衝撃 広ひずみ速度域を対象とした各種材料グループに適用し得る実用構成式

Abstract

This paper presents a practical viscoplastic constitutive model covering a wide range of strain rates, large deformation, and applicable to various grouped metals. The essential new feature of the constitutive model is employment of a specific function between quasistatic yield strengths and strain rate sensitivities of grouped metals in the strain rate range where thermally activation for dislocation motion is the dominant mechanism of the material strain rate sensitivity. This new feature enables us to use unified or common material constants to describe the dynamic behavior of grouped materials in the strain rate range mentioned above. In the model, formulations for the strain rate sensitivity at higher strain rates of up to 104-105s-1, and for the temperature dependence of flow stress are also made so that the strain rate sensitivity in the wide range of strain rates, and at various temperatures are successfully described. In order to verify the validity of the proposed constitutive model, simulations of stress-strain curves at an elevated strain rate and variations of stress with the logarithm of strain rate at various temperatures are compared with the corresponding experimental results. It is found that the simulations based on the proposed constitutive model are in fairly good agreement with experimental results.