Modeling mechanical behaviors of plant stems undergoing microstructural changes

This study presents a constitutive material model for describing nonlinear and hysteretic responses of plant tissues subjected to mechanical loadings. The nonlinear and hysteretic response is associated with the viscoelastic nature of the constituents and microstructural changes of plant tissues during loadings. In order to incorporate the effect of microstructural changes on the macroscopic response of plant tissue, we assume that as the tissue is deformed, an additional micro mechanism arises affecting the mechanical response of the tissues. The plant tissue is assumed to consist of two networks, the initial network which is associated with an original reference configuration and the new network that is formed during the deformation. The newly formed network has a new natural configuration. The responses obtained from the proposed model are compared with available experimental data of plant tissues. The model is easily extended to incorporate responses of different tissues, i.e., outer strengthening skin and inner soft core, in determining the overall nonlinear behaviors of the plant stems, which are composite materials. Thus, we can examine the contributions of different constituents in the plant tissues on their macroscopic mechanical responses.