E-glass Research Articles

Drawing potential of fiber metal laminates in hydromechanical forming: A numerical and experimental study

It is known that fiber metal laminates as one of hybrid materials with thin metal sheets and fiber/resin layers have limited formability in conventional forming methods. This paper presents an experimental and numerical study for drawability of glass fiber-reinforced aluminum laminates under hydromechanical drawing technique. Fiber metal laminates comprised of a layer of woven glass fiber-reinforced prepreg, sandwiched between two layers of aluminum alloy. In order to produce fiber metal laminates, the laminates were subjected to a sufficient squeezing pressure under a controlled heating time and temperature by using a hydraulic hot press. A hydromechanical tooling equipped with blank-holder force and fluid pressure control system was used to form the initial circular fiber metal laminate blank. Finally, the effect of parameters such as pre-bulging pressure, final chamber pressure, and drawing ratio on process variables was evaluated. Also, the characteristic curve of hydromechanical drawing of fiber metal laminate i.e. chamber pressure in terms of drawing ratio was achieved by means of experimental tests and numerical simulations. The results showed that the maximum drawing ratio of defect-free fiber metal laminates, namely without any tearing, wrinkling, and delamination was obtained at pre-bulging and chamber pressure of 35 and 80 bar, respectively.

Effectiveness of short and straight carbon nanotubes on dispersion state and static/dynamic mechanical properties of woven glass fibre-reinforced polymer laminates

This study reports about the dispersibility of short, straight and pristine multi-walled carbon nanotubes (pCNTs) in epoxy and their effectiveness on the mechanical properties of three-phased GF/epoxy/pCNT laminates. These nanotubes were produced by arc discharge method and had an average aspect ratio (l/d) of 100. Glass fibre-reinforced polymer samples with four different weight fractions of these nanotubes (0.5, 1.0, 1.5 and 2.0 wt.% of the total matrix system) were fabricated and tested for their thermo-mechanical and mechanical properties. These carbon nanotubes with small aspect ratio contributed well to the strengthening mechanism due to their homogeneous dispersion. Fractography revealed that these nanotubes formed aligned arrays that minimized entanglements between the individual tubes, thus leading to lesser agglomerates up to 1.5 wt.% of carbon nanotube loading. However, the samples modified with 2.0 wt.% of nanotubes had lesser individual tubes and more of their aggregates. Unmodified glass fibre-reinforced polymer samples had a glass transition temperature (Tg) of 139.2℃, whereas addition of 1.5 wt.% of multi-walled carbon nanotubes increased the same to 160℃. Similarly, these specimens witnessed about 21% and 34% enhancement in tensile and flexure strength over the control samples, respectively. However, these trends dropped at 2.0 wt.% carbon nanotube loading owing to nanotubes aggregation but were higher than those of the neat epoxy composite. Samples containing carbon nanotubes witnessed higher fatigue life which proves that multi-walled carbon nanotubes with smaller aspect ratio are capable of obstructing fatigue crack growth.

Damage initiation in composite materials under off-centre impact loading

The effect of off-centre impact loading on damage initiation in a woven glass fibre reinforced epoxy resin was studied experimentally. Low velocity impact tests were conducted, in which the incident impact energy was increased until damage was observed in the laminates. It was shown that multiple impacts, with increasing incident energy at the same location, did not greatly influence the critical force for damage initiation, Pcrit. Subsequent testing on a range of panel sizes showed that the critical force is highest for central impacts, decreasing slowly as the impact location moves towards the boundary. It was also shown that, for off-centre impact loading, Pcrit, follows a t3/2 (t = laminate thickness) relationship that has previously been established for central impact. The slope of the plot of Pcrit versus t3/2 decreases as the impact location moves away from a central location, suggesting that the effective interlaminar shear stress also decreases with increasing offset. Tests at energies well above the damage threshold confirmed that off-centre impact is more serious than central impact loading.An energy-balance model was used to predict the off-centre impact response of the panels. Agreement between the energy-balance model and the measured impact response was good at energies that did not generate significant damage. Finally, it is suggested that the energy-balance model can also be used to predict a lower bound on the damage threshold energy in composite plates.

Influence of patch lay-up configuration and hybridization on low velocity impact and post-impact tensile response of repaired glass fiber reinforced plastic composites

This paper aims to investigate the effect of homogenous and hybrid external patches based on plain weave woven glass and Kevlar fabric on low velocity impact and quasi-static tensile after impact response of adhesively bonded external patch repairs in damaged glass/epoxy composite laminates. In all hybrid patches, the proportion of Kevlar and glass fibers were equal (i.e. 50% of Kevlar and 50% of glass by volume fraction), while lay-up configuration was different. This further enables to study the associated effect of hybridization and lay-up configuration on impact response of the repaired laminates. The intent of using hybrid external patches is to combine the excellent high displacement-to-failure property of Kevlar fiber as a ductile reinforcement with the superior mechanical property of glass fiber as a brittle reinforcement. The effect of glass/Kevlar content on impact response and tensile after impact response was investigated for various incident impact energy levels, such as 2, 4, 6, and 8 J. Results showed that hybridization and lay-up configurations of the external patches played a significant role on low velocity impact and quasi-static tensile after impact response of the repaired glass/epoxy specimens. Specimens repaired using intra-ply hybrid patches showed better impact properties and damage tolerance capability than that of the virgin and other repaired specimens. In specific, the use of intra-ply hybrid patches reduced the impact energy absorption by 10.17% in comparison to the virgin specimens at impact energy of 8 J.

A numerical homogenization of E-glass/acrylic woven composite laminates: Application to low velocity impact

For recyclability purposes, an acrylic resin (Elium 150) has been recently developed for the elaboration of laminated composites at room temperature. This new resin is endowed with some interesting mechanical properties that allow it to replace some epoxies in some industrials applications where a high strength is required. In this paper, the Mechanics of Structure Genome (MSG) and a finite element based micromechanics approaches were conducted to evaluate the effective thermomechanical properties of a plane woven glass fiber/acrylic resin composite laminate. Through a two-step and the asymptotic homogenization approach, the present investigation aims to predict the elastic properties of the glass fiber/Acrylic resin laminated composites. Prior to numerical simulations, some experimental observations have been performed on the laminate samples in order to accurately represent the geometry of a periodic representative volume element (RVE). The obtained numerical results were compared with those issued from some previous experimental investigations on laminated composites. A satisfactory agreement was observed between the numerical predictions and experimental data. In order to test the relevance of the proposed numerical procedure, the effects of the strain rate and the temperature on the predicted results were then discussed. Finally, a finite element model has been implemented for the simulation of low velocity impacts on the studied laminated composite.

Influence of cement particles on the mechanical and buckling behavior of laminated GFRP composites with variation of end conditions of buckling

Mechanical behavior of particle-loaded laminated composites depend upon the type of matrix, filler, reinforced fibers and architecture of fibers. Further, buckling behavior of a laminated composite varies with its end conditions, i.e. free-free or fixed-fixed. Failure mechanisms like delamination, debonding and fiber fracture vary with the end conditions of buckling. Presence of hard filler may also change the buckling behavior. Thus, in the present article, the mechanical and buckling behavior of cement loaded woven glass fiber reinforced epoxy matrix composites were investigated. Cement was varied as 1%, 3% and 5% by weight of epoxy. Thickness of composites were also varied as 3.1 mm, 4.4 mm and 6.3 mm by varying the number of reinforced glass fiber mats. Tensile, Izod impact and Vickers micro-hardness tests and, buckling tests under free-free and fixed-fixed conditions were performed to assess the mechanical and buckling behavior respectively. Fractured composites were analyzed under scanning electron microscope (SEM). The results showed that tensile strength decreased and hardness increased with increase in percentage of cement. Composites with minimum thickness showed lowest tensile strength. Critical buckling load increased with increase in thickness of composites for both end conditions. However, the nature of variation of buckling load with the percentage of filler varies for every thickness. SEM images showed that damage of composites mainly involved fiber breakage and delamination. Cement particles were effective in deflecting the advancing crack.

The influence of incorporation of silica and carbon nanoparticles on the mechanical properties of hybrid glass fiber reinforced epoxy

Recently, the study of hybrid nanocomposites has attracted much attention because they are highly expected for being used in many applications. In this context, there is an insisting need to investigate the effect of incorporation of silica and carbon particulates nanofillers into epoxy reinforced with woven and nonwoven tissue glass fiber. The influence of incorporation of silica (SiO2) and carbon black nanoparticles (C) with different weight fractions on the tensile properties, impact strength and fatigue performance of epoxy matrix reinforced with two types of E-glass fiber was investigated. The results showed an improvement in tensile properties, impact strength and fatigue life with addition of almost all nanoparticles contents considerably with respect to that of the neat glass fiber reinforced epoxy composites (NGFRE). Hybrid composites filled with 0.5 wt.% C exhibited the highest tensile strength and fatigue performance with an enhancement of 19% and 60% compared to NGFRE, respectively. An increase of 57% and 28% in tensile modulus and impact strength over NGFRE was obtained respectively with hybrid composites filled with 1 wt.% C. Adding 0.25 wt.% SiO2 and 0.25 wt.% C simultaneously showed an improvement in mechanical properties. SEM images of tensile and impact fracture surfaces are presented for CS 0.5 specimens which in turn reveal weak fiber/matrix interface.

Interlaminar Tension-Tension Fatigue of Woven Glass Fiber Reinforced Plastic Composite Laminates at Low Temperatures

Experimentally characterizing the through-thickness tensile behavior of composite laminates is challenging. This paper investigates the through-thickness tensile fatigue behavior of woven glass fiber reinforced plastic (GFRP) composite laminates at low temperatures. Cyclic through-thickness tensile tests were performed with cross specimens at room temperature and liquid nitrogen temperature (77 K), and the maximum interlaminar stress versus number of cycles to failure (S-N curve) was evaluated. The interlaminar tensile fatigue mechanisms of the woven GFRP composite laminates at low temperatures were also discussed. It was shown that resin fracture is dominant at room temperature, and the interface bonding fracture between the fiber and the matrix is dominant at 77K.

Application of box‐behnken design and neural computation for tribo‐mechanical performance analysis of iron‐mud‐filled glass‐fiber/epoxy composite and parametric optimization using PSO

This study investigates the possible utilization of iron mine waste for developing a new class of hybrid polymer composites. The composites were fabricated using hand‐layup process by reinforcing woven glass fibers in the epoxy polymer filled with different weight proportions of iron‐mud. Abrasion wear experiments were conducted according to Box‐Behnken design approach under controlled laboratory conditions using a dry abrasion tester. It was found that hardness, tensile modulus, impact energy and abrasion resistance of the fabricated composites improved with filler addition. Also, a prediction tool based on artificial neural network was implemented to investigate the tribological properties of the composites and the results were compared with the experimental ones. A metaheuristic approach like particle swarm optimization was also used to reveal the minimum wear (in volume) at optimal parametric combination. The results showed increase in both wear (in volume) and specific wear rate with respect to increase in the loads as well as sliding velocity. It also exhibited an increase in the wear with decrease in the specific wear rate with respect to the abrading distance. Finally, the morphology of the abraded surfaces was examined by using scanning electron microscopy and the possible abrasion mechanisms were critically examined and presented. POLYM. COMPOS., 40:1433–1449, 2019. © 2018 Society of Plastics Engineers

Investigation on Mechanical and Thermal Properties of Stainless Steel Wire Mesh-Glass Fibre Reinforced Polymer Composite

This work cope with the fabrication of hybrid structure composite made of woven glass fibre and Stainless Steel Wire Mesh (SSWM) embedded in Epoxy resin. The hybrid structure composite made using Hand layup method with weight fractions of 50, 52.5, 55, 57.5, 60 wt.% of Woven glass fibre, SSWM uniformly maintained (10 wt.%) in all the laminate except plain Glass Fibre Reinforced Polymer(GFRP) (Weight fraction of 60 wt.% Woven glass fibre and 40 wt.% Epoxy resin) composite. In this work, the investigation on effect of SSWM and woven glass fibre in mechanical properties have been characterised, based on tensile, flexural, shear, inter delamination and impact strength. The thermal properties are also analysed using a thermogravimetric instrument that shows better thermal stability. Morphology study is carried out using Scanning Electron Microscope (SEM). The results indicate that the 52.5 wt.% of Woven Glass Fibre with 10 wt.% SSWM and 37.5 wt.% Epoxy has superior properties compared to other combinations. This is evident that the SSWM as a reinforcing agent in the polymer composite.

Effect of salt water conditioning on novel fiber metal laminates for marine applications

One of the issues with the widespread use of polymer matrix composites in marine applications is their high susceptibility to environmental degradation, particularly hygrothermal conditions. Therefore, the present research intends to contribute to the better protection of the marine polymer matrix composites through the introduction of a newly developed fiber metal laminate for marine applications. This type of fiber metal laminate consists of a marine aluminum alloy of 5083 alternating with glass fiber reinforced epoxy composite layers. In order to evaluate the characterization of the environmental durability of this novel material, the specimens made of fiber metal laminates as well as commercial woven glass–epoxy composites were exposed to hygrothermal aging and hygrothermal cycling in boiling salt water. Then, to study the structural degradation caused by exposure to salt water, the mechanical properties of fiber metal laminate and woven glass–epoxy specimens under three-point bending and impact loading were evaluated. Results show that exposure to the saline environment generally decreased the flexural strength of woven glass–epoxy and fiber metal laminate specimens, whereas a smaller deterioration in flexural stiffness of both laminate types was found. Moreover, it was observed that the hygrothermal conditioning in salt water did not affect significantly the impact properties of both the fiber metal laminate and woven glass–epoxy specimens as compared to the flexural properties.

Effect of Manufacturing Method to Tensile Properties of Hybrid Composite Reinforced by Natural (Agel Leaf Fiber) and Glass Fibers

This paper described the effect of different type of manufacturing method to tensile properties of hybrid composite woven agel leaf fiber and glass fiber as an alternative of LSU structure material. The research was done by using 3 ply of woven agel leaf fiber (ALF) and 3 ply of glass fiber (wr200) while the matrix was using unsaturated polyester. Composite manufacturing method used hand lay-up and vacuum bagging. Tensile test conducted with Tensilon universal testing machine, specimen shape and size according to standard size ASTM D 638. Based on tensile test result showed that the tensile strength of agel leaf fiber composite with unsaturated polyester matrix is 54.5 MPa by hand lay-up and 84.6 MPa with vacuum bagging method. From result of tensile test, hybrid fiber agel composite and glass fiber with unsaturated polyester matrix have potential as LSU structure.

Stitched shape memory alloy wires enhance damage recovery in self-healing fibre-reinforced polymer composites

A major issue in composite technology is matrix micro-cracking due to low-velocity impact damage, which may severely limit service lifetimes of composite parts. In a novel approach, remarkable levels of healing of impact damage are obtained using shape memory alloy (SMA) wires to close longitudinal cracks in woven glass fibre-reinforced polymer plates with an epoxy-polycaprolactone (EP-PCL) matrix that shows dual-phase continuity. Thermal actuation of SMA wires stitched through the thickness of the stacked glass fibre plies introduces compressive loads to the cracks thanks to anchoring of the SMA loops at the fabric surfaces and debonding of the intervening threads, which prevents local deformation of the SMA, so that crack closure by about 200 μm is achievable. Concomitant expansion of the vascular network formed by the molten PCL fills the compressed cracks, resulting in highly effective healing on cooling, as demonstrated by C-scan images. Specimens stitched with SMA wires hence show almost complete healing, i.e. damage area recovery of 85%, after low-velocity impact at up to 17 J followed by heat treatment at 150 °C. This represents a 55% improvement over previous results for unstitched EP-PCL composites, and hence significantly greater degrees of healing than so far reported for this range of impact energies and this type of system.

Manufacturing and Mechanical Properties of Graphene Coated Glass Fabric and Epoxy Composites

The processing characteristics and mechanical properties of glass fabric reinforcements coated with graphene nanoparticles were investigated. Graphene was coated onto either one or both sides of a plain weave glass fabric. The coated fabrics were investigated to measure key process characterization parameters used for vacuum assisted resin transfer molding (VARTM) process which are, reinforcement compaction response, in-plane, and transverse permeability. It was found that graphene coated glass reinforcements were stiffer than the pure glass reinforcements which will have direct influence on final fiber volume fraction obtained during VARTM processing. The permeability measurement results show that the graphene coated reinforcements filled relatively slower compared with the pure glass samples. Composite samples were then tested for flexural and low velocity impact. The initial results show that the flexural modulus did not change as the wt % of graphene increases. However, a decrease in flexural strength with increasing wt % of graphene was observed. It was also observed that the coating of graphene on glass reinforcements caused delamination between plies and resisted localized damage under low velocity impact as compared to pure glass samples.

Mechanical properties of on/off-axis loading for hybrid glass fiber reinforced epoxy filled with silica and carbon black nanoparticles

In this study, mechanical properties of silica (SiO2) and carbon black nanoparticles (C) with different weight fractions embedded on epoxy matrix reinforced with two types of E-glass fiber was investigated. The hybrid glass fiber consists of woven glass fiber reinforced epoxy laminated between several layers of nonwoven glass tissue. The nanoparticles were incorporated into epoxy resin as a single nanoparticle (either SiO2 or C alone) or combining SiO2 and C nanoparticles simultaneously. Fatigue performance, on-axis and off-axis tensile behaviors of these hybrid composites were investigated. The incorporation of all nanoparticles contents leads to improvement in on/off axis ultimate tensile strength, failure strain, tensile modulus and toughness when compared to neat glass fiber reinforced epoxy composites except for the hybrid nanocomposites reinforced with 0·5 wt-% SiO2 and 0·5 wt-% C simultaneously. On/off-axis tensile properties were obviously improved with adding single SiO2 or C nanoparticles rather than with adding combined ones.

Evaluation of delamination crack tip in woven fibre glass reinforced polymer composite using FBG sensor spectra and thermo-elastic response

This paper details a study which was carried out on the application of FBG sensors for investigation of delamination crack status in glass fibre reinforced composite materials. A woven glass (0/90) epoxy composite sample containing a purposely created delamination and an embedded FBG sensor was investigated to study the behaviour of delamination crack under applied axial quasi-static tensile load. The reflected spectra from FBG sensor and the thermo-elastic response using an infrared camera were recorded to detect the propagation of delamination crack tip. In addition a finite element analysis (FEA) was performed using cohesive elements to simulate delamination crack tip. It has been seen that the propagation of delamination crack tip monitored from thermal stress analysis (TSA) was consistent with the prediction of the FBG sensor response. Further it has been observed that the experimentally observed delamination damage propagation was in a good agreement with FEA simulation results.

Mechanical characterization of natural nano-structured zeolite/polyurethane filled 3D woven glass fiber composite sandwich panels

3D woven glass fibers sandwich panels have become the focus of interest due to their inherent light weight and, thus, their remarkable stiffness. However, a question is that whether their hollow galleries could be filled with still light materials which even at the same time contribute to their mechanical performance. This work examines the effect of porous polymer nanocomposites filling galleries of such panels on mechanical response of newly formed hybrid composites. To achieve this, the nanocomposites of natural nano-structured zeolite/polyurethane foams were fabricated and injected within 3D woven glass fibers sandwich panels. Mechanical characterization techniques including the flatwise compression, edgewise compression, three-point bending and drop weight impact were carried out to understand the effect of addition of the reinforced foam on the mechanical response of the specimens. It is shown that the polyurethane foam reinforced with natural nano-structured zeolite particles significantly improves the flexural strength, ultimate load and energy absorption of the filled composite sandwich panels. It is also demonstrated that the damage and local wrinkling failure compared with other typical sandwich panels do not occur due to the presence of the glass fiber yarns vertically located between panel sheets. These type of composites provide high specific strength results from high-performance and low-density structure.

The compressive properties of sandwich structures based on an egg-box core design

Abstract Lightweight cores, based on an egg-box core design, have been manufactured using a simple compression-moulding technique. Two types of composite prepreg were used to manufacture the core materials, these being a woven carbon fibre reinforced epoxy and a woven glass fibre reinforced epoxy. The resulting cores were of a high quality, exhibiting little or no wrinkling following the manufacturing procedure. Subsequent compression tests at quasi-static rates of loading showed that the compression strength of the core depended strongly on the level of constraint applied during testing, with sandwich panels based on composite skins bonded to an egg-box core offering a load-bearing capability that was more than double that of its unconstrained counterpart. The quasi-static compression strength of the carbon-based cores has been shown to be slightly higher than the glass fibre systems, particularly at higher core densities. Local splitting damage at cell joining regions and crushing of the cell of the egg-box structure was identified as the primary failure mechanism in the sandwich panels. Impact tests, conducted using a drop-weight impact tower, have shown that the compression strength of the egg-box cores is higher at dynamic rates of loading than at quasi-static rates. Here again, the local splitting and crushing was the primary mode of failure in the sandwich structures. Finally, the finite element technique has been used to model the mechanical response of these core designs under both quasi-static and impact loading testing conditions. Here, agreement between the predicted and observed responses was found to be good for both extremes of loading-rate.

Impact Response for Two Designs of Athletic Prosthetic Feet

The present work evaluated the differences in mechanical properties of two athletic prosthetic feet samples when subjected to impact while running. Two feet samples designated as design A and B were manufactured using layers of different orientations of woven glass fiber reinforced with unsaturated polyester resin as bonding epoxy. The samples’ layers were fabricated with hand lay-up method. A theoretical study was carried out to calculate the mechanical properties of the composite material used in feet manufacturing, then experimental load-deflection test was applied at 0 degree position and 25 degree dorsiflexion feet position and impact test were applied for both feet designs to observe the behavior of the feet under static and impact loading and compare properties like stiffness, efficiency, rigidity, and shock absorption at different drop angles range from 25 degrees to 60 degrees which perform the foot positions while running. The load-deflection test result shows that the maximum deflection of the proposed design B was 32.2 mm at 0° and 38.45mm at 25°. While it was 41mm at 0˚ and 39mm at 25˚ for design A. Impact test result shows that design B foot gives peak load of 128 .7 kg with a peak time of 0.06 sec, while design Afoot gives 125.32 kg peak load with a time of 0.069 sec.

Failure maps to assess bearing performances of glass composite laminates

Aim of this article is the assessment of the bearing mechanical performances of pin‐loaded glass laminates as function of their geometrical configuration. To this concern, 32 specimens having different hole diameter (D), laminate width (W), and hole center to laminate free edge distance (E) have been tested under bearing conditions. The maximum bearing stress and the stress‐displacement curves were analyzed as function both of hole to laminate free edge distance E and hole diameter D. Moreover, an experimental 2D failure map was created by placing the experimental results (i.e., the kind of failure mechanism occurred for each geometrical configuration) in the plane E/D versus W/D ratios. In order to identify a simplified methodology able to design mechanically fastened joints in an easy and effective way, a simplified theoretical failure map on E/D and W/D axes was proposed. The theoretical model showed a good matching with the experimental results validating the proposed approach. In particular, the proposed simplified failure map highlighted that woven glass fiber composite laminates fastened joints should have E/D and W/D ratios higher than 1.6 and 2.1, respectively, in order to stimulate a progressive bearing failure mechanism and achieve the full laminate strength. Finally, another goal of this article was to assess failure mechanisms evolution by drawing a 3D plot (i.e., at varying E/D and W/D geometrical ratios) of the failure index evaluated for each failure mechanism according to the maximum stress criterion. POLYM. COMPOS., 40:1087–1096, 2019. © 2018 Society of Plastics Engineers