Hygrothermal aging effects on impact resistance and post-impact tensile performance of GFRP T-joints

Glass fiber-reinforced polymer (GFRP) T-joints are widely used as critical load-bearing components in marine structures, where prolonged exposure to hygrothermal environments can significantly degrade their mechanical performance. This study systematically investigates the low-velocity impact (LVI) behavior and post-impact tensile strength of GFRP T-joints subjected to hygrothermal aging. Specimens were fabricated using an improved vacuum-assisted resin transfer molding process and subjected to varying aging temperatures, durations, and protective treatments. LVI tests were performed at four different energy levels, followed by tensile testing to assess residual strength. The results show that higher aging temperatures and longer exposure times substantially reduce both impact resistance and post-impact tensile capacity. In contrast, appropriate protective measures effectively alleviate hygrothermal degradation. For instance, compared to the PA-60-60-20J condition, the maximum contact forces of the PA-25-60-20J and PA-15-60-20J specimens increased by 2.97% and 19.44%, respectively. Meanwhile, their post-impact tensile peak loads increased by 18.13% and 37.85%. These findings provide valuable insights for the durability design and impact performance optimization of GFRP joint structures under hygrothermal service conditions.