高ひずみ速度下における広いひずみ域に適用できる構成式の形式について

抄録

It has been observed that a practical form of the constitutive equation, which is called a logarithmic or a power law type, well represents an experimental stress-strain curve up to the strain rate of about 10³S^-1. The both types show gradual dependency of the strain rate on the stress.
On the other hand, the deformation drug is governed by the viscous drug of dislocation at a high strain rate above 10³S^-1. In the range of high strain rate, the relation between strain rate and deformation drug is linear and one of the Malvern types, where the over stress is a linear function of the strain rate, satisfies the relation described above. However, almost all of the constitutive equations have been investigated only in the small strain range up to now.
In this paper, a new practical form of the constitutive equation which covers a wide strain range at high strain rates was investigated by comparing the experimental strain distribution with the numerical one for a lead specimen of finite length, which was impacted longitudinally.
The results show that the new form, in which the logarithmic or the power law type is superimposed upon the Malvern type, is in good agreement with the experimental results. It is also important that the strain rate appears as a function of the strain in the form.