Stiffness Degradation Model for Fatigue Life Prediction of GFRPs under Random Ocean Current Loading

Abstract

A new phenomenological fatigue model based on stiffness degradation is proposed for life prediction of Glass Fiber Reinforced Plastics (GFRPs) under random ocean current loading. The model used Weibull cumulative density function to account for a shift in failure modes and corresponding change in the rate of damage accumulation. The effects of stress ratio and stress amplitude on the model parameters were characterized using the results from constant amplitude tests. The fatigue life of GFRP coupons under random ocean current loadings was predicted both by the proposed model and by the conventional life prediction methodologies using Palmgren-Miner’s rule. The fatigue life was predicted within a factor of two by the proposed model, which was more accurate than the conventional methods.