Time Dependent Characteristics of Proposed Constitutive Equation Covering Wide Range of Strain at High Strain Rate

In this paper, the time dependent characteristics of the constitutive equation proposed previously was investigated by comparing the experimental time history of strain with the numerical one. The proposed constitutive equation is a new form in which the logarithmic or the power law type is superimposed upon the Malvern type and the strain rate hardening exponent or the coefficient in both equations is a function of strain. The numerical analysis of one dimensional longitudinal impact using the constitutive equation was performed by the characteristic line method. A long rod of lead was collided with a hardened target at various velocities up to 100m/s longitudinally and the deformation process of the specimen was recorded using an image-converter cemera in this experiment. The data in the photograph were read off by a CCD camera system containing a cursor generater. The results show that the time history of strain obtained in the numerical analysis is in good agreement with the experimental one in the region where one dimensional deformation occurred. It is apparent that the proposed constitutive equation predicts the practical material property in a wide range of strain at high strain rates.