Experimental investigation of mechanical properties and parametric optimization in drilling of sisal glass reinforced epoxy composites using taguchi grey relational analysis method

Abstract

newline This study investigated the mechanical characteristics of Sisal glass-reinforced polymer composites containing geometric irregularities when subjected to tensile loading. Test samples were created using vacuum bag molding techniques, consisting of several layers of E-type Sisal glass fibre combined with polyester resin. Analysis of the volume fraction revealed a fiber content ranging between 30-40%. Tensile assessments were conducted on specimens devoid of holes, featuring single central apertures (6, 12mm diameter) and double perforations (6mm diameter) at different intervals (6.2, 12, 48mm) to assess their mechanical response. Fractures consistently occurred transversely during loading across all samples. It is observed that larger single holes significantly compromised the composites compared to smaller double holes at different intervals. This work aims to characterize the mechanical properties specifically tensile strength, fracture toughness, and residual strength ratio of Sisal glass-reinforced polyester matrix composites with different geometric discontinuities. Test specimens were created using several layers of woven E-type Sisal glass reinforcement in a polyester resin matrix through a vacuum bag molding technique. Volume fraction tests were conducted to determine the fiber and resin content. Uniaxial tensile tests were performed on specimens featuring various holes: without holes, with single central holes of 6mm and 12mm diameter, and double 6mm diameter holes spaced at 6.2mm, 12mm, and 48mm. The analysis included studying the residual strength ratio for each case and attempts to determine the fracture toughness using single-edge notch bend testing. The macro scale fracture behavior was also observed to document crack propagation and fracture surface patterns.