Effects of hot water aging on failure behavior of mechanically fastened glass fiber/epoxy composite joints

The present experimental investigation aims to discover how mechanically fastened joints of glass fiber/epoxy composites were influenced by hot water immersion. Specimens were exposed to hot water at temperatures of 50, 70, and 90 °C for 1 and 2 weeks periods prior to the joint assembly and testing. Having conducted tensile tests, it was finally concluded that failure behavior of joints in aged specimens is strictly related to the temperature applied and holding time in hot water. Both extending of immersion time and increasing liquid temperature were found to affect the mechanical characteristics of joint, adversely. In addition, glass fiber reinforced composite plates were realized to have increased in weight due to the moisture absorption, the amount of which is dependent on immersing time and temperature. Another finding derived from experiments is that, the joints with fasteners preloaded under 6 Nm tightening torque offer noticeable advantage in terms of stiffness and strength compared with the finger-tightened ones, just as experienced in unaged specimens.