High Velocity Impact Response Research Articles

High-velocity impact response of titanium-based fiber metal laminates. Part II: Analytical modeling

This two-part article scrutinizes the influence of metal layer distribution through the thickness of titanium-based fiber metal laminates (FMLs) on their high-velocity projectile impact response and damage. The four different layups of FMLs consist of layers of glass fiber/epoxy and Ti-6Al-4V titanium alloy sheets, exhibiting the thickness of the total metal layer the same. Part I presents the experimental investigations of fully clamped FMLs demonstrating performance parameters, damage mechanisms, and ballistic resistance. Part II concerns the ballistic impact behavior of FMLs using analytical modeling, which is based on test results obtained in an accompanying study. An equivalent mass-spring system is used to obtain the transient deformation, ballistic limit, and absorbed energy of the laminate by various mechanisms. Good agreement is obtained between experimental and analytical ballistic limit velocity. The foremost part of the total energy absorption is by bending and membrane energy absorption (68 % - 72 %), with FML 4/3-0.3 absorbing a higher percentage of aforementioned energies followed by that of both FMLs 3/2 and FML 2/1-0.6. The predicted total energy absorption by several damage mechanisms of FMLs at the ballistic limit displays a reasonable matching with experiments.

High-velocity impact response of titanium-based fiber metal laminates. Part I: experimental investigations

This two-part article examines the distribution of metallic layers through the thickness of fiber metal laminates (FMLs) on their response and damage when subjected to high-velocity projectile impact. Glass fiber/epoxy and Ti-6Al-4V titanium alloy sheets are used to obtain four different layups of FMLs fabricating by the hand layup process and exhibiting the same thickness of the total metal layer. Part I deals with experimental investigations of fully clamped square FMLs normally impacting at the center by hemispherical steel projectile using compressed air gun set up. Different parameters are considered to evaluate the FMLs’ performance, which includes damage degree, first cracking energy, crack length, deformation profile, and damage developed on the surface and inside the laminate. The results indicate that the highest permanent deformation and cracking are exhibited by FML 4/3-0.3, exhibiting separation of composite layers with different orientations by the metallic layer. The other FMLs exhibit lower and approximately similar permanent deformations. However, lower cracking and a relatively higher lateral delamination spread and opening of the interlayer are exhibited by FML 2/1-0.6 in which composite layers are arranged together than FML 4/3-0.3, signifying that the damage spreading laterally can be reduced by dispensing titanium layers. The ballistic resistance is found to be similar for FMLs. The levels of permanent deformation, cracking, and delamination with their opening and spreading are lesser for titanium-based FMLs than aluminium-based FMLs. The ballistic response of FMLs will be evaluated using analytical modeling in an accompanying study (Part II).

Stochastic optimization and modeling of high-velocity impact tests on high-temperature carbon\u2013carbon composites

In this study, it is intended to optimize a high-velocity impact case of a composite plate. The case selected from literature focused on the failure response of advanced carbon–carbon (C/C) composites under high-velocity impacts. Based on the stochastic optimization method, three unique models are introduced within the present study's scope as dimensionless damage areas of front and back sides and the composite impact energy response. The difference between the equations found in the present study and the base study is the number of variables. Obtained prediction models consist of only the tests' input variables; thus, these models can be considered the essential prediction functions of high-velocity impact response of C/C composites under high temperatures. Multiple nonlinear regression method is used for objective functions of the optimization problem. Since the determination coefficient values have been found quite similar to the ones in the literature, the presented models can be considered successful in predicting the results. By utilizing the novel regression functions presented in this study, the damaged areas are minimized. Without the necessity of experimental research, further predictions can be made by operating the models found in the present study.

High Velocity Impact Response and Damage Mechanism of an Aluminium/Glass-Carbon Fiber/Epoxy Composite Plate Reinforced with Graphene Nano-plates

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.

High-velocity impact response of fiber metal laminates: Experimental investigation of projectile's deformability

The aim of this research is to investigate the influence of projectile's deformability on ballistic impact response of fiber metal laminates. High-velocity impact experiments have been carried out via a light gas gun setup using rigid, semi-rigid and deformable projectiles with the same diameter, nose shape and mass. Fiber metal laminates have been made of two identical aluminum facing plates and different number of glass/epoxy composite plies in the middle. Several local and global mechanisms for kinetic energy absorption of projectiles have been detailed and ballistic limit velocity, as well as specific perforating energy for all cases have been determined. The results indicated that by increasing the deformability of the projectile, the amount of local and global wasting energy mechanisms for dissipating the velocity of projectiles have been increased. Furthermore, the interaction between non-rigid projectiles and fiber metal laminate targets as well as permanent deformation of non-rigid projectiles, had important effects on preventing the projectile penetration. By increasing the deformability of projectiles and/or increasing the number of composite plies, permanent deformation of facing plates, fiber breakage, crushing as well as delamination and debonding have been increased and local damage modes in facing plates changed from petalling to plugging. Besides, rigid projectiles possessed less specific perforating energy compared with deformable projectiles and required minimum initial velocity for full penetration.

High velocity impact response of hybridized pseudo-woven carbon fiber composite architectures

This paper presents the automated fiber placement (AFP) manufacturing and high velocity impact response of hybrid pseudo-woven IM7/8552 carbon/epoxy composite laminates. Three 24 ply laminate configurations are studied where pseudo-woven sub-laminates are combined with traditional layups on the inside and outside, along with a third quasi-isotropic control laminate [45/90/-45/0]3s. Pseudo-woven sub-laminates are manufactured using a specialized in situ AFP process implementing tow skips. The pseudo-woven architecture is macroscopically heterogeneous with spatially varying fiber orientations both in-plane and through thickness resulting in multiple interfaces and an expanded design space. The impact experiments are performed according to ASTM D8101 in the range of 250–400 ft/s (76.2–121.92 m/s) using a single stage gas gun while utilizing digital image correlation and high-speed video to assess the laminate's response. Experimental results show that the hybridized configurations have a 45% reduction in back face surface damage, 19.5% less back face deflection and an increase of 5.5% in V50 velocity when compared to traditional laminate.

High velocity impact response of composite laminates using modified meso-scale damage models

High velocity impact response of quasi-isotropic carbon fiber reinforced polymeric laminates cured from unidirectional plies is studied using finite element models. Rigid steel spheres are used as projectiles. The intraply meso-model originally proposed by Ladevèze (LMT-Cachan) for the ply behavior based on continuum damage mechanics, is extended in this paper to take into account ply fracture energies and in-situ strengths. Constitutive modeling relies on mesh size regularization (via Bazant-type crack-band/smeared-crack formulation), orthotropic material aligned mesh and element erosion. Three different types of post-peak degradation strategies are considered and compared in the paper: (a) damage rate bound model, and smeared-crack formulation based (b) linear and (c) exponential softening laws. Models (b) and (c) are original contributions. Intraply and interply damage models are implemented via user routines in LS-Dyna, for explicit dynamic analyses. The efficiency of the novel material models to predict high velocity impact response and to mitigate the mesh size effects is studied. Predictions from the developed models are validated by comparing with test data and numerical results from the literature, and demonstrated that the two new models based on smeared-crack formulation provide accurate results.

High-Strain-Rate Behavior of a Viscoelastic Gel Under High-Velocity Microparticle Impact

Impact experiments, routinely performed at the macroscale, have long been used to study mechanical properties of materials. Microscale high-velocity impact, relevant to applications such as ballistic drug delivery has remained largely unexplored at the level of a single impact event. In this work, we study the mechanical behavior of polymer gels subjected to high-velocity microparticle impact, with strain rates up to 107 s−1, through direct visualization of the impact dynamics. In an all-optical laser-induced particle impact test, 10–24 μm diameter steel microparticles are accelerated through a laser ablation process to velocities ranging from 50 to 1000 m/s. Impact events are monitored using a high-speed multi-frame camera with nanosecond time resolution. We measure microparticle trajectories and extract both maximum and final penetration depths for a range of particle sizes, velocities, and gel concentrations. We propose a modified Clift-Gauvin model and demonstrate that it adequately describes both individual trajectories and penetration depths. The model parameters, namely, the apparent viscosity and impact resistance, are extracted for a range of polymer concentrations. Laser-induced microparticle impact test makes it possible to perform reproducible measurements of the single particle impact dynamics on gels and provides a quantitative basis for understanding these dynamics. We show that the modified Clift-Gauvin model, which accounts for the velocity dependence of the drag coefficient, offers a better agreement with the experimental data than the more commonly-used Poncelet model. Microscale ballistic impact imaging performed with high temporal and spatial resolution can serve as direct input for simulations of high-velocity impact responses and high strain rate deformation in gels and other soft materials.

High-velocity impact response of metallic sandwich structures with PVC foam core

In this study, the deformation and damage behaviors of sandwich plates with composite foam core subjected to high velocity impact of metallic foam projectile are investigated. A series of experiments was conducted to address the dynamic response, failure modes and energy absorption characteristics of the sandwich plates with different configurations. The dynamic behavior of the sandwich plates was analyzed by using 3D-DIC technique with high speed cameras. The failure modes of the sandwich plates as well as front face sheet, foam core and rear face sheet were identified and discussed. The results indicate that the symmetric deformation of rear face sheet increased with the impact loading increasing, and the core with greater thickness lengthen the responding time of the structures effectively. Compared with the thickness of core, core density played the more important role on improving the impact resistance of the sandwich plates at same areal mass. The effect of sequence of core layers on the impact resistance can be neglected in this study. Additionally, the energy absorption analysis of the six different configurations exhibited that the plates with high density core provided more stable and superior energy absorption efficiency. The study could provide a valuable reference for designing more efficient light weight protective structures.

Comparative study of high velocity impact response of aluminium 3105-H18 and carbon fibre-epoxy composite double hat bumper beams

The quest to reduce the energy consumption in automotive has resulted in the development and use of lightweight materials for the design of vehicles. Also, stiffer legislation is being put in place to enforce the utilization of lightweight components for vehicles in order to guarantee the safety of both pedestrians and passengers. Hence, the bumper beams of a vehicle which is a major contributor to its total weight must be made of lightweight materials capable of absorbing kinetic energy developed during a collision. In this paper, the impact response of a double hat bumper beam made with two different materials, aluminium Al (3105-H18) and carbon fibre-epoxy composite and subjected to a high-velocity impact was simulated using finite element analysis code, Abaqus CAE/2019. The response of both materials was compared, and the results show that carbon fibre-epoxy composite absorbed equal amount of energy as aluminium during collision and thus, can be used as a bumper beam for vehicles.

High-velocity impact response of CFRP panels reinforced with stiffeners

With a goal of reducing the weight of fan blade containment system for jet engine, the high-velocity impact response of carbon fiber reinforced polymer (CFRP) panels reinforced with stiffeners were tested and analyzed. Ballistic impact tests on stiffened panels have been carried out with cylindrical Ti-6Al-4V projectiles at different velocities (210 m/s, 70 m/s and 90 m/s). Results showed there was a significant influence observed due to different impact velocities on the response of the panel skin and the stiffener, and the middle stiffener played an important role in impact energy absorption. Numerical simulations were conducted to provide further insight into the target response by employing a user subroutine VUMAT with revised Hou criteria in commercial finite element (FE) software ABAQUS. The stiffened CFRP panel was found to possess a 14% higher critical penetrating velocity than the CFRP laminated plates with same mass by using validated FE models. Combining with detailed discussion of high-velocity penetration process, the energy absorption mechanism of the stiffened panel under high-velocity impact was analyzed, indicating that the improvement on high-velocity impact response is due indirectly to structural alteration induced better energy absorption by less punch-shear laminate breakage and more fiber tensile failure.

Mechanical and high velocity impact performance of a hybrid long carbon/glass fiber/polypropylene thermoplastic composite

This research explores mechanical and high velocity impact response of hybrid long carbon/glass fiber-reinforced polypropylene thermoplastic composites (HLFT) with different fiber lengths. The work examines three hybrid long fiber thermoplastic composites, i.e., 5, 10 and 20 mm. The HLFTs were prepared by a combination of extrusion and pultrusion processes and using a cross-head die. Tensile and Izod impact tests were carried out to evaluate the mechanical performance of each HLFT compound. A gas gun with a spherical projectile was used to conduct high velocity impact tests at three velocities of 144, 205 and 240 m/s. The results showed that internal mixing operation caused extensive reduction in fiber length of all three LFT lengths. Tensile strength, modulus and Izod impact test results were the indications of higher values with increase in HLFT length. Comparison of these results for the HLFT with that of corresponding glass/PP LFTs, adopted from earlier work by Shayan Asenjan et al. (J Compos Mater 53:353–360, 2019), showed better performance of HLFT. The high velocity impact results showed a steady higher impact performance with the increase in HFLT fiber length for all impact velocities tested. Comparison of HLFT high velocity impact performance revealed better results for all impact velocities tested with that of the corresponding glass/PP LFT composite.

Anti-impact behavior of auxetic sandwich structure with braided face sheets and 3D re-entrant cores

The effectiveness of sandwich structure with auxetic 3D re-entrant lattice core and semi-auxetic braided composite face sheets subjected to high-velocity impact have been investigated. Braided carbon fiber composite used in face sheets of sandwich structure with a through-thickness negative Poisson’s ratio significantly improves the impact performance. A semi-analytical Mori-Tanaka asymptotic homogenization, mechanics of structure genome, and multiscale finite element scheme have been applied to study the mechanical properties and auxeticity of the braided composite. The properties obtained at the lower scales are used in a macroscale progressive damage analysis and impact simulations of semi-auxetic braided composite. The results obtained have been compared with experimental data from the literature for validation. The sandwich core holds further scope for tailoring its architecture that can enhance the sandwich performance. The high-velocity steel ball impact response of the sandwich structure with two types of auxetic 3D re-entrant lattice core have been simulated and compared with a non-auxetic core. Parametric studies have been performed at the mesoscale to study the influence of lattice angle on homogenized effective properties of the core. Compared to non-auxetic foam, proposed auxetic sandwich structures are lightweight, have better energy absorption and high stiffness values in the in plane along with out-of-plane directions. A case study of trauma plate for the application of proposed auxetic lattice reinforced polyethylene composite in body armors is presented.

High Velocity Impact Response of Aluminum- Carbon Fibers-Epoxy Laminated Composites Toughened by Nano Silica and Zirconia

This research work investigated the effects of SiO2 and ZrO2 nanoparticles type and content incorporated into an epoxy matrix on the high velocity impact behavior of carbon fiber reinforced aluminum laminates (CARALL). CARALL specimens consisted of a 0/90/90/0 stacking sequence of a carbon-epoxy composite containing 0, 1, 3, 5 and 7 wt% of each of nanoparticles sandwiched between two layers of aluminum 2024-T3. To observe the toughening effects of the nanoparticles on the fracture surface of the impacted CARALL, a typical field emission scanning electron microscope (FESEM) was employed. Impact energy absorption of CARALL was at most increased by 18 % and 12 % with the nanoparticles content of 5 wt% SiO2 and 3 wt% ZrO2, respectively. Overloading of the nanoparticles content up to 7 wt% resulted in the creation of nanoparticles aggregated sites associated with loss in the energy absorption capacity. FESEM fractography procedure also showed that the crack deflection and pinning were the most recognizable toughening mechanisms exhibited by nanoparticles. Overall, the controlled addition of SiO2/ZrO2 rigid nanoparticles to CARALL was found to be a promising method for improving the high velocity impact energy absorption of CARALL.

The effect of hybridization on high-velocity impact response of carbon fiber-reinforced polymer composites using finite element modeling, Taguchi method and artificial neural network

In this paper, the effect of hybridization of carbon fiber-reinforced polymer (CFRP) composite laminates was investigated on the high-velocity impact responses of laminates using a validated finite element model, the Taguchi and the artificial neural network methods. The CFRP laminates were hybridized by replacing half of the carbon layers with glass and Kevlar laminae. It was found out that employing the right hybrid materials on the right position of the laminate can considerably change the damage pattern and consequently reduce the projectile residual velocity by increasing the energy absorbed by the CFRP laminate. Introducing four Kevlar laminae on the back of the CFRP composite laminate instead of the four carbon layers resulted the highest improvement in the laminate energy absorption by 67%. The hybrid laminates experienced wider damage zone and more extensive delamination compared to the CFRP laminate. Introducing the hybrid materials with high strength and strain to failure material such as Kevlar on the back of the laminate in the presence of CFRP front face can be considered as an appropriate hybrid composite laminate when exposed to high-velocity impact loading.

Compression after ballistic impact response of pseudoelastic shape memory alloy embedded hybrid unsymmetrical patch repaired glass-fiber reinforced polymer composites

This paper investigated the influence of embedding pseudoelastic shape memory alloy within the external bonded patch made up of glass fibers on the compression after impact response of adhesively bonded external patch repaired glass/epoxy composite laminates. Unsymmetrical patch repair was employed in the current studies. Three innovative pseudoelastic shape memory alloy configurations (straight wired, meshed and anchored) were embedded inside the patch and the changes in high-velocity impact response and damage tolerance at four impact velocities (70, 85, 95, 105 m/s) were compared with the conventional glass/epoxy (glass fiber-reinforced polymer) patch. Anchored specimens showed the best response by improving the compressive strength by 25% under non-impacted conditions and restoring it by 88%, 77%, 29%, and 28% at the impact velocity of 70, 85, 95, and 105 m/s, respectively, in comparison to the conventional normal specimens.

Investigation into high velocity impact response of pre-loaded hybrid nanocomposite structure

Pre-loaded polymer composite structures subjected to high velocity impact have received little attention compared to the corresponding structure under static impact test. In fact, no report was found on such structures, which incorporate nanoparticles as a secondary reinforcement. The main objective of this research work is to assess the high-velocity impact response of polymer composite plates containing nanoclay under different pre-loads. E-glass woven roving and unsaturated polyester resin were used to prepare composite plates and 1.5 wt% nanoclay was introduced into the resin system. High velocity impact with full perforation as well as impact tests with rebound were conducted via a gas gun in a velocity range of 138–185 m/s. Three types of pre-loading were applied and compared with no pre-load condition, namely: uniaxial compression, uniaxial tension, and biaxial compression/tension hybrid pre-load. The results indicated significant better energy absorption performance by the nanoclay modified specimens under all pre-load conditions compared to the specimens without nanoclay. Results further showed that biaxial compression/tension and uniaxial compression pre-loads are more critical than tension pre-loads. Nanoclay reinforced composite plate showed greater damage extension compared to composite plates without nano reinforcement. Major failure modes identified include delamination, matrix cracking, and fiber breakage.

High Velocity Impact Response of Basalt Fibers/Epoxy Composites Containing Graphene Nanoplatelets

The effects of adding surface modified graphene nanoplatelets (GNPs) in various weight percentages (0, 0.1, 0.2, 0.3, 0.4, 0.5 with respect to matrix) on the high velocity impact response of basalt fibers/epoxy composites were evaluated. High speed mechanical stirrer and ultrasonic waves were used for the dispersion of GNPs in the epoxy matrix, and hand layup method was utilized for the fabrication of the composite samples. High velocity impact testing was performed using a conical projectile. The results demonstrated that the maximum improvement in the impact limit velocity and energy absorption occurred in the 0.3 wt.% GNPs nanocomposite, i.e., 11 and 23 %, respectively. Also, the electron microscopy studies revealed that the addition of GNPs contributed in improving the impact properties by influencing the matrix and thus enhancing the interfacial characteristics between the basalt fibers and the matrix.

Long fiber thermoplastic composites under high-velocity impact: Study of fiber length

This study experimentally investigates the high-velocity impact response of long glass fiber-reinforced polypropylenes with different fiber lengths. The study considers three long fiber thermoplastic composites, i.e. 5, 10, and 20 mm prepared via a combination of extrusion and pultrusion processes and a crosshead die. An internal mixer was used to obtain an isotropic compound. The dispersion quality of each compound was confirmed using burn off test. A gas gun with a spherical projectile was employed to conduct high-velocity impact tests at three velocities of 144, 205, and 240 m/s. Internal mixer operation resulted in extensive fiber length reduction for all three long fiber thermoplastic lengths. Results from mechanical tests (Tensile and Izod impact) revealed an increasing value with increase in long fiber thermoplastic length, i.e. fiber length. High-velocity impact results showed higher impact performance for 20 mm long fiber thermoplastic compound compared to 5 and 10 mm long fiber thermoplastic containing specimens. Rate of increase in energy absorption from neat polypropylene to 5 and 10 mm long fiber thermoplastic compounds is much higher than from 10 to 20 mm long fiber thermoplastics. High-velocity impact tests indicated that there may be a threshold value for fiber length beyond which the fiber length plays a lesser role. Scanning electron microscopic analysis showed more fiber breakage at the impact point at a higher impact velocity than the lower end of high-velocity impact.

Effect of the polymer interlayer on the high-velocity soft impact response of laminated glass plates

The choice of the polymer interlayer is a key consideration for laminated aircraft windshields. Such windshields often employ chemically strengthened glasses and are required to withstand impact by birds, hail-stones and other foreign bodies. In the present study, windshields employing three different polymer interlayer materials were investigated under high-velocity impact by a soft projectile: Thermoplastic Polyurethane (TPU), Polyvinyl Butyral (PVB) and Ionoplast interlayer-SentryGlas® Plus (SGP). Parameters such as the polymer interlayer type and thickness, multi-layering the interlayer and the sensitivity of the behaviour of the windshield to the environmental temperature were studied. The performance was assessed through a series of laboratory-scale impact experiments (using a bird-substitute material) and modelled via finite element simulations (using a smoothed particle hydrodynamics approach). The experimental and numerical results were found to be in good agreement for the three polymer interlayers investigated. The polymer interlayer type was found to have the most significant effect on both the deformation and the failure of the laminated glass windows at room temperature, i.e. 25 °C. However, the influence of the polymer interlayer type became less pronounced at lower temperatures. The novel modelling that has been developed assists in the choice of the best polymer interlayer, including the multi-layering of interlayers, for complex windshield designs.