Glass Fiber Reinforced Epoxy Composites Research Articles

Experimental Analysis on the Impact Behaviour of Graphite-Filled Glass Fibre Reinforced Epoxy Composites Subjected to Sea Water Ageing and Notch Depth

Experimental Analysis on the Impact Behaviour of Graphite-Filled Glass Fibre Reinforced Epoxy Composites Subjected to Sea Water Ageing and Notch Depth

Numerical and Experimental Investigations on the Low Velocity Impact Properties of Glass Fiber Reinforced Epoxy Composites: Effects of Radius of Curvature

Numerical and Experimental Investigations on the Low Velocity Impact Properties of Glass Fiber Reinforced Epoxy Composites: Effects of Radius of Curvature

Electrical degradation dynamics of glass fiber-reinforced epoxy composites considering different fiber orientation

Glass fiber-reinforced epoxy composites (GFREC) have been widely used in the mechanical components of electrical and electronic devices because of its lightweight, high mechanical strength, excellent electrical insulation properties and corrosion resistance. The research on the electrical degradation dynamics of GFREC is of great significance to avoid the failure of electrical insulation system. Herein the composite samples were prepared using vacuum impregnation technique. The electrical degradation morphology and statistical characteristics (electrical tree length, width, expansion coefficient, breakdown probability and breakdown time) were discussed. The results show that the electrical tree will develop towards the fiber side and grow rapidly along the interface in GFREC. The interfacial orientation will affect the growth characteristics of electrical tree. When the angle between the glass fiber and the needle electrode is 45°, the composite material has relatively superior tree propagation resistance performance, lower breakdown probability and higher breakdown time. The effects of electric field distribution on the tree initiation and electrical degradation are discussed, which reveals the relationship between the electrical degradation and the fiber orientations. The electric field-driven tree growth (FDTG) model is used to explain the growth of trees along interfaces with different orientations from the perspective of dynamic electric field distribution.

Low-velocity impact behavior of 3D woven structural honeycomb composite

This paper describes the in-plane impact behavior of 3D woven honeycomb sandwich composites comprising glass fiber reinforced epoxy composite. In this study, 3D woven honeycomb structures with similar cell shapes were developed with different cell geometry by varying the cell size, free wall length, bonded wall length, opening angle, and the number of honeycomb layers keeping the overall thickness of the composite constant. The variation of cell geometry was carried out by changing the number of picks in the honeycomb walls. Composite samples were made using VARIM (vacuum-assisted resin infusion method) process. The behavior of the force-displacement curve and the energy-time relationship under impact loading of 100 J were analyzed. The total energy absorption was determined for different cell geometry and the number of layers of the honeycomb composites. The results showed that structural changes in honeycomb composite significantly affect the specific energy absorption. The specific energy absorption increases with a large cell size, less opening angle, higher wall length, and a greater number of layers.

Evaluation of self-healing capability of a polycaprolactone interphase in epoxy/glass composites

Self-healing composites possess the ability to self-repair in response to damage, either autonomously (i.e., without human intervention), or when subjected to an external stimulus such as heat. This work was focused on the evaluation of the interfacial self-healing capability of glass fiber-reinforced epoxy composites in which polycaprolactone nanoparticles were deposited as a coating on the surface of the fibers. Polycaprolactone nanoparticles were synthesized following solvent displacement technique and deposited on the fibers (with and without the sizing agent) by electrophoretic deposition. Scanning electron microscopy revealed high-quality nanoparticles deposition, with good level of homogeneity and compactness. Epoxy microdroplets were cured on the fibers and microdebonding tests were performed to estimate the interfacial self-healing capability, calculated as the ratio of the interfacial shear stress measured before and after the thermal mending process. An interfacial adhesion recovery of about 50 % was obtained, thus indicating an interfacial self-healing capability induced by the polycaprolactone nanoparticles.

Effect of Water Absorption on Graphene Nanoplatelet and Multiwalled Carbon Nanotubes-impregnated Glass Fibre-Reinforced Epoxy Composites

Effect of Water Absorption on Graphene Nanoplatelet and Multiwalled Carbon Nanotubes-impregnated Glass Fibre-Reinforced Epoxy Composites

Waste Iron Filings to Improve the Mechanical and Electrical Properties of Glass Fiber-Reinforced Epoxy (GFRE) Composites

Several studies have been conducted to improve the mechanical and other value-added properties of glass fiber-reinforced epoxy (GFRE) composites by the addition of different fillers. In this work, waste iron filings (WIFs) obtained from the steel industry were incorporated into GFRE composite samples in varying amounts of up to 50% (%w) to improve their mechanical and electrical properties. The results showed that, with increasing WIF loading from 0 w% to 50 w%, the resultant composite density gradually increased from 1.4 to 2.1 g/cm3. Surface hardness, Young’s modulus, and tensile strength also increased significantly with the addition of up to 9 w% of WIF followed by a significant drop with more WIF addition due to agglomeration. Overall, Young’s modulus of the GFRE samples with any WIF content was higher than that of the GFRE composite with no WIF. The elongation at break results showed that the GFRE samples were less ductile upon WIF addition, which decreased from 2% to 0.6% upon loading the composite with 50% WIF. In terms of electrical conductivity, the GFRE samples with WIF content of 15% or more were electrically conductive and their electrical conductivity increased with WIF content. It was clear that more WIF was needed to establish a percolated network in the GFRE composites to render them conductive. The electrical conductivity of the GFRE samples containing 15% WIFs was around 2.9 kS/m and increased to 35 kS/m upon the addition of 50% WIFs. These novel electrically conductive GFRE composites could be promising for structural dynamic monitoring systems in the construction industry. They also support the efforts for the utilization of waste materials towards a circular economy.

New designs of sandwich panels to mitigate high-frequency noise inside space vehicles

Radiation of noise to the interior of a space vehicle during liftoff and transonic climb is a long-standing problem. To attenuate noise inside the crew compartment during launch and in-space operation, sandwich panels have been employed in the pressurized outer shell to passively reduce the exterior noise transmission. However, the layouts and the sound transmission loss of the implemented sandwich panels have not been made available for public release. Against this idiosyncratic practice, this study envisioned disseminating the know-how on the sound attenuation ability of dissimilar sandwich panels. To efficiently absorb and dampen the acoustic energy, the sandwich panels were specifically configured using a honeycomb core, felts and a closed cell aluminum-foam in the material lay-up. The face sheets of the sandwich panels consisted of either glass fiber-reinforced epoxy or carbon fiber-reinforced epoxy composites. The sandwich panels were tested as acoustic barriers to a diffuse sound field in a sound transmission suite. As found, an increase in the panel thickness brought a decrease in the anti-symmetric coincidence frequency of sandwich panels. A rubber damping layer in the material lay-up added limp mass to a sandwich panel and reduced the panel vibration at excitation frequencies beyond 500 Hz. Multiple felts reinforced the sound transmission loss of a sandwich panel by dissipating the acoustic energy into thermal energy at the felt interstices in the frequency regime beyond 315 Hz. In conclusion, this study proposed optimized sandwich configurations considering the constitutive materials, number of material layers, material layer thickness and stacking sequence. The optimized sandwich configurations could fairly deliver the demanded sound transmission loss in the high-frequency regime.

Effect of cellulose nanofibers on the fracture toughness mode II of glass fiber/epoxy composite laminates

Cellulose nanofibers (CNFs) were used to improve the fracture toughness of glass fiber reinforced epoxy composites (GFRPs). Different CNF suspensions were prepared and sprayed onto the surface of woven glass fiber laminates. The vacuum resin transfer molding (VaRTM) process was used to manufacture the GFRP composites. End notch flexure tests were conducted to evaluate the effect of CNFs on the critical energy release rate in mode II fracture toughness GIIC. The results revealed that 0.05 wt% was the optimum concentration. The interlaminar fracture toughness GIIC was improved by 28% with the addition of 0.05 wt% of CNFs to GF/epoxy composites. Whereas 0.1 wt% of CNFs resulted in decreasing GIIC due to the uncomplete impregnation of GF with epoxy resin caused by the thicker CNF layer at the interfacial laminates. The toughening mechanisms were investigated using a field-emission electron microscope. Large epoxy deformations and shear hackles were predominant for improving the interlaminar fracture toughness of GFRP composites.

The effect of nano-gelcoat on freeze-thaw resistance of glass fiber-reinforced polymer composite for marine applications

Glass fiber-reinforced polymers and protective gelcoats are important construction materials used in marine structure engineering. This study focused on the effect of freeze-thaw test on the properties of glass fiber-reinforced epoxy composites coated with nano-gelcoat. Nanoclay and nano TiO2 (1, 2, 3 wt%) were used to prepare nano-gelcoat and applied to composite surfaces. After the 45 and 90 freeze-thaw cycles, the change in the mechanical properties of the composites was determined and the thermal stability of the coatings was investigated. Mechanical features were investigated by tensile, flexural, short beam and compression tests. The thermal stability of the gelcoats was determined using Differential thermal analysis (DTA) and Thermogravimetric analysis (TGA). The morphology of the coatings was investigated by SEM (Scanning electron microscope). Water absorption properties were tested in hydrothermal environment. Finally, a statistical analysis, ANOVA (Analysis of variance), was conducted to determine whether the experimental results were significant or not. Nano TiO2 improved the water absorption property by 15.09% and preserved the mechanical properties by up to 8.8% compared to pure gelcoat. Nano TiO2 increased the melting temperature from 224.46 °C to 261.59 °C and provided a 16.54% improvement and also increased the decomposition temperature. Since the thermal conductivity of nanoclay is higher than nano TiO2, the nanoclay contribution increased this value by 7.14% and the nano TiO2 contribution by 3.57%. However, nanoclay has reduced the protection property of pure gelcoat due to its shape and size disadvantages. ANOVA analysis also revealed that the results were statistically significant.

Interface damage driven electrical degradation dynamics of glass fiber-reinforced epoxy composites

The damage of glass fiber-reinforced epoxy composites (GFRP) caused by mechanical loads is an important reason for the related electrical breakdown. In this paper, the L-shaped needle-wire electrode is used to simulate the coupling direction of mechanical stress and electric field, and the influences of equivalent tension and compression load on the electrical tree degradation of GFRP are obtained. It is found that both tensile and compressive loads will aggravate the electrical tree degradation in GFRP and reduce the average breakdown time. Under tensile load, the damage area of electrical tree increases, and even the sample breaks at the moment of electrical breakdown. However, the color of electrical tree channels is light and the number of branches is small under compression load. The narrow carbonization channels after breakdown will be accompanied by spherical damage areas. The simulation results of GFRP interface damage confirm that the increase of tension and compression load will lead to different degrees of damage at the fiber-matrix interface, and then cause local electric field distortion. At the same time, the combined action of high temperature and high pressure and external mechanical load will aggravate the electrical tree degradation process of GFRP.

Dynamic mechanical analysis of glass fiber reinforced epoxy filled nanoclay hybrid composites

In this work, dynamic mechanical analysis (DMA) of hybrid composite material made up of glass fiber reinforced epoxy polymer filled with nanoclay particles is investigated. The effect of fiber architecture, orientation and concentration on DMA properties of hybrids is studied. Three different types of glass fiber mats were chosen, namely, unidirectional glass fiber (UD-GF), woven glass fiber (W-GF) and chopped strand mat glass fiber (CSM-GF) and they were individually reinforced in epoxy polymer matrix at three different varying concentration (25 wt%, 50 wt% and 75 wt%). The nanoclay particles were added as filler material and its concentration was varied from 1 to 5 wt% in all the hybrid series. In UD-GF reinforced hybrid, the fibers are oriented at different orientation (0° to 90°) with respect to loading condition and the DMA properties was evaluated. The structure and fiber–matrix interface morphologies were examined by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) analysis. The effect of interface properties on DMA properties is studied by theoretical and Cole-cole methods. The result shows that the DMA properties such as storage module, glass transition temperature (Tg) and Tanδ curve (peak and width) were affected by both the concentration and morphology of glass fiber reinforcement and the nanoclay fillers. In general, nanoclay reinforcement in glass fiber reinforced epoxy composites improves the hybridization effect and positively improves the DMA properties.

Tribo-performance of saw dust filled natural fiber – Glass fiber reinforced epoxy composites: Modelling and optimization

Tribo-performance of saw dust filled natural fiber – Glass fiber reinforced epoxy composites: Modelling and optimization

The dependence of interfacial shear strength on temperature and matrix chemistry in glass fibre epoxy composites

The present work focuses on a fundamental investigation into the influences of the chemistry of epoxy and the testing temperature on the stress-transfer capability of the fibre-matrix interface in a glass fibre reinforced epoxy composite. We discuss how the interfacial shear strength (IFSS) is influenced by the hardener-to-resin ratio, testing temperature and fibre silane coating respectively. It was observed that the IFSS showed a significant inverse dependence on testing temperature for both silanes, with IFSS values dropping as the temperature was increased, for all ratios studied. Notably, it was shown that once the testing temperature was raised above the glass transition temperature that ratios possessing excess amine hardener had larger IFSS values. From the results presented it is hypothesized that residual radial compressive stresses at the interface are influenced by the chemistry of the matrix system and then relax away at the higher testing temperatures.

Experimental and numerical determination of interlayer shear strength of glass fiber-reinforced epoxy composites

This study aims to produce glass fiber composite plates by vacuum infusion method and to determine the interlaminar shear strength (ILSS) under the short beam test. For this purpose, composite plates were produced under the effect of vacuum and temperature by adding glass fiber layers on a flat vacuum table. Short beam tests were carried out on the obtained laminated composite plates and the interlayer shear strength, which is generally characterized by delamination damage, was investigated. In the numerical part, the tests were modeled using the LS-DYNA finite element package program, and the Hashin damage criterion-based material model was used to see the damages that occurred in the composite structure after the tests.

An experimental study on the sound transmission loss of dissimilar fuselage sandwich panels of turbojet aircraft

The analysis of acoustic performance of sandwich panels, designed explicitly for fuselage sidewalls of turbojet aircraft, has been revisited numerous times. However, the layouts and the sound transmission loss of the airborne fuselage sandwich panels have not been made available for public release. Against this idiosyncratic practice, this study envisioned disseminating the know-how on the sound attenuation ability of dissimilar sandwich panels implemented in the fuselage of turbojet aircraft. To efficiently absorb and dampen the acoustic energy, the sandwich panels were systematically configured using a honeycomb core, felts and a closed cell aluminum-foam in the material lay-up. The face sheets of the sandwich panels were composed of either glass fiber-reinforced epoxy or carbon fiber-reinforced epoxy composites. The sandwich panels were tested as acoustic barriers to a diffuse sound field in a sound transmission suite consisting of two adjacent sound reverberation rooms. As found, a rubber damping layer in the material lay-up of a sandwich panel reinforced the sound transmission loss at frequencies beyond 500 Hz. Multiple felts augmented the sound transmission loss in the frequency regime beyond 315 Hz. The panel edges needed to be sealed properly to reproduce the sound transmission loss of a sandwich panel in successive experiments. This study leveraged many-faceted insights into the configuration (constituent materials, number of material layers, thickness, and stacking sequence) of commercially feasible sandwich panels. Besides, this study proposed optimized sandwich configurations based on the sound transmission loss, which will help aircraft manufacturers to apply these sandwich panels without further modifications.

Comparative Study on the Effect of Aluminium Trihydrate and Carbon Nanofillers on Thermal Properties of Glass Fiber Reinforced Epoxy Composites

High performance glass fiber reinforced epoxy composites are in greater demand in several industrial applications, from civil structures to aviation industry. The epoxy has highly cross-linked structure and is found to be high performance polymer. Further, carbon nanofillers such as multi-walled carbon nanotubes (MWCNT), graphene nanoplatelets (GNP) and thermally stable microfiller aluminium trihydrate (ATH) are being used to improve the thermal properties. GNP and MWCNT posses high aspect ratio and specific surface area contributing to improvement in thermal properties of composites. In spite of this, there are difficulties connected with nanofiller addition, such as dispersion and interaction. The fabricated nanocomposites are based on ECR glass fiber and epoxy resin by adding GNP, MWCNT and ATH fillers using pultrusion process assisted by ultrasonication. For the purpose of comparison, composites containing only MWCNT, GNP and ATH were also tested. The XRD and SEM were used to study the fillers dispersion and interaction. The thermogravemetric analysis(TGA) was carried out to determine the thermal stability of composites. From the thermal analysis result, it is found that the epoxy-MWCNT-GNP-ATH composite has enhanced thermal stability due to the addition of ATH micro filler.

The Effect of MWCNT and GNP on the Flame Retardant Properties of Glass Fiber Reinforced Composites

Nanotechnology in engineering is intended for achieving newer materials with immensely improved electrical, thermal and mechanical properties. The effectiveness of different fillers (micro and nanoscale) on the flame retardant behaviour of glass fiber reinforced epoxy composites were studied using cone calorimetry. In the present investigation, the fabrication of epoxy composites with ECR glass fiber reinforcement using the pultrusion method was taken up. The effect of incorporation of micron-sized ATH, carbon nanofillers like multi-walled carbon nanotubes (MWCNT) and Graphene nanoplatelets (GNP) is investigated. With respect to flame retardant properties, the composites with the combination of alumina (ATH) and carbon nanofillers show better results as compared to composites with individual fillers. The results exhibit a good agreement with more compact chars formed on the surface of the charred polymer. However, the cone calorimetry results of glass fibre reinforced composite show no significant improvement with respect to heat release rate. Further, Flame parameters of the composites show minimal deterioration due to the incorporation of the ATH and carbon fillers. Studies on the morphology using FESEM are well correlated with the flame properties.

Study on the ratchetting behavior of glass fiber-reinforced epoxy composites: Experiment and theory

To discuss the ratchetting behavior of short glass fiber-reinforced epoxy polymer composites, experimental and theoretical studies were carried out. The effects of the fiber content and peak stress on the ratchetting behavior of the composite materials were discussed. The results show that the ratchetting strain decreases with increasing fiber content and decreasing peak stress. It was also found that the residual strain after unloading partly recovers with time, which indicates that the ratchetting strain consists of viscoelastic strain and plastic strain. Based on the experimental results, a viscoelastic-viscoplastic constitutive model is proposed, which can well simulate the ratchetting behavior and strain recovery of composites with different fiber contents.

Mechanical and thermo-mechanical properties of glass fiber reinforced epoxy composites with boron carbide nanofiller

This research aims to analyze the influence of boron carbide particles (B4C) on the mechanical and thermo-mechanical characteristics of glass fabric reinforced epoxy to identify the suitability of fabricated composites in an automotive application. The influence of B4C up to 0.4 wt% is analyzed by mixing with epoxy resin using a magnetic stirring approach, followed by compression molding with the glass fiber reinforcement. The results revealed that the hardness of glass strengthened epoxy was increased by 38%, and the other mechanical characteristics such as tensile and flexural strength were raised by 25% and 19%, respectively, when the weight fractions of B4C were raised to 0.3 wt%. From the fractography, it was observed that the fiber pull-out and fiber fracture were the dominant failure mechanisms in the developed composites during the application. The findings of the dynamic mechanical analysis revealed that the storage and loss modulus of the composites was increased by 50% and 43%, respectively, with the 0.3 wt% of B4C showing the increase in the dynamic ability of materials even at elevated temperatures.