INVESTIGATION OF THE FATIGUE FAILURE MECHANISMS FOR STITCHED AND UNSTITCHED UNIDIRECTIONAL COMPOSITES

摘要

The traditional glass fabrics used in composite structures are usually in the form of two dimensional (2D) fibre architectures. They are relatively inexpensive and usually provide good in-plane mechanical properties. However, most of them have relatively poor through-thickness mechanical properties because the load applied the translaminar direction is predominately carried by the resin matrix. During last two decades, a considerable amount of research has been devoted to improving the through-thickness mechanical properties of composite laminate by developing the 3-D fibre architecture that includes braiding, knitting, weaving and stitching. The purpose of this study is to apply the stitching technologies into the composite materials in wind turbine blades that are designed to have fatigue life of 20 years and more.