Fiberglass-reinforced Polymer Research Articles

Evaluating the Mechanical Properties of Fiberglass-reinforced Polymer Bar

Evaluating the Mechanical Properties of Fiberglass-reinforced Polymer Bar

Prediction of the Damage Effect on Fiberglass-Reinforced Polymer Matrix Composites for Wind Turbine Blades.

The structure of wind turbine blades (WTBs) is characterized by complex geometry and materials that must resist various loading over a long period. Because of the components’ exposure to highly aggressive environmental conditions, the blade material suffers cracks, delamination, or even ruptures. The prediction of the damage effects on the mechanical behavior of WTBs, using finite element analysis, is very useful for design optimization, manufacturing processes, and for monitoring the health integrity of WTBs. This paper focuses on the sensitivity analysis of the effects of the delamination degree of fiberglass-reinforced polymer composites in the structure of wind turbine blades. Using finite element analysis, the composite was modeled as a laminated structure with five plies (0/45/90/45/0) and investigated regarding the stress states around the damaged areas. Thus, the normal and shear stresses corresponding to each element of delaminated areas were extracted from each ply of the composites. It was observed that the maximum values of normal and shear stresses occurred in relation to the orientation of the composite layer. Tensile stresses were developed along the WTB with maximum values in the upper and lower plies (Ply 1 and Ply 5), while the maximum tensile stresses were reached in the perpendicular direction (on the thickness of the composite), in the median area of the thickness, compared to the outer layers where compression stresses were obtained. Taking into account the delamination cases, there was a sinuous-type fluctuation of the shear stress distribution in relation to the thickness of the composite and the orientation of the layer.

Constructing a two-level computational model of cross-ply fiberglass-reinforced plastic from micromechanical testing

This paper deals with solving the problem of constructing two-level computational models relating the stress-strain state at the microscale to the stress-strain state of the structural component at the macroscale for layered polymer composite materials with unidirectional fiber stacking in a monolayer. The paper presents a two-level computational mechanical model of a ten-layer cross-ply fiberglass-reinforced polymer composite with (0/90) laying patterns. The model is based on microindentation data. The model is constructed using the finite element method. The constructed model has allowed us to predict the elastic properties of the composite and to calculate stresses at the microscale and macroscale levels of a specimen prior to fracture under tensile conditions. The elastic properties of the polymer composite material predicted by the computational model are compared with the properties obtained from real experiments. Calculated for fiberglass, the elasticity modulus and Poisson’s ratio are 31 GPa and 0.11, respectively. Similar elastic properties obtained from real experiments are 28 GPa and 0.10. The technique used in the paper can be applied to computational experiments with an actual structural component made of a multilayer polymer composite in order to determine the stress-strain state at the micro- and macroscale under external mechanical impact on the structure.

Effects of a Crossarm Brace Application on a 275 kV Fiberglass-Reinforced Polymer Crossarm Subjected to a Lightning Impulse

The crossarm is an important component of transmission towers, providing insulation for transmission lines at different voltage ratings. Recently, composite crossarms were widely used as a composite tower component and were found to be the most favorable choice for replacing old wooden crossarms. Owing to the satisfactory pilot operation and multiple sets of testing, fiberglass-reinforced polymer (FRP) composite crossarms have been used in Malaysia in both 132 and 275 kV transmission lines since the late 1990′s. Since then, some modifications have been proposed to improve the mechanical performance of the crossarm, in order to ensure the reliability of its performance. In this investigation, the effect of a proposed improvement, achieved by installing a brace for the crossarm, was investigated numerically. A simulation study was conducted, with a consideration of the lightning impulse voltage (LIV) and swing angle exhibited by the crossarm. The potential and electric field (E-Field) distribution were analyzed and are presented in this paper. It was found that the potential distribution and E-Field strength for the crossarm and the surrounding air were greatly affected by the installation of the brace.

A comparison LCA of the common steel rebars and FRP

The use of fiberglass-reinforced polymer (GFRP) as an alternative solution in strengthened concrete technology significantly has been increased recently. Fiberglass rebar (GFRP) took a stronger position in modern construction. This is due, on the one hand, to its high specific strength (ratio of strength to specific gravity) and on the other hand, too high corrosion resistance, frost resistance, and low thermal conductivity. Its non-corrosive nature has turned the attention of many researchers to make several studies on the different types of GFRP products. Insufficient resources for metal increase the requirement for renewable resources such as composites. However it is considered the environmental issues as a most significant problems which needs to study in every case, from this point of view despite all the GFRP advantages the environmental impacts of this material takes an important place to study, in this study the production stage of GFRP has been studied, in addition to better understand of the issue a comparison between steel rebars and GFRP was conducted, a significant environmental impact was seen in GFRP production process which needs to be considered for production of these materials.

Evaluation of pyrolysis parameters for fiberglass reinforced polymer composites based on multi‐objective optimization

SummaryThis study was conducted to investigate the ability of global, multi‐objective/variable optimization methods to estimate material parameters for comprehensive pyrolysis models—thermo‐physical and optical properties of two fiberglass reinforced polymer (FRP) composites that share the same fiberglass. With these optimization methods used in pair with a comprehensive pyrolysis model, parameter estimation was carefully conducted with considerations given to applying appropriate thermal decomposition kinetic models (three different models from simple to complex) and optimization targets (cone calorimeter data irradiated at 50 kW/m2). Estimation results are compared with independently measured effective properties—thermal conductivity, specific heat capacity, and emissivity of polymer resins and FRPs. Additionally, fiberglass properties estimated from the two FRPs are compared to analyze for consistency in optimized values. The results show that for a well‐configured parameter estimation exercise using the optimization method described earlier, (1) estimated results are within ±100% of the measurements in general and sometimes comparable to effective property values, (2) increasing complexity of the kinetic modeling for a single component system has insignificant effect on estimated values, and (3) increasing complexity of the kinetic modeling for a multiple component system with each element having different thermal characteristics has positive effect on estimated values. Copyright © 2014 John Wiley & Sons, Ltd.

Gas-phase plume from laser-irradiated fiberglass-reinforced polymers via imaging fourier transform spectroscopy.

Emissive plumes from laser-irradiated fiberglass-reinforced polymers (FRP) were investigated using a mid-infrared imaging Fourier transform spectrometer, operating at fast framing rates (50 kHz imagery and 2.5 Hz hyperspectral imagery) with adequate spatial (0.81 mm(2) per pixel) and spectral resolution (2 cm(-1)). Fiberglass-reinforced polymer targets were irradiated with a 1064 nm continuous wave neodymium-doped yttrium aluminum garnet (Nd:YAG) laser for 60 s at 100 W in air. Strong emissions from H(2)O, CO, CO(2), and hydrocarbons were observed between 1800 and 5000 cm(-1). A single-layer radiative transfer model was developed for the spectral region from 2000 to 2400 cm(-1) to estimate spatial maps of temperature and column densities of CO and CO(2) from the hyperspectral imagery. The spectral model was used to compute the absorption cross sections of CO and CO(2) using spectral line parameters from the high-temperature extension of the HITRAN. The analysis of pre-combustion spectra yields effective temperatures rising from ambient to 1200 K and suddenly increasing to 1515 K upon combustion. The peak signal-to-noise ratio for a single spectrum exceeds 60:1, enabling temperature and column density determinations with low statistical error. For example, the spectral analysis for a single pixel within a single frame yields an effective temperature of 1019 ± 6 K, and CO and CO(2) column densities of 1.14 ± 0.05 and 1.11 ± 0.03 × 10(18) molec/cm(2), respectively. Systematic errors associated with the radiative transfer model dominate, yielding effective temperatures with uncertainties of >100 K and column densities to within a factor of 2-3. Hydrocarbon emission at 2800 to 3200 cm(-1) is well correlated with CO column density.

Evaluating effects of applying different kinetic models to pyrolysis modeling of fiberglass‐reinforced polymer composites

SummaryThis research evaluates the effects of applying different kinetic models (KMs), developed based on thermal analysis using thermogravimetric analysis data, when used in typical 1D pyrolysis models of fiberglass‐reinforced polymer (FRP) composites. The effect of different KMs is isolated from the FRP heating by conducting pyrolysis modeling based on measured temperature gradients. Mass loss rate simulations from this pyrolysis modeling with various KMs show changes in the simulations due to applying different KM approaches are minimal in general. Pyrolysis simulations with the most complex KM are conducted at several heat flux levels. Mass loss rate comparison shows there is good overlap between simulations and the experimental data at low incident heat fluxes. Comparison shows there is poor overlap at high incident heat fluxes. These results indicate that increasing complexity of KMs to be used in pyrolysis modeling is unnecessary for these FRP samples and that the basic assumption of considering thermal decomposition of each computational cell in comprehensive pyrolysis modeling as equivalent to that in a thermogravimetric analysis experiment becomes inapplicable at depth and higher heating rates. Copyright © 2014 John Wiley & Sons, Ltd.

Numerical and Experimental Characterizations of Damping Properties of SMAs Composite for Vibration Control Systems

Shape memory alloys (SMAs) are very interesting smart materials not only for their shape memory and superelastic effects but also because of their significant intrinsic damping capacity. The latter is exhibited upon martensitic transformations and especially in martensitic state. The combination of these SMA properties with the mechanical and the lightweight of fiberglass-reinforced polymer (FGRP) is a promising solution for manufacturing of innovative composites for vibration suppression in structural applications. CuZnAl sheets, after laser patterning, were embedded in a laminated composite between a thick FGRP core and two thin outer layers with the aim of maximizing the damping capacity of the beam for passive vibration suppression. The selected SMA Cu66Zn24Al10 at.% was prepared by vacuum induction melting; the ingot was subsequently hot-and-cold rolled down to 0.2 mm thickness tape. The choice of a copper alloy is related to some advantages in comparison with NiTiCu SMA alloys, which was tested for the similar presented application in a previous study: lower cost, higher storage modulus and consequently higher damping properties in martensitic state. The patterning of the SMA sheets was performed by means of a pulsed fiber laser. After the laser processing, the SMA sheets were heat treated to obtain the desired martensitic state at room temperature. The transformation temperatures were measured by differential scanning calorimetry (DSC). The damping properties were determined, at room temperature, on full-scale sheet, using a universal testing machine (MTS), with cyclic tensile tests at different deformation amplitudes. Damping properties were also determined as a function of the temperature on miniature samples with a dynamical mechanical analyzer (DMA). Numerical modeling of the laminated composite, done with finite element method analysis and modal strain energy approaches, was performed to estimate the corresponding total damping capacity and then compared to experimental results.

Multifunctional fiberglass-reinforced PMMA-BaTiO 3 structural/dielectric composites

Fiberglass-reinforced polymer composites were investigated for potential use as structural dielectrics in multifunctional capacitors that require simultaneous excellent mechanical properties and good energy storage characteristics. Composites were fabricated employing poly(methyl methacrylate), PMMA, as the structural matrix. While barium titanate (BaTiO 3) nanopowder was added to the composites for its high room temperature dielectric constant, fiberglass was employed to confer high stiffness. A conductive polymer blend of poly (3,4-ethylenedioxythiophene) and polystyrene sulfonate (PEDOT:PSS) was used to coat the BaTiO 3 nanoparticles with the purpose of further elevating the dielectric constant of the resultant PMMA-composites. FTIR spectroscopy, TGA and SEM measurements were conducted to prove the successful coating of BaTiO 3 nanoparticles with the PEDOT:PSS blend. TEM measurements revealed a good dispersion of coated nanoparticles throughout the PMMA matrix. The fiberglass-reinforced-PMMA composites containing neat and coated BaTiO 3 were found to exhibit excellent stiffness. In addition, the use of PEDOT:PSS in conjunction with BaTiO 3 was observed to improve the dielectric constant of the composites. Finally, the dielectric constant of the structural composites was found to vary only slightly with temperature.

An alternative method for in vitro fire smoke toxicity assessment of polymers and composites using human lung cells

AbstractAn alternative method for in vitro fire smoke toxicity assessment of polymers and composites using human lung cells has been investigated. A range of building and train interiors including polyethylene (PE), polypropylene (PP), polycarbonate (PC), polymethyl methachrylate (PMMA), polyvinyl chloride (PVC), fiberglass‐reinforced polymer (FRP), and melamine‐faced plywood (MFP) were studied. The exposure of combustion toxicants to human lung cells (A549) at the air/liquid interface was acquired using a Harvard Navicyte Chamber. Cytotoxic effects on human cells were assessed based on cell viability using the MTS assay (Promega). Cytotoxicity results were expressed as no observable adverse effect concentration (NOAEC), 10% inhibitory concentration (IC10), 50% inhibitory concentration (IC50), and total lethal concentration (TLC) values (mg/l). Mass loss data and toxic product yield were also determined. Results suggested that PVC (IC50 1.99 mg/l) was the most toxic materials followed by PP, FRP‐16, PC, PMMA, FRP‐10, PE, and melamine plywood. Some materials revealed to be more toxic under flaming combustion (PP, PC, FRP‐16, and FRP‐10), while others (PVC, PMMA, PE, and melamine plywood) appeared more toxic under non‐flaming combustion. The method developed can be used to screen the toxicity of materials which would be important information in building and mass transport material selection. Copyright © 2010 John Wiley & Sons, Ltd.

Mechanical Evaluation of Polymer Composite Hip Protectors

Hip fractures often result in serious health implications, particularly in the geriatric population, and have been related to long-term morbidity and death. In most cases, these fractures are caused by impact loads in the area of the greater trochanter, which are produced in a fall. This work is aimed at developing hip protectors using composite materials and evaluating their effectiveness in preventing hip fractures under high impact energy (120 J). The hip protectors were developed with an inner layer of energy absorbing soft material and an outer rigid shell of fiberglass-reinforced polymer composite. According to the experimental results, all tested configurations proved to be effective at reducing the impact load to below the average fracture threshold of proximal femur. Furthermore, an addition of Ethylene Vinyl Acetate (EVA) to the impacted area of the composite shell proved to be beneficial to increase impact strength of the hip protectors. Thus, composite hip protectors proved to be a viable alternative for a mechanically efficient and cost-effective solution to prevent hip fractures.

Synchrotron X-ray Tomography for 3D Chemical Distribution Measurement of a Flame Retardant and Synergist in a Fiberglass-Reinforced Polymer Blend

A fiberglass-reinforced polymer blend with a new-generation flame retardant is studied with multienergy synchrotron X-ray tomography to assess the blend homogeneity. Relative to other composite materials, this sample is difficult to image due to low X-ray contrast between the fiberglass reinforcement and the polymer blend. Also, the glass fibers are only slightly larger than the 3.26 microm voxels and, due to their high concentration, exist as partially aligned bundles in the polymer matrix. To investigate the chemical composition surrounding the glass fibers, new procedures were developed to find and mark the fiberglass and then assess the flame retardant distribution near the fiber bundles. On the basis of the multienergy imaging across Br and Sb K-edges, the absorbance values were converted to volume percent concentrations. Besides the basic question of the successful and stable blending of the flame retardant and synergist within the polymer matrix, we are also interested in precipitation reactions that might concentrate or diminish concentrations in the close vicinity of the fiberglass reinforcement. Thus, a procedure was developed to analyze radial concentrations about selected, well-isolated fiberglass bundles. Overall, the results show a nicely homogeneous system to the level of the tomography resolution, 3.26 microm, with some enhanced concentration near, approximately 20 microm, the fiber bundles.

An alternative method for fire smoke toxicity assessment using human lung cells

An alternative method for fire smoke toxicity testing using human lung cells has been investigated. A laboratory-scale vertical tube furnace was used for the generation of combustion products. Experiments were conducted under isothermal oxidative non-flaming conditions. A range of building and train interiors including polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyvinyl chloride (PVC), fiberglass reinforced polymer (FRP), and melamine-faced plywood (MFP) were studied. The exposure of combustion toxicants to human lung cells (A549) at the air/liquid interface was acquired using a Harvard Navicyte Chamber. Cytotoxic effects on human cells were assessed based on cell viability using the MTS assay (Promega). Cytotoxicity results were expressed as NOAEC (No Observable Adverse Effect Concentration), IC 10 (10% inhibitory concentration), IC 50 (50% inhibitory concentration) and total lethal concentration (TLC) values (mg/L). These cytotoxicity results were compared to published combustion toxicity data. Mass loss data and toxic product yield were also determined. The following toxicity ranking was observed from the most toxic to the least toxic: PVC>PE>PP> FRP-10>PC> FRP-16>MFP. The method described here could potentially be an alternative to current fire toxicity standard test methods.

Novel toe driving for thin-walled piles and performance of fiberglass-reinforced polymer (FRP) pile segments

Despite the rapidly growing use of pile foundations, it is presently difficult to assure the integrity and uniformity of the cross-sectional area of cast-in-place piles when using normal concrete. Cavities and soil encroachments leading to soil pockets can jeopardize their load-bearing capacity. Moreover, corrosion in reinforced concrete and steel shell piles has been very costly, exceeding US$2 billion in annual repair costs in the United States alone. To address these two challenges, extensive research has been underway at the University of Western Ontario to develop novel technology for the construction of piles. Self-consolidating concrete (SCC), a material that flows under gravity and assures the integrity of piles, is cast into fiberglass-reinforced polymer (FRP) tubes that provide corrosion-resistant reinforcement. A toe driving technique was developed to install the empty FRP shells into the soil, and SCC is subsequently cast into the shells. Driving tests using this new technique were carried out on large-scale model FRP and steel pipe piles installed in dense dry sand enclosed in a pressure chamber. FRP–SCC and steel closed-end piles were also driven using conventional piling at the pile head. Static load tests were conducted on the various pile specimens under different vertical and horizontal confining pressures. The pile specimens were instrumented to investigate their dynamic behaviour under driving and their response to static compressive, uplift, and lateral loading. It is shown that the toe driving technique is very suitable for installing FRP piles in dense soils. Results from the driving tests and static load test indicate that FRP–SCC hybrid piles are a very competitive and attractive option for the deep foundations industry.Key words: FRP, self-consolidating concrete, piles, pile drivability, toe driving, axial load, uplift load, lateral load, large-scale modeling, shaft resistance, dense sand.

Development of composite insulators in China

The development of composite insulators in China dates back to the early 1970's. In the 1990's they have become widely used in China. At present, up to 600000 composite insulators are operating on 35 to 500 kV ac overhead transmission lines. They are to be introduced into the 500 KV HVDC transmission schemes. In China all composite insulators in service are silicone rubber and are operating in various Contamination conditions. They have successfully and efficiently avoided serious pollution flashover, which occurred frequently when conventional ceramic insulators were used, and radically reduced the maintenance cost of transmission lines in pollution areas. Study of composite insulators is very active in China. The main aspects include properties of materials such as silicone rubber and fiberglass reinforced polymer (FRP) rods, electrical and mechanical performance, aging as well as evaluation and inspection of composite insulators. These fruitful works greatly promote the development of composite insulators in China.

Interfacial phenomena in composite high voltage insulation

This paper deals with two different types of composite insulating materials for HV outdoor insulation technology. For outdoor applications fiberglass reinforced polymer (FRP) are used mainly as transmission line insulators (composite long rods),and as power apparatus housings (composite hollow core insulators). During the last decades mineral filled polymer (MFP) are found to be very suitable for outdoor insulation in the medium and HV ranges. To meet the outdoor demands, long-term stability and durability against environmental stresses are necessary, Composite insulation consists of more than one dielectric component, and linking at least two different kinds of materials leads to interface problems. These regions always appear as weak material structures that can be attacked by various aging mechanisms. Especially the long-term performance and aging resistance are determined by the interface quality. One can distinguish four principal kinds of interface: microscopic, e.g. those between fillers and matrix components; macroscopic, e.g. those between glass fiber rod and polymeric shielding material; internal, in the insulation bulk; and external, solid surface against a liquid or gaseous phase. Today the use of composite insulating materials in HV technology is state of the art. They offer a wide range of superior properties for indoor as well as for outdoor applications. Further improvements should focus on the hydrophobicity and on the long term resistance of the external interface and the stability of the internal interface.

The effect of the fiber/matrix interface on the flexural fatigue performance of unidirectional fiberglass composites

Fatigue tests were conducted on oriented fiberglass-reinforced polymer matrix composites using four-point bending with a stress ratio of −0·8. Composites in which the fiberglass was treated with a commercial diaminofunctional silane coupling agent were found to possess a relatively high flexural fatigue performance compared with composites without coupling agents. Using the interlaminar shear strength as an indication of the interface strength, it was found that composites having a high interface strength possess a high fatigue performance. The failure sequence of the flexural (tensile) fatigue was identified as: nucleation and growth of superficial damage (including fiber ridging, transverse matrix cracking, longitudinal matrix cracking, fiber breaking and local delamination), sudden fiber-bundle breakage and, finally, macroscopic delamination. A strong interface between fiber and matrix delayed the occurrence of fiber ridging and longitudinal matrix cracking, thus improving the fatigue performance of the unidirectional composites.

Use of Polymer/Composite Insulators in Construction, Maintenance and Temporary Procedures

The use of high-strength polymer insulators is examined and discussed with respect to new construction and maintenance techniques which these insulators have introduced to the industry. Also discussed are new uses for fiberglass-reinforced polymer insulators as construction tools, rigging devices and as solutions to emergency restoration of transmission lines.