Evaluation of tensile properties of hybrid kevlar-glass reinforced epoxy composite for multi holes configuration

Abstract

Abstract Most modern structures are comprised of synthetic composites with more number of cut outs. For the design of synthetic composite with varying shapes with different sized cut-outs are often used in engineering structures. The effects of stress concentration factor and tensile behaviour has to be thoroughly investigated for providing better design aids to be utilized by design engineers. The present paper focuses on the tensile behaviour of the Kevlar and glass fiber reinforced hybrid polymer composite by varying size and position of the cut outs. The test specimens are prepared according to the ASTM standard D3039. The composite laminates are prepared by traditional hand layup method. The overall dimension of plates were 25 mm*250 mm (width*length) and with the gauge length was 110 mm. These plates were drilled with the circular holes of 8 mm and 5 mm. The larger hole of diameter 8 mm was drilled at centre of all the specimens and smaller holes of diameter 5 mm was drilled on either sides of 8 mm hole. The pitch for smaller 5 mm holes were increased in the order of 0, 15, 20, 25 and 30 mm respectively. The specimen with smaller holes at 25 mm pitch showed highest allowable stress of 97.22 MPa. The experimental results were compared to find the optimum position for placing the holes. This research also intends to find out if there exists any relationship between the pitch, diameter of smaller and larger holes present in the specimen.