Numerical laboratory for granular solids : Trent, B C; Margolin, L G Engng ComputV9, N2, April 1992, P191–197

Abstract

The behavior of cemented granular material is complex and difficult to characterize. Physical tests on laboratory-size specimens are time consuming and often inconclusive, due to the variable nature of the bulk material. As an alternate approach, we have used the distinct element method to construct numerical samples of cemented granular material. The model allows us to verify which are the important microphysical processes determining material behavior. We can do parameter studies, continuously varying the material properties of the bonding material and the topology of the bonds themselves, to see how the macroscopic properties depend upon the microscopic structure. We illustrate our program with two types of calculations. The first series consists of measuring the macroscopic p-wave and the s-wave speeds of the numerical sample, and using them to infer elastic properties of the bulk material. We also investigate how the number and size of the bonds influence bulk response. In the second series, we look at crack growth in granular materials. The Griffith theory of crack growth assumes an ideally flat crack. In granular materials and in our simulation, the crack is formed when many consecutive bonds in the material are broken.