Edge treatment of short beam shear tests for improved assessment of structural strength

The certification and quality control of large aerostructures relies on testing of small-scale coupons, which may be unrepresentative of the final product. Edge effects, which are either non-existent or less significant in large aerospace components, cause coupon failure and often lead to considerable strength underpredictions. In this work, a resin treatment is applied to the edges of short beam specimens, resulting in a net strength improvement of 16% and 36% in laminates using two carbon-fibre reinforced plastic material systems. The effects of the treatment are analysed in detail using experiments, computed tomography, high-fidelity linear and non-linear finite element models allowing for damage propagation. The treatment produces interlaminar shear strength predictions which are more representative of those found away from edges in large aerostrucures by reducing interlaminar stresses at the free edges and delaying delamination onset. The procedure can be used to improve testing and weight/cost efficiency of aerospace components.