Failure Criteria for Composite Blades with Wavy Edge in Aerospace Applications

Abstract

In many structural applications, either a notch or a hole is used for some specific design intent. The notch could be contained within the plane of structure, or it could be partially located along the edge of the structure. Although theoretical formulae are available for computing the stress variation along the section passing through a simple hole or a notch, for complicated structure or loading conditions, it becomes difficult to evaluate the stress variation. One such example of complicated structure is proposed wavy trailing edge on the composite fan blade where waviness on the edge of blade could be in-plane as well as out of plane. It is important that for evaluation of stress variation in these type of structures, a methodology (i.e., failure criteria based on notch or hole strength) should be developed which will help in predicting the mechanical behavior/failure load of new designs of these structures. Based on preliminary coupon bending tests (coupons with and without wavy trailing edge) and FEA analysis of the coupon models, the characteristic distance from the edge is evaluated and later used to predict the failure for new wavy trailing edge designs for composite fan blade.