ポリプロピレンの大変形負荷下および繰り返し負荷後における非弾性変形挙動とその温度および静水圧依存性

抄録

Inelastic deformation behavior of Polypropylene (PP) in tensile large strain and after axial precyclings is investigated experimentally and analyzed using the three elements model based on the overstress theory. In this experiments, cylindrical tubular specimen as well as solid bar specimen is used for torsional loading and volume change is measured to get the true stress-true strain curves. It is found that flow stress is almost constant in strain range of more than 0.1, Poisson's ratio varies depending on strains and the viscosity does not change even after cyclic pre-loadings in tension, torsion and compression. The quasi-static stress-strain curve g is represented as a function of temperature. A very good agreement can be obtained between predicted results based on the obtained constitutive equations having the first invariant of stress (static pressure) effect and the experimental results on both of flow stress and relaxation.