Fatigue Delamination Behavior of GFRP Composites under Mixed-Mode I/II Loading

Delamination is a severe threat to the wide use of composite laminates in primary structural applications. Delamination grows under fatigue loading and leads to structural failure. Very few studies exist on mixed-mode delamination on carbon fiber however glass fiber was not studied under mixed mode. The objective of this paper is to investigate fatigue delamination growth under mixed-mode loading in Glass Fiber Reinforced Polymer (GFRP). A mixed-mode bending fixture was developed and fabricated. Fatigue delamination growth tests were performed for different mixed-mode loading using that fixture. With the help of a Scanning Electron Microscope, micro examinations of the crack surface were carried out. The results showed a high growth rate for the case with more contribution of mode I. The Fractographic investigation performed on the different samples showed the existence of mode-I and mode-II features and broken fiber’s confirming fiber bridging during delamination growth. The fractographic features varied systematically with mode shift.