A New Method for Predicting the Fatigue Life of Fiber-reinforced Plastic Laminates

Abstract

This article introduces a new methodology for predicting the fatigue life of fiber-reinforced plastic (FRP) laminates at various stress levels. This method is based on the evolution of the center of gravity (CG) of the hysteresis loops (HL), and is termed the CG method. The CG method provides precise information regarding the fatigue behavior and damage situation within FRPs, offering highly accurate predictability of fatigue failure. Furthermore, the CG method can be constructed by tests performed on only one specimen by utilizing a new periodic function that represents the response of FRP specimens under dynamic loading fatigue tests - either in displacement control mode or load control mode. The authors originated the CG method in (Momenkhani, K. (2003). Using Geometric Properties of Hysteresis Loops for Predicting Fatigue Damage Accumulation in Fiber Reinforced Plastic Laminates, Doctoral Dissertation, The George Washington University, pp. 49-130), and published it in (Momenkhani, K., Sarkani, S. and Jones, D.L. (2005). Development and Application of a Model Using Center of Gravity of Hysteresis Loops to Predict Fatigue Damage Accumulation in Fiber Reinforced Plastic Laminates, Journal of Composite Materials, 39(6): 557-575). The present article applies the CG method as an alternative model to replace and supersede S-N curve methods for fatigue life predictions of FRPs.