Investigation of Cross-Ply Laminates Behaviour in Three Point Bending Tests. Part II: Cyclic Fatigue Tests

Abstract

The main goal of this paper is to study and highlight the effects of the reinforcement on mechanical behaviour during the loading and to study the different damage modes induced in the rupture of laminates. The experimental investigation was conducted using three point bending tests in cyclic fatigue for different cross-ply laminates constituted of glass, Kevlar, and hybrid fibres and resin epoxy. At first the composite properties were evaluated in static loading. Then, stiffness loss curves in fatigue were derived for different applied loading levels. The Wöhler curves were deduced using N10 criterion, corresponding to 10% decrease in initial stiffness. The properties of glass fibre laminates in cyclic fatigue were compared with the ones obtained with Kevlar and hybrid fibre laminates.
The obtained results show the performance of glass fibre laminates during fatigue tests compared with the results obtained with Kevlar and hybrid laminates. The rupture of Kevlar and hybrid laminates is much less brittle when compared with glass fibre laminates. The presence of Kevlar fibre in laminate involves a lower strength in fatigue.