Abstract
The transverse stress-strain relation of the unidirectional fiber composite is investigated theoretically taking into account of the matrix yielding and the interfacial adhesion. The matrix yielding is determined by the average tensile stress in the matrix. Three types of the fiber/matrix interfacial bondings are considered ; (1) perfect adhesion, (2) interfacial slippage and (3) cavity formation. Numerical results are compared with the experimental data on the unidirectional Boron fiber/Aluminum composite reported by Kyono et al., and the following conclusions are obtained. The stress applied to the composite corresponding to the matrix yielding increases gradually with the increase of the fiber volume fraction (Vf). Comparing with this increase of the stress applied to the composite, the transverse Young's modulus of the composite increases more rapidly as Vf increases. Therefore, the strain of the composite corresponding to the matrix yielding decreases remarkably with the increase of Vf. Because the radial tensile stress at the fiber/matrix interface is larger for Vf=30% than for Vf=50%, the interface is easy to be debonded and to form the cavity for Vf=30%.
