Experimental study on dynamic mechanical behavior of Q345 steel under different strain rates

Quasi-static and dynamic tensile tests of Q345 steel were performed with INSTRON and Zwick/Roell HTM5020 testing machine. Simulations of these tensile tests under different strain rates were developed using LS-DYNA of ANSYS. And their true stress-strain relationships after necking were obtained through a hybrid experimental-numerical method. The simulation results show that the true stress-strain relationship of Q345 steel can be approximately described with Ludwik model at quasi-static strain rates and with Voce model at higher strain rates. The linear combination of Hollomon and Voce (H/V-R) model is adopted to fit the experimental data. The results show that the H/V-R model can predict the strain rate effects of Q345 steel although there is still a little deviation between the experimental and fitting results. To establish a better constitutive model, the Wagoner rate law is introduced into the H/V-R model. Then an empirical constitutive model H/V-R2 which can reflect the strain rate effect of Q345 steel accurately is finally obtained by further improvement. © 2015, Southeast University. All right reserved.