Multiscale simulation of elastic modulus of rice stem

The objective was to obtain a quantitative relationship between the multiscale structural parameters and the elastic modulus of rice stem. Anisotropic elastic properties of rice stem were calculated via multiscale simulation. The elastic constants of the sub-layers of cell wall were calculated by the Halpin-Tsai equations and the rule of mixtures. Cellular structure of stem cross section was reconstructed via a skeletonisation method and used to create the finite element models. The influence of multiscale structural parameters, including the volume fractions of skin and vascular bundle, the cell wall thickness of different types of cells, the volume fraction and stiffness of compound composition, the volume fraction of S2 layer and the microfibril angle (MFA) in the layer, on the overall stiffness of rice stem was determined. Numerical results showed that if the volume fraction and stiffness of each cell wall component are assumed to be constant, increasing the volume fraction of the mechanical tissue layer, thickening the fibre cell wall and decreasing the MFA in S2 layer are the most effective ways to increase the longitudinal tensile modulus of rice stem. Changing the cell wall thickness and the volume fraction of vascular bundle is useful for controlling the tangential modulus. However, more effective is to change the cell wall thickness of parenchyma cell and the volume fraction of the vascular bundle for controlling the radial tensile modulus of rice stem. (C) 2019 IAgrE. Published by Elsevier Ltd. All rights reserved.