Experimental and numerical investigation of Weibullian behavior of grain crushing strength

Abstract

The Weibullian behavior of single grain crushing strength was investigated experimentally and numerically with the aim of enhancing the understanding of rock grain breakage. The morphologies of pebble grains were obtained using white light 3D laser scanning and image processing. A grain shape library was constructed for grain shape analysis with different shape descriptors. The use of the shape library and grain stability analysis is discussed for a suggested procedure to rotate a grain to its most stable configuration. Single grain crushing tests were performed for 30 pebbles to obtain force-displacement curves and fracture patterns. Each grain was compressed diametrically between flat platens. As expected, the values of the stress at bulk fracture follow a Weibull distribution. A procedure for generating crushable agglomerates with realistic particle shapes was demonstrated, which was accomplished in the discrete element modeling (DEM) of the single grain crushing test. The work presented here is novel in that both the heterogeneous micro-structures and randomly distributed flaws are considered. The DEM results demonstrate that the proposed modeling approach and calibrated parameters are reliable and can reflect the crushing behavior of rock pebbles. Finally, three parametric studies were presented evaluating the effects of micro-crack density, micro-crack disorder, and grain morphology on the Weibullian behavior of the crushing strength, none of which has previously been thoroughly considered. These three studies provide a deeper insight into the origin of the Weibullian behavior of single grain crushing strength.