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Plasticity and Fracture Behaviors of Marine Structural Steel, Part III: Experimental Study on Failure Strain

조선 해양 구조물용 강재의 소성 및 파단 특성 III: 파단 변형률에 관한 실험적 연구

  • Received : 2011.02.28
  • Accepted : 2011.06.20
  • Published : 2011.06.30

Abstract

This is the third of several companion papers dealing with the derivation of material constants for ductile failure criteria under hydrostatic stress. It was observed that the ultimate engineering stresses and elongations at fracture from tensile tests for round specimens with various notch radii tended to increase and decrease, respectively, because of the stress triaxiality. The engineering stress curves from tests are compared with numerical simulation results, and it is proved that the curves from the two approaches very closely coincide. Failure strains are obtained from the equivalent plastic strain histories from numerical simulations at the time when the experimental engineering stress drops suddenly. After introducing the new concept of average stress triaxiality and accumulated average strain energy, the material constants of the Johnson-Cook failure criterion for critical energies of 100%, 50%, and 15% are presented. The experimental results obtained for EH-36 steel were in relatively good agreement with the 100% critical energy, whereas the literature states that aluminum fits with a 15% critical energy. Therefore, it is expected that a unified failure criterion for critical energy, which is available for most kinds of ductile materials, can be provided according to the used materials.

Keywords

Failure strain;Stress triaxiality;Average stress triaxiality;Equivalent plastic strain;Ductile fracture;Shear fracture

References

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Cited by

  1. Formulation of Failure Strain according to Average Stress Triaxiality of Low Temperature High Strength Steel (EH36) vol.27, pp.2, 2013, https://doi.org/10.5574/KSOE.2013.27.2.019
  2. Fracture Simulation of Low-Temperature High-Strength Steel (EH36) using User-Subroutine of Commercial Finite Element Code vol.28, pp.1, 2014, https://doi.org/10.5574/KSOE.2014.28.1.034
  3. Development of Three Dimensional Fracture Strain Surface in Average Stress Triaxiaility and Average Normalized Lode Parameter Domain for Arctic High Tensile Steel: Part I Theoretical Background and Experimental Studies vol.29, pp.6, 2015, https://doi.org/10.5574/KSOE.2015.29.6.445
  4. Development of Three-Dimensional Fracture Strain Surface in Average Stress Triaxiaility and Average Normalized Lode Parameter Domain for Arctic High Tensile Steel: Part II Formulation of Fracture Strain Surface vol.29, pp.6, 2015, https://doi.org/10.5574/KSOE.2015.29.6.454
  5. Punching Fracture Simulations of Circular Unstiffened Steel Plates using Three-dimensional Fracture Surface vol.30, pp.6, 2016, https://doi.org/10.5574/KSOE.2016.30.6.474
  6. Ductile Fracture Predictions of High Strength Steel (EH36) using Linear and Non-Linear Damage Evolution Models vol.31, pp.4, 2017, https://doi.org/10.26748/KSOE.2017.08.31.4.288
  7. Mechanical and Immersion Characteristics of Weled EH36 Steel with Different Heat Input vol.22, pp.3, 2018, https://doi.org/10.9726/kspse.2018.22.3.051

Acknowledgement

Supported by : 한국연구재단