High compression of granular assemblies of brittle hollow tubular particles

Abstract

This paper is devoted to the micro-mechanical origins of the high compressibility of brittle tubular particle assemblies. The material is extremely porous due to the presence of a large hole within the tube-shaped particle. The release of the inner void, protected by a fragile shell, gives the material a very strong ability to compress. The compressive response is investigated by means of the Discrete Element Method, DEM, using crushable-elements. To address the complexity of the model, a step-by-step break-down is developed.The paper comprises the comparison of the numerical results with both results obtained by the authors and existing experiments. With the insights provided by the DEM, we have sought to better understand the phenomena that originate at the grain scale, and that govern macroscopic behaviour. Grain breakage was proven to control the compressive behaviour, and thus, the importance of internal pores dominates the inter-particle voids. Then, a novel concept of compressibility analysis has been proposed using the separation of the double porosity and the quantification of the pore collapse through primary grain breakage. Finally, a general, geometrical development of a semi-analytical model has been proposed aiming the prediction of the evolution of double porosity vs axial strain.