On the Prediction of Failure at a Fiber/Matrix Interface in a Composite Subjected to a Transverse Tensile Load

This paper deals with the 3-D stress field of a cylindrical fiber which is embedded into a resin matrix. The composite is then subjected to a uniform tensile load s_o. The strain energy release rate is computed and the criterion is used to predict debonding initiation at the fiber/matrix interface. The analysis shows that this failure is most likely to occur at the free surface, i.e. the region where the fiber intersects a free surface, for example a hole, an edge, or a crack. Moreover, it will occur at approximately (1/10) the load value required for the same failure to commence at the center of the fiber length.

The results are also extended to include a doubly periodic array of fibers which are embedded into a matrix. Based on 3-D considerations, the stiffness matrix is shown to increase as the volume fraction of the fibers increases. Similarly, the stress s_r, in the matrix is shown to decrease as the volume fraction of the fibers increases.