Fatigue characterization of GFRP and composite sandwich panels under random ocean current loadings

A comprehensive fatigue characterization of Glass Fiber Reinforced Plastic (GFRP) and composite sandwich panels under random ocean current loadings is presented in this paper. Two sources of randomness in ocean currents were considered in the calculation of fatigue load: one is turbulence in the ocean currents and the other is the wake flow behind the support structure of the turbine. Calculated random loading was applied to conduct fatigue tests on GFRP and composite sandwich coupons using a materials testing machine. Fatigue life of GFRP coupons followed a power function pattern with respect to number of spectrum passes, while that of sandwich panels was linear in semi-log scale. The failure modes, S-N curve, and the constant life diagram under constant amplitude test are also discussed.