An alternative to the conventional triaxial compression test

A new test for measurement of the mechanical properties of granular powders is proposed, consisting of upsetting the powder inside a metal tube. Varying the tube material as well as its wall thickness allows superimposing of a variable radial pressure. By pre-compacting the powder inside the tube in a closed die it is possible to test the powder at different densities. The radial pressure is found by correlating measurements of radial bulging of the tube with numerical analysis of tube bulging. Estimates of the error on the determination of the radial pressure are given and it is found that this error may be kept less than ± 4%. The coefficient of friction between powder and tube for a specific case is evaluated and found to be between 0.05 and 0.1 at pc > 400 MPa. Data from the test with axial pressures up to 1100 MPa and radial pressures up to 500 MPa are presented. Data on the yield surface for BSCCO (ceramic powder (Bi,Pb)2Sr2Ca2Cu3Ox for manufacturing of superconductors) at 74% density are given and found to be in good agreement with previously published data determined by closed die compaction and fracture tests. sults obtained show that the new test may be a good alternative when high pressures are required or when pressurizing by fluid is impractical.