Viscoelastic modeling of wood in the process of formation to clarify the hygrothermal recovery behavior of tension wood

To explain the hygrothermal recovery (HTR) behavior of tension wood (TW) from the physical and chemical point of view in relation to the time, species and microfibril angle, a theoretical discussion using an analytical one-dimensional viscoelastic modeling was made. The chosen model includes an elastic element, a deformation mechanism and two viscoelastic elements called also as Kelvin–Voigt model. In this analysis, a top-down approach between the model and the experimental data was introduced to find the realistic parameters for the model. It enables us to fit the model to the HTR experimental data for three wood species: konara oak (Quercus serrata Murray), urihada maple (Acer rufinerve Siebold et Zucc.) and keyaki wood (Zelkova serrata Makino). The fitted experimental data show that the two compliances of the two viscoelastic elements are the most important parameters that explain the evolution of TW longitudinal strain during the thermal treatment.