An approach in parametric identification of high strain rate constitutive model using Hopkinson pressure bar test results

In the present work, an optimization approach has been introduced based on Levenberg-Marquardt method to identify the parameters of two different material constitutive models at high strain rate. This new procedure has been used to identify the parameters of two different steels, i.e. 1018 and 4340 steel within definite strain rate ranges. The experimental data has been taken from the split Hopkinson pressure bar data found in the literature. Firstly, the experimental data have been processed using the finite element optimization procedure in which the deformation has been applied to a specimen. An optimal set of material constants for Johnson-Cook (JC) and Zerilli-Armstrong (ZA) constitutive models have been computed by minimizing the standard deviation of the numerically obtained stress-strain curve from the experimental data. Then, the new procedure and new identified parameters have been validated successfully. It has been shown that the numerical algorithm has a very low dependency on the initial guess for the parameters. Finally, it has been shown that the algorithm is stable, and acceptable results can be obtained from data with Guassian noise.