High Velocity Impact Tests Research Articles

Study on high velocity impact response of aramid fibers-epoxy/aluminum laminate composites toughened by ZrO2 and SiO2 nanoparticles

The present study investigates the improvement in high-velocity impact response of fiber metal laminates through modification of epoxy using different percentages (0, 1, 3, and 5 wt.%) of SiO2 and ZrO2 nanoparticles. To ensure a good distribution of nanoparticles into epoxy resin, the nanoparticles were dispersed by a high-speed shear mixer followed by an ultrasonic device. By using the hand lay-up technique followed by a mold pressing process, FML samples were made of 2024-T3 aluminum sheets (0.5 mm thick) and woven Kevlar fabric impregnated with modified epoxy. The high-velocity impact test on FML samples was conducted to determine the influence of epoxy modification on their specific energy absorption. The study revealed that the modification of epoxy increased the specific energy absorption up to 130% and 91% at samples with 3 wt.% of SiO2 and 5 wt.% of ZrO2, respectively. It was also observed from scanning electron microscopy analysis that incorporation of ceramic nanoparticles changed the delamination failure mechanism of matrix cracking to fiber breakage. Furthermore, finite element simulation (FES) was additionally conducted with Abaqus to predict the residual velocity and model impact response. The simulation results agree well with experimental data.

Influence of stacking sequence on the impact behaviour of UHMWPE soft armor panels

Mechanical behavior of Ultra-High Molecular Weight Polyethylene (UHMWPE) under high-velocity impact is critical for the design of soft armor vests. Several types of UHMWPE are available with different mechanical properties. However, no validated methodology has been published in literature to analyze the influence of stacking sequence combining different UHMWPE materials to maximize the ballistic limit. In this work, a combined experimental–numerical methodology is proposed to predict the change of the ballistic limit with the stacking sequence, and hence to find the optimum combination. First, the FEM model is fitted using high-velocity impact tests on single layer specimens. Then, the FEM model is validated with the comparison of impact tests on 6 stacking sequences. Once validated, the FEM model is used to analyze 17 stacking sequences with similar areal densities to find the best configuration. In the optimum stacking sequence, for the conditions studied in this work, the material with highest ultimate strain in back face, the material with lowest ultimate strain in the front face, and the intermediate material in the middle. This combination can improve the ballistic limit of the best material reducing the final cost. Conclusions obtained can be used by composite design engineers to improve ballistic performance of UHMWPE protections.

Enhancing the material properties of carbon fiber epoxy composite by incorporating electrospun polyacrylonitrile nanofibers

Composite materials are a superior class of material used in almost every field of engineering like construction, military, aerospace, ocean structures, communication, and various other high-performance applications owing to their high specific strength and modulus, increased design flexibility, desirable thermal expansion characteristics good resistance to fatigue and corrosion, and economic efficiency. However, their ply-by-ply nature makes them susceptible to delamination, which originates from the propagation of microcracks in the weak resin-rich layers. Many attempts have been made to address the lack of mechanical properties of this weak interlaminar region. A particularly promising approach involves the incorporation of nanofibers between the reinforcement layers as the composite is laid up. This work involves studying the propertyimprovements in carbon fiber epoxy composite by interleaving electrospun polyacrylonitrile (PAN) nanofibers. Experimental testing involving Tensile, Izod, Charpy and high velocity impact tests showed improved material properties for the PAN nano-interleaved composite. These improvements achieved by nanofiber interleaving shows a greater potential in addressing major concerns for critical application of composite materials in future.

Impact resistant properties of Kagome truss reinforced composite panels

This paper presents an experimental study exploring impact resistant properties of Kagome truss reinforced composite panels. Three types of panels with different materials and reinforcements, i.e., ultra-high-performance mortar, steel fiber, and Kagome truss, were designed and manufactured. High-velocity projectile impact tests were performed to investigate the impact response of panels with dimensions of 200 mmx200 mmx40 mm. The projectile used in the testing was a steel slug with a hemispherical front; the impact energy was 1 557 J. Test results showed that the Kagome truss reinforcement was effective at improving the impact resistance of panels in terms of failure patterns, damaged area, and mass loss. Synergy effects of a combination of Kagome truss and fiber reinforcements for the improvement of impact resistance capacity of ultra-high-performance mortar were also observed.

Performance Comparison of Wood, Plywood, and Oriented Strand Board under High- and Low-Velocity Impact Loadings

Abstract In this article, the behavior of wood, plywood, and oriented strand board (OSB) under high- and low-velocity impact loadings was investigated experimentally. For the high-velocity impact test, limit velocity (Vbl) and impact energy absorbed (Eab) were determined by subjecting the material to different impact loading by conical nose projectile. For the low-velocity impact test, the materials were subjected to four levels of energy—10, 39, 78, and 98 J—and the time history responses of velocity, energy, load, and displacement were obtained. Additionally, quantitative data for damage size are presented. The results show that in comparison with OSB and solid wood plates, plywood presents better characteristics in response to both high- and low-velocity impact loadings.

Experimental and numerical assessment of high-velocity impact behavior of syntactic foam core sandwich structures

In this study, the high-velocity impact behavior of new designed sandwich structures with syntactic foam core and FML skins is investigated by experimental and numerical approaches. An appropriate numerical model is developed in order to modelling of the impact behavior of sandwich structures using the finite element software ABAQUS/Explicit. In this model, two VUMAT subroutine are presented to simulate the constitutive models of GFRP composite and syntactic foam. In addition, a multiscale finite element procedure is employed to predict the effective mechanical properties of woven orthogonal composite from known properties of its constituents. This procedure is implemented the numerical homogenization techniques using Python scripting. High-velocity impact tests are performed using a gas-gun and steel conical projectiles to assess the accuracy of the numerical model. To this end, the numerical model is validated by comparing the high-velocity impact behavior of sandwich structures to that obtained from experimental study and demonstrated to be effective and accurate. The presented numerical model can predict the residual velocity and perforation energy with 88.8% and 97.4% accuracies, respectively. Then the validated numerical model is employed to investigate the effect of projectile shape, projectile mass, and stacking sequence of skins on the impact behavior of the sandwich structure.

The impact performance of Vectran/Epoxy composite laminates with a novel non-crimp fabric architecture

The present research aims to evaluate the impact performance of novel non-crimp fabrics Vectran/Epoxy composite laminates under low and high velocity impact loading conditions. Extensive experimental works consisting of low and high velocity impact tests have been conducted to examine the load-deflection response and the damage mechanism. The impact performance is also compared with GF/Epoxy laminates, having similar fabric architecture and areal weight. Superior impact response was observed for Vectran/Epoxy under both velocity regimes, mainly due to the fabric architecture and fibre properties. It is evident that the results from this work may be beneficial and useful as a secondary component or reinforcement where impact protection is required.

High-velocity micro-projectile impact testing

High-velocity microparticle impacts are relevant to many fields, from space exploration to additive manufacturing, and can be used to help understand the physical and chemical behaviors of materials under extreme dynamic conditions. Recent advances in experimental techniques for single microparticle impacts have allowed fundamental investigations of dynamical responses of wide-ranging samples, including soft materials, nano-composites, and metals, under strain rates up to 108 s−1. Here we review experimental methods for high-velocity impacts spanning 15 orders of magnitude in projectile mass and compare method performances. This review aims to present a comprehensive overview of high-velocity microparticle impact techniques to provide a reference for researchers in different materials testing fields and facilitate experimental design in dynamic testing for a wide range of impactor sizes, geometries, and velocities. Next, we review recent studies using the laser-induced particle impact test platform comprising target, projectile, and synergistic target-particle impact response, hence demonstrating the versatility of the method with applications in impact protection and additive manufacturing. We conclude by presenting the future perspectives in the field of high-velocity impact.

Identification of Impact Force Location and History by using Transfer Matrix determined based on High-velocity Impact Tests

Identification of Impact Force Location and History by using Transfer Matrix determined based on High-velocity Impact Tests

3D printing of a continuous fiber-reinforced composite based on a coaxial Kevlar/PLA filament

Additive manufacturing has allowed for the production of complex and mass customized geometries, but often at the expense of mechanical performance, a penalty which can be in part mitigated with the fabrication of composite parts. Thermoplastic structures fabricated with material extrusion additive manufacturing stand to be improved in terms of fracture toughness with the integration of continuous fibers. The present research program has investigated the production of a continuously reinforced filament to be used in open-source fused filament fabrication systems. Three different volume fractions of Kevlar fibers were incorporated into a polylactic acid (PLA) thermoplastic filament. It was observed that a 20% fiber volume fraction resulted in a doubling of the tensile strength relative to the unreinforced PLA parts. High-velocity impact tests were also performed on the reinforced printed thermoplastic material, and it was observed that the composite with the highest fiber volume fraction provided an impact energy resistance improved by a factor of four, relative to the plain PLA. The reinforced fibers have shown to restrain the penetration of the projectile at velocities similar to those that perforated the unreinforced PLA. The present work has demonstrated the production of printed composites without the need of modifying the extruding systems of a commercial 3D printer. This approach could represent an alternate and feasible process for producing continuously reinforced 3D-printed thermoplastic parts with utility for high-velocity impact applications.

Compression after high-velocity impact behavior of pseudo-elastic shape memory alloy embedded glass/epoxy composite laminates

The compression after high-velocity impact (CAI) behavior of pseudo-elastic shape memory alloy (PE-SMA) embedded glass/epoxy composite laminates manufactured via vacuum-assisted resin infusion (VARI) technique was investigated experimentally. High-velocity impact tests were performed on the glass/epoxy composites using an in-house build gas-gun set-up at four different velocities (70, 85, 95, and 105 m/s). To elucidate, the series of damage events undergone on the composites under the high-velocity impact, a high-speed camera was used. Quasi-static compression-after-impact (CAI) tests were performed to evaluate the damage tolerance of different composites subjected to high-velocity impact. Real-time damage progression during the CAI as well as the extent of damage was characterized by using a 2D Digital Image Correlation (DIC) technique. Three different types of embedment configurations of PE-SMA wire, namely, with length variation (35, 70, and 150 mm) and also with and without anchors, were used. The impact test results show that the ballistic limit of anchored PE-SMA composites with an embedment length of 35 mm is 72.72% higher than that of the homogeneous glass/epoxy composites. CAI results indicate that the PE-SMA based composites have better damage tolerance with respect to the homogeneous ones at 70 m/s. In contrast, at higher velocities, the delamination area decreases in the homogenous glass/epoxy composites due to more localized damage and present a higher compressive strength.

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.

The fracture properties of fiber metal laminates based on a 3D printed glass fiber composite

Fiber Metal Laminates (FML) are structures that contain a sequential arrangement of metal and composite materials, which are of great interest to the aerospace sector due to the superior mechanical performance. The traditional manufacturing process for FML involves considerable investment in manufacturing resources depending on the design complexity of the desired components. To mitigate such limitations, 3D printing enables direct digital manufacturing to create FML with customized configurations. In this work, a preliminary mechanical characterization of additively-manufacturing-enabled FML has been investigated. A series of continuous glass fiber-reinforced composites were printed with a Markforged system and placed between layers of aluminum alloy to manufacture hybrid laminate structures. The laminates were subjected to tensile, interfacial fracture toughness, and both low-velocity and high-velocity impact tests. The results showed that the FMLs appear to have a good degree of adhesion at the metal-composite interface, although a limited intralaminar performance was recorded. It was also observed that the low and high-velocity impact performance of the FMLs was improved by 9–13% relative to that of the constituent elements. The impact performance of the FML appeared to be related to the fiber fracture, out of plane perforation and interfacial delamination within the laminates. The present study can provide an initial research foundation for considering 3D printing in the production of hybrid laminates for static and dynamic applications.

The Mechanical Properties of Fiber Metal Laminates Based on 3D Printed Composites.

The production and mechanical properties of fiber metal laminates (FMLs) based on 3D printed composites have been investigated in this study. FMLs are structures constituting an alternating arrangement of metal and composite materials that are used in the aerospace sector due to their unique mechanical performance. 3D printing technology in FMLs could allow the production of structures with customized configuration and performance. A series of continuous carbon fiber reinforced composites were printed on a Markforged system and placed between layers of aluminum alloy to manufacture a novel breed of FMLs in this study. These laminates were subjected to tensile, low velocity and high velocity impact tests. The results show that the tensile strength of the FMLs falls between the strength of their constituent materials, while the low and high velocity impact performance of the FMLs is superior to those observed for the plain aluminum and the composite material. This mechanism is related to the energy absorption process displayed by the plastic deformation, and interfacial delamination within the laminates. The present work expects to provide an initial research platform for considering 3D printing in the manufacturing process of hybrid laminates.

Investigating the High Velocity Impact Behavior of the Laminated Composites of Aluminum/Jute Fibers- Epoxy Containing Nanoclay Particles

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.

Survivability of integrated fiber Bragg grating sensors in ballistic protection fabrics for high velocity impact testing

Abstract This research demonstrates that fiber Bragg grating (FBG) strain sensors can survive and provide useful strain information when integrated into a woven fabric subjected to ballistic impact testing. In this work, FBGs were integrated into a single-layer, Kevlar® fabric, sensing mat, placed between a 30-layer Kevlar® fabric shoot pack and clay backing material, and then impacted with an 8.23 g, 12.69 mm diameter, steel ball bearing at velocities up to 285 m/s. Three different optical fiber types, with differing fiber coatings and fiber diameters, were tested. The FBG strain response was determined from the full-spectrum FBG response which was interrogated at 100 kHz throughout the impact event. The difference in FBG strain response for the different coatings and fiber diameters were compared. Additionally, the degradation of the coatings after repeated impacts were visually characterized, showing that smaller diameter fibers behaved better with a more elastic coating.

Simple estimation method for strain rate sensitivity based on the difference between the indentation sizes formed by spherical-shaped impactors

The Johnson-Cook (JC) flow stress model is widely used in finite element analysis (FEA) in various fields to express the deformation behavior of metallic materials under high strain rate conditions. There is a need to facilitate an easier estimate of the JC parameter C, which is a material constant in the JC model associated with strain rate sensitivity. In this study, a simple estimation method for the JC parameter C, based on the difference between the indentation sizes formed by two spherical-shaped impactors, was proposed. The proposed method allows us to estimate the JC parameter C only by measurement of the indentation sizes formed via a high-velocity impact test, a drop impact test, or an indentation test. The fundamental equation was theoretically derived based on the energy conservation during the impact process of the impactor and the expanding cavity model, combined with the JC model and the equation of thermal conduction. To validate the proposed method, FEA was conducted using ten types of target materials under five impact velocity conditions, from 6 × 10−6 to 180 m/s. Based on the indentation depths obtained from FEA, the JC parameter C was estimated and compared with that input into FEA. As a result, it was confirmed that the estimated C is in agreement with that input into FEA within the relative errors of 10% under all impact velocity and target material conditions, except the target material of Ti6Al4V. From the results, it was demonstrated that the proposed method can easily estimate the JC parameter C, that is, the strain rate sensitivity, in the wide range of strain rate from 102 to 105 s−1.

Enhancement of the ballistic performance of aramid fabric with polyurethane and shear thickening fluid

Conventionally, the shear thickening fluid (STF) is used to improve the ballistic performance of aramid fabric because its shear thickening property increases the friction of inter-yarns. However, intuitively, enhancing the inter-yarn adhesion is an easier method. In this study, the adhesive polyurethane (PU) was utilized. The aramid fabrics impregnated with STF, the composite of STF and PU (STF-PU), and PU were compared in terms of the resistance to single yarn pull-out, the flexibility of fabric and the high-velocity impact test, respectively. Due to the robust adhesion of PU, comparing with STF/aramid fabric, a small amount of PU within STF-PU could strengthen the resistance of inter-yarn relative motion significantly and decrease mass loading intensively. Meantime, the flexibility had a little compromise due to unique heterogeneous structure in striking contrast with PU/aramid whose flexibility was impaired extremely. When it came to the high-velocity impact test, STF-PU/aramid showed outright advantages over STF/aramid and PU/aramid composite. It was also illuminated that excessively strong resistance to the yarn mobility was adverse for the high-velocity impact. Confidently, this work provides a new avenue in the development of flexible armor.

Simulation of high velocity impact test on GFRP

The fundamental requirement in different applications of composites is resistance to high velocity impact loading. The present study is about simulating and investigating high velocity impact tests on E-glass/epoxy composite. The modelling of the composite plate and the projectile is done using Ansys Composite Prepost. The material used for the projectile is mild steel. The impact tests were simulated in Ansys Explicit Dynamics with hemispherical nose configuration and compared with results obtained from experiments done by previous work. Additional simulations were carried out using conical and cylindrical nose configurations. The ballistic limit of the composite is also obtained in each of these cases. Different aspects of the impact mechanism such as formation of cone on the back face of the target, distribution of stress on both the faces were investigated. The impact tests were carried out in previous works using gas gun method where a compressed gas gun bullet is used to penetrate the target. It is concluded that the simulated results had a good agreement with the experiments.

Ferrocement Panels under High Velocity Impact by Incorporating Waste Foundry Sand

Ferrocement is widely used because of its excellent behavior pf ferrocement under flexural, and impact strength. Ferrocement also has excellent mechanical properties. In this study, total 16 ferrocement panels were modelled of M50 grade of concrete. The thickness of ferrocement panels considered is 15mm, 20mm and 25mm. Galvanized welded mesh is used as reinforcement in panels. This wire-meshes were layered in 2, 3, 4 and 5 layers. High velocity impact test is done by Ak-47 bullet striking with a velocity of 150, 250, 350, 450, 550, 650 and 750 m/s for each panel. All this panels were modelled in design modeler of Ansys explicit Dynamics. Deformation, Equivalent Stress and Normal Stress of all the panels are evaluated and compared by analyzing in ANSYS Explicit Dynamics. From the past researches and the conclusions made by these researches, we can see positive chance in the utilization of waste foundry sand in construction field. As these results gives the great emphasis towards the development on environment friendly and economical constructions.