Abstract: “The experimental investigation here focuses on the study of flexural and shear properties of sandwich composites. Rigid unfilled thermoset Polyisocyanurate (PIR) foam is used as the core material and glass fabric reinforced epoxy based laminates are used as the outer skin layers of the sandwich. PIR foams with densities of 125kg/m3 and 250kg/m3 are used for the study. Skin to core weight ratios of 3:1 and 4:1 were maintained for the panels fabricated separately with the vacuum bagging technique. Specimens with varying span to depth ratios of 16:1, 12:1 and 6:1 were tested using an Instron UTM machine. The investigation follows a three-point bending test method carried out for finding bending strength, flexure rigidity, shear deflection, shear stress, shear strain etc. The test results were compared and analyzed in depth to find the influence of the core density and span to depth ratios on the flexural and shear properties of the sandwich composite. Useful conclusions have been drawn ba”

Keywords: Rigid polyisocyanurate foam, Flexural properties, Sandwich composites, Foam Density, Span to depth ratios.