LAUSR

Numerous food and agricultural materials are stored and processed in a particulate form. Cereal grains and rapeseed are also important raw materials for food industry. Properties of the material serve as parameters for engineers designing storage systems or processing plants. Mechanical properties of grain bedding depend on properties of individual grains, friction between particles, interparticle contact geometry and load history. Recently demand of industrial practice resulted in revision of several silo design codes, which included standardization of methods for determination of mechanical properties of granular materials. European Standard Eurocode 1 (1996) and Polish Standard (DYDUCH et al. 2000) recommend to determine properties under load condition which are similar to the operation loads. Some properties are determined using shear test (Jenike tester or triaxial compression test) other using uniaxial compression test. The aim of performed experiments was to evaluate and comprise values of mechanical constants characterizing elastic deformation (modulus of elasticity E and Poisson’s ratio) of rapeseed and wheat bed determined with two methods adopted from geotechnique. First approach used was a method proposed by SAWICKI (1994) who used first phase of unloading in uniaxial compression experiment to determine elastic constants. This type of examination was applied to estimate values of E and ν for wheat and rapeseed beddings for five levels of moisture content ranging from 6% to 20%. With the second method values of E were determined based on measurement of shear wave velocity (TIMOSHENKO, GOODIER 1970). Tests were performed for bedding of wheat and rapeseed under equilibrium moisture content.