Numerical Simulation of Split Hopkinson Tensile Bar Test Using Johnson-Cook Deformation and Fracture Model

Damage and fracture due to impact loading are critical considerations in various mechanical engineering applications including automotive and power generation equipment. They are also vital in assessing the integrity against sabotage, such as terrorist attacks. Previous studies have demonstrated strain rate hardening, where material strength increases under high-speed deformation, and adiabatic heating, where trapped heat from rapid impacts increases temperatures and reduces strength. Therefore, accurate prediction of damage and fracture under impact loading requires the experimental quantification of the effects of temperature and strain rate on deformation and fracture. However, the commonly used Charpy impact test, due to its small specimen size, can lead to non-conservative results when applied to larger structures. Although alternative testing methods using larger specimens have been proposed, these are often time-consuming, costly, and carry associated risks. Consequently, the necessity for numerical-based impact assessments using finite element (FE) analysis methods has become increasingly critical. In this study, Johnson-Cook (J-C) deformation and fracture models under impact loading considering strain rate and temperatures were determined using limited experimental results and validated. To apply the determined J-C models to impact and penetration situations, it was validated using Split Hopkinson Tensile Bar (SHTB) test, a widely conducted test for analyzing materials’ deformation and fracture behavior under very high strain rate tensile loading. The SHTB tests using smooth round bar were simulated using determined J-C models and FE damage analysis. In the future work, the determined model will be further validated by simulating SHTB test using notched bars