A Full-Scale Experimental Investigation of Utility Poles Made of Glass Fibre Reinforced Polymer

Utility poles made of glass fibre-reinforced polymer (GFRP) are becoming increasingly common in European countries. Therefore, it is necessary to accurately examine their structural properties to ensure the integrity and safety of the poles. The purpose of this article is to compare the bending resistance of GFRP composite lighting columns obtained using European standard procedures with full-scale experimental tests. Several composite lighting columns were tested as part of the research study, and coupon tests were performed to assess the material properties required to calculate their bending resistance according to European Standard (EN) 40-3-3. The results obtained differed significantly. Furthermore, it was observed that the current standard rules for obtaining the resistance of GFRP poles based on the limit state method show a higher load capacity of the column in comparison to the capacity obtained from the tests.

Ultrasonic guided wave-based debond identification in a GFRP plate with L-stiffener

This paper presents a robust assessment of debond in a glass fibre-reinforced polymer composite structure with L-stiffener attachment. Towards this, the ultrasonic guided wave (GW) propagation based laboratory experiments have been carried out on a stiffened composite panel with piezoelectric transducers (PZT) for the excitation of GWs and a scanning laser Doppler vibrometer (SLDV) for sensing the GW propagation. To study the changes caused by the stiffener and debond a signal processing based multi-point analysis has been carried out. The proposed methodology consists of two steps. Step 1 using the full wavefield root mean square energy map-based approach to check the presence of debond. Step 2 using point-wise measurements to study debond localization and size estimation using a baseline free signal coefficient difference algorithm (SCDA). The proposed processing approaches are applied for an in-depth analysis of the experimental signals that provide information about the interaction of GWs with stiffener and debond. The mentioned approaches take advantage of the asymmetry caused by the damage. For the applied SCDA methodology there is no need for full-wavefield measurements, healthy case measurements, as only a few measurement points can be enough for the assessment of stiffener debond in such structures.

Investigation of anisotropy effects in glass fibre reinforced polymer composites on tensile and shear properties using full field strain measurement and finite element multi-scale techniques

Designing highly stressed offshore renewable energy composite structures (e.g. wind and tidal turbine blades) necessitates characterisation of woven fabric composite under off axial loading. In this work a combined method of finite element analysis, digital image correlation and microscopy is used to assess the effect of ply orientation on the tensile/shear properties and failure modes of woven glass fibre reinforced polymer composites. Full field strain maps obtained by the digital image correlation method were used to evaluate the damage development and the inhomogeneity of strain localisation. The development of finite element models of mechanical test specimens is based on the analysis of micro-mechanical models of representative volume elements using a homogenisation technique in order to calculate the effective orthotropic properties. The agreement between numerically and experimentally calculated strains obtained in the elastic regimes indicates that stress analysis conducted by numerical methods is useful when characterising the effect of ply orientation on mechanical behaviour. Strain measurement conducted by the digital image correlation method indicated that there is a strong relationship between the strain distribution and the microstructure/ply orientation. In addition, it was found that the levels of localised tensile strain are higher than the global strain indicating the structural heterogeneity of the composite material. Finally, microstructural analysis of tension and shear test specimens showed that the main failure modes are de-bonded fibres, fibre pull out, in-plane/inter-laminar shear cracks and delamination.

Performance of variously shaped glass-fibre-reinforced polymer bars in concrete columns

An investigation was carried out into the structural performance of concrete columns reinforced with various shapes of glass-fibre-reinforced polymer bars and stainless-steel stirrups under concentric loading at ultimate limit state. Six square-section columns were cast to investigate the effects of different reinforcement types. The results showed failure modes depended on reinforcement material, shape and stirrup spacing. Across all specimens, steel-reinforced columns had higher loading capacity and better ductile performance, followed by L-shape and then round polymer bars. Smaller spiral spacing increased confinement efficiency and ductility and provided sufficient restraint against longitudinal polymer bar buckling. Finite-element models were also calibrated, and the results were in close agreement with experimental measurements. Based on the calibrated models, numerical parameters were studied to understand further the behavior of composite columns reinforced with glass-fibre-reinforced polymer.

Effect of nano-silica/alumina hybrid coating on erosion resistance of glass fibre-reinforced polymer for the application of wind turbine blades

Polymeric coatings reinforced with nanoparticles have recently occupied special focus by researchers and have been used in several industrial applications such as wind turbine manufacturing, oil and gas, aerospace and automotive industries. Yet, still more investigations are required to improve the tribological and mechanical properties of these coats and increase its service life. The effect of adding nano-silica/alumina to polyurethane coatings have been studied, however, their erosion resistance has not been investigated yet. The main purpose of this research is to investigate the erosion resistance of hybrid nano-silica/alumina polyurethane compositions with different weight fractions. To do this, erosion resistance experiments, scanning electron microscope and Zetasizer experiments to assess the agglomeration percentage were carried out. Results showed that the hybrid composition of nano-silica/alumina polyurethane significantly decreased the erosion rate and that the reduction in agglomeration was mirrored in much enhanced erosion resistance of the nanocomposites.

Experimental Study on Strengthening of Concrete Cylinders Using GFRP Sheets with Boron Carbide-Epoxy Composite

Usage of composite materials as a concrete strengthening agent had increased evidently in recent years. One of those materials is the Glass Fibre Reinforced Polymer (GFRP) which is used in various fields for strengthening and retrofitting of concrete structures. Various studies have shown that, the wrapping of concrete specimens with Glass Fibre Reinforced Polymer (GFRP) resulted in increase in the Compressive Strength as well as the ductility of the concrete members. The main Objective of this project is to enhance the axial compressive strength of concrete block wrapped by Glass Fibre Reinforced Polymer sheets tested with various compositions of Boron Carbide (B4C) mixed with epoxy resin to find out the increase in the compressive strength. Cylindrical Concrete specimen of standard size 150mm diameter and 300mm height were casted of M30 Grade Concrete. Totally 6 batches were casted which consists of 18 specimens composing of different compositions of Boron Carbide varying 1.5%, 3.0%, 4.5% and 6.0% of boron carbide (B4C) were added and mixed with epoxy resin. Finally, Glass fibre Reinforced Polymer is wrapped around the Concrete specimen with a single wrap and the results obtained from Compressive strength of the specimens were studied.