Numerical modelling of the effects of bin inserts on stress distribution in storage bins for cohesive powder material

Abstract

A study was undertaken to demonstrate the applicability of modified Cam-clay model to the study stress distribution in storage bins. Effects of insert location, insert size, insert friction, hopper outlet size, hopper slope, and bin wall friction on stress distribution in ground feed inside storage bin were investigated using finite element models. Simulations were carried out for filling of the storage bin and initiating draw-down. Stress distribution were plotted after the bin was filled with ground feed and after draw-down was initiated. Results of simulation were compared to results of experiments on model size bins. The modified Cam-clay model is an elastoplastic model that uses three critical state parameters in the constitutive equation: $\lambda,\ \kappa,\ {\rm and}\ \Gamma.$ The Cam-clay parameters for ground feed were determined by triaxial tests. The parameters $\lambda,\ \kappa,\ \Gamma,$ and M were 0.045, 0.016, 2.003, and 1.977, respectively. SIGMA/W software was used to prepare models of storage bins and solve finite element equations. Stress distribution changed in the bin when any of he insert or bin parameters were changed. The region near the hopper outlet had low vertical and horizontal stresses in bins where high flowability was expected. It was observed that mounting method of insert resulted in change of flow behaviour. Flowability increased and then remained unchanged as the insert was mounted higher up in the bin. Flowability increased as insert size and friction was decreased. Flowability increased with increase in size of hopper outlet but decreased as the hopper slope was reduced. Chances of interrupted flow decreased with decrease in wall friction.