The effective moduli of short fiber composite with graded interphase

Five effective elastic constants for a uniaxially aligned short fiber composite, which contains graded interphase between fiber and matrix, are presented by a simple recursive algorithm under considering only two concentric cylinders at a time. The method is based on the modification of a three phase concentric cylinder model in which the cylindrical fibers are replaced by composite fibers to reflect the distance between fiber ends in the aligned short fiber composite. We confirm the Halphin's result such that the major Poisson's ratio, transverse Poisson's ratio and shear modulus are not significantly affected by the fiber length, the corresponding quantities in the continuous fiber case can be used for the discontinuous fiber case. But the longitudinal and transverse moduli are significantly affected by the fiber aspect ratio, not as Halphin's result.