Quantifying the plastic anisotropy for particulate metal matrix composites

The failure of orthotropic materials, traditionally described by Hill's criterion, in terms of the anisotropy ratio r, i.e. the ratio of transverse to through thickness increments of logarithmic strain, is studied in the present work. In spite of the critical role of r for the description of the failure of such materials, its quantification is not yet standardized. Based on results obtained from long series of experiments r is here quantified, for the case of a modem particulate composite material, extensively used in aerospace applications. The variation of r versus the level of the plastic strain is determined and it is concluded that its values depend both on the orientation of the specimen and load with respect to the initial orthotropy axes as well as on the plastic strain induced in case the specimen and load are not oriented along one of the axes of orthotropy.