Numerical simulation of wall pressure during discharge of granular material from cylindrical silos with eccentric hoppers

One of the main causes for failure in grain silos is due to the excessive pressures exerted on the silo wall during discharge. Within traditional theories, several attempts have been made to obtain mathematical expressions reflecting the overpressures produced due to eccentric discharge. These start from the calculation of pressures in a concentric static condition, making the corrections needed due to outlet eccentricity and then applying majoration coefficients in the discharging condition. A new research possibility appears now with the application of the finite element method to present-day engineering. This method is used worldwide by many teams for silo design. In this work, an elasto-plastic constitutive law is applied to cylindrical silos with eccentric hoppers and rigid walls, using the Drucker-Prager criterion. In this model, the distribution of plastic areas according to eccentricity is analysed. The study of the influence on static pressures of the internal friction angle combined with the variation of the hopper eccentricity is also carried out. The results obtained are compared to elastic behaviour. For the development of this work, the commercial programme ANSYS 5.5 has been used, and it has been necessary to develop the analysis in three dimensions. (C) 2003 Silsoe Research Institute. All rights reserved Published by Elsevier Science Ltd.