Analysis of debonding and frictional sliding in fiber-reinforced brittle matrix composites: basic problems

Abstract

Using the axisymmetric cylindrical composite model, a comprehensive finite element analysis (FEA) has been carried out for a single fiber pullout problem. The FEA completely satisfies the mechanical boundary conditions and mechanical continuities over the fiber—matrix interface. Thermally induced stresses due to thermal expansion mismatch and the Coulomb frictional shear stress transfer at the debond interface are used in the FEA. The debond length is determined based on the calculated interfacial debond crack tip energy release rate. Shear and axial stress distributions along the fiber—matrix interface and the singular stress field in the crack tip are also obtained. The numerical results are used to discuss basic problems: (i) interface mechanical boundary conditions and mechanical continuity near the debond crack tip, (ii) singularity of thermal residual stress and loading stress fields, (iii) slip and stick conditions at the debond interface, and (iv) influence of frictional resistance on the debond crack energy release rate. The differences of the FEA results from the analytical ones based on Lame´solution with Coulomb frictional shear sliding resistance are discussed with a special attention to the four basic problems. Limitations of the conventional analytical solutions are also pointed out based on the present FEA results.