Curved-fiber pull-out model for nanocomposites. Part 2: Interfacial debonding and sliding

This paper is the second part in a series of works in which an analytical curved-fiber pull-out model for nanocomposites is proposed. The model includes the three stages of interface conditions-well-bonded, debonding, and sliding-involved in the entire pull-out process of a single curved fiber. In the first paper, the fiber and matrix are well-bonded, while in this second paper, the fiber and matrix are allowed to debond and slide, two relevant mechanisms in the later stages of pull-out. With either a constant or Coulomb friction interface, the pull-out model predicts higher pull-out forces as the fiber curvature increases, with zero fiber curvature (a straight fiber) producing the lowest pull-out forces. Fiber curvature effects are more pronounced, however, for the Coulomb friction model than the constant friction model because it considers radial compressive stresses at fiber/matrix interface. For the Coulomb friction model, two-dimensional finite element simulations are performed to test some of the model's approximation. Results indicate reasonable agreement between the two. (C) 2008 Elsevier Ltd. All rights reserved.