A study of localisation in dual-phase high-strength steels under dynamic loading using digital image correlation and FE analysis

Abstract : Tensile tests were conducted on dual-phase high-strength steel in a Split-Hopkinson Tension Bar at a strain-rate in the range of 150-600/s and in a servo-hydraulic testing machine at a strain-rate between 10-3 and 100/s. A novel specimen design was utilized for the Hopkinson bar tests of this sheet material. Digital image correlation was used together with high-speed photography to study strain localisation in the tensile specimens at high rates of strain. By using digital image correlation, it is possible to obtain in-plane displacement and strain fields during non-uniform deformation of the gauge section, and accordingly the strains associated with diffuse and localised necking may be determined. The full-field measurements in high strain-rate tests reveal that strain localisation started even before the maximum load was attained in the specimen. An elasto-viscoplastic constitutive model is used to predict the observed stress-strain behaviour and strain localisation for the dual-phase steel. Numerical simulations of dynamic tensile tests were performed using the non-linear explicit FE code LS-DYNA. Simulations were done with shell (plane stress) and brick elements. Good correlation between experiments and numerical predictions was achieved, in terms of engineering stress-strain behaviour, deformed geometry and strain fields. However, mesh density plays a role in the localisation of deformation in numerical simulations, particularly for the shell element analysis.
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https://hal.archives-ouvertes.fr/hal-00200976
Contributor : François Hild <>
Submitted on : Saturday, December 22, 2007 - 11:57:33 AM
Last modification on : Saturday, May 25, 2019 - 1:43:33 AM
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V. Tarigopula, O.S. Hopperstad, M. Langseth, A.H. Clausen, François Hild. A study of localisation in dual-phase high-strength steels under dynamic loading using digital image correlation and FE analysis. International Journal of Solids and Structures, Elsevier, 2008, 45, pp.601-619. ⟨10.1016/j.ijsolstr.2007.08.021⟩. ⟨hal-00200976⟩

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