Glass Fibre-reinforced Polyester Research Articles

Ultrasound enhanced 50 Hz plasma treatment of glass-fiber-reinforced polyester at atmospheric pressure

Glass-fiber-reinforced polyester (GFRP) plates are treated using a 50 Hz dielectric barrier discharge at a peak-to-peak voltage of 30 kV in helium at atmospheric pressure with and without ultrasonic irradiation to study adhesion improvement. The ultrasonic waves at the fundamental frequency of around 30 kHz with the sound pressure level of approximately 155 dB were introduced vertically to the GFRP surface through a cylindrical waveguide. The polar component of the surface energy was almost unchanged after the plasma treatment without ultrasonic irradiation, but drastically increased approximately from 20 up to 80 mJ m−2 with ultrasonic irradiation. The plasma treatment with ultrasonic irradiation also introduced oxygen- and nitrogen-containing functional groups at the GFRP surface. These changes would improve the adhesion properties of the GFRP plates.

Low-velocity impact behavior of CNF-filled glass-reinforced polyester composites

A significant improvement in fiber-reinforced polymeric composite materials can be obtained by incorporating a very small amount of nanofillers in the matrix material. In this study, an ultrasonic liquid processor was used to infuse carbon nanofibers into the polyester matrix which was then mixed with a catalyst using a mechanical agitator. Both conventional and carbon nanofibers-filled glass fiber-reinforced polyester composites were fabricated using the vacuum-assisted resin transfer molding process. Low-velocity impact tests was performed at 10 J, 20 J, and 30 J energy levels on conventional as well as 0.1–0.3 wt% carbon nanofibers-filled glass fiber-reinforced polyester composites using Dynatup8210. The morphology of fractured specimens was examined using digital photographs and optical microscopy. There was an increase in the peak load for the nanophased glass fiber-reinforced polyester composites compared with the conventional one. The absorbed energy of nanophased glass fiber-reinforced polyester composites was less than that of conventional one at different energy levels. The extent of damage was more pronounced in the conventional glass fiber-reinforced polyester composites compared to nanophased ones. Failure mechanisms comprised of indentation, debonding, delamination, matrix cracking, and fiber fracture. The extent of damage was pronounced in conventional composite compared to nanophased ones.

Conformal thin film silicon photovoltaic modules

A polymer composite material system and a process for encapsulation of thin film solar cells were developed for profiled roofing elements, in view of building-integrated photovoltaic (PV) applications. Amorphous silicon cells were deposited on a polyethylene naphthalate film and encapsulated with additional polymer layers in the form of a flat laminate using industrial processes. The process technology developed in this work included a pre-forming step of the PV laminate and a moulding step of a glass fibre-reinforced polyester composite. These two steps were optimised using thermo-elastic analyses, with attention paid to laminate designs and process windows compatible with the thermo-mechanical limits of the fragile active PV layers. A demonstrator with standard 1.0 m×1.8 m corrugated roofing profile, a weight of 6.3 kg and 60 W of output power was produced. The long-term endurance of the conformal modules was also validated using humidity-freeze, damp-heat and water immersion tests.

Principal component analysis and fuzzy embedded Taguchi approach for multi-response optimisation in machining of GFRP polyester composites: a case study

This paper proposes an extended multi-objective optimisation philosophy applied in a case study of machining (turning) of randomly oriented glass fibre-reinforced plastic polyester composites. Design of experiment has been selected based on Taguchi’s L9 orthogonal array design with varying process control parameters, such as spindle speed, feed rate and depth of cut. Multiple surface roughness parameters of the machined fibre-reinforced polymer product along with material removal rate of the machining process have been optimised simultaneously. A principal component analysis coupled with fuzzy inference system has been proposed for providing feasible means for meaningful aggregation of multiple objective functions into an equivalent single performance index. This multi-performance characteristic index has been optimised using Taguchi method.

Analyzing Process Capability of Drilling on Glass Fiber Reinforced Polyester (GFRP) Composites with Taguchi Loss Function

The delamination is a major problem associated with the drilling of chopped glass fiber reinforced polyester (GFRP) composites. It reduces the structural integrity of the material, results in poor assembly tolerance and has the potential for long term performance deterioration. Thus it is important to evaluate the process capability of drilling on this material. It will thereby reveal the spectrum of delamination to be accepted from the view point of process capability for a chosen range of material thickness, drill diameter, speed and feed rate combinations. In the present analysis, therefore, Taguchi loss function is derived for the particular process based on the experimental data. Process capability index is then evaluated. The range of delamination factor is determined based on the consideration that process capability index should be one or more. The results are presented.

Prediction of fatigue life of glass fiber reinforced polyester composites using modal testing

The main objective of the present work is to investigate the capability of experimental modal analysis as a nondestructive tool to characterize and quantify the fatigue behavior of laminated composite beam with different lamina orientations and cantilevered boundary condition. In the present work, experimental modal analysis was conducted on the specimens previously subjected to fatigue loading to determine the modal parameters (natural frequency, damping ratio and mode shape). This was achieved through studying the response of modal testing with different specimens of different lamina orientations as a main factor affecting fatigue life. This correlates modal parameters such as: damping ratio, natural frequency and mode shape to fatigue behavior. The composite material used in experiments is glass fiber reinforced polyester (GFRP) laminate. Plane bending fatigue tests were performed on standard fatigue specimens. The fatigue test was interrupted at different fatigue life ratios (n/Nf) and modal testing was conducted to determine the change in modal parameters. The results showed that the changes of modal parameters provide a proper means for predicting the fatigue behavior of composite structures. From the experimental results of both dynamic and fatigue tests, curve fitting technique was used to correlate modal parameters to fatigue life. An exponential and quadratic equations have been obtained which correlate fatigue life ratio to damping ratio and resonant frequency respectively. It was noticed from the curves representing exponential and quadratic equations that the value of damping ratio ξ is more noticeable than the value of frequency, which means that the extent of fatigue damage determines the damping ratio, hence damping ratio could be said to be a good indicator of the fatigue life ratio.

Apparent hoop tensile strength prediction of glass fiber-reinforced polyester pipes

The apparent hoop tensile strength of glass fiber-reinforced polyester pipes plays an important role during their design procedure. In some cases, glass fiber-reinforced polyester pipes industry used hydraulic failure pressure to obtain this value. In addition to the expensive and time-consuming characteristics of this experiment, it underestimates the apparent hoop tensile strength. A sequential failure modelling is developed to predict apparent hoop tensile strength modelling integrating classical lamination theory and progressive damage modelling. Developed modelling takes into account influence of incorporated sand layer in glass fiber-reinforced polyester pipe wall construction. Experimental study is conducted to validate developed technique. A very good agreement is observed between experimentally measured apparent hoop tensile strength of glass fiber-reinforced polyester pipes and predicted values employing sequential failure modelling.

Betelnut fibres as an alternative to glass fibres to reinforce thermoset composites: A comparative study

For the current work, investigations were carried out using treated betelnut fibre-reinforced polyester (T-BFRP) and chopped strand mat glass fibre-reinforced polyester (CSM-GFRP) composites. Results revealed that T-BFRP showed competitive performance of about 1.16%, 17.39% and 4.92% for tensile, flexural and compression tests as compared to the latter. Through tribological performance tests, T-BFRP composite showed superiority in wear for the dry and wet tests of about 98% and 90.8% while the friction coefficient was reduced by about 9.4% and 80% respectively. The interface temperature was lower by about 17% for T-BFRP composite subjected to dry test as compared to CSM-GFRP. SEM analysis revealed that the brittle effects observed on glass fibres during the tribo test enhanced the material removal rate which increased the thermo-mechanical effects at the rubbing zone. As such, evidence of adhesive to abrasive wear transition was observed when the CSM-GFRP composite was subjected to the stainless steel counterface. On the contrary, T-BFRP composite formed a thin layer of shield (i.e. back film transfer) on its worn surface during the test, which assisted in lowering the material removal rate.

Modelling and Analysis of Thrust Force in Drilling of GFRP Composites Using Response Surface Methodology (RSM)

In recent days, Glass Fiber Reinforced Polyester (GFRP) Composites play important role in aircraft primary structures due to their high strength and low thermal expansion. The drilling process is a traditional cutting process in which hole is made in the material that is being drilled. The drilling process and tool parameters play a major role in deciding the quality of holes. In this paper an attempt has been made to establish an empirical relationship between the thrust force and drilling parameters (tool rotational speed, tool feed rate, drill diameter and fiber orientation angle) in drilling of GFRP Composites. Statistical tools such as design of experiments, analysis of variance, and regression analysis are used to develop the relationships. The developed empirical relationship can be effectively used to predict the thrust force of drilled holes at the 99 per cent confidence level.

Energy Absorption and Strength Evaluation for Compressed Glass Fibre Reinforced Polyester (GRP) for Automobile Components Design in Crash Prevention Scheme

This paper utilized the compressive tests results to establish some critical mechanical properties and crashworthiness parameters that may be required to design GRP composites of polyester matrix in automobile structures. Third order polynomial function was used with numerical methods to establish the elastic properties whish could not be established due to sensitivity of the Monsanto tensometer used to obtain the compression results. This study showed that the finite difference method captured the general trend of experimental solution giving optimum value of compressive stress as 23.78MPa at strain of 0.018 and elastic limit of 12.01MPa at 0.01 strain through finite difference analysis while the solution with third order polynomial interpolation gave optimum compressive stress as 36.57MPa at 0.018 strain and elastic limit of 12.143MPa. Also established with compression data is the compressive or buckling moduli of 1.2GPa. Gauss-Legendre two point rule was used to evaluate the area under the stress-strain curve which measured the amount of energy absorbed per unit volume of sample from where the energy absorbed at ultimate strength of 0.025J/M3- 0.22 J/M3 , energy at fracture of 0.62 J/M3- 1.62 J/M3 and the absorbed specific work 0.001J/Kg are established.

Behavior of [0]8 woven composites under combined bending and tension loading: part - I experimental and analytical

The objective of this work is to investigate the mechanical properties of [0]8 woven glass fiber reinforced polyester (GFRP) composites under monotonic and combined tension/bending loading. The results show that the failure of combined test specimen was at its ends, which have zero deflection and maximum bending moment and stress. This behavior agrees with the analytical stress distribution along the specimen length. Adding a tensile load at the ends of woven composite beams that designed to carry pure bending loads, such as bridge decks, can duplicate bending capacity of the beam. The relationship between combined bending moment and tensile load was constructed.

Improving damage resistance of a composite pole using a computer experiment strategy

Transmission poles are widely used for transmitting electricity from power plants to industrial and commercial sites as well as residential areas. The total cost of a transmission line is partly driven by the maintenance cost of poles and wires. To reduce this cost, designers can choose more durable materials and optimal design strategies. In recent years, the use of polymer composite transmission poles has become more popular and they have been implemented in a number of power systems. In this paper, a tapered composite pole under lateral wind load is modelled and its damage resistance under a set of composite failure criteria is investigated. The composite pole is made of glass fibre-reinforced polyester and is manufactured by filament winding. By focusing on fibre orientation angles in the pole layers, a computer experiment (simulation) strategy is designed along with a maximin space-filling sampling criterion. The goal is to choose the best combination of ply angles that can minimise pole damage while maintaining minimal computational cost. A 37% improvement in the matrix cracking failure index was achieved from the initial value of 1·00 (i.e. a damaged pole) to the optimised value of 0·63 (no damage).

Layup Analyzing of a Carbon/Glass Hybrid Composite Wind Turbine Blade Using Finite Element Analysis

This thesis use AOC15/50 blade as baseline model which is a composite wind turbine blade made of glass/epoxy for a horizontal axis wind turbine. A finite element modeling of composite wind turbine blade was created using the SHELL element of ANSYS. Then we study how to use the carbon fiber material replaces the glass fiber to make the hybrid blade, and find a suitable layup to improve the performance of the blade. The hybrid blade was made through introducing carbon fibers. Different models, with introducing different number of carbon fibers, 75% carbon fibers replace unidirectional glass fibers in spar cap of blade model which can achieve best structure performance. The wind turbine blades are often fabricated by hand using multiple of glass fiber-reinforced polyester resin or glass fiber-reinforced epoxy resin. As commercial machines get bigger, this could not to meet the demands. The advantages of carbon fiber composite materials are used by blade producer. Studies show that carbon fiber has high strength-to-weight ratio and resistance fatigue properties. Carbon fiber is mixed with epoxy resin to make into carbon fiber-reinforced polymer. Carbon fiber-reinforced polymer is the one of best blade materials for resistance bad weather. The stiffness of carbon fiber composite is 2 or 3 times higher than glass fiber composite [1], but the cost of carbon fiber composite is 10 times higher than glass fiber composite. If all of wind turbine blades are made of carbon fiber composite, it will be very expensive. Therefore carbon/glass fiber hybrid composite blade has become a research emphasis in the field of blade materials. This paper gives an example of finite element modeling composite wind turbine blade in ANSYS by means of the medium-length blade of AOC 15/50 horizontal axis wind turbine. This model can be directly used in dynamics analysis and does not need to be imported from the CAD software into finite element program. This finite element modeling of composite wind turbine blade was created using the SHELL element of ANSYS. Then we study how to use the carbon fiber material replaces the glass fiber to make the hybrid blade, and find a suitable lay-up to improve the performance of the blade.

Ultrasound Enhanced Plasma Treatment of Glass-Fibre-Reinforced Polyester in Atmospheric Pressure Air for Adhesion Improvement

A glass-fibre-reinforced polyester (GFRP) plate was treated with dielectric barrier discharge (DBD) at atmospheric pressure in air for adhesion improvement. The effects of ultrasonic irradiation using a high-power gas-jet generator during the treatment were investigated. The optical emission spectrum of the discharge remained almost unchanged by the ultrasonic irradiation, indicating that the bulk property of the discharge was not significantly influenced by the ultrasound. However, the ultrasonic irradiation during the plasma treatment suppressed occasional arcing in the DBD, preventing damage of the GFRP plates. The polar component of the surface energy of the polyester plate was 21 mJ/m2 before the treatment, increased markedly to 52 mJ/m2 after 2-s plasma treatment without ultrasonic irradiation, and further increased slightly after longer treatments. In addition, the polar component of the surface energy increased due to the simultaneous ultrasonic irradiation, indicating that the adhesive property would be further improved. This result shows a good agreement with surface characterization by X-ray photoelectron spectroscopy. Time-of-flight secondary ion mass spectrometry ion images show that nitrogen-containing functional groups were uniformly attached after the treatments. The roughness of the GFRP surfaces increased after the plasma treatment, but the ultrasonic irradiation did not enhance surface roughening.

Mechanical property evaluation of woven coir and woven coir–glass fiber-reinforced polyester composites

The fiber that serves as a reinforcement in reinforced composites may be artificial or natural. Past studies show that artificial fibers such as glass, carbon, etc., have been generally used in fiber-reinforced composites. Although glass and other synthetic fiber-reinforced composites possess high specific strength, their fields of application are very limited because of their inherent higher cost of production and low biodegradability. In this study, woven coir and woven coir–glass fiber-reinforced polyester composites were developed and their mechanical properties were evaluated. Scanning electron micrographs of fractured surfaces were used for qualitative evaluations of the interfacial properties of woven coir and woven coir–glass hybrid polyester composites. The results indicated that the properties of woven coir composites can be considerably improved by incorporation of glass plies.

The effect of fire‐retardant additives and a surface insulative fabric on fire performance and mechanical property retention of polyester composites

AbstractThis study investigates the simultaneous use of conventional fire‐retardant additives and an insulative intumescent thermal barrier/mat to improve the fire performance and mechanical property retention of glass‐fibre‐reinforced polyester (GRP) composites. Significant reductions in the peak heat release rate (PHRR) and total heat release (THR) were observed from measured cone calorimetric data following the addition of nitrogen, phosphorous, halogen containing and hydroxylated fire‐retardant additives. Some fire‐retarded glass‐fibre‐reinforced composites further protected by an intumescent mat containing silicate fibres, expandable graphite and borosilicate glass bound together by an organic matrix show further reductions in PHRR. Despite improving the fire retardancy of the composites, the presence of fire‐retardant additives alone does not improve flexural modulus retention following exposure to a heat source. However, the introduction of a ‘passive’ fire proofing insulative fabric enhances fire performance while preserving the mechanical properties of composites exposed to high heat fluxes or fires. Copyright © 2010 John Wiley & Sons, Ltd.

Gliding arc surface treatment of glass-fiber-reinforced polyester enhanced by ultrasonic irradiation

A gliding arc is a plasma generated between diverging electrodes and extended by a high speed gas flow. It can be operated in air at atmospheric pressure. It potentially enables selective chemical processing with high productivity, and is useful for adhesion improvement of material surfaces. The efficiency of such a plasma treatment at atmospheric pressure can be further improved by ultrasonic irradiation onto the surface during the treatment.In the present work glass fiber reinforced polyester (GFRP) plates are treated using an atmospheric pressure gliding arc with and without ultrasonic irradiation to study adhesion improvement. The airflow at the arc ignition directed the GFRP surface at a grazing angle of approximately 30°. The ultrasonic waves of the frequency range between 20 and 40kHz were introduced vertically to the GFRP surface through a cylindrical waveguide. It is found that ultrasonic irradiation reduced the OH rotational temperature of the gliding arc. The wettability of the GFRP surface was significantly improved by the plasma treatment without ultrasonic irradiation, and tended to improve furthermore at higher power to the plasma. Ultrasonic irradiation during the plasma treatment consistently improved the wettability. It is seen that polar functional groups were introduced at the surface by the gliding arc treatment, and that the treatment efficiency was enhanced by the ultrasonic irradiation, indicating that the adhesive property would be improved. TOF-SIMS ion images indicate that oxygen and nitrogen are uniformly attached at the treated surfaces with and without ultrasonic irradiation. The principal effect of the ultrasonic irradiation is attributed to enhanced oxidation during the plasma treatment.

Applicability of empirical models for evaluation of stress ratio effect on the durability of fiber-reinforced creep rupture–susceptible composites

Fiber-reinforced polymer–matrix composites are known to exhibit loading rate- and time-dependent mechanical response. Their fatigue strength is determined by a complex interaction of damage processes governed by loading duration and cycle number. Apart from mechanistic approaches, a number of empirical models of various sophistication have been proposed to predict the durability of composites, differing in the amount of experimental data needed for their application. The accuracy of several such models is evaluated by comparing the prediction to the experimentally determined stress ratio effect on fatigue life of glass fiber-reinforced polyester–matrix composite. It is found that the accuracy of prediction generally improves with increasing the amount of test data needed for model calibration. However, the most accurate method of fatigue life estimation, among the selected ones, is by the modified Goodman diagram.

Testing of Fiber Composite Leaf Spring for Heavy Axle Loads

This paper presents the results of quasi-static and dynamic testing of glass fiber-reinforced polyester leaf suspension for rail freight vehicles named Euroleaf. The principal elements of the suspension’s design and manufacturing process are initially summarized. Comparison between quasi-static tests and finite element predictions are then presented. The Euroleaf suspension have been mounted on a tipper wagon and tested dynamically at tare and full load on a purpose-built shaker rig. A shaker rig dynamic testing methodology has been pioneered for rail vehicles, which follows closely road vehicle suspension dynamic testing methodology. The use and evaluation of this methodology have demonstrated that the Euroleaf suspension is dynamically much softer than steel suspensions even though it is statically much stiffer. As a consequence, the suspension dynamic loading at laden loading conditions is reduced compared to the most advanced steel leaf suspension over shaker rig track tests.

Development of a slim window frame made of glass fibre reinforced polyester

This paper presents the development of an energy efficient window frame made of a glass fibre reinforced polyester (GFRP) material. Three frame proposals were considered. The energy and structural performances of the frames were calculated and compared with wooden and aluminium reference frames. In order to estimate performances, detailed thermal calculations were performed in four successive steps including solar energy and light transmittance in addition to heat loss and supplemented with a simplified structural calculation of frame load capacity and deflection. Based on these calculations, we carried out an analysis of the potential energy savings of the frame. The calculations for a reference office building showed that the heating demand was considerably lower with a window made of GFRP than with the reference frames. It was found that GFRP is suitable for window frames, and windows made of this material are highly competitive in their contribution to the energy savings. A rational product development method was followed, and the process clearly identified the objectives of the investigation and set out the appropriate way to attain them. Using simple rational development methods, a well-defined and effective window was achieved smoothly and quickly, as is illustrated in the case study.