A new theoretical model is developed in order to predict the stress transfer during the quasistatic single-fibre pullout process. The theoretical approach retains all relevant stress and strain components, and satisfies exactly the interfacial continuity conditions and all the stress boundary conditions. For both matrix and fibre, the equilibrium equations along radial direction are satisfied strictly, while the equilibrium equations along axial direction are satisfied in the integral forms. Three normal stress-strain relationships are strictly satisfied, while the radial displacement gradient with respect to the axial direction is neglected for shear stress-strain relationship. The general solutions of the axial and radial displacements in both fibre and matrix are obtained in explicit forms. In the debonded region, a modified Coulomb’s friction law, in which the frictional coefficient is a decreasing function of pullout rate, is applied to determine the interfacial frictional stress. A theoretical analysis for the single-fiber pullout with unload process is presented based on the energy-based debonding criterion and the modified analysis of stress transfer between fiber and matrix. The relationship between the applied stress and the interfacial relative displacement is expressed as a function of the radial residual thermal stress, fiber pullout rate and volume content as well as the length of reverse frictional sliding. The influence of fiber pullout rate on interfacial frictional coefficient is also taken into consideration. The theoretical results from present model agree well with the results from finite element model. The calculation results show that the applied stress result in further debonding increases with the increase of the radial residual thermal stress and the fiber volume content and the decrease of the fiber pull-out rate. There is a drop for the applied stress when the interface debonding close to the model length and the drops of short models are larger than those of long models. Under different conditions, the model length almost has no influence on the debonding and reverse sliding in unloading processes at the initial debonding region.
