Toughening by plastic cavitation around cylindrical particles and fibres

A model for toughening from spherical particles is extended to cylindrical rods and fibres. The equations describing the plastic cavitation are of similar form to those of spheres. The results are used to analyse the toughening of an epoxy resin using carbon nano tubes and ZnO nano-rods in a thermoplastic. Both quasi-static fracture and fatigue are included. The effects of fibre size distribution and agglomeration are also discussed. It is proposed that the surface energy at debonding is some fraction of the matrix toughness which is governed by the particle and plastic zone sizes. Rod-like nano particles appear to be more effective as tougheners although agglomeration is the major problem.