HIGH SPEED TENSILE TEST OF STEEL SHEETS FOR THE STRESS-STRAIN CURVE AT THE INTERMEDIATE STRAIN RATE

HUH, H.; LIM, J. H.; PARK, S. H.

International Journal of Automotive Technology > Volume 10(2); 2009 > Article

Automobile Body and Safety

International Journal of Automotive Technology 2009;10(2): 195-204.

HIGH SPEED TENSILE TEST OF STEEL SHEETS FOR THE STRESS-STRAIN CURVE AT THE INTERMEDIATE STRAIN RATE

H. HUH¹, J. H. LIM², S. H. PARK²

¹Korea Advanced Institute of Science & Technology
²POSCO

ABSTRACT

This paper presents stress-strain curves of steel sheets for an auto-body obtained at intermediate strain rates with a servo-hydraulic type high speed tensile testing machine. The apparatus has the maximum stroke velocity of 7.8 m/sec to obtain the tensile material properties at a strain rate of up to 500/sec. A special jig fixture is specially designed for accurate acquisition of tensile loads with reduction of the load-ringing phenomenon induced by unstable stress wave propagation at high strain rates. Tensile testing of steel sheets for an auto-body was carried out to obtain stress-strain curves of mild steel and advanced high strength steels at strain rates ranged from 1/sec to 200/sec. The test results provide interesting information regarding the stress-strain curves at intermediate strain rates ranged from 1/sec to 200/sec and demonstrate that strain rate hardening is strongly coupled with strain hardening.

Key Words: High speed tensile testing machine, Strain rate hardening, Load ringing phenomenon, Auto-body steel sheets

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