Investigations on MWCNT Embedded Carbon/Epoxy Composite Joints Subjected to Hygrothermal Aging under Bolt Preloads

The present work emphasizes the effects of hygrothermal aging on the bolted joints prepared from carbon/epoxy nanocomposites at different bolt preloads. The effect of multiwalled carbon nanotubes (MWCNT) was investigated by incorporating 0.1 to 0.5 wt.% of MWCNT in composite laminates with 0.3 wt.% of MWCNT giving the best mechanical properties. The water absorption studies at three hygrothermal conditions i.e., 25 °C, 45 °C, and 65 °C for 30 days, were conducted for neat and 0.3 wt.% of MWCNT added composite specimens, as per ASTM D5229. The bolted joints were designed using ASTM D5961 having a width to diameter ratio (W/D) and edge to diameter ratio (E/D) equal to 6 and 5, respectively. The bolt torque effect at different levels i.e., 0, 2, and 4 Nm were studied to estimate the ultimate failure loads in the nanocomposite joints. In all aspects, incorporating MWCNT shows better results than neat configured composites. The statistical investigations were performed using the central composite design on different control factors i.e. temperature, duration, bolt torque, and material.