Dynamic strain hardening curve in simulation of electro-hydraulic sheet metal forming using ls-dyna®
The article presents an investigation of the influence that variation of the parameters of a dynamic strain hardening curve has on the calculation error in electro-hydraulic impulse metal drawing. Finite-element LS-DYNA 971 code was used. Computer simulation in this study was carried out for 0.24 mm-thick CuZn33 brass sheet blank under free drawing into a die 60 mm in diameter. We have investigated the influence of the type of quasi-static strain hardening curve. We have considered two different techniques of obtaining the curves: the tensile test method and the method of repeatedly rolled metal strip with different degrees of deformation. Moreover, we have considered methods of approximating the strain hardening curve and methods of obtaining the approximation coefficients for computer calculations. We have also estimated the error of taking into account dynamic hardening with a constant dynamic coefficient in comparison with using the Cowper-Symonds functional dependence.