Interfacial debonding in single fibre-composite with a cracked matrix – Part 2: Debonding during loading

The calculation method, which has been presented to describe the debonding behaviour during cooling in single elastic fibre–elastic matrix composite, was modified to obtain the outlines of the matrix crack–induced debonding behaviour during loading. The present method was applied first to the case where the matrix is cracked or is fractured perpendicularly to the fibre axis. It was shown that the larger the mismatch of thermal expansion between fibre and matrix, the lower the volume fraction of fibre and the higher the Young's modulus of the matrix, the higher becomes the energy release rate for debonding, resulting in lower stress of the composite for the initiation and growth of debonding. It was also shown that two cases arise for the growth of debonding: one where the debonding grows unstably upon initiation, and another where it grows stably with increasing stress in the early stage and unstably in the late stage. The present method was also applied to the case where the matrix is fractured above the stress level of initiation of debonding. It was shown that the debonding tends to occur unstably with increasing fracture strain of the matrix.