DETERMINATION OF ELASTOPLASTIC CONSTITUTIVE PARAMETERS FOR WHEAT EN MASSE.

A constitutive stress-strain equation, formulated from P. V. Lade's elastoplastic theory, was used to model en masse behavior of wheat. Triaxial tests were performed at a moisture content of 8. 1% (d. b. ) and an initial bulk density of 817 kg/m**3 (51 pcf) to evaluate the material property parameters included in the theory. The estimated fourteen parameters were used in the constitutive equation to calculate stress-strain relationships for wheat en masse in axial compression and isotropic compression loading conditions. Results showed that Lade's theory adequately describes the stress-strain behavior of wheat en masse for the conditions tested.