Under transverse loading, unidirectional brittle matrix composites such as those having ceramic and glass-ceramic matrices, are susceptible to matrix/coating cracking, interface debonding (probably with friction), and possible fibre breaks. In order to predict the influence of these forms of damage, including their possible interactions, we have developed a model which attempts to accurately represent the stress field in their presence. The present formulation is based on the use of Reissner's variational theorem in conjunction with an equilibrium stress field in which ther-dependence is assumed. The model is based on the geometry of a sector composed of a cylindrical core surrounded by a number of concentric cylindrical wedges which, in turn, may simulate a composite representative volume element. Each one of the wedges or the core can be mathematically subdivided in the radial direction to enhance the accuracy of a given numerical solution. The proposed model is then utilized to evaluate the effective elastic moduli and the internal displacement and stress fields of a unidirectional composite in which the constituents are either completely bonded or debonded. Numerical results are obtained for a common glass matrix composite material and comparisons made with existing elasticity solutions to validate the accuracy of the new model.
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