Finite Element Analysis of Bulk Solids Flow: Part 1, Development of a Model Based on a Secant Constitutive Relationship

Abstract

Silos and bins are used in agriculture and many other industries for the storage and handling of bulk solids. This paper deals with a secant constitutive relationship for bulk solids for a transient finite element analysis of stresses, displacements and velocities in the solids during discharge of a silo filled with soybean. The constitutive relationship will be presented for the modelling of flow of cohesionless granular materials in a silo or bin. Stresses and strains are related by a secant relationship that has an elastic and a plastic component. The Drucker-Prager yield criterion is used to indicate the switch from elastic to plastic behaviour.Wall pressures in a model bin were measured and used to verify numerical results. Finite element analyses with the secant constitutive model proved to be very stable during the entire emptying process. Wall pressures predicted with the numerical model for the entire emptying process compared well with those measured in experiments.