THE PREPARATION AND FATIGUE PROPERTIES OF COPPER - TUNGSTEN FIBRE COMPOSITES

Abstract

The principles and theory of the tensile behaviour of fibre reinforced composites is reviewed, and a mechanism of fatigue failure is proposed. A technique for preparing copper - tungsten fibre composites was developed. Tensile tests showed the composites to behave normally, and the number of fibres breaking was shown to increase rapidly with stress up to the U.T.S. Fatigue below a small critical volume fraction of fibres was shown to be dominated by the matrix, which under repeated tension foiled by cyclic creep. Above tills volume fraction the fibres dominated the fatigue failure and cracks were observed to propagate through the matrix; a process not observed in tension. Matrix fatigue cracks were initiated around breaks in the fibres, and could propagate through other breaks, and along fibre - matrix interfaces and could circumnavigate unbroken fibres. The fatigue ratio of high fibre volume fraction samples was poor.