Experimental validation of incipient failure of yield stress materials under gravitational loading

Recent theoretical work has investigated incipient failure of a cylinder of yield stress material under gravitational loading [Chamberlain et al., Int. J. Mech. Sci. 43, 793-815 (2001); 44, 1779-1800 (2002)]. This theoretical work, using the slip-line field method of plasticity, suggests that the height of incipient failure increases as the radius increases. In contrast, a simple heuristic model, the "uniform stress model," predicts that the height of incipient failure is independent of the radius. We present detailed quantitative comparison of the slip-line and uniform stress models with experimental measurements, verifying the predictions of the slip-line model. (C) 2003 The Society of Rheology.