Abstract
In order to study an influence of a consolidation stress upon yield loci of powders, a family of reduced yield loci and their corrersponding voidages were measured by a constant volume direct shear tester over a consolidation stress range of 10 to 350gf/cm2. The reduced locus was directly drawn in the plane of the shear and normal stresses as the coordinate axes reduced respectively by a factor of corresponding consolidation stress. The Warren Spring equation was also rewritten by the reduced shear and normal stresses. The reduced Warren Spring equation included a shear index, a ratio of a cohesive to a tensile stress and an effective angle of internal friction at steady state failure as parameters. The values of these three parameters were determined from the reduced locus experimentally obtained. In the range of consolidation stress 10 to about 150gf/cm2 the three parameters decreased with a decrease in the voidage, but in the range of 150 to 350gf/cm2 they did not change without change in the voidage.
A relationship between the unconfined yield stress and the major consolidation stress was found to be superior in an estimation of the flowability of powder to Jenike's failure function which was available only in a limited case when the parameter values were characteristic of the powder.
