Experimental and numerical studies in model composites Part II: Numerical results

Abstract

A numerical approach using the boundary element method for strength and toughness of a composite with long aligned fibers is reported. The three-dimensional problem is reduced to a two-dimensional one by substituting the rows of fibers with layers of appropriate width and elastic constants. The configuration examined in this work is a compact tension specimen similar to that used in the experimental studies (Part I, [1]). The experimental results on strength and apparent fracture toughness are compared with the numerical results. For the particular geometry and fiber spacing, the numerical simulations are in good agreement with the experimental findings, i.e. the composite's strength σ _A , scales with the fiber spacing λ, in the form of σ _A . Using the numerical formalism a number of different geometries was examined. The simulations suggested that if the external specimen characteristics remain the same and the fiber spacing in the direction of crack advance is changed, then the strength of the composite specimen can be expressed σ _A . If the fiber spacing varies in both directions simultaneously, for a certain range of λ, it can be considered that the composite's strength σ _A , is proportional to σ _A .