THE DEFORMATION OF DISCONTINUOUSLY REINFORCED MMCS .1. THE INITIAL YIELDING BEHAVIOR

A new method of defining the onset of yielding is proposed. This is sh own to be physically more appropriate than a conventional proof stress for the comparison of the yield behaviour of inhomogeneous materials such as MMCs. For whisker reinforced materials, the criterion adopted is shown to be sensitive to the localised plastic relief of the inhomo geneous matrix stress. Further, through a comparison with the conventi onal 0.2% proof stress, it is possible to interpret both the early wor k hardening behaviour and the initial inhomogeneity of internal stress development in MMCS