Glass Fiber Reinforced Plastic Composites Research Articles

Novel patch shape design to repair π/4 quasi-isotropic E-glass/epoxy laminate under uniaxial tensile loading condition

The entitled technical subject in its comprehensive and broadly viewed study is presented by stating that the prevailing glass fiber–reinforced plastic composites play a vital role in replacing the metallic structures in automotive, aerospace, and marine applications and their more usage necessitates the better understanding of such structure’s damage and effective repair practices of the same. In the course of repairing the composite structures, optimum usage of patch material helps to maintain the original strength, eliminate “over design,” and reduce contribution to the substantial performance change of original structure. Optimum usage of repair material brings down the significant percentage of mass and repair cost. In order to apply the concept of optimum patch shapes over actual structures, it is important to design such effective shapes which are equivalent to the conventionally proven repair designs in strength perspective. This technical paper describes one of such ways to design the optimum patch shape using finite element analysis (FEA) tool and in comparison with one of the conventional repair practices, like circular patching, used circular, rectangular, square, elliptical and trapezoidal patch shapes, each of which has its own merits and demerits when compared to the other. But, none of them was arrived at in the perspective to use the minimum material to repair the damage. The object of this work is carried out in order to arrive at the optimum patch shape (minimum material in its in-plane direction) in repairing the damaged structure and it has been demonstrated using π/4 quasi-isotropic E-glass/epoxy specimen with hole using FEA. Moreover, the effectiveness of optimum patch shape design in “strength” and “load transfer efficiency” perspectives is experimentally proven and highlighted by the scope of repair material saving (36%) in repair practice by the usage of this optimized approach, as well.

Optimization of process parameters on machining force and MRR during end milling of GFRP composites using GRA

PurposeThis 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/approachExperiments 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.FindingsIt 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/valueOptimization of process parameters on machining force and MRR during endmilling of GFRP composites using GRA has not been attempted previously.

Effect of Tool Wear on Machining GFRP and AISI D2 Steel Using Alumina Based Ceramic Cutting Tools

The alumina based ceramic cutting tools are used to machine glass fibre reinforced plastic (GFRP) composite material and AISI D2 steel. The machining studies were conducted using Ti[C,N] mixed alumina based ceramic cutting tool (CC650) and SiC whisker reinforced alumina based ceramic cutting tool (CC670). Machining process was performed at different cutting speeds at constant feed rate and depth of cut and the flank wear of the cutting tools were measured. From the machining studies, the wear behaviour of the cutting tool are studied and compared with reference to the work material. Very smooth wear land was observed while machining GFRP composite whereas, ridges and groves were observed while machining steel using alumina based ceramic cutting tools. The hard metal chips produced during machining has induced to undergo the severe in changes on machining D2 steel. Based on the flank wear, tool face fibre / matrix chip has prone to maximum wear of 0.4mm compared to machining a metal. On machining AISI D2 steel the machining has reduced one fold (1:2) than the GFRP composite material. In summary, Ti[C,N] mixed alumina cutting tool performance better on machining AISI D2 steel and SiC whisker reinforced alumina cutting tool for machining GFRP composite.

Multi-response optimization for machining GFRP composites using GRA and DFA

PurposeThe purpose of this paper is to optimise the process parameters, namely, fibre orientation angle, helix angle, spindle speed, and feed rate in milling of glass fibre-reinforced plastic (GFRP) composites using grey relational analysis (GRA) and desirability function analysis (DFA).Design/methodology/approachIn this work, experiments were carried out as per the Taguchi experimental design and an L27 orthogonal array was used to study the influence of various combinations of process parameters on surface roughness and delamination factor. As a dynamic approach, the multiple response optimisation was carried out using GRA and DFA for simultaneous evaluation. These two methods are best suited for multiple criteria evaluation and are also not much complicated.FindingsThe process parameters were found optimum at a fibre orientation angle of 15°, helix angle of 25°, spindle speed of 6,000 rpm, and a feed rate of 0.04 mm/rev. Analysis of variance was employed to classify the significant parameters affecting the responses. The results indicate that the fibre orientation angle is the most significant parameter preceded by helix angle, feed rate, and spindle speed for GFRP composites.Originality/valueAn attempt to optimise surface roughness and delamination factor together by combined approach of GRA and DFA has not been previously done.

Optimisation of machining parameters on milling of GFRP composites by desirability function analysis using Taguchi method

Milling of GFRP composite materials is a rather complex task owing to its heterogeneity and the number of problems, such as surface delamination, which appear during the machining process, associated with the characteristics of the material and the cutting parameters. Optimization of machining parameters is an important step in machining. This paper presents a new approach for optimizing the machining parameters on milling glass-fibre reinforced plastic (GFRP) composites. Optimization of machining parameters was done by an analysis called desirability function analysis (DFA), which is a useful tool for optimizing multi-response problems. In this work, based on Taguchi’s L27 orthogonal array, milling experiments were conducted for GFRP composite plates using solid carbide end mills with different helix angles. The machining parameters such as, spindle speed, feed rate, helix angle and fibre orientation angle are optimized by multi-response considerations namely surface roughness, delamination factor and machining force. A composite desirability value is obtained for the multi-responses using individual desirability values from the desirability function analysis. Based on composite desirability value, the optimum levels of parameters have been identified, and significant contribution of parameters is determined by analysis of variance.Keywords: GFRP composites; Taguchi; Desirability function analysis; ANOVA; Solid carbide end mill

Retraction Note to: Evolution of the Health of Concrete Structures by Electrically Conductive GFRP (Glass Fiber Reinforced Plastic) Composites

The function and performance of self-diagnostic composites embedded in concrete blocks and piles were investigated by bending tests and electrical resistance measurement. Carbon powder (CP) and carbon fiber (CF) were introduced into glass fiber reinforced plastic (GFRP) composites to provide electrical conductivity. The CPGFRP composite displays generally good performance in various bending tests of concrete block and piles compared to the CFGFRP composite. The electrical resistance of the CPGFRP composite increases remarkably at small strains in response to microcrack formation at about 200 μm strain, and can be used to detect smaller deformations before crack formation. The CPGFRP composite shows continuous change in resistance up to a large strain level just before the final fracture for concrete structures reinforced by steel bars. It is concluded that self-diagnostic composites can be used to predict damage and fracture in concrete blocks and piles.

Retraction Note to: Self-Diagnosis of GFRP Composites Containing Carbon Powder and Fiber as Electrically Conductive Phases

The electrical characteristics of glass fiber reinforced plastic (GFRP) composites have been investigated in order to incorporate a self-diagnosis function suitable for monitoring the health of structural materials. The electrical conductivity was introduced by adding carbon powder (CP) or carbon fibers (CF) into GFRP rods and sheets. The self-diagnosis ability of the composites was evaluated by measuring the change in electrical resistance as a function of stress (or strain) in tensile tests. The resistance of CFGFRP changed only slightly at small strain levels and increased nonlinearly with the applied stress due to cutting of the fibers at higher levels. CPGFRP showed high sensitivity to stress and the resistance changed linearly over a wide strain range. During cyclic loading tests, a residual resistance was also observed in CPGFRP composites after unloading. The residual resistance increased with maximum applied strain, showing that it can be used as an indicator of previously applied strain or stress. It is concluded that the CPGFRP composite is a promising material for simple diagnosis of dynamic damage and cumulative strain.

Impact of the ambiance on GFRP composites and role of some inherent factors: A review report

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.

The effect of processing methods on the improvement of tensile properties of Random Ramie Fiber – Reinforced Tapioca Starch Biocomposites

The disposal of Glass Fiber-Reinforced Plastic (GFRP) composites is becoming an environmental issue. To overcome the problem, biocomposites made of ramie fibers and tapioca starch might become an alternative to GFRP composites, due to their renewable properties, environmental friendly and easily degraded by nature. However, mechanical properties of fiber-reinforced starch based biocomposites are quite low due to high void content and poor fiber-matrix interface. In this research, the effect of the processing methods on tensile properties of tapioca starch - reinforced random ramie fiber biocomposites were studied. Ramie fiber reinforced tapioca starch biocomposites were fabricated by means of solution casting and compression molding technique. Random ramie fiber-reinforced tapioca starch biocomposites were succesfully made with the highest tensile strength and modulus elasticity of biocomposites were 18 MPa and 959 MPa respectively. The use of 1% NaOH alkalization process on ramie fiber increased tensile strength and modulus elasticity of biocomposites 64% and 54% respectively. Application of 120 °C compression temperature, increased tensile strength and modulus elasticity of biocomposites 18% and 74% respectively. Homogenous dispersion of ultimate fiber increased the tensile strength up to 91%. However, the addition of glycerol decreased the tensile strength and modulus elasticity for 46% and 39% respectively.

Critical Analysis in Milling of GFRP Composites by Various End Mill Tools

Glass Fiber Reinforced Plastic (GFRP) composites are widely used in various industrial applications due to their higher strength to weight ratio. During the machining process the stress concentration may lead to catastrophic failure of the structure while in service. Need to minimize these surface defects in machining; the research is still going on some what extent, which is important aspect in engineering production. Hence, the importance of this study to evaluate the machinability of uni-directional Glass Fiber reinforced Polyester (UD-GFRP) composites by four different end mill tools with 10mm diameter: two number of customized two fluted brazed carbide tipped toolswith different tool angles; commercially availed one number four fluted High Speed Steel (HSS) end mill tool and one number four fluted solid carbide end mill tool. The milling operations were conducted with help of Taguchi L25 Design of Experiments (DOE) to optimize the process parameters of spindle speeds from 690RPM to 2500 RPM and the feed rates 0.6mm/Sec to 1.4mm/Sec at constant depth of cut is 3mm. These effects definitely influenced on the output responses such as machining force and surface roughness. From the results of the Analysis of Variance (ANOVA), the feed rate is highly influenced factor on the machining force and the spindle speed is significant factor for the surface roughness. And from the experimental evaluation it is showed that the performance of customized end mill tool-2issuperior in terms of better surface quality. Finally, the machined surface texture was thoroughly examined with Scanning Electron Microscope (SEM), and found that the surface defects were low, when machined with customized end mill tool among the other tools.

Comparative Study of Damping in Pristine, Steel, and Shape Memory Alloy Hybrid Glass Fiber Reinforced Plastic Composite Beams of Equivalent Stiffness

<p class="p1">Several efforts were made over the years to control vibration of structural components made of composite materials. This paper consists of study on effect of using shape memory alloy (SMA) to increase the damping of glass fiber reinforced plastic (GFRP) composites. A comparative study between SMA and steel was made as reinforcement material in GFRP composites to enhance damping. Dimensions of each beam were calculated such that all the beams i.e. pristine GFRP beam, GFRP beam embedded with steel wires and GFRP beam embedded with SMA wires have same flexural stiffness and first mode of frequency of vibration. Damping ratio was measured experimentally through logarithmic decay method. Through experiments damping ratio obtained for SMA hybrid composite beam was found to be higher as compared to the pristine and steel hybrid GFRP composite beams.</p><p class="Text"><span> </span></p>

Analysis of thrust force and delamination in drilling GFRP composites with candle stick drills

Drilling is an indispensable process for assembling the composites components. The drilling-induced delamination damage generally refers to the peel up delamination on the entrance surface and the push down delamination on the exit surface. Many researchers have carried out studies on drilling force and delamination damage in composites using special drills. Candle stick drills have been recognized as advantageous tools for the reduction of thrust force and delamination damage in drilling composites. Drilling experiments of glass fiber-reinforced plastic (GFRP) composites and finite element simulations were carried out in this paper. Three candle stick drills with different drill tip geometries and one twist drill were compared in terms of thrust force, peel up delamination, and push down delamination. The results revealed that, compared to twist drill, not all candle stick drills could get relatively good drilling results. What is more, drilling results of candle stick drills had a great relationship with the drill tips geometry angles. Finally, an optimized candle stick drill with appropriate drill tip geometry achieved relatively excellent drilling results.

Designing a phthalonitrile/benzoxazine blend for the advanced GFRP composite materials

High performance resin must be used in the high performance glass fiber-reinforced plastic (GFRP) composites, but it is sometimes difficult to balance the processabilities and the final properties in the design of advanced thermoset GFRP composites. In this study, a phthalonitrile/benzoxazine (PPN/BZ) blend with excellent processability has been designed and applied in the GFRP composite materials. PPN/BZ blend with good solubility, low melt viscosity, appropriate gel condition and low-temperature curing behavior could enable their GFRP composite preparation with the prepreg-laminate method under a relatively mild condition. The resulted PPN/BZ GFRP composites exhibit excellent mechanical properties with flexural strength over 700 MPa and flexural modulus more than 19 GPa. Fracture surface morphologies of the PPN/BZ GFRP composites show that the interfacial adhesion between resin and GF is improved. The temperatures at weight loss 5% (T 5%) and char residue at 800 °C of all PPN/BZ GFRP composites are over 435 °C and 65% respectively. PPN/BZ GFRP composites with high performance characteristics may find applications under some critical circumstances with requirements of high mechanical properties and high service temperatures.

Mechanical characterization of pseudoelastic shape memory alloy hybrid composites

Shape memory alloys (SMAs) are embedded in fiber reinforced plastic (FRP) composites material to achieve properties like higher toughness, shape morphing, variable stiffness etc. Pseudoelastic SMAs are mostly used in improving the energy absorbing capability of composites subjected to impact loading. Pseudoelastic SMA material has the property of absorbing higher strain energy without failure as compared to other engineering materials. Embedding SMA in FRP composites may affect its in-plane properties. This paper deals with study on SMA hybrid GFRP (Glass Fiber Reinforced Plastic) composites to find out the effect of embedding SMA in composites on the mechanical properties such as longitudinal tensile and compressive strength, transverse tensile strength and compressive strength and in-plane shear strength. Experimental results show that longitudinal compressive strength of shape memory alloy hybrid composites (SMAHCs) increases by approximately 30% over pristine composites. There is a marginal change in values of longitudinal tensile strength and in-plane shear strength in SMAHCs as compared to pristine composites whereas there is reduction observed in transverse tensile and compressive strength in SMA hybrid GFRP composites as compared to pristine GFRP composites.

A simple repair method for GFRP delamination using ultraviolet-curable resin

Fiber-reinforced plastic (FRP) composites are widely used in engineering because of their high strength and light weight in comparison to monolithic metal alloys. They are mostly used in laminate form and are stronger within layers than between layers, making them prone to cracking and peeling. This type of structural degradation can be dangerous during operation. For this reason, research on FRP composites with the ability to self-repair has attracted much attention. In this study, we developed a new method to repair glass fiber-reinforced plastic (GFRP) composites by using ultraviolet-(UV) cured resin. As GFRP composites are UV transmissive, the repair process can be carried out externally by exposing the damaged part to UV light. The transmittance of EP GFRP is about 40%. Holes were pre-drilled with wires in order to facilitate the injection of UV resin between the layers of the composite, and this process was accomplished without degrading the mechanical properties of the material. A double cantilever beam (DCB) test was performed on the GFRP composite to induce interlaminar fracturing. UV-curable resin was then injected between the layers of the composite through a series of pre-drilled holes. Following this repair, the DCB test was performed again to evaluate the repair rate. A compressive after impact (CAI) test was also performed on the GFRP composite to induce delamination. Compressive strength before and after the repair was also evaluated.

Effect of Fiber Orientation on Carbon/Epoxy and Glass/Epoxy Composites Subjected to Shear and Bending

In this study, the Interlaminar shear strength (ILSS) and flexural properties for five different laminate orientations [0°, 45°, [45°/-45°/45°]s, [±45°/0°/90°]s and 90°] of unidirectional carbon fiber reinforced plastic (CRP) and glass fiber reinforced plastic (GRP) composites are investigated. The different approach is used by applying the tensile load on notched specimens for measuring the inter-laminar shear strength. The theoretical flexural properties are obtained using the classical laminate theory [CLT]. The good agreement is obtained between the theoretical model and experimental results. The results indicate that the flexural strength and stiffness are higher for 0° laminate whereas flexural strain is higher for [45°/-45°/45°]s laminates as compared to other laminates. The scanning electron microscopy is used to observe the fracture surface of all laminate orientations of CRP and GRP composites.

THE EFFECT OF DRILLING PARAMETERS ON STRENGTH OF GLASS FIBRE-EPOXY LAMINATES BY PRODUCED HAND LAY-UP

In this study, the effects of delamination factor on strength of glass fiber reinforced plastic (GFRP) composite with +45/-45 orientation angle fabrics were investigated. GFRP composite specimens, which contain 36% fiber volume, were produced by hand lay-up. The all specimens were prepared according to ASTM D5766-2002 standards. The experiments were conducted the different drilling parameters such as cutting speeds and feed rates using tungsten carbide (WC) and Brad Spur drill tools. Delamination factors of drilled specimens were determined by optical microscope. The tensile strength values of the drilled GFRP composite specimens were determined by universal tensile testing machine. As results, it was determined that the increasing cutting speed and feed rate increased the delamination factor. The strength of GFRP composites decreased with increasing delamination factor .

Multi-objective optimisation on end milling of hybrid fibre-reinforced polymer composites using GRA

PurposeThis study aimed to develop a mathematical model for delamination and surface roughness during end milling by using grey relational analysis (GRA) and to determine how the input parameters (cutting speed, depth of cut, helix angle and feed rate) influence the output response (delamination and surface roughness) in machining of hybrid glass fibre-reinforced plastic (GFRP) (abaca and glass) composite using solid carbide end mill cutter.Design/methodology/approachThe Four factors, three levels Taguchi orthogonal array design in GRA is used to conduct the experimental investigation. The Shop Vision inspection system is used to measure the width of maximum damage of the machined hybrid GFRP composite. The Shop Handysurf E-35A surface roughness tester is used to measure the surface roughness of the machined hybrid GFRP composite. “Minitab 14” is used to analyse the data collected graphically. Analysis of variance is conducted to validate the model in determining the most significant parameter.FindingsThe GRA is used to predict the input factors influencing the delamination and surface roughness on the machined surfaces of the hybrid GFRP composite at different cutting conditions with the chosen range of 95 per cent confidence intervals. Analysis on the influences of the entire individual input machining parameters on the delamination and surface roughness has been conducted using GRA.Originality/valueEffect of milling of the hybrid GFRP composite on delamination and surface roughness with various helix angle solid carbide end mill has not been analysed yet using the GRA technique.

Application of the Taguchi based Desirability Function Analysis to Improve a GFRP Micro-drilling Performance

Drilling on GFRP composite materials in micron level is a complex work due to its heterogeneity and the problems such as delamination, fiber push up/pull out, overcut, dimensional deviation and circularity error which show during the machining process. This work presents optimizing the machining parameters on drilling Glass Fiber Reinforced Plastic (GFRP) composites. Optimization of machining parameters was carry out by an analysis called desirability function analysis (DFA), which is the technique for optimizing multi-response problems. In this work, as per the design of experiment, drilling processes were carrying out on GFRP composite using solid carbide drill. The cutting speed and feed are optimized by multi-response considerations namely hole size, delamination factor and circularity error. Based on analysis, the optimum levels of factors have been identified and significant contribution of parameters is determined by analysis of variance.

Comparative evaluation on milled surface quality of GFRP composites by different end mill tools

Milling is a machining process that used in the production industry to make components to mate with other component in the assembly. The GFRP materials are not generally subjected to machining unless otherwise the perfect mating is required. The extensive and expensive experimental work is necessary to evaluate the cutting process parameters for achieving the preferred machined quality. In this regard, the present work is focused on minimising the machined surface damage. Moreover, the paper presents the comparative analysis and performance of two different mill tools (one is customised the two fluted brazed carbide tipped tool and other is four fluted solid carbide tool). Subsequently, comparative evaluation of two tools was illustrated by the plotting graphs. Finally experimental results were thoroughly analysed by the scanning electron micrographs to study the cutting characteristics of machined glass fibre reinforced plastic (GFRP) composite surface.