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There is no native support for the modeling of woven fabric composites within Abaqus. A new approach has been implemented within Abaqus, which is shown to be robust and capable of modeling woven composites across a range of loading conditions. This approach predicted the bending modulus and displacement at failure of woven carbon-fiber composites under three-point bending within the standard deviation of experimental results. Under high-velocity impact loading, the critical perforation velocity of woven aramid panels was predicted to within 3% of the experimental results, while the back face deformation to within the experimental error. [ABSTRACT FROM AUTHOR]

This study presents STF/Fabric composite configurations by impregnating single‐phase shear thickening fluids (S‐STF) and multi‐phase shear thickening fluids (M‐STF) into aramid fabrics. S‐STFs were first prepared at different concentrations by weight (25%, 40%, 55%, and 65%). In addition, M‐STFs were produced by adding silicon carbide (SiC) additive to S‐STFs. As a result of the impregnation of the produced STFs on Aramid fabrics, 30‐layer composite samples were prepared. To determine the ballistic performance of the produced samples, tests were carried out with a single‐stage gas gun system. The shots were performed at an average velocity of 670 m/s. Ballistic tests show that STF‐impregnated fabric samples have better ballistic performance compared to fabric without STF. The STF65/Aramid sample is notable for a 238% increase in energy absorption. In addition, the STF40SiC10/Aramid composite sample produced with M‐STF was found to absorb 18.7% more energy compared to the STF40/Aramid sample. It has been confirmed that keeping the weight ratio of the additive at an optimum level will contribute to ballistic performance. These results contributed to determining the optimum concentration amount for STF/Aramid composites at high speed. Highlights: S‐STF and SiC additive M‐STFs were produced.STFs were impregnated into 30‐layer Aramid fabrics.Ballistics tests were performed on S‐STF/Aramid and M‐STF/Aramid composite samples with a single‐stage gas gun system.The effects of S‐STF and M‐STF on ballistic performance were investigated.The addition of STF enhanced ballistic performance by increasing energy absorption. [ABSTRACT FROM AUTHOR]

The two-dimensional triaxially braided composites are prepared by the resin transfer molding process. The mechanical response of two-dimensional triaxially braided composite under high and low velocity impact are investigated through the air gun system and drop hammer impact test system with different energies. The delamination damage under different impact energies are obtained by ultrasonic C-scan to analyze the damaged failure characteristics. The behaviors of compression after impact are studied in combination with digital image correlation. It is shown that the damaged area of the two-dimensional triaxially braided composite increases proportionally with the low velocity impact energy， but the energy absorption increases almost 2 times. Severe damage occurs and extends along the axial fiber under impact with an energy of 6.7 J/mm， leading to a significant reduction in its residual strength. The ballistic limit velocity of the two-dimensional triaxial braided composite is about 138.5 m/s. The projectile is embedded in the plate. When the impact velocity is greater than the ballistic limit velocity， a rectangular hole is formed on the impact surface， and a tearing fracture can be observed on the back surface. The damage area decreases with the increase of the incident velocity.

Abstract Functionally graded materials are a class of composite materials that finds widespread use in aerospace, defense and automobile applications due to their tailored material properties for the specific need. In the present research, impact dynamics and the damage behavior of functionally graded plasma spray coating (FGPS) on an aluminium 6061-T6 substrate under high velocity impact at various temperatures were studied. The FGPS coating consists of four layers having various proportions of Al and SiC (50/50, 40/60, 30/70 and 20/80 weight percentages) and the coating thickness was measured to be 232.8 μm. Experiments were carried out at 260 J of impact energy on the FGPS samples at various temperatures using a single-stage gas gun along with the thermal setup. A finite element model was developed with the Johnson-Cook damage model and piecewise linear plasticity material model, along with suitable contact algorithms. Impact simulations at various temperatures reveal that the stiffness reduction at higher temperatures results in decreased peak contact force, decreased rebound velocity and increased central deflection. The molten splats observed through the micro-morphological study have spread several micrometers, which indicates excellent bonding between the particles and the porosity content was found to be 1.35%. The research findings on the impact dynamics and damage behavior of FGPS can significantly improve material design for a wide range of applications.

As a new type of protective structure, it is of great practical significance to study the high velocity impact behavior of fiber metal laminates(FMLs) under preload. A nonlinear finite element model is established based on ABAQUS/Explicit software platform to study the penetration process and damage characteristics of preloaded FMLs under high velocity impact compression of hemispherical bullet. The strain rate effect of composite materials is considered and the in-plane damage of composite layer is predicted based on 3D Hashin criteria. Johnson-cook model is applied to simulate the high velocity impact mechanical response of metal layer. Cohesive elements are introduced to simulate the delamination phenomena of metal/composite and composite laminates interfaces. The finite element model is validated with existing experimental results in nonpreload condition and then applied to predict the high velocity impact behavior under compressive preloads. The effects of compressive preload and impact velocity on the mechanical properties of fiber metal laminates are discussed, and the damage characteristics under corresponding loads are also analyzed. [ABSTRACT FROM AUTHOR]

The need for thin and highly deformable textile reinforcements is constant in sectors like thin composites, catching nets, and complex construction designs (like dome-shape). The conventional rectangular-patterned meshed wovens are used in thin composite structures as reinforcement at the commercial level. These woven textiles are bidirectional and exhibit approximately the same strength along both axes. However, these conventional rectangular-patterned mesh designs show poor impact stress distribution capacity. Interestingly, very thin and fine mesh designs are available in nature. One such example is the spider web structure. These structures have evolved with time and optimised their mesh pattern design for better impact damage resistance and load transfer. In this study, the basalt fibre reinforced mortar textile composites are considered for the investigation due to their growing interest in civil and construction applications. To demonstrate how the mesh geometry in textiles significantly influences the stress transfer, energy absorption, and deformation of reinforcements under various impact situations, three different geometries, (a) square shape mesh, (b) diamond-shaped mesh, and (c) bio-inspired spider web mesh, are modelled and meshed based on the reference geometry's meshing pattern and dimensions. The results of numerical simulations show that a meshed reinforcement design inspired by spider-orb-web has improved mechanical features compared to conventional square and diamond shape mesh designs under high velocity impact loading. [ABSTRACT FROM AUTHOR]

In this study, the high velocity impact response of a lightweight composite structure comprising an aramid honeycomb core sandwiched between two aluminum sheets was investigated against conical and hemispherical projectiles. It used a pneumatic gas gun and Abaqus software to conduct experimental and numerical research, respectively, focusing on damage behavior and failure modes, with a systematic parametric and optimization study for optimum ballistic performance. Results revealed that varying the rear sheet thickness and cell length had the most significant effects. Overall, the multifaceted approach advances the development and optimization of advanced composites for impact-resistant technologies where weight savings are critical. [ABSTRACT FROM AUTHOR]

This work investigated the effect of hybridization of flax fabric (FF) with carbon/Kevlar fabric (CK) on the flexural, dynamic mechanical analysis and high velocity impact. Hand lay-up technique was used to fabricated different ratio of flax to carbon/Kevlar hybrid composites, which were hot-pressed and then cured. It was revealed that increase in ratio of CK has improved the flexural properties, storage modulus, loss modulus, energy absorption and ballistic limit of the composites. Interestingly, hybrid composite with ratio 25:75(FF:CK) has highest flexural properties, storage modulus and loss modulus among the other composites. The cole-cole plot and damping factor reveals that hybrid composite with ratio 25:75(FF:CK) has the strongest fibre/matrix adhesion. The hybrid composite with ratio 25:75 (FF:CK) displayed the highest Tg. Based on high velocity impact test, it was shown that there is not much different in energy absorption and ballistic of the hybrid composites compared to plain CK composite. FF/CK hybrid composites have the potential to be used in high performance application such as ballistic helmet.

This paper aims at the development and implementation of an algorithm for the treatment of damage and fracture in smooth particle hydrodynamic (SPH) method, where free surface, crack opening, including its propagation and branching is modelled by weakening the interparticle interactions combined with the visibility criterion. The model is consistent with classical continuum damage mechanics approach, but does not use an effective stress concept. It is a difficult task to model fracture leading to fragmentation in materials subjected to high-strain rates using continuum mechanics. Meshless methods such as SPH are well suited to be applied to fracture mechanics problems, since they are not prone to the problems associated with mesh tangling. The SPH momentum equation can be rearranged and expressed in terms of a particleparticle interaction area. Damage acts to reduce this area, which is ultimately set to zero, indicating material fracture. The first implementation of the model makes use of Cochran-Banner damage parameter evolution and incorporates a multiple bond break criterion for each neighbourhood of particles. This model implementation was verified in simulation of the onedimensional and three-dimensional flyer plate impact tests, where the results were compared to experimental data. The test showed that the model can recreate the phenomena associated with uniaxial spall to a high degree of accuracy. The model was then applied to orthotropic material formulation, combined with the failure modes typical for composites, and used for simulation of the hard projectile impact on composite target. [ABSTRACT FROM AUTHOR]

In this work, the failure mode and ballistic protection capability of the carbon fiber aluminum alloy laminated target plate under the impact of high‐speed projectile body were studied by ballistic impact test. The effects of the lamination sequence and warhead shape difference on the impact resistance of the laminated aluminum alloy and carbon fiber laminates were analyzed. Two kinds of projectile bodies, flat and oval head, were used to carry out multiple high‐speed impact experiments on four groups of targets with different stacking sequences. By analyzing the result, it is found that the lamination sequence of the target plate has a significant effect on the anti‐impact performance only when the flat head projectile impacts, while the ovoid projectile has almost no effect. In the fiber‐metal composite configuration, the aluminum plate placed in front of the carbon fiber plate showed the best resistance to flat head bullet impact, the ballistic limit speed reached 135 m/s, and the overall impact resistance improved by up to 26% compared with other configurations. Unlike the shear failure caused by flat head projectile, ovoid projectile impact can cause serious tensile and tear damage. Based on the experimental results, it is clear that the laminated structure has better penetration resistance against the flat head projectile, and the placement of aluminum plate on the impact surface can change the failure mode of carbon fiber laminates and improve the energy absorption level of composite plates. Highlights: Unlike traditional fiber‐metal laminates, the target plate used in this experiment does not use adhesive, which makes the deformation of the two materials will not affect each other, which is conducive to the study of its own impact resistance.The mechanical behavior and damage failure mode of the target plate under high speed impact load were studied.The impact of ovoid projectile changes the damage failure mode of the target plate. For the configuration of fiber‐metal laminates, the ballistic limit value is as low as 100 m/s, and the energy absorption value fluctuates in the range of 145–190 J with the change of impact velocity.Compared with ovoid projectile, laminated material has stronger impact resistance to flat head projectile.The metal plate arranged on the impact surface can change the damage mode from shear failure to tensile failure, thus greatly improving the ballistic limit and impact resistance, overall impact resistance can be improved by up to 26%. [ABSTRACT FROM AUTHOR]

In this work, the effect of different concentration (0.5, 1 and 1.5 wt%) of reduced graphene oxide (r-GO) on the mechanical, microstructural and high velocity impact behaviours of novel fibre intermetallic laminates (FIL) made up of Nitinol foils and carbon/aramid fibres were experimentally investigated. The vacuum assisted resin infusion process is employed to fabricate the FILs with alternatively stacked woven fibres. The mechanical and chemical surface treatments were performed to ensure the improved adhesion and interaction between epoxy matrix and nitinol foils. The mechanical properties such as tensile, flexural and high velocity impact strengths were investigated for unreinforced, and r-GO reinforced FILs. Results revealed that the assimilation of r-GO fillers exhibit the capable of improving ultimate tensile strength of 16.5%, ultimate flexural strength of 13.9% and impact strength of 7.62% compared to unreinforced FILs. Improved tensile, flexural and impact strengths were obtained at the concentration of 1wt% r-GO infused FILs. On the contrary, the mechanical properties are deteriorated with further addition of r-GO fillers above the optimum levels. Moreover, the morphologies of surface treated Nitinol foils, nano filled epoxy matrix and the mechanical fractured surfaces were investigated with the aid of SEM to assimilate the failure mechanisms with respect to the inclusion of reduced-graphene oxide.

In order to effectively mitigate the risk of bird strikes, it is imperative that radomes situated in areas prone to such incidents possess the capability to endure the impact loads caused by bird collisions. Additionally, these radomes must maintain their electromagnetic transparency. Therefore, glass fibre reinforced polymer (GFRP) with Nomex honeycomb sandwich material is used for radome structural design. The current research is intended to examine the dynamic behavior of sandwich composite panels in order to determine the penetration velocity by testing them at three distinct bird impact velocities, such as 88 m/s, 135 m/s, and 153 m/s. It is necessary to find the velocity at which the bird will penetrate / rupture the radome for the safety of Antenna / Electronic units mounted behind the radome. Finite element explicit code LS-DYNA simulates all three impacts. Extension of the simulation estimated the threshold bird impact velocity to be 146 m/s at which it penetrates the sandwich panel under fixture-controlled boundary condition.

Impact studies are performed to evaluate the ballistic performance of material subjected to a high strain rate. At high velocities, the projectile penetrates through the material which leads to a fracture of the target body. The fracture behavior depends upon the condition of the target body. It is anticipated that the fracture behavior should depend upon the prestress condition of the target. Considering the aforementioned concern, the thermo-elastic-plastic finite element model is formulated using MSC Marc MentatTM to analyze the effect of the prestress condition of the target body on fracture behavior. A detailed comparison has been presented considering four different prestress states subjected to impact by a blunt-shaped projectile. The continuum damage mechanics using a stress triaxiality-based damage model is used to simulate damage evolution and fracture. It is found that the presence of prestress alters the overall fracture response of the structure subjected to high strain rate deformation. In the presence of tensile prestress, the material resists the accumulation of damage which is due to the lower values of stress triaxiality and equivalent plastic strain. It is also found that the presence of tensile prestress inside the target body increases the ballistic performance, whereas the presence of compressive prestress inside the target body degrades the performance.

• AuxHex core exhibits a superior energy absorption capacity, absorbing 15 % and 12 % more energy than hexagonal and star cores, respectively. • The back face sheet residual deflection is 12–15 % higher than the striking sheet. Also, compared to conical projectile, the deflections in the back face sheet are found to be 20–25 % higher for ogive projectile. • Compared to hexagonal HSP, a remarkable increase of 9 % and 23 % respectively in ballistic limit and SEA of Auxhex HSP were reported. The pursuance of lightweight yet robust materials and structures has led to the rapid evolution of protective technologies. Additive Manufacturing (AM) has emerged as a transformative tool, enabling the fabrication of intricate cellular structures with tailored properties. The use of additively manufactured honeycombs in the field of ballistic protection has not been explored extensively. In this view, the current work presents a comprehensive investigation involving experimental and numerical procedures, to understand the impact response of sandwich panels embedded with additively manufactured honeycomb cores against ogive and conical projectile impacts. Three different honeycomb cores, namely Hexagonal, Star, and AuxHex are additively manufactured using AlSi10Mg powder via selective laser melting technique. Each core is bonded to a pair of 1 mm thick SS 316 sheets. The projectiles are launched at velocities varying between 180 m/s and 260 m/s. Finite element models are created in ABAQUS/Explicit to simulate ballistic impact scenarios. A strong consistency between the predicted results and experimental outcomes in terms of deformation, damage modes and residual velocities was obtained. The results revealed that the sandwich panel featuring an AuxHex core exhibits a superior energy absorption capacity, absorbing 15 % and 12 % more energy than hexagonal and star cores, respectively. Additionally, it was observed that, when compared to a conical projectile, an ogive projectile requires 14 % more energy to perforate the same sandwich panel. Furthermore, the ballistic limit of star and AuxHex panels is found to be increased by 5 % and 9 %, respectively compared to panels with hexagonal honeycomb cores. This work contributes valuable insights into the application of additively manufactured honeycomb cores, offering potential scope for the development of lightweight and resilient structures crucial in aerospace and defense industries. [ABSTRACT FROM AUTHOR]

The structure of shock waves in pressed porous samples of nickel nanoparticles was investigated in a series of uniaxial planar plate impact experiments in the pressure range of 1.6–7.1 GPa. The initial porosity of the samples was about 50%. Wave profiles were obtained using laser velocimetry techniques. The nanomaterial demonstrated a complex response to shock loading including the development of a two-wave structure associated with precursor and compaction waves. The effect on profiles and measurements of the observed precursor reverberations propagating between the front of a compaction wave and a monitored sample surface was described. The obtained wave profiles were used to estimate the thicknesses of precursor and compaction wave fronts. [ABSTRACT FROM AUTHOR]

The Hybridization concept creates a niche within the composite segment to customize materials for specific applications with reduced cost without sacrificing strength and durability. The composite structures develop strain during continuous operation, and any sudden impact on these preloaded parts might result in catastrophic accidents. Studying impact response during such conditions is essential in designing and developing structures. This study experimentally investigates the high velocity impact response of Hybrid (Carbon-Glass) composite under normal and hydrostatic preload conditions. Mechanical tests involving Tensile, Izod, and Charpy are conducted. High velocity impact testing is carried out with a vertical single-stage gas gun with additional provision for hydrostatic preloading. An oscilloscope with a laser source measures the initial velocity, and Photogrammetry using a high-speed camera measure the residual velocity of a projectile. The mechanical test results suggest that Hybridization resulted in a significant property enhancement. The high velocity impact resistance and energy absorption are higher for Hybrid under both normal and preloaded impact. [ABSTRACT FROM AUTHOR]

In this study, the anti-penetration performance of polyurea/ASTM1405-steel composite plate subjected to high velocity projectile was analyzed. Two kinds of modified polyurea material (AMMT-053 and AMMT-055) were selected and a ballistic impact testing system including speed measuring target system and high-speed camera was designed. This experiment was conducted with a rifle and 5.8 mm projectile to explore the effects by the polyurea coating thickness, the polyurea coating position and the glass-fiber cloth on the anti-penetration performance of polyurea/ASTM1405-steel composite plate. The result showed that the effects of polyurea coating position were different between two types of polyurea, and that the effects of glass-fiber position were disparate between two types of polyurea as well. For AMMT-053 polyurea material, it was better to be on front face than on rear face; whereas for AMMT-055 polyurea, it was better to be on rear surface although the difference was very subtle. Additionally, formulas had been given to describe the relationship between the effectiveness of polyurea and the thickness of polyurea coating. In general, AMMT-055 had better anti-penetration performance than AMMT-053. Furthermore, five typical damage modes including self-healing, crack, local bulge, spallation and local fragmentation were defined and the failure mechanism was analyzed with the results of SHPB test. Additionally, the bonding strength played an important role in the anti-penetration performance of polyurea/steel composite plate.

• Hierarchical honeycomb panel absorbed 9.6% more energy, needing 4.8% more for perforation than AuxHex sandwich panel. • Front sheet failed through ductile shearing; core crushed, back sheet plugs detached after impact. • Back sheet deflection 12–15% higher, indicating longer contact and force disparity during impact. Honeycomb sandwich panels (HSPs) are extensively employed across various industries owing to their outstanding strength and capacity for energy absorption. Despite their widespread use, the potential of additively manufactured (AM) honeycombs in ballistic protection remains relatively unexplored. This study aims to comprehensively assess the energy absorption performance of two distinct HSP configurations, namely AuxHex and Hierarchical, through high-velocity impact tests spanning velocities ranging from 220 to 270 m/s. The high-velocity impact experiments are conducted using a single-stage pneumatic gun, complemented by simulations executed via Abaqus/Explicit. Our findings reveal that the hierarchical HSP demonstrated a notable 9.6 % enhancement in energy absorption compared to panels featuring an AuxHex honeycomb. Interestingly, the hierarchical panels also necessitated 4.8 % more energy for perforation. In terms of failure mechanisms, both sheets of the HSPs experienced ductile shearing, with the formation of characteristic petal-like structures. Concurrently, the honeycomb core underwent fragmentation on the side facing the projectile, while plugs were ejected from the back sheet. Moreover, our analysis indicates that the residual deflection of the back sheet surpassed that of the striking sheet by 15–20 %. This disparity can be attributed to prolonged contact duration and variations in interaction forces between the sheets. Overall, this investigation provides valuable insights into the energy absorption capabilities of AM honeycomb-based HSPs under high-velocity impact conditions, shedding light on their potential for enhanced ballistic protection in various applications. [ABSTRACT FROM AUTHOR]

The mechanisms of projectile penetration of composite sandwich panel with empty, trapezoidal corrugated cores have been experimentally investigated. The panels have been designed to investigate the influences of specific parameters, like the fiber type of corrugated core, the projectile nose shape and the stacking sequence of face-sheets, on the impact performance from the aspects of sequential deformation, failure modes and associated mechanisms. Experimental results demonstrated that usage of Twill glass fiber in corrugated core is attained highest performance in term of energy absorption and residual velocity for the fully perforated specimens. Comparisons of panels with different stacking sequences for face-sheets verify that the corrugated core composite sandwich structures with ( 0 ° ∓ 45 ° 90 ° ) s stacking sequence is indicated the highest energy absorption. This panel is displayed a superior resistance over the ones with other stacking sequences. The hemispherical projectile is showed no deviation from the direct line of path flight relative to the conical and blunt projectile in the high velocity impact test. Moreover, the deviation of the projectile decreases the damage area in specimens. [ABSTRACT FROM AUTHOR]

Ultra-High molecular weight polyethylene (UHMWPE) fibers are among the strongest and lightest fibers available and are widely used in high-performance ballistic applications. Despite the great advancement of computational analysis in recent years, precise calculations have not been performed to identify the failure of these fibers due to the complexity of the material behavior to impact. In this research, using the most advanced finite element modeling method of composites (Abaqus-Explicit) has been used to study the composite behavior of these fibers subjected to high-velocity projectile impact. Fiber and matrix are designed using solid elements and 3D Hashin failure criterion was used to determine the behavior of the material. Since this criterion is not available in Abaqus, the VUMAT subroutine has been used to implement this criterion. Velocity diagrams and damage evaluation have been reported. To evaluate and validate this method, six samples of Ultra High Molecular Weight Polyethylene (UHMWPE) Composite panels, consisting of 20 and 45 layers, respectively, were experimentally studied by high-velocity projectiles at different velocities. The simulation results are in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Aluminum honeycomb framework reinforced Al/PTFE material is a kind of high inert energetic material, which has higher strength and structure advantages than that of pure Al/PTFE material. In order to meet the requirements of special penetration/blasting performance, this paper adds aluminum honeycomb framework with arm length of 1.5 mm into the traditional formula Al/PTFE (mass percentage of Al and PTFE is 26.5% and 73.5%). The energetic material reinforced by aluminum honeycomb framework (20.5% Al/73.5% PTFE/6% aluminum honeycomb) is obtained by cold pressing sintering，and the experimental evaluation of release energy generated by high velocity impact in vacuum was performed by using two-stage light gas gun loading system, transient optical fiber pyrometer measurement system, overpressure measurement system and infrared thermal imager measurement system. Experimental results show that the impact reaction temperature is about 700 °C in vacuum in the velocity range of 0.96–1.5 km/s, and the energy release of the specimen increases with the increase of impact velocity. When the impact velocity is greater than 1.5 km/s, the specimen fully reacts, and the energy released by the complete reaction of the specimen does not exceed 8.3 kJ/g.

Simulation and analysis of the projectile impact and penetration problem and its effects are among the practical topics that can be used to design bulletproof panel and military equipment, construction of impact and penetration resistant structures, design of projectiles with appropriate penetration strength and high performance noted. One of the most important parameters affecting penetration is the impact velocity of the projectile. The mechanism of penetration varies in different speed ranges. In this paper, Ansys Autodyn software is used for penetration simulation. The simulation carried out in this study is based on the accuracy and physical conditions of the problem and the compatibility of numerical simulation with the governing analytical relations indicates the validity and accuracy of the assumptions made in the simulation. In this study, we selected materials such as material behavior, grating, contact surfaces, and controls, as well as collision of the blunt projectile with angles of 0�,15�,30�,45� by of high velocity impact 1000 m/s with the same mass and diameter and shape of the projectile nose and properties. Ceramic materials are discussed. The result of the numerical simulation comparison shows relatively good agreement between them.

This study is undertaken to explore the use of natural fiber Jute-epoxy (JE), Jute-epoxy-rubber (JRE) sandwich composite for ballistic energy absorption. Energy absorbed and residual velocities for these composites are evaluated analytically and through Finite Element Analysis (FEA). FE analysis of JE plates is carried out for different thicknesses (3, 5, 10 and 15 mm). JE plates and JRE sandwiches having the same thickness (15 mm) are fabricated and tested to measure residual velocity and energy absorbed. The analytical results are found to agree well with the results of FE analysis with a maximum error of 9%. The study on JE composite plate reveals that thickness influences the energy absorption. Experimental and FE analysis study showed that JRE sandwiches have better energy absorption than JE plates. Energy absorption of a JRE sandwich is about 71% greater than JE plates. Damages obtained from FEA and testing are in good agreement. SEM analysis confirms composites failed by fiber rupture and fragmentation.

The high-velocity impact tests were carried out on the basalt fiber cloth/Al-plate composite shields, the ballistic limit velocity was obtained in the range of ballistic impact velocity. The diameter of 2017 Al-sphere projectile was 3.97 mm, and the impact velocity of Al-spheres was varied between 1.49 and 3.65 km/s. The residual velocity of Al-sphere projectile penetrating thin Al-plate and basalt fiber cloth bumper was analyzed. Furthermore, the shielding performance of the basalt fiber cloth/Al-plate composite shields was studied based on the critical impact kinetic energy for the failure of the single Al-plate. The results show that the velocity reduction of the constant diameter projectile penetrating the same basalt fiber cloth bumper at different velocities is a constant when the projectile is not broken. The velocity reduction of the projectile decrease with increasing diameter. For the same areal density, the shielding performance of composite shield with aluminum plate as the first wall is better than that of composite shield with basalt fiber cloth as the first wall. [ABSTRACT FROM AUTHOR]

At sufficiently high velocities, a microparticle impacting a metal substrate can cause ejection of material from the substrate and impact-induced melting, both of which can result in erosion. Here, we directly image the impact of individual hard steel microparticles on soft tin substrates, at controlled impact velocities in the range of ~100 to 1000 m/s. By using scanning electron and laser scanning confocal microscopy, we characterize the surface morphology, depth, and volume of each impact crater. We observe a gradual onset of impact-induced melting in the craters, as well as the production of increasing amounts of ejecta from the target metal. By comparing measurements of impact and rebound velocity to an elastic-plastic model, we observe that at a high enough impact velocity, melting and ejection begin to consume additional kinetic energy beyond that expected by plastic deformation of the target material alone. By calculating the excess energy dissipation using this elastic-plastic model, we show that although this divergent behavior is associated with the onset of melting, the majority of the ejected volume must be solid rather than liquid. [ABSTRACT FROM AUTHOR]

In the last few decades, several full-scale tests have been performed to study the behavior of Ultra High-Performance Fiber Reinforced Concrete (UHPFRC). However, only limited research has been devoted to simulate performance of UHPFRC subjected to special load and impact, such as high-velocity impact. Accurate modeling and simulation of the UHPFRC panel subjected to high velocity impact is a big challenge involving costly experimental characterization of material and verification of ballistic impact response with actual test data. This article investigates the dynamic behavior of UHPFRC panel against multiple bullet impacts using the Holmquist-Johnson-Cook damage model incorporating both the damage and residual material strength. The projectile used in this study is chosen with high-speed and low-weight like the fragments which can be formed by industrial accidents or in an explosion. The kinetic and internal energies of the UHPFRC panel are also evaluated. The analysis results are compared to the High Strength Concrete (HSC) in terms of capability to absorb energy and reduce the damage on target panel.

Purpose: In many military applications, composite materials have been used because of their high velocity impact resistance that helps absorption and dispersion energy. It is therefore used in armour and vehicles, aircraft and spacecraft that are subjected to impact of various shapes and velocities. Design/methodology/approach: In the theoretical part, the absorption energy equation for the sample was established by constructing an energy balance equation consisting of five types of energies, it is the compressive energy in the first region (the impact region), the tensile energy in the first region, the tensile energy in the second region, the energy of the shear plugging and the friction energy. Findings: It was found in the experiments that the tensile stress value increased by increasing the volume fraction of fibres to the polyester, and the value of compressive stress decreased. Also manufactured different types of impact samples with dimensions (20*20 cm2 ) and deferent thickness. The results were an increase in the amount of energy absorbed by increasing the ratio of the fibre to the polyester. It is found that the greatest effect in the equation of energy balance is the shear plugging energy, in which the value of the energy absorbed reached 38% of the total energy. And in the second degree friction energy, in which the value of the energy absorbed reached 27% of the total energy. while the other energies are relatively small but with important values, except for the tensile energy in the second region, the Kevlar-Polyester (40-60)%, so that the increase was more than four times the previous case. Research limitations/implications: Three types of reinforcing fibres were used: Kevlar, Carbon and Glass fibres with a matrix material as polyester. Six samples are made for tensile and compression testing, Kevlar-Polyester (30-70)%, Carbon-Polyester (30-70)%, Glass-Polyester (30-70)%, Kevlar-Polyester (40-60)%, Carbon-Polyester (40-60)% and Glass-Polyester (40-60)%. Practical implications: On the experimental part, experimental work tests were carried out to determine the mechanical properties of the samples such as tensile and compression tests as well as conducting the natural frequency test conducting the impact test by bullet to identify the effects and penetration incidence and compare this with the theoretical results. Originality/value: In this research high velocity impact is used with a bullet it diameter 9 mm, mass of 8 g, and a semi-circular projectile head with a specific velocity ranging from 210-365 m/s. The effect of the impact is studied theoretically and experimentally. The elastic deformation is increased for increasing the ratio of the fiber to the polyester and the depth of penetration is decreasing. The hybrid sample is affected in absorption energy and decreasing the penetration. Finally calculated for penetration behaviour theoretically and experimentally for different composite materials and comparison for the results calculated. [ABSTRACT FROM AUTHOR]

• Six different preloaded CFRP laminates under high velocity impact are investigated. • Preloading conditions reduce the ballistic limit and energy absorption rate. • Failure modes including delamination are identified and discussed. • An analytical model has been proposed to predict ballistic limit velocity. In this research, we explore the effects of complex in-plane quasi-static loads on the high-velocity impact response of Carbon Fiber Reinforced Plastic (CFRP) composite laminates, grounded in the practical context of various working loads combined with potential high-velocity impacts experienced by aircraft. The specific complex in-plane loads studied include uniaxial tension and compression, biaxial tension and compression, and a combination of tension and compression preloading. The results show that the complexity of in-plane preloads, along with pre-compression, reduces the ballistic limit velocity. Biaxial preloading, especially in compression, greatly compromises the specimen's ballistic resistance. The study also proposes a theoretical model based on energy conservation principles to predict the ballistic limit velocity of CFRP laminates under various preloading conditions. The research provides valuable insights for designing composite structures and highlights the importance of considering in-plane preloads in assessing thin CFRP ability to withstand ballistic impacts. [Display omitted] [ABSTRACT FROM AUTHOR]

• Conducted MD simulations to analyze the interaction of W dust with W walls at varying velocities (1000–4500 m/s), benchmarked against experimental data. • Observed that increased impact velocities enhance dust absorption by the wall and escalate the ejection of wall material. • Demonstrated excellent agreement between MD results and experimental findings, affirming the reliability of the simulation approach. • Proposed theoretical models to extrapolate the results, facilitating broader applicability and understanding of dust-wall interactions in PFMs. This research investigates the interaction between high-speed tungsten (W) dust and plasma-facing components (PFCs) in fusion reactors, particularly focusing on W walls. Through molecular dynamics (MD) simulations, the study covers a broad spectrum of W dust velocities to evaluate their effect on wall materials with various crystal orientations. We found that high-speed impacts cause considerable damage, including sputtering, degradation, and deformation. The study introduces a damage model derived from experimental and simulation data that reveals the patterns and mechanisms of damage caused by dust impacts. The proposed model significantly improves our understanding of dust-wall interactions and underscores the importance of MD simulations as a reliable technique for exploring such phenomena in the challenging conditions of fusion devices. These insights are crucial to predict and mitigate damage to PFCs, helping to develop more resilient and efficient components. Overall, the research offers valuable knowledge on the atomic-level dynamics of dust impacts and represents a notable advancement in the durability and efficiency of materials used in fusion energy technologies. [Display omitted] [ABSTRACT FROM AUTHOR]

• Hygrothermal coupling conduction model is adopted. • Time-varying hygrothermal dynamic damage constitutive is established. • High velocity impact performance of CFRP sheet is analyzed. The different loading conditions often occur in polymer matrix composites during their service life. In order to use effectively the materials in high-performance applications, analyzing the effect of hygrothermal effects on a ballistic impact event is necessary. This paper considers a heat sink and humidity sink for the hygrothermal diffusion in the composites and solves the Luikov equations by means of the differential quadrature method (DQM). Then, failure and partial failure of a projectile with high velocity into the composites are studied based on the conservation of energy. Further, as hygrothermal deformation reaches equilibrium, the effect of hygrothermal effects on the ballistic impact event is studied. Finally, based on carbon fiber reinforced composite (CFRP), the effects of the hygrothermal diffusion are discussed on the ballistic impact event. [ABSTRACT FROM AUTHOR]

The interface of fiber-polymer matrix has a critical role in controlling the mechanical features of polymer composites. Most of the studies focused on the application of reduced graphene oxide in enhancing the interfacial properties of the composite. In this study, we focused on utilising the Graphene nano-plates (GNPs) with average diameter of 5–10 µm. The GNPs were assessed by different techniques of XRD and AFM. The GNPs incorporated into the epoxy matrix, and then the high velocity impact response was evaluated. The result of GNPs incorporation into the epoxy matrix showed that the 0.3 wt.% GNPs incorporation into the glass fiber epoxy matrix and 0.9 wt.% GNPs incorporation into the glass-carbon fiber/epoxy were destructive on the absorption energy of the composite. The optimum concentration of the incorporated GNPs highly dependent upon the type of fiber in the matrix and the level of initial velocity in the impact test. Although the high concentration of GNPs (up to 0.9 wt.%) dispersed at the interface of the glass fiber/epoxy resin can induce the high velocity impact performance, but it resulted in the reduction of the impact performance of glass-carbon fiber/epoxy due to the agglomeration of the GNPs. [ABSTRACT FROM AUTHOR]

In this study, the effects of the core layering of sandwich structures, as well as arrangements of these layers on the ballistic resistance of the structures under high-velocity impact, were investigated. Sandwich structures consist of aluminum face-sheets (AL-1050) and polyurethane foam core with different densities. Three sandwich structures with a single-layer core of different core densities and four sandwich structures with a four-layer core of different layers arrangements were constructed. Cylindrical steel projectiles with hemispherical nose, 8 mm diameter and 20 mm length were used. The projectile impact velocity range was chosen from 180 to 320 m/s. Considering constant mass and total thickness for the core, the results of the study showed that the core layering increases the ballistic limit velocity of the sandwich structures. The ballistic limit velocity of the panels with a four-layer core of different arrangements, compared to the panel with the single-layer core, is higher from 5% to 8%. Also, for the single-layer core structure, by increasing the core density, the ballistic limit velocity was increased. Different failure mechanisms such as plugging, petaling and dishing occurred for the back face-sheet. The dishing area diameter of back face-sheets was proportional to the ballistic resistance of each sandwich structure. [ABSTRACT FROM AUTHOR]

In this research work, the effect of adding nanoclay on the high velocity impact behavior of fibers metal laminates (FMLs) of aluminum- Jute fibers/epoxy was investigated. To do so, the nanoclay particles with different percentages (0, 1, 3 and 5 wt.%) were firstly added into the epoxy matrix. In the following, the FMLs with the configuration of 0/90/0/90/0 were made by hand lay-up method. After that, the fabricated samples were tested by high velocity impact test. In order to investigate the effect of nanoparticles on the impact properties, the field emission scanning electron microscope (FESEM) was used. The obtained results showed that the samples with 0, 1, 3 and 5 wt.% had the limit velocity of 81.9, 83.7, 87.4 and 85.4 m/s, respectively. The limit velocity increment in these samples by adding nanoclay were 2.2, 6.7 and 4.3 %, respectively. Also, the obtained results showed that by adding the 1, 3 and 5 wt.% nanoclay, the absorbed energy was improved about 4.5, 14 and 8.8 %, respectively. The sample with 3 wt.% nanoclay had minimum delamination length between aluminum shell and composite core, which was due to the effect of nanoclay in the interface adhesion of core-shell. The microscopically analysis showed that the nanoclay increased the fibrillation of Jute fibers as one of the absorbed energy mechanisms in the Jute fibers. Also, the agglomeration phenomenon in the sample with the 5 wt.% nanoclay was illustrated, which was the decreasing factor of its impact properties, as comparison with sample with 3 wt.% nanoclay. [ABSTRACT FROM AUTHOR]

In this paper, a numerical model is developed to simulate the ballistic impact of a projectile on a sandwich panel with honeycomb core and composite skin. To this end, a suitable material model for the aluminum honeycomb core is used taking the strain-rate dependent properties into account. To validate the ballistic impact of the projectile on the honeycomb core, numerical results are compared with the experimental results available in literature and ballistic limit velocities are predicted with good accuracy. Moreover, to achieve composite skin material model, a VUMAT subroutine including damage initiation based on Hashin's seven failure criteria and damage evolution based on MLT approach modulus degradation is used. To validate the composite material model VUMAT subroutine, the ballistic limit velocities of the projectile impact on the composite laminates are predicted similar to the numerical results presented by other researchers. Next, the numerical model of the sandwich panel ballistic impact at different velocities is compared with the available experimental results in literature, and energy absorption capacity of the sandwich panel is predicted accurately. In addition, the numerical model simulated the sandwich panel damage mechanisms in different stages similar to empirical observations. Also, the composite skin damages are investigated based on different criteria damage contours. [ABSTRACT FROM AUTHOR]

Long rod eroding penetrators exhibit hydrodynamic behaviour upon impact against the target plates. An experimental study was carried out to investigate the factors affecting the penetration of tungsten alloy rods against rolled homogenous armour at ordnance velocities. Experiments were carried out for range of projectile length to diameter ratios to determine the penetration efficiency of the projectile, where the projectile penetration efficiency is the penetration depth per unit projectile length. Analytical Alekseevski–Tate model was implemented to predict the penetration depth across the length to diameter range and the results were compared with the experimental data. The tungsten percentage of the projectile material was also varied to change its mechanical properties and thus observe the effect of the same on the penetration depth. The experimental results showed a linear relationship between the penetration efficiency and the length to diameter ratio across the considered range of length to diameter ratios. The Alekseevski–Tate model predictions were not consistent across as the model does not consider the effect of length to diameter ratio. The projectiles with high impact energy were able to perforate the target plate. [ABSTRACT FROM AUTHOR]

Simulation and analysis of the projectile impact and penetration problem and its effects are among the practical topics that can be used to design bulletproof panel and military equipment, construction of impact and penetration resistant structures, design of projectiles with appropriate penetration strength and high performance noted. One of the most important parameters affecting penetration is the impact velocity of the projectile. The mechanism of penetration varies in different speed ranges. In this paper, Ansys Autodyn software is used for penetration simulation. The simulation carried out in this study is based on the accuracy and physical conditions of the problem and the compatibility of numerical simulation with the governing analytical relations indicates the validity and accuracy of the assumptions made in the simulation. In this study, we selected materials such as material behavior, grating, contact surfaces, and controls, as well as collision of the blunt projectile with angles of 0º,15º,30º,45º by of high velocity impact 1000 m/s with the same mass and diameter and shape of the projectile nose and properties. Ceramic materials are discussed. The result of the numerical simulation comparison shows relatively good agreement between them. [ABSTRACT FROM AUTHOR]

This study is undertaken to explore the use of natural fiber Jute-epoxy (JE), Jute-epoxy-rubber (JRE) sandwich composite for ballistic energy absorption. Energy absorbed and residual velocities for these composites are evaluated analytically and through Finite Element Analysis (FEA). FE analysis of JE plates is carried out for different thicknesses (3, 5, 10 and 15 mm). JE plates and JRE sandwiches having the same thickness (15 mm) are fabricated and tested to measure residual velocity and energy absorbed. The analytical results are found to agree well with the results of FE analysis with a maximum error of 9%. The study on JE composite plate reveals that thickness influences the energy absorption. Experimental and FE analysis study showed that JRE sandwiches have better energy absorption than JE plates. Energy absorption of a JRE sandwich is about 71% greater than JE plates. Damages obtained from FEA and testing are in good agreement. SEM analysis confirms composites failed by fiber rupture and fragmentation. [ABSTRACT FROM AUTHOR]

As primary structures and protective structures, fiber metal laminates (FMLs) in practical application are always in preload states before possible impact damage threats. In this work, a nonlinear finite element (FE) model is developed to study the impact damage scenario where tensile preloaded FMLs are impacted by a hemispherical nose projectile at high velocities. In the modeling, the intra-layer damage in aluminum sheets and composite laminates and the delamination between adjacent plies are entirely included. The FE model is verified with available experimental results in non-preload condition and then applied to predict the high velocity impact behavior in uniaxial and biaxial tensile preload cases. The ballistic performance and damage response of representative FMLs with different preloads and impact velocities are discussed and analyzed in detail. The numerical results and modeling strategy here provides applicable reference for preloaded impact issues in other FMLs. [ABSTRACT FROM AUTHOR]

In this work we studied the high velocity impact of Cu 45 Zr 45 Al 10 metallic glass nanoparticles onto substrates of the same material using molecular dynamics simulations. In particular we studied the effect of the impact velocity, nanoparticle temperature on the maximum penetration depth, damping coefficient, heat generated by the impact, and mechanical deformation. We observed that the velocity is the most important parameter affecting the impact behavior of the nanoparticle. A critical velocity was defined as the velocity required for the center of mass to remain just below the surface of the substrate. Mechanical deformation depended on this parameter. At values below the critical velocity, plasticity was almost negligible, while at values above, significant strains deep within both the substrate and the nanoparticle were observed, causing the latter to disintegrate completely. This deformation was accompanied by a relevant increase in liquid-like polyhedra as revealed by structural characterization based on Voronoi analysis. • Adhesion of a metallic glass nanoparticle on a substrate is studied. • Impact velocities in the range of 0.5–2.0 km/s are considered. • The critical velocity for adhesion depends on the thermal history of the nanoparticle. • At high velocities the nanoparticle disintegrates completely. [ABSTRACT FROM AUTHOR]

• The deep penetration of long steel rods into aluminum targets are numerically simulated in this work. • The 2D and 3D simulations follow the complex behavior of these rods at high impact velocities. • We found that the failure of spherical nosed rods is due to their nose deformation at certain threshold velocities. On the other hand, ogive nosed rods do not deform and their failure is due to inclination angles at high impact velocities. A numerical study concerning the deep penetration of long steel rods into 6061-T6511 aluminum targets at high impact velocities is presented. The range of impact velocities where these rods lose their penetration capability due to their nose deformation, or impact inclination, is explored. The numerical simulations follow several complex phenomena such as the onset of rod deformation and erosion, encountered in the tests with spherical and ogive nosed rods. It turns out that penetration depth decrease of spherical nosed rods at high impact velocities, is due to their nose deformation, while ogive nosed rods are more sensitive to impact inclination. At very high impact velocities both types of rods experience significant mass erosion, and their penetration process can be described by conventional hydrodynamic penetration model for eroding rods. The numerical simulations in this work are shown to follow test results for spherical and ogive nosed rods, impacting an aluminum alloy target at a large range of impact velocities. We show that these agreements can be achieved with relatively simple constitutive relations for the steel rods and the aluminum target. [ABSTRACT FROM AUTHOR]

The paper presents the results of numerical simulation and experimental data on the high-speed penetration of the impactor into the obstacle. In the calculations, a discrete-element model has been used, based on the representation of the impactor and the target by a set of close packed interconnected particles. This class of models finds an increasingly wide application in the problems of high-speed interaction of bodies. In the previous works of the authors, the questions of application of the discrete-element model to the problem of the penetration of spherical impactors into massive targets were considered. On the basis of a comparative analysis of the data of computational and physical experiments, it was found out that for a wide class of high-speed penetration problems, a high accuracy of discrete-element modeling can be achieved using the two-parameter Lennard-Jones potential. The binding energy was identified as a function of the dynamic hardness of materials. It was shown that the use of this approach makes it possible to describe accurately the penetration process in the range of impactor velocities 500-2500 m/c. In this paper, we compare the results of discrete-element modeling with experimental data on penetration of high-strength targets of different thickness by steel impactors. The use of computational parallelization technologies on graphic processors in combination with 3D visualization and animation of the results makes it possible to obtain detailed spatio-temporal patterns of the penetration process and compare them with experimental data. A comparative analysis of the experimental and calculated data has shown a sufficiently high accuracy of discrete-element modeling for a wide range of target thicknesses: for thin targets pierced with preservation of the integrity of the deformed impactor, for targets of medium thickness, pierced with practically complete fragmentation of the impactor at the exit from the target, and for thick impenetrable targets.