Parametric analysis of energy absorption capacity of thin aluminum plates impacted by rigid spherical projectiles

A finite element axisymmetric model has been developed to study the energy absorption capacity of thin Aluminum plates (0.2–20 mm thickness) in terms of the ballistic limit. The Johnson-Cook material model was used to describe the mechanical behavior of the 2024-T3 Aluminum. Numerical results were validated by comparison with experimental tests carried on similar plates using a gas gun with two high-speed cameras to measure impact velocities in the order of 100 m/s to 200 m/s. Plastic work (60%) and friction (10%) dissipate the impact energy, while the remaining energy is absorbed in the plate as elastic and kinetic energy. A parametric analysis was performed for projectile radius and plate thickness to study their influence on the perforation energy. Ballistic curves and energy balances were used to obtain the ballistic limit from numerical simulations. Ballistic limit shows a non-linear relation with plate thickness to projectile diameter ratio, while the mean perforation stress shows a linear relation with plate thickness to projectile diameter ratio. From numerical results, a semi-empirical relation is suggested to estimate mean perforation stress and consequently obtain the ballistic limit for a given plate-projectile configuration.

Impact resistance, flexural and tensile properties of amorphous metallic fiber-reinforced cementitious composites according to fiber length

In this study, we examined the effects of the lengths of amorphous metallic fibers on the flexural and tensile properties and the impact resistance of cementitious composites. Cementitious composites were fabricated following the addition of 1.0 or 2.0 vol% of amorphous metallic fibers (lengths of 15 or 30 mm). After the static flexural and tensile tests, high-velocity impact tests were conducted (impact velocities of 170 and 300 m/s) with a spherical projectile (diameter of 25 mm). Amorphous metallic fibers with lengths of 30 mm inhibited the propagation of fractures based on the absorption and distribution of stress until they fractured without being pulled out, which significantly improved the flexural and tensile properties of cementitious composites; this resulted in better inhibition of scabbing in fibers with lengths of 30 mm compared to fibers with lengths of 15 mm. Meanwhile, the amorphous metallic fibers with lengths of 15 mm were pulled out from the matrix owing to their relatively smaller bonding areas compared with the 30 mm fibers. This caused smaller improvements in flexural and tensile properties as well as impact resistance compared with the 30 mm fibers.

Energy absorption characteristic of sandwich shell structure against conical and hemispherical nose projectile

Present study addresses the ballistic performance and energy absorption behaviour of the hemispherical sandwich shell structure having hexagonal honeycomb core against conical and hemispherical nosed projectile. The sandwich shell had two face sheet of radius 100 and 80 mm for outer and inner shells respectively, whereas for the honeycomb core cell thickness 0.05 mm, cell size 3.2 mm and core height 20 mm were considered. Al −1100 H12 was used for both the shell, whereas for the honeycomb core Al − 3003 H18 was employed. The projectiles of diameter 19 mm, length 50.8 mm and mass 52.5 g were hit on the crown of the sandwich shell. The experiments were performed using the pneumatic gun, whereas the ABAQUS/explicit solver was used for numerical simulations. The response of the sandwich shell was studied in terms of ballistic limit, residual velocity, failure modes and energy absorption by the sandwich structure. Numerical study further extended to perform parametric studies to investigate the effect of the face sheet thickness, core cell size and cell wall thickness on the response of the sandwich shell against conical and hemispherical projectile impact. The conical projectile required less energy for perforation as compared to the hemispherical nosed projectile.

Experimental Simulations of Hypervelocity Impact Penetration of Asteroids Into the Terrestrial Ocean and Benthic Cratering

AbstractSeafloor cratering is an important process that records the impact history of the Earth, affects projectile survivability, and determines the mass of ejecta from benthic rock that is transported to the atmosphere. We report experimental hypervelocity impacts of chondrite and other projectiles (olivine, stainless‐steel, polycarbonate) on a water‐covered iron target to derive a scaling relationship for benthic cratering. In situ observations of 5‐km/s impacts quantify the deceleration of projectiles in the water column by shock‐induced deformation and fragmentation. The minimum water depths at which multiple craters appeared on the benthic target were two and four times the projectile diameter for chondrite and stainless steel, respectively. Based on the observed deceleration of projectiles in water, the cratering efficiency of a benthic target for a given impact velocity is predicted to follow an exponential decay law in terms of water depth normalized by projectile diameter (H/d), given by πv ∝ exp(−(H/d)/κ), when a projectile of original mass collides with the target. Comparing the volume of the largest crater in the experiments and that derived from the scaling relation, mass ratios of the largest projectile fragment to original projectile in the 5‐km/s impact were calculated to be 0.1–0.3 (H/d = 2–6) and 1.0 ± 0.3 (H/d = 5.5) for chondrite and stainless steel, respectively. Using the scaling relationship, the volume of the transient crater on oceanic crust by an asteroid impact is estimated to be smaller than previously predicted by hydrocode simulation when the asteroid fragmentation in the water column controls seafloor cratering.

Assessment of confinement’s influence on a concrete target’s ability to approximate semi-infinite perforation performance

The ability to accurately evaluate impact penetration resistance of a structural element in an experimental setting often requires the experimental impact specimen configuration to be as close as possible to a structural element in a fielded protective design scheme. This includes the target’s capability to estimate the semi-infinite response of a structural element such as a wall where inertial confinement is provided by undamaged material surrounding the area damaged by impact. Artificially simulating this confinement in an experimental target can take several forms, including use of a circumferential steel ring as a confining medium. Experimental data gathered from impact tests were utilized to create a representative numerical simulation of a confined target design. This simulation evaluated artificial and inertial confinement on concrete perforation by varying target to projectile diameters with and without artificial confinement. Perforation performance was found to be unaffected by confinement type when the target diameter to projectile diameter ratio was 16. Semi-infinite surface approximation was found to occur when the target diameter to projectile diameter ratio was 64 despite the confinement type at higher impact velocities; however, this ratio could be reduced while maintaining semi-infinite performance for lower velocity impacts.

Simulation Study of Area Effect at Shock Initiation of Shield Explosive

To get the rule of area effect changing with diameter, velocity and height of projectile and thickness and material of target, the process of projectile perpendicular impacting target was simulated by AUTODYN and the pressure and velocity of observing points that set at the opposite side of hitting were analysed. And then simulation value and calculation value of experience formula in existence were compared. The result shows that experience formula is feasible, which provides a new method for the study of shield explosive shock initiation.

Study on large area laser reflective precision target

In view of the increasing demand for the effective target surface of testing equipment in the modern high-tech weapon vertical target density parameter testing, a large area laser reflective CCD precision target is designed in this paper. The measuring principle of laser reflective CCD precision target is studied, and the measuring model is established. Using laser light source, reflecting device, receiving device and special calibration technology and software, the principle experiment of precision target system with an effective target surface of 7 m × 4 m is completed. According to the images collected by CCD camera, the laws of simulated projectiles with different projectile diameters passing through targets at different positions are analyzed. Experiments prove that the sensitivity of the overall design meets the requirements of large-area testing, which provides a reference for solving the problem that CCD vertical targets are difficult to realize large-area coordinate testing at present.

Comparative study of impact response of GFRP and CFRP composite plates against blunt nosed projectile

Three-dimensional finite element simulations were carried out to explore the perforation behavior of the unidirectional GFRP and CFRP plates against the blunt nosed projectile within sub-ordnance velocity regime. The ballistic performance of both the composite plates of 140 mm × 140 mm × 3.3 mm comprising of four layers (each 0.825 mm thick) having unidirectional fibres was evaluated. The mass, diameter and length of projectile was kept constant as 52.5 gm, 19 mm and 50.8 mm respectively. To carry out the numerical simulations, commercial finite element code Ansys/Ls-Dyna was employed. To simulate the high strain rate behavior of GFRP composite material, enhanced composite damage material model was considered whereas for CFRP, Composite failure material model offered better results. The performances of both the plates were evaluated based on residual velocity, ballistic limit and energy absorption. The numerical results were found to be close enough with the experimental results available in the literature. It was found that GFRP plates underperformed than that of CFRP plates.

Development of Energy-Based Impact Formula—Part I: Penetration Depth

Predicting the damage to a concrete panel under impact loading is difficult due to the complexity of the impact mechanism of concrete. Based on the experimental results obtained by various researchers, the energies involved in the impact mechanism are classified into seven categories: Kinetic energy, deformed energy of a projectile, elastic penetration resistance energy of the panel, overall deformed energy of the panel, spalling-resistant energy, tunneling-resistant energy, and scabbing-resistant energy. Using these impact mechanisms and the energy conservation law, a new energy-based penetration depth formula is proposed to predict the penetration depth. This is validated using 402 impact test results, which include those with high-strength concrete, ultra-high-performance concrete (UHPC), or steel fiber-reinforced concrete, those under very high-velocity impact, and those with a very low ratio of target panel thickness to projectile diameter. It is found that the new impact formula predicts the penetration depth quite well.