Tension-tension fatigue properties of multiaxial laminated carbon/epoxy composites molded by high-pressure resin transfer molding (HP-RTM) process

Engineering structures are often subjected to cyclic-loading conditions, which detrimentally affect the component’s service life and damage tolerance. The fatigue behavior of multiaxial laminated composites manufactured with unidirectional plies has been analyzed. Carbon/epoxy composite laminate was molded by a high-pressure resin transfer molding (HP-RTM) process. Specimens were subjected to tension-tension (T-T) fatigue stress of 65 %–75 % of static tensile strength until failure or up to one million cycles. An analysis of the maximum stress-cycle number (S-N) curve is conducted to determine the fatigue limits of the material. The predetermined fatigue limit has been obtained at 717.5 MPa stress, which is about 67 % of static tensile strength under tension-tension stress conditions. Fatigue failures under tension-tension loading conditions are associated with fiber breakage, fiber pull-out, and plies delamination. This research aimed to understand the fatigue behavior and fracture mechanism of multiaxial laminated composites under tension-tension cyclic loading conditions and collect more data for future research.