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In this study, the axial compressive stresses of hollow circular composite tubes were investigated. For this purpose, hollow circular composite tubes with various inner diameters (Ø12 and Ø13 millimeters), a height of 80 millimeters, and an outer diameter kept constant at Ø17 millimeters were fabricated using a fiber winding process. In the production of hollow circular tubes, epoxy was used as resin, and glass fiber, carbon fiber, and Kevlar fiber were used as reinforcement materials. Experimental investigations were carried out for three different reinforcement materials, two thin-wall thicknesses, and five orientation angles. Axial compression tests were performed to research the influences of reinforcement materials, thin-wall thickness, and orientation angles on the compressive stresses. The axial compressive strength of the samples was observed experimentally by applying the load in the vertical direction. The reinforcement material, orientation angle, and thin-walled thickness had an important influence on the axial compressive stress. The glass/epoxy reinforcement material was found to have the highest axial compressive strength at 204 Mpa. When the orientation angle increased from 45° to 88°, the axial compressive stress increased by 2.27 times in glass/epoxy, 2.36 times in carbon/epoxy, and 2.37 times in Kevlar/epoxy specimens, respectively. In addition, by increasing the specimen wall thickness by 0.5 millimeters, the axial compressive stress at an 88° orientation angle increased by 9.67 % glass/epoxy, 11.85 % carbon/epoxy, and 7.14 % Kevlar/epoxy specimens. [ABSTRACT FROM AUTHOR]

This study presents the tensile properties and cost-property efficiency analyses of a novel composite material type composed of expanded polystyrene as filler, chopped glass fibers as reinforcement agent and epoxy resin as matrix material. Composite specimens were fabricated via expanded polystyrene beads with two different densities, two different length of chopped glass fibers and three levels of fiber/filler weight ratios. Specimens were subjected to tensile tests and cost property analyses were carried out. Experimental studies revealed that novel composite specimens had significantly low density and high specific modulus. Cost-property efficiency analyses revealed that the novel composite is relatively highly efficient material and could be utilized instead of its more expensive counterparts such as conventional plastics or laminated composites especially for non-load bearing applications. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effects of seawater on the failure mode, first failure load and bearing strength behaviour of the pinned joint of fibreglass-reinforced woven epoxy composite prepregs. The specimens were kept in seawater for 3- and 6-month periods. After each period, their mechanical properties were examined. The edge distance-to-upper hole diameter (E/D), the two hole-tohole centre diameter (K/D), the distance from the upper or the lower edge of the specimen to the centre of the hole-to-hole diameter (M/D), and the width of the specimen-to-hole diameter (W/D) ratios were selected as parameters. Moreover, the finite element models of the specimens were developed using ANSYS software, and the Tsai-Wu criterion was used to obtain the first failure load. The numerical and experimental results were compared and were found to be in good agreement for the first failure load. [ABSTRACT FROM AUTHOR]

Fatigue life of GFRP (glass-fiber reinforced plastic) composites used in wind turbine rotor blades has been evaluated considering the glass fiber orientations. Three different laminate composites with the respective laminating orientation of 0°, ±45°, and 0°±45° were prepared using vacuum infusion method. Tensile properties and S-N curves for these composites were experimentally determined at room temperature. From the tensile tests, it was found that tensile properties were greatly dependent upon the fiber orientation and the tensile strength of unidirectional composite was the largest and bidirectional (45°) composite was the weakest among three composites. The fatigue properties were determined under constant amplitude load control at different stress ratios, R, of 0.5, 0.1 and −0.2. The properties also show the dependency of stress ratios and fiber orientation. The fatigue life diagrams of these three composite were relatively well presented with the double logarithmic S-N curve. The linear slopes of the respective S-N curves for three composite were not greatly different. The fatigue limits for the composites were evaluated and predicted with linear Goodman and Gerber diagrams. [ABSTRACT FROM AUTHOR]

Fibre metal laminates (FMLs) are layered materials based on stacking arrangements of metals and fibre reinforced plastic (FRP) composite laminates. These hybrid fibre metal laminates combine the advantages of both metallic materials and the reinforced hard and strong fibrous materials. A series of low velocity impact and tensile tests were carried out on the fabricated hybrid fibre metal laminates with different orientations and stacking sequences. Aluminium metal, carbon and glass fibres were the layers used for fabricating the hybrid composites and the fabrication was done by varying the position and orientation of the laminates and as well as the stacking sequences. The effect of the different stacking sequence of the metal laminates and the fibre layers on the impact and tensile strengths of the hybrid composites are studied. The stress-strain curve analyses were carried out for tensile properties, while the force-time and energy-time curves were analysed for impact charcteristics of the developed composites. [ABSTRACT FROM AUTHOR]