High Velocity Impact Response Research Articles

High-Velocity Impact Response of Directly Recycled Aluminium Alloy AA6061 Plates

High-Velocity Impact Response of Directly Recycled Aluminium Alloy AA6061 Plates

Experimental investigation of high-velocity impact response and compression after impact behavior of continuous carbon fiber thermoplastic composites

In order to meet the urgent needs for the application of thermoplastic composite structures in aircraft manufacturing and other fields, the impact resistance and damage tolerance of continuous carbon fiber reinforced thermoplastic composite laminates (CCFRTP) are investigated by high-velocity impact (HVI) and compression after impact (CAI) experiments in this paper. The impact experiment results show that the ballistic response of laminates under small-angle conventional impact is similar, and the impact resistance of laminates under large-angle oblique impact is significantly improved. The failure mechanism of laminates under high-velocity impact is revealed by analyzing the impact process of the projectile, the energy absorption level, the failure morphology and internal damage degree of laminates comprehensively. It is clear that the impact angle and velocity of the projectile will significantly affect the coupling form of the failure mechanism and lead to differentiated results. The results of in-plane compression experiment of laminates with impact damage show that the bearing capacity of laminates is significantly weakened by high velocity impact damage, and the residual strength of laminates is directly determined by the mode and degree of impact damage. In particular, through the analysis of the energy absorption mechanism, a trend prediction model of ballistic limit value with impact angle is established, and the influence of high-velocity impact damage on the residual strength of laminates is revealed. This study provides a better understanding of the mechanical response of thermoplastic composite structures to high-velocity impact loads.

Ballistic performance of thin CFRP laminates under complex in-plane preload

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.

Experimental and numerical investigation on high-velocity hail impact response of TC4 titanium alloy plates

This work studied the dynamic response of hail impacting on TC4 titanium alloy plates under different influence factors. Experiments were performed according to China Civil Aviation Regulations Airworthiness Standards. The damage to the plate was recorded by in-situ cameras. The experimental results indicate that the greater the hail velocity, the more severe the damage to the titanium alloy plate. In the simulation, Smoothed Particle Hydrodynamics (SPH) method was used to model the hail. The reliability of numerical model was verified by the comparison with the test results of hail impact response. The numerical results show that the deformation of the plate increases as the impact angle and hail diameter increases. Moreover, the changes in impact angle and position will both alter the displacement and strain distribution within the plate. Through comparative analysis of the impact velocity, hail diameter, impact angle, and impact position on the impact force peak, plastic strain energy, and maximum kinetic energy of the plate, it is found that changes of hail diameter and velocity have great effect on the response of titanium alloy plate, and the impact position has little effect on it. There is a power-law relationship between the hail impact peak force and the hail velocity with an index of 1.912.

Dynamic behavior of multilayered skin structure: A preliminary numerical and analytical microscopic analysis

High-velocity micro-particle impact on multilayered skin structure is of interest in the framework of transdermal drug delivery system. The understanding of the physical impact process in this phenomenon is complex and lack of experimental investigations in the literature. This work aims to investigate the impact responses of multilayered skin structure impacted by high-velocity micro-scale particle utilizing numerical and analytical analysis. Numerical and analytical analysis were conducted based on Smoothed Particle Hydrodynamics (SPH) method and Poncelet model, respectively. A good agreement exits between analytical and numerical penetration trajectories and velocity-penetration relationships with an initial impact velocity of 200 m/s, while the discrepancies increase with a higher velocity of 600 m/s. The comparison between analytical and numerical results reveals that the developed numerical model is able to reasonably predict the impact responses of different skin layers under micro-particle impact. The present work is a first step to study high-velocity micro-particle impact responses applying real multilayered skin structures and mechanical properties, which could be further investigated to interpret and guide the design of transdermal drug delivery equipment.

Bio-inspired interleaved hybrids: Novel solutions for improving the high-velocity impact response of carbon fibre-reinforced polymers (CFRP)

We propose a novel design methodology consisting of bio-inspired (BI) and interleaved layups to develop hybrid carbon fibre-reinforced polymer (CFRP) composite structures for improved high-velocity impact (HVI) performance. Firstly, we apply a BI helicoidal design method consisting of various pitch angles (considering both thick- and thin-ply CFRP) to develop BI monolithic CFRP laminates. Secondly, we apply the interleaving design method to develop BI hybrid CFRP-based laminates interleaved with blocks of BI Zylon fibre-reinforced polymers through the thickness. We evaluate their response and compare it with traditional quasi-isotropic (QI) hybrid bulk layups. In addition to hybridising with Zylon, we apply titanium (Ti) foils to both the monolithic and hybrid CFRP-based laminates to investigate and compare their response. For all our hybrids, we kept the ratio of the hybridising material(s) to be less than 50% to ensure suitable in-plane mechanical properties and aimed at a target areal weight of 0.95 g/cm2. We also manufactured QI thick- and thin-ply monolithic CFRP laminates as baselines. We tested all laminates at 170 and 210 m/s and studied their response and failure modes. Our results show that the average energy dissipation of the QI monolithic thin-ply baseline improved by up to 22% by changing the layup from QI to BI, and by about 118% by changing the baseline QI layup to BI hybrid interleaved. Post-mortem analysis reveals that there are additional failure mechanisms activated in the BI hybrid interleaved layup with respect to the baseline.

Novel zone-based hybrid laminate structures for high-velocity impact (HVI) in carbon fibre-reinforced polymer (CFRP) composites

We propose novel zone-based hybrid laminate concepts for improving the high-velocity impact (HVI) response of baseline carbon fibre-reinforced polymer (CFRP) composites while maintaining similar areal weights and retaining substantial in-plane mechanical properties by requiring that about 80% (by mass) of the baseline CFRP is kept in the hybrid concepts. We identify three zones along the thickness of the laminate according to their role during HVI and implemented tailored materials in these zones to improve the HVI response. We studied a wide range of materials, including: fibre reinforcements of carbon (thin- and thick-plies), glass, Zylon and ultra-high molecular weight polyethylene (UHMWPE); a shape memory alloy/carbon fabric; and ceramic, alumina and titanium sheets. All laminate concepts have similar areal weights for a meaningful comparison. After defining the various concepts, we manufactured and measured their specific dissipated energy under HVI, and finally carried out post-mortem analysis (including C-scan and microscopy). The results show up to 95% improvement in energy dissipation over the baseline quasi-isotropic (QI) CFRP configuration.

High velocity impact response of carbon/epoxy composite laminates at cryogenic temperatures

Composite laminates are subjected to cryogenic temperatures in exposed aircraft structures during flight or in cryogenic tanks. The combination of cryogenic temperatures and high velocity impacts represents a threat to their integrity. This work investigates the behaviour of carbon-epoxy laminates under high velocity impacts (from 70 to 500 m/s) at room and cryogenic (-150 °C) temperatures and under two different plate orientations with respect to the projectile direction. The damage pattern of impacted specimens at low temperature, revealed by C-scan and X-ray tomography, exhibits a higher density of fiber breaks and shear matrix cracks which do not translate to a larger projected damaged area. The experimental analysis through interlaminar shear strength tests and the calculation of ply thermal stresses exclude the association of this particular pattern to damage mechanisms induced during the temperature decrease.

Experimental and numerical study on the dynamic response of aluminum alloy wood sandwich panels under high-velocity impact

The purpose of this study was to investigate the high-velocity impact response and failure modes of three-layer sandwich panels consisting of aluminum alloy sheets and plywood. The energy absorption mechanism and interaction between the plywood core and aluminum alloy panels were investigated by a high-velocity impact test. Different types of bullets were used in the impact test, and impact velocity parameters were obtained using a high-velocity camera to assess damage patterns. A full-scale finite element model was established to simulate the response mode of plywood sandwich under high-velocity impact. After the finite element model was verified by the experimental results, the energy absorption of the sandwich structure was further discussed. The results showed that the sandwich structure provided better protection than the double-layer structure. The analysis and predictions were in good agreement with the experimental results and numerical calculations. The experimental and numerical studies proposed in this paper are expected to provide new references and ideas for the design of multilayer structures with better impact resistance and lightweight characteristics.

High velocity impact response of sandwich structures with auxetic tetrachiral cores: Analytical model, finite element simulations and experiments

This paper investigates the energy absorption and deformation characteristics of sandwich structures with auxetic tetrachiral core under high velocity projectile impact. The finite elementmodel of the structure is developed using the Johnson-Cook material model and is used to studythe effects of projectile impacts forvelocities between150 and 450 m/s. TheFE model is validated usingin-houseexperiments on 3D printed PLA sandwich with tetrachiral core under hemispherical projectile impact and also using experimental datareported in the literature. Further, a semi-analytical model is developed to estimate the residual velocities and energy absorption of sandwich structure under blunt projectile impact, which shows good agreement with the FE results with an error of less than 8%. Finally, the performance of the sandwich structure with tetrachiral cores is studied under projectile impact for velocities ranging from 150 to 350 m/s and compared with sandwich structures with re-entrant and double arrowhead cores. The results show that for velocities above the ballistic limit, the energy absorbed by the facesheets, and core are nearly constant and is greatest for blunt projectile impact, followed by hemispherical, ogive, and conical geometries. Furthermore, sandwich structures with auxetic cores exhibit better energy absorption characteristics compared to those with hexagonal honeycomb cores.

Review of mechanical properties and impact response of PLA auxetic structures

In this paper, mechanical properties under quasi-static loading conditions and low to high-velocity impact response of Poly-lactic acid (PLA) material produced by the Fused Deposition Modeling (FDM) 3D printing method, having auxetic and non-auxetic geometric structures are critically assessed. Specifically, the load–displacement curve under various loads and parameters, such as energy absorption and the existence of the NPR effect with varying applied loads, are investigated. The effect of a large collection of material parameters, process parameters, and geometrical effects on load–displacement curves, strength, stiffness, and energy absorption are discussed in detail. The in-depth studies on auxetic structures of PLA, for quasi-static compressive load and low to high-velocity impact load, have shown that its impact resistance is superior to that of its non-auxetic counterparts. Also, a method for predicting peak load and maximum displacement for low-velocity impact derived from quasi-static loading data is discussed.

The origin of high-velocity impact response and damage mechanisms for bioinspired composites

Natural materials such as nacre abalone shells are often leveraged for inspiration in developing high-performing materials for impact protection applications. However, a comprehensive understanding of the microstructure-property relationships and their corresponding damage mechanisms in bioinspired designs under high-speed impact has not yet been fully studied. In this paper, the mechanism of the high-speed impact performance of nacre-inspired microstructures is presented, considering a set of design parameters using high-throughput computational simulations. Results show that adding interfacial waviness to traditional nacre designs enlarges the damage area, and an inclined interface helps to effectively block the crack and stress wave propagation, leading to superior impact performance. Moreover, an asymmetric microstructure tends to rotate an impactor, causing it to travel a longer path yielding larger energy dissipation. It is envisioned that pinpointing the superior features embedded in nacre-like structures can provide unique design guidelines for next-generation impact-resistant materials. • Impact resistance of bioinspired composites studied using computational simulations • Toughening mechanisms presented by investigating crack and stress wave propagations • Microstructural design effects on impact performance under different velocities Lee et al. present the mechanism of high-speed impact performance of bioinspired microstructural designs using high-throughput computational simulations. Results show that adding interfacial features such as waviness and incline can enlarge the damage area and help to effectively block the crack and stress wave propagation, leading to superior impact performance.

High velocity impact behavior of Hybrid composite under hydrostatic preload

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.

High-velocity impact response of cylindrical tubes with linear gradient grooves: A comparative study

Grooved tubes benefit from optimized energy absorption characteristics compared to regular tubes. This paper investigated the crashworthiness characteristics of cylindrical tubes with various types of grooves under high-speed impact loads. Furthermore, the dynamic load response of tubes with external grooves having linear thickness distribution was studied experimentally and numerically for the first time. To assess the performance of gradient grooved tubes (GGTs), the crashworthiness of typical cylindrical specimens and tubes having internal or external grooves with uniform thickness distributions was compared. The results showed that the dynamic crush mode of GGTs was axisymmetric, progressive, and sequential. Furthermore, the mean crushing force (MCF) in GGT tubes was considerably less compared to other tubes (e.g., 89% difference between GGT and non-gradient tube). Moreover, the initial peak forces of all types of tubes having the same number of grooved sections were almost in the same range. However, the crushing force efficiency of GGTs was remarkably lower than other tubes due to their non-uniform load response. The numerical results showed that by increasing the number of grooves in GGTs, peak force, energy efficiency, and axial shortening decreased, but mean crushing and overall crushing forces increased. Altogether, the highest energy efficiency belonged to the GGT specimens, in which 17%, 4.2%, and 96% increases were observed compared to external and internal groove tubes and typical cylindrical tubes, respectively. Also, the energy efficiency increased with the number of grooves.

High-velocity projectile impact response of rubber-coated aramid Twaron fabrics

The impact response of aramid Twaron CT709 fabrics thinly coated with a commercially available spray-on rubber material has been studied for the first time. Both neat and rubber-coated fabric targets were subjected to impact using 12 mm, 7.05 g spherical steel projectiles. The impact velocities ranged from 150 to 250 m/s. Each target consisted of three plies of neat or coated fabrics. Residual velocities, impact velocities and transverse deformation profiles were recorded using a high-speed camera, and the mechanism of failure and energy absorption were studied. It was observed that the ballistic limit velocity (BLV) increased by 18% in the rubber-coated specimens compared with neat fabric specimens. A critical velocity (Vc) was established below which the coated targets absorbed higher energy than their neat counterparts. The rubber coating was found to promote a membrane effect with global deformation to failure leading to higher energy absorption than the neat counterparts. However, the coated samples absorbed lower energy for impact velocities greater than Vc. At these velocities, the rubber-coated specimens showed localised failure leading to lower energy absorption than the neat counterparts. A novel numerical modelling approach was proposed to simulate coated fabrics, and the models predicted the BLV with high accuracy (error < 4%).

Experimental investigation of high velocity impact response of CFRP laminates subjected to flyer plate impact

Carbon fiber reinforced plastic (CFRP) composites are widely used in aircraft and automotive industries due to their extremely high specific strength and stiffness. High velocity impact is inevitable throughout the service life of composite structure and it is important to understand its impact response. In this study, high velocity impact response of CFRP laminates subjected to flyer plate impact were investigated in the velocity range of 32∼100 m/s by a gas gun coupled with 3D Digital Image Correlation (DIC) analysis. For comparison purposes, similar tests were carried out on 2A12 aluminum alloy plates of equivalent thickness. The PVDF pressure sensor was used to measure the impact pressure of the target plate, and the influence of impact velocity and target type on the impact pressure was analyzed. The damage and failure mechanism of CFRP laminates during impact were analyzed by digital microscope, ultrasonic C-scan and sectional image. The results show that the variation trend of the theoretical impact pressure is consistent with that of the experimental impact pressure, and the experimental impact pressure is smaller than the theoretical impact pressure. The damage and failure mechanism of two target plates are different under high velocity impact. For 2A12 plate, a truncated circular cone-shape bulge is generated on the 2A12 plate and this damage patterns appears regardless of the impact velocity. For CFRP laminates, impact indentation with elongated splits extending from the indentation edges is observed on the impacted surface of the target plate. The delamination zone of the adjacent layers is distributed in a fan-shaped area and the delamination direction is consistent with the direction of the fibers in the front ply. The data from the experiments can be used to evaluate and refine composite material models and computational methodologies that are used to predict the impact response of composite.

Optimization of target thickness and investigation on the effect of heat treatment on the ballistic performance of aluminium alloy 7075 targets against hard steel core projectile

Optimization of target thickness and influence of heat treatment condition on the high velocity impact response of aluminium alloy 7075 targets have been determined. Both experimental and numerical studies were conducted using a 7.62 mm hard steel core projectile. The numerical simulation used a 7.62 mm Ogival nose shaped projectile with a target thickness ranging from 20 to 26 mm. High velocity impact experiments on T651 and solution treated targets, with rolled plate thicknesses ranging from 21 to 25 mm were carried out to validate the numerical findings. The microhardness of the targets was measured using Vicker's microhardness tester and fractographs were examined using a scanning electron microscope. The projectile penetrated regions were analyzed using light microscopy. A good correlation between the numerical and experimental ballistic behaviour of aluminium alloy 7075 targets was observed and an optimum target thickness of 21 and 24 mm was observed for the T651 and solution treated targets to prevent the projectile's penetration. It was also noted that, after the projectile's impact, solution treated targets had higher microhardness compared to T651 condition targets. This is due to higher work hardening of solution treated targets near the penetration channel. Even though T651 targets have a lower depth of penetration compared to solution treated targets, ‘splintering’ failure of the T651 targets is observed. In contrast, ‘petalling’ and ‘plugging’ kinds of failures were noticed on the solution treated targets. Thus, solution treatment of ballistic targets may enhance the ballistic limit of armoured vehicles.

High velocity impact response of corrugated core composite sandwich structures

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 [Formula: see text] 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.

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.

Experimental and numerical analysis of the ballistic response of agglomerated cork and its bio-based sandwich structures

Considering the susceptibility of sandwich structures to impact events and the increasing environmental awareness due to pollution, the present work provides a thorough understanding of the ballistic impact behavior of agglomerated cork and of the resulting green sandwich structures produced with polypropylene (PP) skins reinforced with a flax/basalt intraply hybrid fabric. The effect of density on the agglomerated cork response was evaluated (NL10 ρ = 0.14 g/cm3, NL20 ρ = 0.20 g/cm3 and NL25 ρ = 0.25 g/cm3) and a comparison with commercial polyvinyl(chloride) foams was provided (HP130 ρ = 0.13 g/cm3, HP200 ρ = 0.20 g/cm3 and HP250 ρ = 0.25 g/cm3). The effect of a maleic anhydride coupling agent on the mechanical properties of the skins and of the overall sandwich structures was also investigated. The results highlighted a compromising effect of the weak interface between cork granules and polymeric binder on the impact resistance of the agglomerated cork, but a clear improvement of its performance was observed when embedded as core material between the two skins. Indeed, the two classes of sandwich structures produced with neat PP skins and with the two cores with the same density, i.e. agglomerated cork NL10 and PVC foam HP130, displayed the same ballistic limit of 171 m/s confirming that cork integration in the overall structures allows to approach PVC foam performance. The high-velocity impact response of one agglomerated cork (NL25) and one PVC foam (HP130) was also subjected to finite element analysis employing the CRUSHABLE FOAM model available in ABAQUS obtaining a good fitting with the experimental data.