圧縮荷重下におけるウレタンゴムに関する材料モデルの構成要素の影響

抄録

In our studies, material models for urethane rubber have been proposed for relationship with viscoelasticity. However, viscoelasticity only might not be sufficient to describe the relationship because it does not depend on strain rate. In this study, to investigate the contribution of internal friction, which is not viscoelasticity, a material model of the stress-strain relationship of urethane rubber under cyclic compression was assumed to consist of hyperelasticity and internal friction. The influence of the components was investigated by obtaining the parameters of each component when the strain rate or the maximum nominal strain was varied for a cylindrical specimen. To clarify the contribution of internal friction, the compressive nominal stress measured experimentally was subtracted from the value obtained from the Neo-Hookean equation. Then, appropriate equations for the obtained results on the process of loading and unloading were considered. As a result, the equations for the relationship of nominal compressive stress and nominal compressive strain were described as a sum of hyperelasticity, Mullins effect, and internal friction. Coefficients in the equations were obtained by fitting to the experimental results. The present material model expressed could correspond to the experimental results when the maximum nominal strain and strain rate were changed.