Determination of modulus of elasticity of cereals and rapeseeds using acoustic method

摘要

The objective of presented project was to validate acoustic method as a tool for determination of elastic parameters of a bulk of cereal grains and rapeseeds. Six kinds of cereals were tested at five levels of moisture content 10%, 12.5%, 15%, 17.5% and 20% while rapeseeds were tested at four levels of moisture content of 6%, 9%, 12%, 15%. Tests were performed in 70 mm in diameter, 150 mm high cylindrical chamber equipped with piezoelements, that allowed for generating and recording of acoustic shear waves. Values of shear wave velocity V_s were found to increase with an increase in hydrostatic pressure p_h for all tested materials. The highest variability of V_s with changing hydrostatic pressure was observed in the case of wheat (from approximately 50 m s~(-1) in initial state to approximately 240 m s~(-1) for maximum hydrostatic pressure of 90 kPa). Modulus of elasticity E calculated on the base on V_s was found increasing with an increase in hydrostatic pressure and decreasing with increasing moisture content. The highest course of E(p_h) ranging from 20 to 140 MPa was obtained in the case of wheat of 10% of m.c., while location the curve for corn of 20% of m.c. was the lowest, ranging from 10 to 32 MPa.