Predicting Thermally Induced Pressures in Grain Bins

Abstract

ABSTRACT IN a filled grain bin the thermal contraction of the bin wall, when subjected to a decrease in ambient temperature, is partially restrained by the stored material. This restraint produces lateral pressures on the bin wall in excess of the static pressures. The magnitude of the lateral pressure increase is dependent upon many factors including the radius, thickness, and stiffness of the bin wall, the modulus of elasticity (MOE) of the grain, the Poisson's ratio of the grain, the bulk density of the grain, and the ambient temperature decrease. The factors which are the least well defined are the properties of the grain. Herein it is demonstrated that the MOE of wheat en masse in a typical bin is directional dependent. Also, it is shown that the MOE of wheat en masse is dependent upon both the magnitude of stress and the ratio of lateral to vertical stress in the grain masse. Finally, using empirical three dimensional load-deformation relationships for wheat en masse, the level of thermal pressures are predicted for a typical grain storage bin filled with wheat.