A refinement of the yield surface of a pressure-dependent and elastic-perfectly plastic constitutive model for a particulate compact by considering specimen barreling in triaxial testing

The effects of barreling of a particulate compact specimen caused by the end restraint and rubber membrane during a conventional triaxial test on the yield surface of a pressure-dependent and linearly elastic-perfectly plastic constitutive model are investigated via finite element analysis. The combined influence of the end restraint and rubber membrane results in barreling of the specimen which causes artifacts in the experimental deviator stress vs. strain curve determined in the triaxial test. Values of the shear-failure deviator strengths at varying confinement pressures have been modified to exclude the artifact caused by the specimen barreling, followed by the refinement of the yield-surface parameter set of the constitutive model. The refined set predicts the experimental curve better than the unrefined one does.