The interface plays a particularly important role in fiber-reinforced composite materials. The interface region with a few nanometers to tens of microns is the weak area in the composite materials and seriously affects the mechanical properties. The mechanisms of the interfacial stress transfer and the interfacial debonding can be investigated by micro-scale experimental mechanical methods which explore the relationships among microstructure

interfacial micromechanics and macroscopic fracture. As a preferred method

micro-Raman spectroscopy has been applied to study the interfacial micromechanics and the fiber bridging technique is also introduced in detail. The bridging stress

the crack propagation and the interfacial stress transfer are mainly discussed and the micromechanics of crack/bridging fiber is finally summarized.