Determination of plastic and rate-dependent properties of bulk solids using low pressure cubical triaxial tester

Since many of the issues in processes involving powder arise in lower pressure regime where self weight is the main source of the pressure, it is valuable to understand the behavior of powder in that pressure range. For this, a flexible-membrane cubical triaxial tester (CTT) with the capability to test a bulk solid's mechanical properties under dynamic conditions was used. Herein, alumina's mechanical responses were measured with the CTT. Three different loading rates of 6 kPa/min, 60 kPa/min, and 600 kPa/min were used to determine alumina's mechanical properties. Hydrostatic compression triaxial tests and conventional compression triaxial tests were conducted. To validate and predict mechanical responses of the alumina powder, parameters were evaluated for the modified Cam-clay model. Test results showed that alumina's mechanical properties were sensitive to the applied loading rate. Compression index values indicated that alumina became more compressible with the increase of loading rate. Shear strength increased with the loading rate whereas shear modulus decreased when the loading rate increased.