Fatigue crack propagation and delamination growth in Glare

Fibre Metal Laminate Glare consists of thin aluminium layers bonded together with pre-impregnated glass fibre layers and shows an excellent fatigue crack growth behaviour compared to monolithic aluminium. The fibres are insensitive to the occurring fatigue loads and remain intact while the fatigue cracks occur in the aluminium layers. As a consequence, part of the load is transferred through the fibre layers instead of around the crack tip in the aluminium layers, reducing the crack growth rate. The major concept in this thesis is the stress intensity at a crack tip in the metal layers of a Fibre Metal Laminate being the factor determining the extension of that crack under cyclic loading. The stress intensity factor consists of a crack opening contribution of the far field stresses in the aluminium layers, similar to monolithic aluminium, and a crack closing contribution of the intact fibres in the wake of the crack. An analytical model has been developed based on the crack opening relations. Validation with a wide range of test data, reveals a good correlation between predicted and experimental crack growth rates, crack opening contours and delamination shapesAerospace Engineerin