인장형 홉킨슨 바의 오차 분석 및 자동차용 냉연강판의 고속인장 특성 연구

Abstract

The dynamic behavior of vehicle body materials is dependent on material strain rates. In high speed tensile test of sheet metals, a new tension split Hopkinson bar specially designed for sheet metals is used. The tension split Hopkinson bar has some sources of errors such as grips and the plate type specimen. In this paper, these errors estimated and minimized. The results from both quasi-static and dynamic tests show that the strain rate hardening effect for sheet metals can not be described by the original Johnson-Cook constitutive relation. This relation has been modified to include a higher-order term for the hardening effect.