McCartney, L N (1996) Generalised framework for the prediction of ply cracking in any symmetric laminate subject to general in-plane loading. NPL Report. CMMT(A)51

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Abstract

This report describes a general theoretical framework that leads to a new method of predicting ply crack formation in the 900 plies of general symmetric laminates subject to general in-plane loading involving combined biaxial and shear loading. The methodology takes full account of thermal residual stresses and assumes that there is at least one 90º ply in the laminate. The analysis assumes that the plies deform as linear thermo-elastic solids, that damage is effectively homogeneous at the macroscopic level, and that the ply cracks are not subject to compressive or shear loading. Within the assumptions made the results presented are independent of any detailed stress analysis associated with stress transfer models for ply cracks in laminates, and are thus exact. The methodology results in relatively simple relationships that are defined at the macroscopic laminate level even though the ply cracking occurs at the microstructural ply level. Stress transfer models predicting the stress and displacement distributions in laminates having a distribution of fully developed ply cracks are needed only to predict the macroscopic effective thermo-elastic constants of cracked laminates. The theoretical framework governing ply crack formation in general symmetric laminates subject to conditions of general in-plane loading, when combined with the accuracy and relative simplicity of results, has good potential for becoming the basis of future design methodology.
The approach described can in principle be extended to deal with any form of damage provided that cracks and delaminations are open, and to include moisture effects, assuming that the moisture distribution is uniform within each ply.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	CMMT(A)51
Subjects:	Advanced Materials Advanced Materials > Materials Modelling
Last Modified:	02 Feb 2018 13:18
URI:	http://eprintspublications.npl.co.uk/id/eprint/709

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