ANISOTROPY OF MECHANICAL PROPERTIES OF MUSHROOMS (AGARICUS BISPORUS (J.E. LANGE)IMBACH)

Abstract. Mechanical and rheological properties of mushrooms in groups selected on account of shape, size and the time of cropping were investigated. Strength tests, hysteresis tests and creep tests of mushrooms compressed between two parallel plates were carried out. Values of the index WP of the work of deformation inputs, modulus of elasticity EC and stress σobl were calculated. Susceptibility to creeping through calculation of the number of days to doubling of the strain value based on MacLeod equation was determined. Anisotropy of mechanical properties was reported, depending on the direction of loading and the size of a mushroom. Modulus of elasticity EC has a value of 0.5 MPa at the load in the axial direction and 0.3 MPa in the radial direction not depending on the size of a mushroom. Diversity of the value of index Wp from 7 J·kg-1 at the load in the axial direction to 3 J·kg-1 the radial direction. Increase of pressures admissible for the axial direction may the reason for limiting the time of storage of this raw material to several days. Key words: strength, hysteresis, creep, mushrooms, anisotropy, plastic flow The list of symbols: Wp – index of the work of deformation unit inputs (J·kg-1), EC – apparent modulus of elasticity (MPa),σobl – determined stress (MPa),ε – deformation of a sample (-), F(λ) – measured instantaneous value of the load (N), dλ – elementary dislocation in the direction of the acting force (m), ξ – coefficient including the size of the sample (m-3)