Low-velocity Impact Characteristics Research Articles

Role of fibre weight fraction on low-velocity impact characteristics of abaca fibre reinforced bio-composites

This work involved an experimental study on Abaca fibre bio-composites subjected to a low-velocity impact test at 2.42 m/s to study the effect of fibre weight fraction on the impact performance. The abaca fibre reinforced composite (AFRC) specimens were fabricated with a 10% increment of fibre, varying from Wf = 20% to 50%, and their impact properties compared with each other. The impact properties such as force-time history, energy-time history, Coefficient of Restitution (CoR), Energy Loss Percentage (ELP) and Energy Absorption Ratio (EAR) were studied. A significant change in impact force and energy absorption was found as the fibre content increased in the composite. The findings show a good relationship between fibre weight fractions, composite laminate stiffness, impact load and total absorbed energy. The experimental results of the impact test show that the composite specimen with Wf = 40% has high impact energy absorption capacity with 4. 09 J 92.94 N and 4.09 J, EAR of 39.94%, CoR of 0.77 and ELP of 40.04%. Low fibre weight fraction composite has shown brittle failure, and high fibre weight fraction has shown ductile behaviour. Scanning electron microscopy (SEM) based study was used for post-impact damage analysis.

Tailoring Basalt Fibers and E-Glass Fibers as Reinforcements for Increased Impact Resistance

The usage of basalt fiber in the engineering industries has gained significant interest due to its characteristics such as alkali resistance and enhanced mechanical properties. Similarly, E-glass-fiber-reinforced composites have been widely used in the fabrication of electrically resistive industrial components such as switches, circuit panels, and covering cases. In the present study, the tensile, flexural, thermogravimetric, and low-velocity impact characteristics of various percentages of basalt/E-glass-fiber-reinforced polymer composites fabricated via vacuum-assisted resin transfer molding were investigated. The results show that a higher volume percentage of basalt (39%) significantly enhances the impact resistance up to 45% with a moderate improvement in flexural properties. The higher the vol % of E-glass (40%), the more the tensile and flexural properties are increased, i.e., 185 N/mm2 and 227.87 N/mm2, respectively. It is concluded that by choosing the optimum hybridization method, impact resistance and other mechanical properties can be improved significantly. The thermogravimetric analysis results show that PC313534 (35 vol % basalt and 34 vol % E-glass) possesses the lowest decomposition temperature of 381.10 °C. The results from the present study indicate that the polymer composite fabricated in the present study is suitable for applications where higher structural-load-resistive properties are required.

Research on low-velocity impact characteristics of Z-pin reinforced quartz/phenolic laminates

The problem of in-plane damage caused by dynamic impact loading of composite laminates can be enhanced by implanting Z-pins. The effect of Z-pin implantation on the impact resistance of composite laminates is investigated experimentally, and the damage process is analyzed by establishing a low-velocity impact finite element model of Z-pin reinforced laminates. The test results show that the maximum impact contact force of Z-pin reinforced laminates can be increased by 8.23%, and the maximum contact force and absorbed energy of Z-pin reinforced samples both increase gradually with the increase of impact energy. The simulation results show that with the increase of impact energy, the expansion of impact damage is hindered by the Z-pin, and it reduces in-plane matrix damage. The expansion path of the interlaminar crack changes when it reaches the Z-pin enhancement area, and the shape of the interlaminar damage changes from circular to elliptical.

Energy absorption properties of a 3D-printed lattice-core foam composite under compressive and low-velocity impact loading

This experimental work aims to investigate the compression and low-velocity impact characteristics of different lattice structures made via Fused Deposition Modeling (FDM) technology to be used as a skeleton of a lightweight polyurethane foam (PUF) composite. Three frame-unit geometries, namely one cubic cell and two pyramidal cell variants, were firstly considered as reinforcement. A stepwise design rationale was adopted to identify better lattice configurations progressively, focusing on manufacturing aspects such as cell geometry and structural density, as well as efficiency requirements. A square-based pyramid geometry was identified as the most efficient in energy dissipation and, therefore, was selected for further investigations, varying bulk density, to identify the lattice reinforcement to be embedded in the polyurethane foam matrix and generate the PUF composite. The experimental outcomes showed enhanced dissipative capacity of the composite structure under static and dynamic loading conditions, suggesting promising applications to preserve the integrity of objects in accidental collisions.

An experimental study on low velocity impact characteristics of glass fiber reinforced epoxy nanocomposites

An experimental study on low velocity impact characteristics of glass fiber reinforced epoxy nanocomposites

Stacking design of uniaxial/biaxial braided composite tube under low-velocity impact load

In this paper, the transverse low-velocity impact behavior of uniaxial and biaxial braided composite tubes is investigated to improve the impact resistance of tubular composite structures and to reveal their energy absorption mechanism. Based on the nonlinear progressive damage model, the finite element method is used for experimental verification and numerical analysis. The composite tubes with different stacking sequences and stacking angles were simulated, and their impact responses were evaluated by the peak load Fmax , the maximum indentation depth αmax and the energy absorption EA. The results show that the numerical simulation results are in good agreement with the experimental data, and can accurately capture the failure behavior in the actual scene. The damage mode of the braided composite circular tube under low-velocity impact load is mainly manifested as matrix cracking and interlayer separation, and the expansion direction of the damaged area is basically consistent with the fiber orientation. The impact resistance depends more on the stacking sequence, while the stacking angle is the main factor affecting the energy absorption. Under reasonable design, the uniaxial/biaxial hybrid braided tube can obtain the best low-velocity impact characteristics.

Experimental investigation on low-velocity impact response of spherical core sandwich structure

In the present work, the low-velocity impact characteristics of the spherical core sandwich structures made of glass fibre reinforced plastic (GFRP) are tested at different strike velocities (3, 5, and 7 m/s). Four different types of core orientation, namely, regular, interlock, inverted, and stagger, are designed and fabricated by the hand-layup method. Vinyl ester resin and woven glass fibre fabrics are used as matrices and reinforcements, respectively. The diameter of the spherical core and the pitch distance is chosen as 16 mm and 32 mm, respectively. The impact behaviour of the novel spherical sandwich structures is examined based on the maximum contact force, energy absorption capacity, coefficient of restitution (COR), and damage behaviour. The Regular model shows enhanced energy absorption capacity with a specific absorbed energy of 0.092 J/(kg/m3) at 7 m/s impact velocity. Similarly the Interlock model shows good damage resistance. The typical failure patterns observed in the Interlock model at 3 m/s are matrix cracking (MC) and fibre breakage (FB), whereas, at 5 and 7 m/s impact velocities, the damage core crushing (C) is observed.

Experimental and numerical research on the dynamic response of sandwich structure with M-type foldcore under low-velocity impact

In the field of lightweight structures, foldcore sandwich structure is regarded as a promising replacement for conventional honeycomb sandwich structure. In this study, a new M-type glass fiber foldcore structure was fabricated by hot-pressing molding technology, and the effects of various factors on the low-velocity impact characteristics were investigated. In addition, a 3 D progressive damage numerical model matching the experimental results was established. The results showed that the impact energy exerted a certain influence on the response characteristics of the sandwich structure, but did not change the development trend of the load curve. The sandwich panel was able to achieve the overall load-carrying potential for the impactor whose size was longer than the foldcore span (25 mm). In addition, as the sharpness of the impactor increased, the damage range of the sandwich panel became concentrated and the load-bearing capacity gradually decreased. As revealed by the findings, the maximum load and specific energy absorption of laminated sandwich panels were improved by 150 and 40% respectively compared to single sandwich panel at base position. Therefore, it is beneficial to appropriately reduce the core span and increase the number of laminations to improve impact resistance of foldcore sandwich in practical applications.

Enhancing low velocity impact characteristics of glass fiber laminates by short fiber reinforcement—Failure evolution and damage mechanisms

AbstractFor enhancing impact characteristics, woven glass fiber epoxy laminates are reinforced with short fibers. The 6‐mm‐long slender fillers, when added up to 4% in the matrix, exhibit no influence on the flexural modulus, but at 2% they maximize the laminate's flexural strength. While the dissipation energy continues to increase up to 30 J of impact, the laminates' post‐impact load bearing capacity gets significantly affected beyond 20 J. The reinforced laminates exhibit better elastic response and enhanced damage resistance with as high as 50% reduction in the visible damage area as well as up to 35% increase in the damage initiation force. The degree of damage shows excellent correlation with the visible damage area. The distinct through thickness conical region, diverging from the impact site, is attributed to the presence of microcracks oriented along the fiber directions. The cone boundary, from where the interlaminar failure initiates, is largely the manifestation of transverse matrix cracks. While the damage cone with greater divergence indicates reduced impact resistance of the laminate, the orientation of transverse matrix cracks remains unaffected by the impact energy or the filler content. At low impact energies, the failure initiated from the fiber/matrix interfaces, coalesce to form the matrix cracks, which act as a precursor to the interlaminar failure. However, at high energy levels, several failure mechanisms simultaneously develop with no clear indication of the order of damage evolution. The short fibers enhance the laminate's impact resistance either by arresting the cracks or by developing tortuous crack path with high energy dissipation.

Comparative Study on the Experimental Results on Low-Velocity Impact Characteristics of GLARE Laminates with Simulation Results from LS Dyna

Comparative Study on the Experimental Results on Low-Velocity Impact Characteristics of GLARE Laminates with Simulation Results from LS Dyna

Experimental Investigation of Mechanical Performance of Basalt/Epoxy/MWCNT/SiC Reinforced Hybrid Fiber Metal Laminates

The primary goal of this study is to see how multi-walled carbon nano tubes (MWCNTs) and nano silicon carbide particles (SiC) affect basalt reinforced epoxy composites made using pressure mould. The aluminium 8090 metal plate was used to strengthen the laminate's core. Tensile, bending, and low velocity impact tests, as well as aesthetics, were investigated and presented for the debate. The physical and low velocity impact characteristics of the produced laminates are considerably improved by including MWCNT/SiC into the epoxy matrix and basalt mixture. The 9 wt. % and 12 wt. % of SiC filled combinations show higher tensile and flexural performances up to 40% than neat composites among the investigated combinations. Drop weight impact tests show a progressive improved energy absorbing response of up to 60% as SiC reinforcement increases. SEM morphology of pure, SiC/MWCNT filled specimens, as well as fragmented surface analyses, were also presented. It was observed from morphological studies that there is a reasonable wettability between matrix/filler/reinforcements. This research work will lay a path for using Basalt/Epoxy/MWCNT/SiC Reinforced Hybrid Fiber Metal Laminates for aerospace and structural applications.

Experimental study of basalt fiber/steel hybrid laminates under low-velocity impact

Due to their excellent impact resistance, fibre-metal laminates are widely utilised in modern engineering industries such as the construction of aircraft, vehicles and ships. In this study, the low-velocity impact characteristics of basalt fibre/steel hybrid laminates with different lay-up structures were studied with a drop hammer. This was done through a series of low-velocity impact experiments with different hammer head shapes and impact energies. It can be seen from the results that the impact behaviour of hybrid laminates largely depends on the shape of the hammer head, impact energy and lay-up structure. The sharper the hammer head, the smaller the peak impact load and the greater the displacement. When the hammer head penetrates the laminate, apparent shear failure occurs under the impact of the flat hammer head. Petal-like fractures caused by tensile tear failure occur under the impact of the hemispherical and conical hammer head. Low-energy impacts may result in large plastic deformation, delamination and debonding in the layers. High-energy impacts may also lead to fibre and metal fractures as well as perforation damage. Consequently, the laminate absorbs the energy from overall deformation under low-energy impact, but mainly absorbs the energy generated by various fibre and metal fractures under high-energy impact.

Developing thermoplastic hybrid titanium composite laminates (HTCLS) at room temperature: Low-velocity impact analyses

Hybrid titanium composite laminates (HTCLs) are high-performance light-weight fiber metal laminates (FMLs) that are being increasingly used in various industries such as aeronautical, military, and marine thanks to their optimized fracture toughness, impact resistance, and thermal performance. In the current study, the low-velocity impact (LVI) characteristics of a new generation of thermoplastic (TP) HTCLs at various energy levels are investigated. To do so, Ti-6Al-4 V sheets, carbon fabrics, and ultra-high molecular weight polyethylene (UHMWPE) fabrics are used to fabricate multiple laminates with different fiber types, metal volume fractions, and lamination layups. A low-cost resin infusion process is employed for manufacturing the laminates at room temperature by using a novel liquid thermoplastic methyl methacrylate resin, Elium® 188. Before fabrication, a multi-step surface treatment method is applied on Ti alloy sheets to enhance the interfacial properties between the composite layer and the metal alloy sheet. In addition to TP-HTCLs, equivalent thermosetting (TS) HTCLs with an epoxy resin, Epolam, are fabricated to compare the results and evaluate the possibility of fabricating recyclable TP-FMLs at room temperature with enhanced out-of-plane properties. Impact properties including contact force, deflection, energy parameters, and related damage modes are investigated and presented for each laminate. It is concluded that the newly developed TP-HTCLs can be cured at room temperature and have enhanced impact properties compared to those of TS-HTCLs. Besides, the HTCL with UHMWPE fabrics on its composite sides (before the Ti alloy sheets) performs better in LVI compared to that with carbon fibers on the top and bottom (of its composite core) since UHMWPE exhibits higher strain to failure and fracture toughness compared to carbon fibers.

Maximum amplitude, quasi-static indentation, and frequency information of the angle-ply laminated curved panel subjected to low-velocity impact

In the presented study, maximum amplitude, frequency, and low-velocity impact characteristics of the angle-ply laminated curved panel under external excitation is presented. Hertz contact theory is used for modeling the contact force between the impactor and angle-ply laminated curved panel. Hamilton’s principle, and first-order shear deformation theory (FSDT) are presented for obtaining the governing equations of the angle-ply laminated curved panel, and impactor. For solving the time-dependent governing equations of the angle-ply laminated curved panel, and impactor, coupled Galerking, and Newmark methods is presented. In the first part of the results, the influence of viscoelastic parameters, young module ratio, the pattern of laminated layers, and other geometry of the angle-ply laminated curved panel on the free vibration characteristics of the current model under low-velocity impact are investigated. In the second one, the influence of density of impactor and young module ratio of the angle-ply laminated curved panel on the indentation, contact force, and indenter velocity are investigated in detail.

Low-Velocity Impact Characteristics of Hybrid Aluminum/CFRP Single Hat Sectioned Beam Adhesively Bonded Using Adhesive Tape

Single hat sectioned hybrid beams composed of aluminum and Carbon Fiber Reinforced Polymeric materials (CFRP), intended for structural applications in the automotive and aviation sectors, have been studied from the point of their energy absorption capabilities when submitted to transverse low-velocity impact loading. Carbon fiber-epoxy composite prepregs were placed on the inside of the single hat sectioned aluminum sheet and completely cured in the autoclave under the recommended curing cycle. The bonding process between the aluminum sheet and composite layers was achieved by using 3M VHB™ 4930 double-sided acrylic foam tape. Bonding the aluminum and composite layers through adhesive tape eliminates the requirement of surface preparation of the aluminum layer through chemical etching or mechanical abrasion and thereby the strength of the metallic layer is not reduced due to the formation micropores during the chemical etching process. Results are shown in terms of load-displacement and damage morphologies diagrams; characteristic trends are compared and discussed. It was observed that the presence of viscoelastic adhesive tape material restricts the rupture (visual cracks) failure of the outer aluminum layer, resulting in the only impact-induced indentation for all impact energies. Numerical simulations were also performed to characterize and predict the failure mechanism of such hybrid beams when subjected to impact loading. Numerical predictions showed good correlation with experimental results for all impact histories at low and medium impact energies but a showed slight discrepancy for highest impact energy and were not able to successfully capture the system response in the unloading region. Current modeling does not consider damage healing or recovery with unloading and it is difficult to account for such change in material state. This study provides the low-velocity impact characteristics and collapse behavior of the hybrid hat sectioned beams under tensile and shear forces developed by impact loading by providing insight to their primary damage mechanisms relative to the impact energies. It was found that the primary damage of the specimen’s changes from impact-induced indentation, minimal fiber breakage to partial perforation accompanied by larger indentation depth as the impact energy is increased from 6 to 12 J.

Drop-Weight Impact Behaviour of Hybrid Fiber/Epoxy Honeycomb Core Sandwich Composites under Hemi-Spherical Impactor

Low velocity impact test is conducted on hybrid fiber honeycomb core sandwich panels filled with different energy absorbing materials such as Rohacell, wheat husk and polyurethane foam (PUF) using an instrumented drop-weight impact testing machine as per ASTM D3763-93 standard. Low velocity impact characteristics such as peak load, absorbed energy and damage mechanisms of the sandwich panels are investigated at 17.16 J, 25.75 J, 34.33 J and 42.91 J energy levels by varying the height of the dropping weight. Image processing technique is performed to calculate the impact damage area of the specimens using MATLAB 2016 A. To observe the damage and failure mode in the failed specimen, optical microscopic observation method is used. As increasing the impact energy, fiber fracture at face sheets, core fractures, delamination between hybrid fabric-epoxy layers and indentations failures are perceived by the visual inspection. According to the obtained results, the low velocity properties such as energy absorption capacity, load at initial damage are significantly improved and impact damage area is decreased considerably by the PUF filled core sandwich panels. Thus, this analysis puts forward that PUF filled honeycomb core sandwich panel may be a preferable material in the field of composites to overcome delamination and impact damages and to reduce the weight especially for the applications of advanced aerospace structures.

Low-Velocity Impact Characteristics of 3D-Printed Poly-Lactic Acid Thermoplastic Processed by Fused Deposition Modeling

The present research has focused on investigation into the low-velocity impact (LVI) behavior of 3D-printed poly-lactic acid thermoplastic material processed by fused deposition modeling. Four different infill density (ID) percentages, namely 40%, 60%, 80%, and 100%, were manufactured and subjected to the LVI test with 50 J energy input. The specimens were impacted using 12.7-mm hemispherical portion with conical head (ϕ 20 mm) striker which introduced two penetration stages. The impact characteristics in terms of velocity–time, force–time, and energy–time curves were investigated and reported. The penetration velocity limit, penetration energy, peak energy, and peak force were measured and discussed. The results revealed that the impact characteristics started to increase as the function of ID. The surface topography and fractured surfaces were examined using SEM. The fracture surfaces of 80% and 100% ID samples exhibited more viscous plastic deformation, indicating more energy absorption and load-carrying capacity.

Low velocity impact and fracture characterization of SiO2 nanoparticles filled basalt fiber reinforced composite tubes

Nano-microscale fracture mechanisms, which affect fracture toughness, play an important role in improving the impact characterization of fiber reinforced polymer composites. Therefore, crack behaviors are tried to be controlled with fracture mechanisms by filling nanoparticles into polymer matrix for improving impact characteristics and fracture toughness in latest studies. In this study, it was aimed to investigate the effects of SiO2 nanoparticles addition into epoxy matrix on the low velocity impact characteristics and fracture toughness in basalt fiber reinforced filament wound composite tubes. SiO2 nanoparticle of 4% wt. filled and unfilled ± [55]6 filament wound basalt fiber reinforced/epoxy composite tubes were subjected to low velocity impact tests at 5 J, 10 J, and 15 J of energy levels. It was seen that while the addition of nanoparticles were increasing the maximum impact forces in the range of about 19%–32%, displacements and absorbed energies decreased because of the increase in the bending stiffness. Charpy impact tests were performed to three different notched arc shaped specimens for determining the impact fracture toughness. SiO2 nanoparticles increased the fracture toughness by 20%–23%. It was observed that SiO2 nanoparticles delayed the formation of failures such as debonding and delamination, and reduced the fiber breakage branching in low velocity impact tests. A liquid penetrant test was used to inspect the crack formations and progressions on the impacted surfaces of all composite tubes as practical inspection for industrial applications. It was seen that microscope and SEM analysis supported the liquid penetrant inspection, which is a non-destructive testing method.

Mechanical and low velocity impact characterization of carbon/glass hybrid composites with graphene nanoplatelets

The present study aims to investigate the ability of graphene nanoplatelets (GnPs) inclusion effects on mechanical (tensile and flexural) and low-velocity impact (LVI) characteristics of carbon and glass fiber reinforced hybrid composites. A high speed of mechanical stirrer was used for mixing of epoxy with GnPs particles at different GnPs weight contents (0, 0.1, 0.25, and 0.5 wt%), and the mixture of the GnPs enriched resin was applied to the carbon and glass fiber fabrics for different lay-up conditions by using the hand-layup method. Impact tests were performed by using a drop weight impact machine for the impact energy of 30 J, and time history responses of load and displacement were evaluated and reported. Damage characteristics of the composite samples after the low-velocity impact tests were characterized and compared according to GnPs loadings. In this way, the combined effects of GnPs loading and carbon/glass fiber hybridization were investigated in detail. Results showed from this study that incorporation of GnPs particles at the certain concentrations significantly affects the impact resistance and mechanical properties of carbon/glass fiber reinforced hybrid composites. However, excessive GnPs particle addition into the epoxy resin caused a reduction in mechanical and impact properties as a result of particle agglomeration with reducing load transferring from particle to matrix resin.

Low-Velocity Impact Characterization of Fiber-Reinforced Composites with Hygrothermal Effect

Abstract In this article, low-velocity impact characteristics of UHN125C carbon fiber/epoxy composite, including unidirectional (0°), cross-directional (0°/90°), and quasi-isotropic layups, were experimentally measured. The effect of the fiber orientation angle and stacking sequences on impact force and induced strain were measured via an instrumented drop-weight apparatus with special concern for the moisture absorption effect. Dried specimens were immersed in distilled water for a certain period of time to absorb water for intermediate and saturated moisture content. It was observed that the impulse was reduced with the increase in moisture content; on the other hand, strain increased with moisture, as measured by DBU-120A strain-indicating software (MADSER Corp., El Paso, TX). Impact damage is widely recognized as one of the most detrimental damage forms in composite laminates because it dissipates the incident energy by a combination of matrix damage, fiber fracture, and fiber-matrix debonding. Therefore, it is extremely important to know the impact strength of a structure, especially for applications in industries such as aerospace, ship design, and some other commercial applications. The use of composite materials in engineering applications is increasing rapidly because they have higher strength-to-weight ratios than metals. The strength, stiffness, and, eventually, the life of composite materials are affected more than conventional materials by the presence of moisture and temperature. Thus, it is necessary to analyze the response of composites in a hydrothermal environment.