BIAXIAL TESTING OF CONTINUOUS FIBER-REINFORCED ALUMINUM TUBES

Composite tubes of aluminium and aluminium alloy containing hoop wound alumina (Altex) fibres were fabricated using a liquid metal infiltrat ion method. The tubes were well consolidated, with low porosity, and g ood bonding between fibre and matrix, as confirmed using 'rule of mixt ures' calculations of elastic modulus. Mechanical properties were eval uated in the principal directions of the tube under uniaxial and biaxi al stress loading conditions, and damage modes were studied. Stress qu arter diagrams were constructed on the basis of a maximum stress failu re mechanism, and failure envelopes were produced using the measured v alues of yield stress and failure strength. The composition and condit ion of the matrix was shown to influence the shape of the failure enve lope and, in turn, the mode of failure of the tube for a given biaxial stress ratio. Good coli elation tvas obtained between predictions mad e from the stress quarter diagrams and the fracture paths observed in tested tubes. MST/4020.