Micromechanical strength formulae of unidirectional composites

When isotropic fibers are unidirectionally arranged in another isotropic matrix material, the resulting composite has different mechanical properties from those of both the fibers and the matrix. Its elastic stiffness can be accurately estimated with some simple micromechanical formulae such as rule of mixture formulae, based on the properties of the constituent fiber and matrix materials as well as fiber volume fraction only. However, little is known about the ultimate strengths of the composite. This letter presents a set of concise micromechanical formulae for the ultimate tensile strengths of the unidirectional composite under individual uniaxial loads. (C) 1999 Elsevier Science B.V, All rights reserved.