An experimental assessment of open-hole tension–tension fatigue behaviour of a GFRP laminate

The drive to improve predictive models and design methodologies of fibre-reinforced polymer composites subjected to fatigue loading is reliant on more accurate and reliable methods for monitoring and assessing material degradation and fatigue life. This paper presents the results of an experimental study carried out to evaluate the applicability of various measurement techniques including digital image correlation (DIC) and multiplexed fibre Bragg grating (FBG) sensors for this purpose. The study focused on the open-hole tension (OHT) fatigue behaviour of a quasi-isotropic glass fibre-reinforced plastic (GFRP) laminate under constant and block amplitude loading. Constant amplitude tests were conducted at two different R-ratios (R = σmin/σmax) and the block amplitude tests involved two or more stress levels. Longitudinal strain and stiffness, and surface temperature are used to assess damage progression and fatigue life. These parameters are shown to be interrelated and potentially suitable for predicting notch fatigue performance.