LOCAL STRESS-CONCENTRATION AND THE PREDICTION OF TENSILE FAILURE IN UNIDIRECTIONAL COMPOSITES

The aim of this paper is to present a new representation of the tensil e failure of a composite material which accounts for the normal stress supported by the matrix and allows a study Of the influence of consti tuent material proper ties and fibre volume fraction on the stress-con centration factors. This is done by micromechanical analysis which all ows the stress and strain in the fibres and the matrix to be related t o the applied stress or strain on the composite. Stress-concentration factors are calculated in the composite transverse section and are fou nd to be smaller than previously published analytical solutions. The d ifference is essentially due to the normal stress supported by the mat rix which is neglected by the shear-lag analysis bur is taken into acc ount in our model. The tensile strength is calculated firstly by numer ical simulations and secondly by Batdorf's methodology which addresses the formation and propagation of fibre fractures. Comparisons with ex perimental measures are satisfactory. (C) 1998 Elsevier Science Ltd. A ll rights reserved.