Investigation of the effects of hydrothermal aging on the crushing properties of carbon/epoxy fiber reinforced pipes

Abstract In this study, the crushing properties of carbon/epoxy fiber‐reinforced composite pipes with different winding angles (±55° and ±70°) aged in different environmental environments were investigated experimentally. The samples produced with the wet filament winding method were kept in distilled water and seawater environments at 30°C for 2500 h. Water absorption amounts were calculated experimentally and theoretically. Aged samples were subjected to crushing tests to determine their mechanical properties such as energy absorption, load‐carrying capacity, and crushing load efficiency. According to the experimental results, the samples aged in distilled water absorbed more water than those aged in seawater. It was also observed that as the winding angle incremented, the water absorption rates increased in both liquid types. The maximum and minimum water absorptions were 3.95% and 2.89% in the samples aged in distilled water with a winding angle of 70° and in seawater with a winding angle of 55°, respectively. From the crushing test results, aging conditions negatively affected the sample performance in all mechanical properties. The main reason for this can be said to be the deterioration of the matrix structure due to aging and the decrease in fiber/matrix bonding ability. The maximum specific energy absorption was obtained from unconditioned pipes with 36.47 J/g, which was 23% higher than the samples kept in distilled water and 33.7% higher than those aged in seawater. In addition, it was determined that the increase in the winding angles examined caused decreases in the load‐carrying capacity and specific energy absorption. Highlights Hydrothermal aging effects on the crushing behaviors of carbon fiber reinforced composites. Water absorption of the carbon fiber composites kept in distilled and seawater. Fracture behaviors of carbon composites subjected to harsh environmental conditions. Fiber orientation effects on crushing characteristics of composite pipes.