Abstract
The residual strength of fatigue-cracked Glare specimens is virtually independent of the relative initial crack length. The number of cut fibres and the amount of delamination determine the residual strength instead.
To obtain fracture, the energy available for crack growth (energy release rate G) must be larger than the crack resistance R of the material. With this knowledge a KR-curve can be determined experimentally. The KR-curve is better for Glare 2 than for Alclad-2524-T3 as regards specific weight. From experimental data it follows that for Glare the KR-curve is a function of: the Metal Volume Fraction, the properties of the metal and fibre layers, the interfaces between these layers, the rolling direction in comparison with load direction and the quantity of fibres in de load direction. A prediction model for the residual strength of Glare was developed, but it can only be used for of Glare types that are based on the 2024-T3 alloy and loaded in either L-T or T-L direction. Additional research is needed to extend the model.
To fulfil the two-bay crack criterion after FOD (necessary for newly designed aircraft), the residual strength of the Glare skin can be improved. This can be done by adding extra “crack stopping” fibre layers in the laminate. A test on a skin panel showed that this idea works and the crack tended to flap to the centre of the stiffener bay.
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References
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© 2001 Springer Science+Business Media Dordrecht
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de Vries, T.J. (2001). Residual strength. In: Vlot, A., Gunnink, J.W. (eds) Fibre Metal Laminates. Springer, Dordrecht. https://doi.org/10.1007/978-94-010-0995-9_13
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DOI: https://doi.org/10.1007/978-94-010-0995-9_13
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