Effect of hygrothermal ageing on the mechanical properties of glass fiber reinforced polymer composite: Experimental and numerical approaches

This paper studied the effect of hygrothermal ageing on the mechanical performance of glass fiber-reinforced polymer composites (GFRPCs), a crucial material for marine applications due to its lightweight and superior resistance to environmental chemicals. However, prolonged exposure to moisture and temperature can degrade its properties, impacting structural integrity. The influence of moisture diffusion in GFRP composite laminates was evaluated by accelerated ageing tests, which involved submerging the composite laminate in seawater at 75 degrees C until it reached full saturation. The composite laminates were fabricated with weight fractions of glass fiber reinforcements 55 %, 60 %, and 65 %. After two months of submersion, mechanical characteristics, namely tensile strength, modulus of elasticity, and interlaminar shear strength (ILSS) were investigated. A computational model was developed using COMSOL Multiphysics to analyse the coupled interfaces of moisture diffusion and heat. The failure mechanism of the GFRP composites was analysed using a scanning electron microscope (SEM). After two months of submersion, the moisture uptake data for the tension test samples showed a maximum saturation of 3.45 % for the 55 % fiber weight fraction, leading to a reduction in tensile strength from 269 MPa to 171 MPa and in modulus of elasticity from 24 GPa to 21 GPa. For the ILSS test samples, the maximum moisture saturation was 2.95% for the 55 % fiber weight fraction, with a corresponding decrease in ILSS from 24 MPa to 21 MPa. However, increasing the glass fiber weight fraction from 55 % to 65% resulted in improved tensile strength, modulus of elasticity, and ILSS in both as-manufactured and aged samples. The results of simulations and experiments showed that hygrothermal ageing causes the fiber surface to debond and causes matrix cracking, which in turn creates an uneven internal stress field.