Fatigue performance investigation of perforated and bolted pultruded glass fiber reinforced polymer laminates based on experiment and digital images

To investigate the fatigue performance of perforated and bolted pultruded Glass Fiber Reinforced Polymer (GFRP) laminates, a series of tests are conducted including static tensile and cyclic fatigue test, while Digital Image Correlation (DIC) and CT tests were implemented to monitor strains around the perforations and damage developed in the samples subjected to tensile and fatigue tests respectively. The stress concentrations of the cyclic loaded perforated GFRP laminates are discussed based on the experiment results. Due to the stress limitation of single bolted laminates, the diameter to width ratio is suggested to be less than 0.3. The GFRP laminates with double holes have a better fatigue performance than that of single hole, which is called the double-hole effect. This effect is also found in double bolted GFRP laminates. Considering the strength of the laminates between the holes and to unify the requirement, the critical distance to width ratio is suggested to be 1.6 and the diameter to width ratio should be less than 0.3.