3D finite-element simulation of a square silo with flexible walls

Most of the studies that have been published to evaluate stresses on silo walls during filling or discharge stages are based on a rigid wall assumption. In a 2D approach, the wall flexibility can be approximately modeled by using a corrective factor applied to the whole pressure distribution. It has been shown that such models are in agreement with experimental measurements on circular silos. But in square or rectangular silos, the variation of the stiffness of the wall due to vertical or horizontal stiffeners produces nonuniform wall deformations that are not taken into account in the previous axisymmetric 2D model. The aim of this paper is to present a full 3D modeling of the filling and discharge stages using a nonlinear finite-element method. The bulk material behavior is based on an elastoplastic law. Contact elements using a Mohr-Coulomb criterion simulate the interaction between the wall and the bulk material, and the flexibility of the silo structure is modeled with beam and shell elements. A detailed analysis of the numerical results computed for a square silo filled with wheat and discharged through a central outlet is presented and discussed.