Abstract: A micromechanics model of a single carbon fiber embedded in an epoxy system containing an elastoplastic interlayer is described. The finite element method is used to study the effect of thickness and modulus of the interlayer on the stress transfer in this composite system after thefiber breakage. Analysis results indicate that the optimum interlayer can decrease the shear stress concentration and improve the load carrying capabilities of the broken fiber under different interfacial bonding conditions.