High Velocity Impact Behavior Research Articles

Experimental and numerical investigation on the compression after high-velocity impact behavior of composite laminates

Considering the differences in damage mechanism between high-velocity impact (HVI) and low-velocity impact (LVI), this study conducted HVI tests and compression-after-impact (CAI) tests to reveal the post-impact compression behavior of laminates manufactured by unidirectional prepreg tape and exposed a completely different mechanical response in residual strength compared to that of LVI. By controlling the impact velocity within the range of 200 m/s ̃ 380 m/s, three kinds of impact results were obtained, including un-penetrated and penetrated conditions. Different CAI damage morphologies can be observed in these laminates. In order to fully understand the CAI damage mechanism induced by different HVI events, a surface-based cohesive behavior and a CDM intralaminar damage model were implemented. In addition, a more complete picture of the compression behavior after HVI was observed through the simulation results, which is of great help in estimating the residual strength of post-impact laminates. However, the HVI damage was introduced through the spherical steel projectiles, and the sample size was determined based on ASTM D7137, which might be different factors from the application conditions.

On strain rate effect and high-velocity impact behavior of carbon fiber reinforced laminated composites

In this paper, the tensile and in-plane shear behaviors of carbon fiber reinforced laminated composites (CFRLCs) under high strain rate loading were experimentally investigated. The strain and damage processes of the specimens were obtained using the Digital Image Correlation (DIC) method and a high-velocity camera. Quasi-static test results were used as the control group for obtaining the dynamic correction factors of the material system under high strain rate conditions. In addition, high-velocity impact (HVI) tests with different impact velocities and angles were conducted on CFRLCs. The dynamic correction factors were used in HVI simulations to consider the effect of strain rate. The energy absorption mechanisms and failure modes of laminates under different impact conditions were analyzed using testing and simulated results. It is found that during the HVI, matrix tension and fiber tension failures are the main failure modes. The energy absorbed by the laminate in oblique impact is larger than the one in normal impact. The possible reason is that the increase rate of the damage area with the four failure modes in oblique impact is larger than the one in normal impact.

High-Velocity Projectile Impact Behaviour of Friction Stir Welded AA7075 Thick Plates

High-Velocity Projectile Impact Behaviour of Friction Stir Welded AA7075 Thick Plates

A numerical study on high-velocity impact behaviour of ceramic composite laminates

Currently, silicon carbide (SiC) is of enormous concern because of its high compressive strength,high thermal conductivity, high thermal shock resistance and small coefficient of thermal expansion. SiC has its applicability in armored vehicles, hypersonic armaments, and bullet-resistant armours in the future. The current focus is on understanding the behavior of SiC as used in laminated ceramic armours during the ballistic impact for its profound use in armoured vehicles. To achieve these objectives, computational simulations have been performed for the aforementioned materials using ANSYS/AUTODYN. It was concluded that when SiC was used as a front layer in laminated armours, it significantly increased the strength of the material against the hitting projectiles. The aforementioned composite material was even successful against the sniper gun projectile. The optimized thickness for the given configuration was found to be 41 mm with the consideration of approximately 50% depth of penetration. The modeled configuration was found to be approximately nine times stronger than the conventional laminated armours. The current study was compared with the previous experimental studies and the results were in good agreement. This agreement solely pertains to the pattern observed and not to individual values. It indicated the difference in % age DOP for the present research and previous studies with the increasing thickness of laminated armour. The trend observed was nearly similar to previous experimental studies. This showed that the DOP was reduced, as the thickness increased. Moreover, the previous studies showed that only ALON (aluminium-oxynitride) and sapphire had the required strength to act as a hard front-faced layer in laminated glass, but the current study improvised it to a Silicon carbide hard front-faced layer also.

Synergistic effect of r-GO on the mechanical, microstructural and high velocity impact behaviour of synthetic fibre reinforced NiTi intermetallic laminates

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.

Microstructural evolution, shielding effectiveness, and the ballistic response of Mg/Al7075/B4C/Pb composite produced by combination of coating and severe plastic deformation (SPD) processes

Light-weight metal matrix composites reinforced by Pb and B4C are of interests in aerospace industry due to high strength to weight ratio and excellent shielding effectiveness. This paper investigates microstructure, shielding effectiveness, tensile properties, and high-velocity impact behavior of Mg/Al/B4C/Pb composite. In this composite, the B4C layer was deposited by electrophoretic deposition (EPD) on aluminum layers, then the sandwich with the stacking sequence of Mg/Al/B4C/Pb was fabricated through accumulative roll bonding (ARB). The optical microscopy (OM) and scanning electron microscopy (SEM) images illustrated that by increasing the cycles, all layers within composite experienced instabilities including necking and fracture. In addition, increasing the number of rolling cycles improved tensile properties, namely Young's modulus, elongation, yield, and ultimate strength. Furthermore, according to the results of the high-velocity impact test, by increasing the rolling cycle, less failure such as cracks and perforation was found on surfaces, indicating the enhanced ballistic resistance of composites. Plus, when composites were subjected to electron radiation, less relative doses of radiation were detected by dosimeter at higher rolling cycles which confirmed the attenuation of transmitted rays and then the enhancement of shielding effectiveness of composites.

High-velocity impact behaviour of curved GFRP composites for rail vehicles: Experimental and numerical study

This study aims to explore the projectile impact behaviour of curved glass fibre reinforced plastics (GFRP) composites for rail vehicles through experimental and numerical methods. Quasi-static material tests were firstly carried out to obtain the tensile, compression, shear and bending properties. Then, high-velocity impact tests under different velocities were conducted for curved GFRP plates, which were cut from hood covers of a rail vehicle. The residual velocity of the projectile, the failure modes and the energy absorption of the composite targets were analysed. The classical Lambert-Jonas equation was used to predict the critical perforation velocity, which was also verified by the following finite element (FE) simulation in LS-DYNA. Based on the validated FE model, the effects of the impact velocity (65.14–152.22 m/s), target thickness (2 mm–8 mm) and impactor shape (flat, blunt, hemisphere and sphere) on the high-velocity impact performance of the target were studied. The results showed that the predicted critical perforation velocity of the curved GFRP plate with thickness of 6 mm was about 101.98 m/s in this study, and only local damages were observed near the trajectory. Increasing the thickness of the GFRP plate can improve its anti-penetration capability, however, the 4-mm plate possesses the highest specific energy absorption among the thickness of 2 mm–8 mm. Compared to the sharp impactors, the flat impactor resulted in the highest peak force of 260.39 kN and the maximum specific energy absorption of 502.65 J in the curved GFRP plates with thickness of 6 mm, due to the shear failure mechanism and the formation of embolism.

Ballistic impact response of flexible and rigid UHMWPE textile composites: Experiments and simulations

This study elaborates on the effects of matrix rigidity on the high-velocity impact behaviour of UHMWPE textile composites using experimental and numerical methods. Textile composite samples were manufactured of a plain-weave fabric (comprising Spectra® 1000 fibres) and four different matrix materials. High-velocity impact tests were conducted by launching a spherical steel projectile to strike on the prepared samples via a gas gun. The experimental results showed that the textile composites gradually changed from a membrane stretching mode to a plate bending mode as the matrix rigidity and thickness increased. The composites deformed in the membrane stretching mode had higher impact resistance and energy absorption capacity, and it was found that the average energy absorption per ply was much higher in this mode, although the number of broken yarns was smaller in the perforated samples. Moreover, the flexible matrix composites always had higher perforation resistance but larger deformation than the rigid matrix counterparts in the tested thickness and velocity range. A novel numerical modelling approach with enhanced computational efficiency was proposed to simulate textile composites in mesoscale resolution. The simulation results revealed that stress and strain development in the more rigid matrix composite was localised in the vicinity of the impact location, leading to larger local deformation and inferior perforation resistance.

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 behavior of lignin/NR/hemp green composite: a comparative study

High-velocity impact behavior of lignin/NR/hemp green composite: a comparative study

High-velocity impact performance of Ramor 500 armor steel

Abstract In this study, the high-velocity impact behavior of Ramor 500 armor steel was investigated experimentally and numerically. For this purpose, the steel specimen was impacted by a 9 mm Parabellum full metal jacket (FMJ) bullet at the reliable polygon. On the other hand, the mechanical properties of specimens were found by a tensile test at different temperatures and Johnson–Cook (J-C) parameters were obtained by Split Hopkinson Pressure Bar (SHPB) test data. By using these data, the same test was simulated by ANSYS Explicit Dynamic. Results show that experimental and numerical results provide NIJ LEVEL IIIA conditions. In addition, the perforation thickness of Ramor 500 at the constant projectile velocity and the perforation velocity at the constant thickness were obtained by using ANSYS Explicit Dynamic.

Assessment of high-velocity impact effects on carbon fiber reinforced polymer sandwich panel with M-shaped core reinforced by nano-SiO2: Experimental and numerical study

This paper describes the high-velocity impact behavior of composite sandwich panels with different amounts of nano-SiO2. The sandwich panels were manufactured by carbon/fiber epoxy composite face sheets and an M-shaped core using the vacuum-assisted resin transfer molding method. To enhance the mechanical strength of the matrix, especially impact resistance, the nanoparticles were added to the resin epoxy matrix as filler with the ratios of 1%, 2%, and 3% of the composite's total weight. A scanning electron microscope was utilized to observe the microscopic structure of the composites, and it revealed an exceptional homogeneous mixture of nano-SiO2 particles in the resin epoxy matrix. Afterward, high-velocity impact tests were carried out using a single-stage gas gun test machine. A spherical steel projectile with a diameter of 8.7 mm was used for the test with a speed of 235 m/s. The experimental results indicated that adding 1–3 wt% of nano-SiO2 into the matrix remarkably increased the impact resistance of the composite. Moreover, the results showed that when the projectile collides with the core of the sandwich panel, it remains in the sandwich panel and its output velocity becomes zero, while when the projectile does not collide with the core, its output velocity is not zero. In order to validate the results, the experimental data were compared to the finite element models, and good agreement was observed.

Post repair high velocity impact behaviour of carbon-glass hybrid composite: Experimental and numerical study

In this work post repair high velocity impact behaviour of carbon-glass hybrid composite was investigated. Two parent hybrid laminates(H1:G2C4G2 and H2:C2G4C2), two double sided patches (P1: G2C2 and P2: C2G2) and two single sided patches (P3: G2C4G2 and P4: C2G4C2)) were used in this study. The velocities in the range of 80-120 m/s were considered for this study. The effect of patch type and stacking sequence of patch plies on the impact resistance were studied. A 3D finite element model based on continuum damage mechanics approach was also developed to further understand the effect of the ratio of glass to carbon plies in a patch. The Hou damage initiation criteria and strain based damage evolution criteria were incorporated in the proposed numerical model. Overall, the P3 patch repair specimen performed better than all patch repaired specimens and the P2 patch repair specimen performed better than all double side patch repaired specimens. The P3 patch repaired specimen showed an 8% higher ballistic limit than the P2 repaired specimen patch. It was also observed that number of glass plies in the patch govern the damage development in the specimen and residual velocity of projectile.

High-velocity impact resistance of doubly curved sandwich panels with re-entrant honeycomb and foam core

This work describes the high-velocity impact behavior of doubly curved sandwich panels. The sandwich panels are manufactured using carbon/fiber epoxy composite face sheets, polyurethane foam core and 3D-printed PLA plastic cellular auxetic (re-entrant) honeycombs. High-velocity impact tests are carried out by using a single-stage air gas gun test machine. A spherical steel projectile with the radius of 5 mm is impacted to the center of the specimens with the speed of 100 m/s. The experimental data are used to validate explicit finite element models of the doubly curved structures. An analytical model is also developed for the ballistic limit of the flat and doubly curved sandwich panels, and the analytical results are compared to those obtained from the numerical ones. Parametric numerical analyses of the high-speed impact of the curved sandwich panels are then carried out considering various radii of curvature of the panels. The results show that the energy absorption is increased as the curvature is decreased for the panels with both foam and re-entrant core. In addition, the core configuration provides a key role in the impact resistance of the sandwich panels. Re-entrant models show an increase in specific energy absorption (SEA) compared to the foam core types.

Finite element study on the influence of fiber orientation on the high velocity impact behavior of fiber reinforced polymer composites

Finite element study on the influence of fiber orientation on the high velocity impact behavior of fiber reinforced polymer composites

Dry Sliding Wear and High-Velocity Impact Behaviour of Spark Plasma Sintered Ti-Ni Binary Alloys

This work investigated the dry sliding wear behaviour of spark plasma sintered (SPSed) Ti-Ni binary alloys produced at varying nickel content with alloy steel ball as the counterface material, at room temperature under varied applied normal loads. Finite element modeling was used to investigate the high-velocity impact response of the sintered alloys due to the dimensional constraint associated with SPSed samples. Microstructural analysis results revealed the presence of intermetallic phases of Ti-Ni with increasing nickel content. The best wear resistance ranging from 0.25 x 10-3 mm3/Nm to 0.22 x 10-3 mm3/Nm across all applied loads was obtained in Ti-6Ni alloy. This was attributed to the compaction of the protective triboxide and carbide layers on the surface of the sample. Oxidative and wear by adhesion were observed at low applied normal load while at high loads the prevalent wear mechanism was abrasive with reduced influence of oxidative and adhesive wear. Finite element analysis results also showed that Ti-6Ni alloy possessed the optimum combination of absorbed energy and ductility to reduce the possibility of brittle failure under impact loading. Keywords: Ti-Ni binary alloys; Spark plasma sintering; Dry sliding wear; High-velocity impact; Finite element analysis.

On the low- and high-velocity impact behaviour of hybrid composite materials at room and extreme temperature

A demand raised is how to improve the survivability of aircraft and naval structures concerning low- and high-velocity impacts. Since fundamental failure is due to mainly by fracture, a fundamental understanding of both mechanisms and mechanics of the material is crucial. It is important to understand the deformation and damage mechanisms involved in the impact to improve the design of composite structures. Several approaches have been exploited to improve the impact damage resistance of composite laminates in different conditions. Among these, the development of composite laminates stacking different fibres in the same matrix results very interestingly. This paper deals to investigate on the high and low speed impact performance of hybrid composite configurations made of glass/carbon and basalt fibres. Low-velocity impact at penetration and high speed tests at different impact velocity were carried out at the room and low temperatures to evaluate the goodness of hybridization proposed and the temperature effect on the composite performances. Among the three proposals, a hybrid basalt carbon configuration was identified as the best both at low speeds and at high impact speeds for both temperatures tested.

Insights into the high-velocity impact behaviour of bio-inspired composite laminates with helicoidal lay-ups

This study explored the impact response of two bio-inspired composite laminates with linear and non-linear helicoidal fibre architectures. The helicoidal laminates, together with quasi-isotropic and cross-ply control samples, were fabricated using heterocyclic aramid fibres and tested against a spherical projectile under high impact velocities. The results revealed that helicoidal lay-ups with small rotation angles led to inferior perforation resistance and energy absorption capacity when compared to the quasi-isotropic and cross-ply counterparts. The cross-ply configuration was confirmed as the optimal fibre architecture for impact perforation. Post-impact inspections highlighted that the failure mechanisms of laminates were significantly affected by their lay-ups. The number of fractured fibres was found to reduce with the decrease of inter-ply angle. This was due to the small rotation angles promoted a wedge-in mechanism. Moreover, a smaller angle mismatch resulted in diminished overall delamination area in a laminate. Due to these two effects, therefore, helicoidal lay-up configurations with small inter-ply angles are not recommended for impact-resistant laminates reinforced by tough fibres.

High-velocity impact behavior of hybrid fiber-reinforced epoxy composites

In this study, non-hybrid and hybrid (Kevlar, carbon and glass) fabric epoxy composite laminates were fabricated with different stacking sequences by hand lay-up followed by hot-compression molding. Experimental tests were conducted to investigate tensile, flexural, and hardness characteristics. It was found that the stacking sequence did not significantly affect the tensile strength and hardness values of the composites; however, it affected their flexural strength. Damage morphology of the specimens through SEM images showed that the major damage mechanisms in the composites were delamination, fiber breakage, pull-out, and matrix cracking. Based on the static experimental results, the high-velocity impact behavior was investigated through simulation study using LS-DYNA finite element analysis (FEA) software. To study the ballistic impact, a steel projectile with a hemispherical penetrating edge at impact velocities of 100 m.s−1, 250 m.s−1, and 350 m.s−1 was considered. Among non-hybrid fabric epoxy composite specimens, Kevlar/epoxy specimen was found to have the highest impact energy absorption followed by carbon/epoxy and glass/epoxy, respectively. Regarding the hybrid fabric epoxy composite specimens, the ones with Kevlar plies in the rear face exhibited better energy absorption compared to other stacking sequences. The non-hybrid glass/epoxy specimen had the lowest energy absorption and highest post-impact residual velocity of projectile among all specimens. From the FEA results, it was noted that impact resistance of hybrid composites improved when Kevlar fabric was placed in the rear layer. Thus, the stacking sequence was observed to be of substantial importance in the development of fabric-reinforced composite laminates for high-velocity impact applications.

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.