Non-axisymmetric matrix cracking in unidirectional brittle matrix composites

Abstract

A model is presented for the analysis of a composite cylinder subjected to an axial tensile load in the fiber direction and containing a non-axisymmetric matrix crack. Considering the non-axisymmetry of the crack within the matrix, a three-dimensional stress analysis based on the consistent shear-lag theory is introduced into the above model. The variational approach founded on the principle of minimum potential energy is applied to the above model to obtain the numerical results for the stress and displacement fields. On the basis of the Irwin-Kies compliance calibration formulation and the strain energy release rate criterion, the fracture analysis of the matrix cracking is carried out. The critical loads for various crack sizes and configurations are presented. Some observations on the role of various model parameters on the matrix cracking are made. It is shown that the crack may grow in two stages; the crack first grows unstably in the radial direction up to the interface, then extends through the entire matrix cross-section around the fiber. It is also found that during the transition from the first to the second stage, the crack growth may be arrested.