Analysis of the single-fiber pullout test using Raman spectroscopy .3. Pullout of Nicalon fibers from a Pyrex matrix

Single-fiber pullout specimens consisting of Nicalon fibers and a Pyrex-glass matrix were fabricated using a specially designed, simple mold. Raman spectroscopy was used to map the distribution of fiber strain within the glass matrix following deformation of the fiber section in air, and the results were compared with those predicted by theoretical analyses. It was demonstrated that the behavior also could be modeled using a partial debonding theory and that the force balance equilibrium allowed the variation of interfacial shear stress along the interface to be derived. The partial debonding theory showed that debonding occurred at an interfacial shear stress of 60 +/- 20 MPa and that the friction shear stress following debonding was 23 +/- 8 MPa for the specimen investigated. Furthermore, it was shown that the fracture toughness of the fiber-matrix interface was 1.8 +/- 0.6 J . m(-2).