Identification of Dynamic Behavior of Sheet Metals for an Auto-Body with Tension Split Hopkinson Bar

In order to evaluate the crash-worthiness of a car, the dynamic response of the car body has to be correctly obtained at each level of car velocity. For the dynamic analysis, the dynamic properties of auto-body materials need to be identified for various strain rates. One of the typical high strain rate tensile tests is a split Hopkinson bar test. The present experiment has been carried out with a new split Hopkinson bar apparatus specially designed for the dynamic tensile test of sheet metals. The experiment provides stress-strain curves for various strain rates ranged from 2500 to 5000/sec. The experimental results from the both quasi-static and dynamic test are used to construct the Johnson-Cook equation as a constitutive relation, which can be applied to simulate the dynamic behavior of auto-body structures.