Cereal Chem 44:392 - 402.  |  VIEW ARTICLE
Evaluation of the Modulus of Elasticity of Wheat Grain.

L. Shelef and N. N. Mohsenin. Copyright 1967 by the American Association of Cereal Chemists, Inc. 

The mechanical properties of Seneca wheat grains subjected to uniaxial compression were studied with the Instron testing machine. Whole grains were loaded by means of parallel plates, a smooth spherical indenter, and a cylindrical indenter. Also, core specimens, prepared by cutting off both ends of the grains, were loaded by means of parallel plates. Under a constant rate of deformation of 0.020 in./min., the load- deformation relation in all four compression tests was linear up to a certain load, nonlinear beyond it. Cyclical loading-unloading to a low constant load within the linear portion of the load-deformation curve showed that the deformation was partly recovered and partly residual. The residual deformations gradually decreased to small constant values in the third cycle, whereas the elastic deformations remained constant. Under these conditions the behavior of the wheat grains was considered approximately Hookean, and the classic theory of elasticity was adapted for evaluation of their modulus of elasticity. Hertz's solution for convex bodies was used for compression of the whole grain by means of parallel plates and by the spherical indenter, and Boussinesq's solution for semi-infinite bodies subjected to concentrated compressive loads was used for the cylindrical indenter. Four values for the apparent modulus of elasticity were thus obtained for Seneca wheat grains of 9.1% moisture content, ranging from 1.6 x 10(5) to 8.3 x 10(5) p.s.i.