Fatigue Behaviour of Woven Composite π Joint

Abstract

Fatigue behaviour of a woven composite adhesive bonded p joint subjected to tensile-tensile cycle loading is studied. Tests were conducted under fatigue and monotonic loadings in order to examine the durability of such type of bonded joints. A careful observation of cracking mechanisms during fatigue life showed that filler and tip zones are the potential weak positions in the joints. The experimental outcomes expatiated that the endurance limit loading, lower than the initial damage loading, is about half of the ultimate static strength. The results also showed that fatigue lifetime of composite p joint comprised of two stages: initiation stage, which is less than 25% of the fatigue lifetime, and the propagation stage for the rest up to failure. Four stiffness degradation modes, named stable slight reduction mode, abruptly decreasing mode, step decrease mode and constant stiffness mode, exhibited in fatigue test.