Micromechanical investigation of milled and unmilled rice grains through experimental study and finite element analysis

Investigation on the effect of starch interface towards mechanical behaviour of rice grains was reported through mechanical tests (compression and three-point bending) and finite element micromechanics model. The model considered starch kernels within the rice grain (for milled rice) as well as a layer of husk on top (for unmilled rice). The interface between the kernels was modelled using cohesive zone model to simulate interfacial damage. Higher fracture stress was reported at lower moisture content from the three-point bending, and linear elastic behaviour was observed from compression tests of milled rice, which was independent of moisture contents. The force-displacement curves of milled rice are linear, whereas unmilled rice showed initial softening before hardening at approximately 0.1 mm displacement. The representative finite element models showed agreement with compression and bending experiments, suggesting significant influence of starch interface damage towards fracture of milled rice grain. (C) 2018 IAgrE. Published by Elsevier Ltd. All rights reserved.