Volume 8, Issue 5, 1999

Application of the Equivalent Constraint Model to InvestIgate stiffness properties of transversally cracked and split FRP laminates

M.Kashtalyan and C.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

A new approach based on the Equivalent Constraint Model (ECM) [1] of the damaged lamina is applied to investigate the stiffness degradation in [0m/90n]s laminates due to matrix cracking both in the 90o (transverse cracking) and 0o (splitting) plies. The advantage of the approach is that it avoids cumbersome consideration of a repeated laminate element defined by the intersecting pairs of transverse cracks and splits, intrinsic to the earlier developed models [2-6]. Instead, two coupled problems for ECM laminates are solved. The stress field in the damaged lamina is determined by means of an improved 2-D shear lag analysis, and the reduced stiffness properties are described with the help of Insitu Damage Effective Functions, for which closed form expressions are obtained. Comparison of the new ECM/2-D shear lag model with the earlier developed models shows a reasonable agreement.