Micromechanical analysis of the strength of unidirectional fiber composites

A micromechanical analysis is presented for the prediction of ultimate stresses of unidirectional fiber composites under complex loading systems. The method is based on micro-failure criteria applied to the fiber and matrix phases as well as to the fiber/matrix interfaces. The theory is implemented for the prediction of the off-axis strength of six types of laminae for which measured data are available, and good agreement is shown to exist in most cases. Several possible generalizations are discussed.