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Investigation and analysis of the dynamic behavior of composite materials and their failure resistance are essential. The main aim of this study is to investigate the improvement of impact properties of incorporated glass fiber reinforced polymer (GFRP) composite specimens with various loading of nanoclay and nanosilica in a corrosive environment. After fabrication of samples by hand layup method, all of them were immersed in 5 wt. % of sulfuric acid solution for 0, 1 and 3 months. As the immersion time increased, the specimens containing nanosilica absorbed more water than the other samples. The force-displacement, force-time and energy-time diagrams showed the superiority of filled composites with nanoparticles over the pure sample in all immersion periods. Low-velocity impact (LVI) test results of specimens containing nanoclay showed a better behavior and with the addition of 5 wt. % of nanoclay, the impact force increased by 15.72% and the displacement decreased by 5.26%. Also, in these samples, the energy absorption rate decreased by 17.15%, which was associated with a reduction in the damage rate. After immersion of specimens in different times, specimens containing 5 wt. % of nanoclay had better strength than other samples and maintained their superior properties. The obtained results illustrated that the addition of 1 and 3 wt. % of nanosilica had no specific effect on the improvement of impact properties. Finally, incorporated GPRP composites with 3 wt. % of nanoparticles were simulated using LS-DYNA software and the experimental and numerical results were compared to investigate their accordance.

In this paper, we have investigated the damages of glass fiber reinforced plastic (GFRP) composite tubes under the effect of low-velocity impact (LVI) at cryogenic environment conditions and room temperature. A GFRP composite tube consists of 6 layered E-glass/epoxy samples with a ± 55° winding angle, which produced by the filament winding method. Composite tubes either at room temperature or conditioned by liquid nitrogen at different temperature values (273 K, 223 K, 173 K, and 77 K) were impacted at 5, 7.5, and 10 J. Also, force-time and force-displacement graphs were plotted. The damaged regions of the samples were scrutinized. The damage areas of the GFRP composite tubes were smaller as the temperature decreased. However, the energy absorbed at low-temperature conditions was slightly higher than that absorbed in room temperature. Besides, no micro-cracks developed in the composite tubes after cryogenic conditioning.

Glass fiber reinforced polymer composites were prepared by different manufacturing technology and are extensively used for various applications. In recent times more research is carried out on glass fiber reinforced composites owing to their excellent mechanical properties. This study deals with the analysis of glass fiber reinforced polymer composites manufactured by different types of glasses, Matrix materials prepared using different production technologies. Glass fibers possesses good properties such as high strength, flexibility, stiffness, durability etc. With an increase in the content of glass fiber volume the properties of GFRP composites were improved. The mechanical & thermal attributes of various polymer composites reinforced by glass fiber when subjected to mechanical loading have been studied and reported.

Mechanical fastening technique plays a vital role in aerospace and automotive industries because of their ability to make large assemblies in composite materials. However, it is challenging to drill holes in composite materials which are free of defects. Thus, the paper investigates the influence of glass fiber content within the GFRP composites during the drilling operation. Different hole quality parameters such as roundness deviation, delamination, fiber pull-out, taper angle were observed as they contribute to better machinability and improved surface quality while drilling. A radial drilling machine was used to perform the drilling process on the composites keeping a constant rotational speed and feed rate. Only fiber weight percentages were varied. The experimental results exhibited that the drilled surface quality is closely related to the percentage of the fiber content of the specimens. In terms of roundness deviation, delamination, fiber pull-out, and taper angle, a better result is achieved for the composite specimen having comparatively lower glass fiber content.

In this experimental investigation, internal scarf repaired composite laminate with a scarf angle ranging from 10° to 18° were examined under low velocity impact. The comparison between simulation and experiment was analyzed based on parameters like maximum contact force, maximum absorbed energy, maximum displacement, depth, damage area, and impact time duration. The residual tensile strength revealed that when the scarf angle was large, it performed best with less absorbed energy and less damage, the reasons for it could be attributed to less material removal from the parent laminate. Furthermore, it was observed that repaired composite with 18° scarf angle recovered 95.71% of the initial tensile strength. Thus it is safely concluded that increasing the scarf angle increases the residual tensile load bearing capacity.

This paper presents the results of an experimental study that investigates the compression behavior of concrete and evaluates the effect of hybrid reinforcement by multiple geometries, and total and partial confinement, using CFRP and GFRP composite materials. A total of nine (09) variants of concrete cylindrical specimens, including one (01) variant of unconfined concrete and eight (08) variants of confined concrete with different geometries were subjected to axial load compression. The objectives of this study were to verify the applicability and effectiveness of partial and total confinement to improve the behavior of concrete, evaluate the effect of the hybrid confinement used, and obtain a typical reinforced model. The results obtained clearly show the effectiveness of the hybrid confinement and partially confined concrete in improving the compressive strength and deformation of the concrete, so it is possible to replace CFRP total confinement by partially confined concrete with two CFRP layers or by a hybrid confinement with a CFRP layer in the central zone and GFRP layers on the top and bottom of the specimen.

Fatigue of structural adhesives has been investigated through joints and a little number of works investigate bulk adhesive behaviour itself. Aerospace and automotive engineering focuses more on joint configuration studies, which are correlated with practical applications. Previous works showed that for thin adhesive joints, material properties measured by bulk adhesive testing and joint testing are similar despite the triaxial stress states developing in the adhesive bondlines. However, with the introduction of structural adhesives in construction industry, thicker bondlines have emerged where the bulk adhesive material dominates the joint behaviour. This review work summarises works on the fatigue of bulk structural adhesives used mainly in the construction industry investigating structural adhesives fatigue behaviour either through experiment on joints or on bulk adhesive specimens. The work focuses on thick adhesive bondlines in joints, and discusses the controversy that is over whether adhesive properties from joints or from bulk material should be used.

Fiber reinforced polymer composites have paved the way for the evolution of the engineering materials. Glass fiber reinforced polymer (GFRP) has become one of the most promising materials among the novel composites due to its low price and high performance. Here, the GFRP composite in investigated by fill atomistic molecular dynamics, which contains the epoxy matrix and amorphous silica substrate. The degradation in chloride environment is revealed through the interfacial interactions, the structural changes of the epoxy matrix and hydrogen bonding in the composites. Compared to dry and aqueous environment, the simulation results show that chloride environment leads to the worst deterioration of interfacial adhesion, which correlates with structural and mechanical degradation of bonded interface, as indicated by the decreased epoxy density close to interface. It is indicated by examining the nano-structures of the interface during the pulling process that the chloride environment hinders the formation of intramolecular and intermolecular hydrogen bonds in the GFRP composites. These findings indicate the deterioration towards bond and matrix is critical in the presence of the chloride environment, which provides the fundamental insight for designing and predicting performance degradation of macroscopic GFRP composites in the marine application.

The present work deals with temperature effects and parametric optimization in the drilling of continuous glass fiber reinforced epoxy composite. Drilling ability was examined operating a drilling system with different drill bits, feed rate, and spindle speed parameters. The investigation was performed by changing the tool and composite interface. Drilling experiments were carried out under the dry condition. Thrust force and drilling temperatures were measured using dynamometer and thermal camera. Peel-up and push-out delamination were evaluated using an image analyzing tool. Results show that the tribo-mechanical behavior of the drilling operation is affected at different levels by tool coating. This behavior is related to the intrinsic friction properties of coating nature. Response surface methodology was used in the evaluation of experiment results. The feed rate of 0.13 mm/rev, spindle speed of 2425 rpm and HSS-TiN drill bit are found as an optimum drilling parameters and drill type.

In this study, a new low-velocity shear impact test was introduced to carefully investigate the resistance of 3D E-glass fiber reinforced polymer composites with shear thickening fluid matrix. The shear thickening fluids were prepared by dispersing silica nano-particles in polyethylene glycol. Pure shear thickening fluid was modified by treating the silica surface with (3-Aminopropyl) triethoxysilane. Despite the low-velocity shear impact test, various experimental tests such as yarn pull-out, quasi-static puncture, flexibility and thickness tests were carried out to study the mechanical behavior of the composites. Results revealed the treated shear thickening fluid up to 60 wt% improves the performance of the impregnated samples against the yarn pull-out and puncture tests by 353% and 45%, respectively, and their shear impact resistance by 130% compared to the neat cases without noticeably affecting the fabric flexibility.

The paper proposes to present the results of the evaluation of glass fiber reinforced plastics (GFRP) used in the construction of wind turbine blades. In a wind turbine, the blades are the most exposed to damages and the defects which appear are various and are connected with the type of manufacture, simple/complex loading, environmental conditions etc. In order to increase the lifetime span and to analyze the degradation phenomena during the materials functioning, destructive evaluation tests are performed to determine the mechanical property, by testing pure shear on specimens Iosipescu, from GFRP with woven reinforcement at [± 45°] and [0°/90°], with the shear fixture, endowment of Technical University Gh.Asachi Iasi.

A comparative study on the tribological properties of GFRP laminated composites containing MWCNTs, graphene and graphene-MWCNT mixture under different conditions is presented. The samples comprised of neat GFRP laminates and GFRP laminates further filled with0.1 wt. % graphene, 0.1 wt. % MWCNT and hybrid 0.05 wt. % graphene and 0.05 wt. % MWCNT mixture. The tests were conducted under three different applied loads of 40, 80 and 120N and sliding velocities of 0.98 and 1.96 m/s. Weight of specimen was taken before and after the experiments and to calculate the wear in terms of weight loss. The experiments showed that graphene filled GFRP composite has lowest coefficient of friction value, whereas the MWCNT reinforced GFRP laminate has the highest resistance against wear

Aerospace structural components are made by adhesively bonded layers of different materials for achieving specific properties for industrial applications. One such advanced structural material is made of glass fibre reinforced plastic (GFRP) composite. This is a layered engineered material with composite adhesively bonded to rubber to one of the surfaces. Such engineered materials can withstand structural, thermal and corrosive environments. GFRP composite have to be bonded with rubber using rubber solution or other adhesive to keep them structurally bonded. Any separation of these two layers will make the engineered structure redundant. In this paper, we report application of various NDE methods for evaluating bonded interfaces of engineered structural composite materials. Conventional methods such as X-ray radiography and ultrasonic (acousto-ultrasonic) methods were experimentally verified for identifying defects at the adhesively bonded interfaces. Disadvantages of these conventional methods were overcome by using advanced single sided nuclear magnetic resonance (NMR) technique. The use of low frequency single sided portable NMR for characterising defects at the adhesively bonded interfaces is discussed. In addition to the defect detection, application of NMR for measuring thickness of adhesive layers coated over rubber is also presented. Advantages of using NMR technique over other conventional methods is discussed.

The goal of this analysis is to establish an insubstantial, rising performance and rising firmness of glass fiber reinforced plastic (GFRP) composite and perform the boring operation with an inside breadth of 8 mm on the fabricated GFRP composite plate with cryogenically treated contort drill geometry instrument and untreated curve drill geometry apparatus. The reaction acquired is the delamination factor with the guide of digital representation investigation. The results reveal that penetrating the produced GFRP composite with a cryogenically treated tool demonstrated the optimal outcome.

This paper demonstrates the effect of small ply angle variation in tensile and compressive strength of woven Glass Fiber Reinforced Polymer (GFRP) composites. Four different plies of (0/90)4, (±5°)4, (±10°)4, (±15°)4 manufactured by hand lay-up followed by the press molding machine. Samples for the tensile and compressive tests were prepared according to ASTM D3039 and ASTM D3410 standards. Three samples of each laminate were tested on a Universal Testing Machine (UTM) at a steady crosshead speed of 1 mm/min. A digital microscope was used for tracking the sample damage pattern. It was observed that fiber orientation in laminates affects the tensile and compressive strength. Fibers ruptured during tensile testing of specimens and in compressive testing, samples failed due to the separation of longitudinal fibers. The experimental results showed that (0/90)4 ply showed the maximum tensile strength and compressive strength followed by (±5°)4, (±10°)4, (±15°)4. Weibull distribution analysis was used for statistical estimation of the tensile and compressive life of specimens.

Abrasive water jet machining (AWJM) is a non-conventional machining process, which is employed for difficult-to-machining of thin, hard and brittle materials. This experimental study reports the influence of process parameters on the surface roughness and dimensional accuracy when drilling of GFRP composites using abrasive water jet technique. In particular, investigated the effects of abrasive flow rate, pressure, standoff distance and fiber orientation on hole quality were examined. Experimental results revealed that standoff distance and fiber orientation has major effect on surface roughness and dimensional accuracy.

This study is based on the water absorption characteristics of Fiberglass reinforced and waste plastics filled hybrid polymer Composites. The fiberglass reinforced polymer Composites are mostly used in the making of boats making, car bodies, etc. As it is subjected to be in contact with water and salty atmosphere for the most of the days, it must have an enhanced water repulsive nature. Moisture absorption property is affected by the addition of fillers and reinforcement materials. This study reveals the optimized selection and composition of the reinforcements and fillers at which the composite exhibits a better water repulsive characteristics. For the making of composite, spray layup process is followed and the moisture absorption nature of the specimens are tested as per the ASTM standards. For optimization MINITAB17 software is utilized and the specimens are produced as per the L9 orthogonal array design in Taguchi method. The results were then optimized to get the minimum moisture absorption property. The optimized results show that the specimen with E type glass fibre, 55 wt℅ of glass fibre composition and 25 wt℅ of plastic waste particulate fillers and remaining binders have minimal water absorption characteristics. The results reveal that the selection of the glass fibre and percentage of the fillers added has more influence on the moisture absorption property of the composites

Composite materials are extensively used in various applications like space, aircraft, and automobile sector because of superior physical and mechanical properties even though they are costly. In recent technological innovations, using Montmorillonite (Nanoclay) to reinforce polymer-based composites has raised attention to academic and industrial sectors since small addition could enhance Mechanical properties thereby decreasing failures like delaminations. In present research work, the effect of AWJ machining parameters on delaminations of glass fibre reinforced epoxy composite is investigated. The Main objective is determining delamination factor and reduce delaminations which is major failure in laminates. This paper investigates on effects of impregnated Nanoclay epoxy in Bi-directional GFRP where previous research has been made only in changing the parameters for reduction of delaminations. The samples were machined using AWJ, delamination factors are measured using image-J software and SEM analysis for comparing micrographs. Finally with increase in nano clay weight fraction, delaminations are checked.

A hollow concrete column (HCC) is a structurally efficient construction system and uses less material. Conventionally, HCCs are reinforced with steel bars, which are prone to corrosion. This study explored the use of glass-fiber-reinforced-polymer (GFRP) composite bars as reinforcement for HCCs and evaluated the effect of the reinforcement ratio on HCC structural behavior. A total of six HCCs reinforced longitudinally with GFRP bars with different reinforcement ratios (1.78%, 1.86%, 2.67%, 2.79%, 3.72, and 4.00%) were prepared and their behavior was investigated. The different reinforcement ratios were achieved by changing the bar diameter (12.7 mm, 15.9 mm, and 19.1 mm) and number of bars (4, 6, 8, and 9 bars). The results show that increasing the diameter and number of bars enhanced the strength, ductility and confinement efficiency of HCC. For columns with equal reinforcement ratios, using more and smaller-diameter GFRP bars yielded 12% higher confinement efficiency than in the columns with fewer and larger-diameter bars. The crushing strain of the GFRP bars embedded the HCC was 52.1% of the ultimate tensile strain. Lastly, the axial-load capacity of the GFRP-reinforced HCC can be reliably predicted by considering the contribution of the concrete and up to 3000 μe in the longitudinal reinforcement.

This research examines the friction and dry wear behaviours of glass fibre-reinforced epoxy (GFRE) and glass fibre-reinforced polyester (GFRP) composites. Three fibre orientations—parallel orientation (P–O), anti-parallel orientation (AP–O), and normal orientation (N–O)—and various sliding distances from 0–15 km were examined. The experiments were carried out using a block-on-ring configuration at room temperature, an applied load of 30 N, and a sliding velocity of 2.8 m/s. During the sliding, interface temperatures and frictional forces were captured and recorded. Worn surfaces were examined using scanning electron microscopy to identify the damage. The highest wear rates for GFRE composites occurred in those with AP–O fibres, while the highest wear rates for GFRP composites occurred in those with P–O fibres. At longer sliding distances, composites with P–O and N–O fibres had the lowest wear rates. The highest friction coefficient was observed for composites with N–O and P–O fibres at higher sliding speeds. The lowest friction coefficient value (0.25) was for composites with AP–O fibres. GFRP composites with P–O fibres had a higher wear rate than those with N–O fibres at the maximum speed.

The application of laser fabrication of fiber-reinforced polymer (FRP) has an irreplaceable advantage. However, the effect of the plasma generated in laser fabrication on the damage process is rarely mentioned. In order to further study the law and mechanism of laser processing, the laser process was measured. CFRP and GFRP materials were damaged by a 1064 nm millisecond pulsed laser. Moreover, the propagation velocity and breakdown time of plasma plume were compared. The results show that GFRP is more vulnerable to breakdown than CFRP under the same conditions. In addition, the variation of plasma plume and material surface temperature with the number of pulses was also studied. The results show that the variation trend is correlated, that is, the singularities occur at the second pulse. Based on the analysis of experimental phenomena, this paper provides guidance for plasma phenomena in laser processing of composite materials.

Since the presence of a notch in a mechanical component causes a reduction in the fatigue strength, it is important to know the kf value for a given notch geometry and material. This parameter is fundamental in the fatigue design of aeronautical components that are mainly made of composites. kf is available in the literature for numerous types of notch but only for traditional materials such as metals. This paper presents a new practice, based on thermographic data, for the determination of the fatigue notch coefficient kf in composite notched specimens. The innovative aspect of this study is therefore to propose the application on composite materials of a new thermographic procedure to determine kf for several notch geometries: circular, U and V soft and severe notches. It was calculated, for each type of notch, as the ratio between the fatigue limits obtained on the cold and hot zone corresponding to the smooth and notched specimen, respectively. Consequently, this research activity provides, for the first time, a little database of kf for two particular typologies of composite materials showing a fast way to collect further values for different laminates and notch geometries.

This paper investigated the static behaviour of glass fibre reinforced polymer (GFRP) built-up hollow and concrete filled built-up beams tested under four-point bending with a span-to-depth ratio of 1.67, therefore focusing their shear performance. Two parameters considered for hollow sections were longitudinal web stiffener and strengthening at the web&ndash, flange junction. The experimental results indicated that the GFRP hollow beams failed by web crushing at supports, therefore, the longitudinal web stiffener has an insignificant effect on improving the maximum load. Strengthening web&ndash, flange junctions using rectangular hollow sections increased the maximum load by 47%. Concrete infill could effectively prevent the web crushing, and it demonstrated the highest load increment of 162%. The concrete filled GFRP composite beam failed by diagonal tension in the lightweight concrete core. The finite element models adopting Hashin damage criteria yielded are in good agreement with the experimental results in terms of maximum load and failure mode. Based on the numerical study, the longitudinal web stiffener could prevent the web buckling of the slender GFRP beam and improved the maximum load by 136%. The maximum load may be further improved by increasing the thickness of the GFRP section and the size of rectangular hollow sections used for strengthening. It was found that the bond&ndash, slip at the concrete&ndash, GFRP interface affected the shear resistance of concrete&ndash, GFRP composite beam.

Composite materials are having good dynamic properties, specific strength, and specific stiffness. The analytical formulations for dynamic analysis of composite tube shafts are mainly equivalent mo...

The confinement with Glass Fiber Reinforced Polymer (GFRP) composites of the concrete columns is effective in increasing their capacity as many authors have shown, but few studies dealt with partially wrapped columns. The main objective of this work is to study the influence of the partially confinement with Glass Fiber Reinforced Polymer (GFRP) composites on the behavior of the concrete cylinder under axial compressive load. Different heights of the confined area are considered in order to follow the evolution of the global mechanical response of the cylinder according to the parameter ‘x / h’ which represents the ratio of the height of the confined zone to the total height of the cylinder. The numerical results show that the partial confinement increases the ultimate stress of the confined short concrete cylinder and influences the mode of rupture. The confrontation of the numerical results with the experimental one shows a good concordance.

The Hole making operation on composite materials is complex and problematic this is due to GFRP’s inherent anisotropy and in-homogeneity as compared with metallic materials. The present work is focusing on the effect of cutting parameters and material parameters on delamination of the drilled hole is analyzed and optimum cutting condition for minimizing the delamination is determined to improve the hole quality. The parameters considered for drilling operation are speed, feed, thickness, fiber orientation and material thickness. The optimization of process parameters done by Taguchi’s S/N ratio analysis for delamination in drilling of GFRP composites. ANOVA (Analysis of Variance) test was conducted to analyze the significant effect of process parameters on delamination. From the experimental results it is evident that Peel-up delamination is highly influenced by the material thickness and followed by the feed rate and fiber orientation, similarly the feed rate having the significant effect on the Push-down delamination next to the material thickness. A Regression–based model is developed to predict the delamination and good agreement between the experimental and predicted results is obtained with order of 98%.

Carbon nanotubes have been considered as good filler materials for enhancing the characteristics of advanced nano-composites due to their excellent properties. In z-axis property, especially interlaminar shear strength (ILSS) is of prime concern for FRP laminates undergoing lateral loads. The present work highlights the effect of MWCNTs on the ILSS of GFRP composites manufactured by vacuum-assisted hand layup technique. Result shows that the addition of 0.5 wt% MWCNTs into the unfilled GFRP composite decreases ILSS by 8.35%. The fracture surface of glass fiber-reinforced polymer composites is analyzed by field-emission scanning electron microscope, and micrographs are used to delineate the ILSS outcomes.

Purpose This paper aims to investigate the effect and parametric optimization of process parameters during milling of glass fibre-reinforced plastics (GFRP) composites using grey relational analysis (GRA). Design/methodology/approach Experiments are conducted using helix angle, spindle speed, feed rate, depth of cut and fibre orientation angle as typical process parameters. GRA is adopted to obtain grey relational grade for the milling process with multiple characteristics, namely, machining force and material removal rate (MRR). Analysis of variance is performed to get the contribution of each parameter on the performance characteristics. Findings It is observed that helix angle and fibre orientation angle are the most significant process parameters that affect the milling of GFRP composites. The experimental results reveal that the helix angle of 45°, spindle speed of 3000 rpm, feed rate of 1000 mm/min, depth of cut of 2 mm and fibre orientation angle of 15° is the optimum combination of lower machining force and higher MRR. The experimental results for the optimal setting show that there is considerable improvement in the process. Originality/value Optimization of process parameters on machining force and MRR during endmilling of GFRP composites using GRA has not been attempted previously.

Glass fiber reinforced polymer (GFRP) composite is a desirable alternative to porcelain for insulators of cylindrical electrical equipment in electrical substation . However, mechanical properties of composite insulator in an event of earthquake are not fully known yet. This study aimed to investigate both the static and dynamic properties of GFRP composite insulators and electrical equipment through impact hammer test, quasi-static flexural tests and full scale shaking table tests. The flexural properties, in terms of flexural stiffness , damping and hysteretic behavior, were investigated, based upon which a mechanical model was proposed. Moreover, the possible failure modes were identified in order that a design and qualification procedure was recommended for engineering application. The procedure has been further validated by a full scale shaking table test of 1000 kV cylindrical composite electrical equipment.

Fibre reinforced composite materials are demanded by the industry especially for the applications where weight reduction is critical because of their high specific strength, ability to resist corrosion. The present work aims on evaluation of various mechanical properties of glass fiber reinforced polymer composites (GFRP) with inclusion of single walled carbon nanotube (SWCNT) in different weight fractions. Before performing the tests, the specimens were allowed to immerse in fresh water and sea water simultaneously for a period of 11 days (110 Hours) under hydrostatic pressure and further observing the amount of moisture content that has been accumulated in the specimens if any. This type of material can be used in marine industries as an alternative material for fabrication of hull of a ship and also used to design and fabricate various components of a ship.

During operational conditions, extreme environments combined with unexpected high loading rates can induce severe damages or, inclusively, premature fails. Therefore, this paper intends to study the effect of different hostile solutions on the longitudinal impact strength in order to establish design criterions. For this purpose, samples of GFRP composites were immersed into alkaline and acid solutions as well as distilled water. Variables like exposure time, temperature and concentration of the solution were analysed in detail. The effect of pre-damages was also studied for different pre-loads, where the severity of the damages introduced was quantified by acoustic emission. It was possible to conclude that, independently of the solution, the exposure time and temperature were determinant to decrease the tensile impact strength. Finally, the magnitude of the initial damage has a significant influence on the impact resistance.

A composite material scores over its metallic counter parts in many aspects and can be tailor-made to suit the specific purpose for which it is conceived. However, during functioning the composite is exposed to the severities of the surrounding ambiance and is damaged and degraded by the atmospheric deterrent-reagents like moisture and heat fluctuations. In order to ensure a safe, extended service life-span of the composite material, it is, therefore, pertinent that the behaviour of the material related to its physical, chemical and mechanical characteristics must be analysed and established under different fluctuating ambient conditions. The present report aims at analysing and presenting the degradation/damages caused to the glass-fibre reinforced plastic (GFRP) composites under different ambient conditions and the role played by some inherent factors like the constituent components of the GFRP composites, its pre-existing flaws created during manufacturing/service-life, volume fraction fibres, length and distribution of the fibres in the matrix phase and the curing processes adopted for strengthening and stabilising the matrix structure.

Buckling is a prominent condition of instability caused to a shell structure as a result of axial loadings. The process of buckling becomes more complex while analyzing thin walled structures like shells. Today such thin walled laminated composite shells are gaining more importance in many defense and industrial applications since they have greater structural efficiency and performance in relation to isotropic structures. Comprehensive understanding of the buckling response of shell structures is necessary to assure the integrity of these shells during their service life. The presence of defects, such as cracks, may severely compromise their buckling behavior and jeopardize the structural integrity. This work aims in conducting numerical analysis of cracked GFRP (Glass fibre-reinforced polymer) composite cylindrical shells under combined loading to study the effect of crack size on the buckling behavior of laminated composite cylindrical shells with different lay-up sequences. The numerical analyses were carried out using the finite element software, ABAQUS in order to predict the buckling behaviour of cracked laminated composite cylinders subject to different combinations of axial compression, torsion, internal pressure and external pressure from the interaction buckling curves.

The composite materials are widely used nowadays as major parts of structures in many industries like aerospace, marine, automobile, space vehicles and also for the repair and replacement of civil infrastructures. Stresses are vital parameters considered in the design of structures. Any irregularities in shape, materials, or the presence of cut-outs create localized stress concentration and reduce the capacity of the material to take loads. The anisotropic behaviour of composite structures also makes the analysis more complex. Shear loading often exists in the engineering practices such as in aerospace due to heavy aerodynamic loads. So in the present study the effects of different parameters like layup sequences, number of plies, proximity of cut-outs, shapes and arrangements of cut-outs under in-plane shear loading on the glass fibre reinforced polymer (GFRP) plate with multiple cut-outs are studied using ABAQUS. The results from the study show that all the parameters considered for the study affects the stress concentration considerably. The observations are analysed then and the final conclusions are presented.

Glass Fiber Reinforced polymer (GFRP) structures are chiefly manufactured using the hand lay-up or carpet sweeper infusion techniques, which are efficient for the gist of able-bodied sailor vessels and aviation industry. The scope of this study is to assess the tensile strength, flexural strength and Izod impact strength analysis on a bidirectional Glass Fiber Reinforced Polymer (GFRP)/0.3mm diameter steel wire embedded laminates. Laminates fabricated with [90/0/0/90], lay-ups of steel wire placed at ¼ th & ¾ th thick with 3, 5 & 7 mm pitch intervals have been fabricated. The tensile strength, flexural strength and total energy absorbed by the specimens were evaluated for both GFRP and Steel Wire embedded Glass Fiber Reinforced Polymer (SWGFRP) sample. From the results, it was evaluating the tensile strength, flexural strength and the impact resistance were enhanced due to the influence of steel wire in the samples at a range of thicknesses.

Till now very few researchers have executed research work on multidirectional and thick (>6mm) glass/epoxy composites. Selecting a proper cutting tool is a great challenge and need immediate attention due to unavailability of the literature investigating the effect of cutting tools during drilling thick multidirectional GFRP composites. Therefore, in this study, twist drills with (TiAlN coating) and without coating are employed in drilling this material. Progressive thrust force, flank wear and delamination for both drills are investigated in details against number of holes drilled. It is found that, uncoated tools demonstrate the better cutting performance with lesser delamination and lesser tool wear.

In the present research work, effects of process parameters on the machine characteristics of GFRP composite and Borosilicate glass have been carried out. The drilling characteristics that have been investigated are material removal rate (MRR) and taper angle of the hole. The four process parameters were considered for the study - stand of distance, pressure, abrasive particle size and time taken. The significant parameters were identified and their effect on the MRR and taper angle were studied. The obtained results reveal that MRR is most influenced by the abrasive particle size and stand of distance.

The production and worldwide use of chicken eggs on an industrial or domestic level leads to a considerable quantity of shell residue, which is considered as a waste or is used as a complement in agriculture. Use of waste materials in polymer matrix composites is on the rise mainly due to environmental and economic apprehensions. The present work is focused on to analyse the influence of egg shell powder as filler materials on the mechanical behaviour of glass fibre, reinforced resin matrix. Different types of composites are fabricated using 5 wt% egg shell powder and 10 wt% egg shell powder with 50 wt% fibre, rest matrix material. The composites are manufactured by hand-layup process. Specimens cut and tested according to ASTM standards. The mechanical and physical properties are studied. The results are compared for different percentage of filler material.

This paper describes a laminate curing process by hand lay-up of plain-weave woven Glass fiber-reinforced polymer (GFRP) composite composed of unsaturated polyester resin reinforced with E-glass fiber fabric, EWR-600B. Symmetrical and non-symmetrical ply orientation arrangements were introduced with respect to different curing pressures to produce consistent composite panels according to the British standard code: BS 1268 (2001) for evaluations of void content and physical properties. Quantitative analysis of volume and weight fractions and void volume content were investigated according to the ASTM code: D 2734. Woven GFRP composites fabricated under different curing pressures of 351.2 (35.8 kg/m2), 687.7 (70.1 kg/m2), 1020.2 (104 kg/m2) and 1355.7 Pa (138.2 kg/m2) showed minimal significant effect on volume and weight fractions of symmetrical and non-symmetrical ply lay-up arrangement, whereas 4 % void content still fulfilled the limit of medium quality composite.

In many present applications is requested decreasing of weight of components and increasing of their strength. Often unique properties are required. These properties could be solved by using of composite materials. However, different material properties of matrix and reinforcing material cause issues during machining, such as rapid tool wear and delamination of composite. Therefore there is afford to enhance machining process by different ways to decrease tool wear as well as delamination of composite. This article deals with comparison of conventional milling and ultrasonic assisted milling of glass fibre reinforced polymer (GFRP) composite material by special designed cutting tool.

A study was undertaken to determine the effects of several key geometry influencing factors on the impact response and energy absorption behavior of the glass fibre reinforced epoxy composites at low and intermediate energies. The energy-balance model was employed for characterising the energy absorption behavior and it depends strongly on the plate diameter and thickness. In addition, the damage vs. energy and force maps is effective in monitoring damage growth within the composite panel. The response of the composite laminate configurations characterized by different stacking sequences subjected to low velocity impacts with different impact energies have also been studied to estimate the damage initiation of composites.

This study reports on the results of an experimental investigation on the impact behaviour of pultruded composites samples subjected to low-velocity impacts with higher impact energies ranging from 16.75 to 67 J. The specimens were placed and supported according to the requirement of ASTM 7136 standard. The results of impact characteristics and performance are demonstrated and compared for different impact energy levels. The damage evaluation is also introduced to compare the failure modes of pultruded composites subjected to different energy levels. The development and propagation of stress during the low-velocity impacts are analysed using the finite element method. The numerical predictions were found to corroborate the experimental results in terms of load-time and central deflection-time curves.

In this experimental work, the behaviour of unidirectional glass fibre-epoxy composites under a cutting force was studied, in order to better understand the cutting mechanisms of processes involving but not limited to composite materials. Starting from composite panels manufactured by resin infusion process, dedicated specimens were obtained and subjected to a quasi-static punch-shear test. Eight different fibre orientation angles with respect to the direction of the cutting force were considered. For each case, different stress-strain behaviours were observed and discussed. The differences were also investigated, in terms of damage propagation, by means of microscopic observations of the cutting zone.

This study evaluated the performance of a hybrid panel in an improved moveable weir after exposure to accelerated environmental climate conditions. When exposed to a river environment, corrosion problems on improved moveable weir steel panels can occur. To address this, a hybrid panel with structure layering glass fiber-reinforced polymer (GFRP) panels on both sides of the steel panel was used. The steel was, therefore, not exposed to the outside. However, this hybrid panel is a structure that uses a mixture of two materials with different properties and there is the possibility of performance degradation when the GFRP composite material, i.e., the structure that wraps around the bond interface, and the steel panel are exposed to a river environment. Thus, we evaluated the durability of the hybrid panels by repeated exposure to long-term high temperatures, dry&ndash, wet environmental cycling, long-term freezing, and freeze&ndash, thaw cycling in an accelerated climate deterioration environment. In the flexural tests, the surface processing of the steel panel was shown to be important, with sand-blasted test specimens showing higher flexural strength. For the control specimens, the flexural strength decreased as the thickness of the GFRP panels increased. However, for the sand-blasted specimens, the flexural strength increased as the thickness of the GFRP panels increased. After exposure to accelerated climate deterioration, the flexural strength tests showed that the residual strength increased with panel thickness and that the residual strengths were greater for specimens incorporating sand-blasted steel panels. The results of our testing show that hybrid panels incorporating sand-blasted steel were adequate for use in improved moveable weirs.

The paper presents an attempt to evaluate the technically important properties of epoxy resin modified alternatively with multi-walled carbon nanotubes and flaked graphene. It is a presentation of experimental results supported by extensive referring to the professional literature. The nano-components were added in the amount which was economically justified and provides hope for a significant improvement of some of the properties of pure resin. Flowability, glass wettability, curing process and gelation time and curing shrinkage of the resin were evaluated. After the resin was cured, inner and outer hardness, thermal conductivity, flexural strength and impact resistance were measured. Glass fibre-reinforced laminates were also prepared with use of the nano-modified resin. The mechanical properties, interlaminar shear strength and flexural strength of the laminates, were evaluated for them. The obtained results showed either no effect or only technically slight effect of the nano-modification on the evaluated properties. Noticeable improvement in interlaminar shear strength and impact resistance for laminates containing resin filled with graphene can predestine this kind of modification as a method of increasing the delamination resistance of laminates.

In this paper, the authors focused on evaluation of fatigue fracture mechanisms accompanying fatigue of polymeric composites with an occurrence of a self-heating effect. In order to reflect degradation processes and their evolution at various values of a self-heating temperature with a possibility of analyzing an internal structure of cracks and delaminations occurring during fatigue, X-ray computed tomography tests were performed. Specimens made of a GFRP composite were subjected to cyclic loading in order to stimulate a non-stationary self-heating of the structure. The performed tests allow for characterization of morphology of damage occurring during fatigue loading of polymeric composites subjected to dominated self-heating, and, based on the performed observations, determination of a critical self-heating temperature value, which causes appearance of internal fracture in a structure. Moreover, a continuous acquisition of a self-heating temperature and acoustic emission during fatigue allows for connection of fracture events with particular events observed in temperature evolution and acoustic emission signals, which, in turn, allows for better understanding of formation of fracture in a structure in such loading conditions.

Non-destructive evaluation (NDE) techniques that can measure both surface and subsurface defects are of critical importance in evaluating the integrity of GFRP composites. In the present work, optical transmission scanning (OTS) technique was proposed for acquiring high-resolution, rapid, and non-contact OT (optical transmittance)-scans of pristine and impacted GFRP samples. Advanced data analysis was developed and implemented to identify the number of delaminations at every scan position. The results agreed very well with the actual number and extent of delaminations observed directly from a cross-section of the specimen. Overall, the presented technique lays the groundwork for cost-effective, non-contact, rapid, and quantitative NDE of GFRP composite structures.

This article presents the results of tensile tests performed on E-glass/Epoxy composite coupons. Eighteen GFRP panels were manufactured and cured in laboratory environment, out of which specimens in size of 25 mm × 250 mm specimens were cut. The specimens were categorised into three groups; the first group was post-cured at 60℃ oven for 16 h while the second and the third groups were placed under seawater at 60℃ for about 60 days and 4 months to represent saturation condition and ageing, respectively. The mechanical parameters such as elastic modulus (E), ultimate tensile strain (ɛu) and shear modulus (G) which are reported here were measured and were compared to one another showing that these are influenced by different conditioning regimes to a great extent.