Volume 8, Issue 4, 1999

A study of matrix crack tip delaminations and their influence on composite laminate stiffness

Maria Kashtalyan and Costas Soutis* 

Department of Aeronautics, Imperial College of Science, Technology and Medicine, Prince Consort Road, London SW7 2BY, UK

*Author to whom correspondence should be addressed

Abstract

Reduction of the stiffness properties of cross-ply [0m/90n]s laminates due to delaminations, growing at the 0/90 interface from the tips of transverse cracks in the 90o plies and splits in the 0o plies, is analysed by means of a theoretical approach based on the Equivalent Constraint Model (ECM). Reduced stiffness properties of the damaged lamina are derived as explicit functions of the crack density and relative delamination area associated with that lamina and implicit functions of the two damage parameters associated with the neighbouring laminae. Transverse crack tip delaminations are found to cause significant reduction in the laminate shear modulus and Poisson’s ratio. Contribution of each damage mode (transverse cracking, transverse crack tip delaminations, splitting and split tip delaminations) into stiffness loss i




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s established.