Integration of a new data acquisition/processing scheme in SHPB test and characterization of the dynamic material properties of high-strength steels using the optional form of Johnson-Cook model

In this study, high strain rate conditions were obtained using a compressive split-Hopkinson pressure bar test apparatus that adopted a new data acquisition and processing scheme utilizing a LabVIEW system. Quasi-static strain rate conditions were obtained using a universal testing machine. The material responses of three high-strength steels under high strain rate and quasi-static conditions were investigated. They were characterized using the Johnson-Cook constitutive model. Two other optional strain rate forms were substituted for the constitutive model to predict material flow stress, especially at high strain rates exceeding 10(4) s(-1). The considered optional strain rate forms were the modified Johnson-Cook and Huh-Kang models, which both showed a non-linear relation between flow stress and logarithm strain rate. The material parameters in the constitutive equations of the three high-strength steels were evaluated by fitting and comparing the data over a wide range of strain rates.