Fatigue life and damage evolution of glass fiber/epoxy laminates containing interacting circular holes

Abstract

The behavior of woven glass fiber reinforced plastic laminates containing interacting circular holes off the loading axis under cyclic loads in tension–tension has been investigated with a fiber volume fraction of 0.65. The tests were conducted in load control mode from 80% of the ultimate tensile strength to the threshhold to draw the stress–life curves. For the unnotched, central holed, and off-center interacting holed specimens, the damage pattern and its evolution are extensively discussed. The damage development in interacting holed specimens occurs in four different stages namely matrix cracking, edge delamination, matrix splitting, and final fracture. The damage pattern depends on the location of the interacting circular hole and stress level. The sectioned parts of laminates fatigued at different stress levels were examined on scanning electron microscope for the damage evaluation.