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International Journal of Automotive Technology 2019;20(S): 31-37. |
| ON THE CONSTITUTIVE MODELS FOR ULTRA-HIGH STRAIN
RATE DEFORMATION OF METALS |
| Hossein Sedaghat, Weixing Xu, Liangchi Zhang, Weidong Liu |
| The University of New South Wales |
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| ABSTRACT |
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Ultra-high strain rate deformation (> 104 s-1) is common in high speed manufacturing and impact engineering.
However, a general constitutive model suitable for describing the material deformation at ultra-high strain rates is still
unavailable. The purpose of this study is of two-folds. The first is to systematically evaluate the performances of four typical
constitutive models, Johnson-Cook (J-C), Khan-Huang-Liang (KHL), Zerilli-Armstrong (Z-A), and Gao-Zhang (G-Z), in
predicting the dynamic behaviors of materials. The second is to obtain an improved constitutive model to better describe the
deformation of materials under ultra-high strain rates. To this end, high strain rate tests were carried out on different crystalline
structures, i.e., BCC, FCC, and HCP over a wide range of strain rate from 102 s-1 to 1.5 × 104 s-1. It was found that before the
critical strain rate, around 104 s-1, all of the previous models can predict the flow stresses. When the strain rate passes a critical
point, however, these models fail to predict the sudden upsurge of the flow stresses. The improved model developed in this
paper, by considering the dislocation drag mechanism, can successfully characterize the dynamic behaviours of materials over
the whole range of strain rates. |
| Key Words:
Ultra high strain-rate, Constitutive model, Dislocations, Drag mechanism |
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Corresponding Author.
Liangchi Zhang , Email. 
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