Experimental Analysis and Modelling of Fatigue Behaviour of Thick Woven Laminated Composites

Abstract

The objective of this work was to analyze the fatigue behaviour and the damage development in unidirectional and angle-ply 2/2 twill weave T800 carbon/epoxy woven fabric composite laminates. Fatigue tensile-tensile tests were performed and internal damage has been observed by using camera and optical microscope during testing. The experimental results show that the damage evolution can be characterized by two or three stages according to the 0° ply and angle-ply laminates respectively. This evolution is correlated with damage mechanisms. Micromechanical three-dimensional finite element models of the twill weave woven fabric are proposed. Numerical simulations exhibit that the local bending of the thread induces local stress and strain gradients in the warp yarns in the vicinity of fill yarns curvature. Finally numerical results are correlated with experimental observation of damage mechanisms in 0° ply laminate and experimental global stiffness reduction (20–25%) has been compared with numerical prediction. An original fatigue criterion for onset delamination during fatigue loading of angle-ply laminates has been proposed. This criterion is based on average values of the components of the stress field. Identification of the different parameters of this criterion has been made with experimental Edge Delamination Tests (EDT). Validation was made with tensile fatigue tests performed on angle-ply textile laminates with drilled circular hole. Further numerical predictions are in good agreement with experimental results.