A New Experimental Technique for the Multi-axial Testing of Advanced High Strength Steel Sheets

• Published in: Experimental mechanics Vol. 48; no. 1; pp. 65 - 77
• Main Authors: Mohr, D., Oswald, M.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.02.2008; Springer
• Subjects: Biomedical Engineering and Bioengineering; Characterization and Evaluation of Materials; Control; Dynamical Systems; Engineering; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Lasers; Measurement and testing methods; Optical Devices; Optics; Photonics; Physics; Solid Mechanics; Structural and continuum mechanics; Vibration; Yield surface; TRIP steel; Sheet metal; Plasticity; Multi-axial testing; Finite strains; Advanced high strength steel; Resistance strain gauge; Measuring machine; Measurement; Correlation; High strain; Image processing; Yield surface, Finite strains; Yield criterion; High strength steel; TRIP steel, Advanced high strength steel; Multi-axial testing, Sheet metal; Digital image; Traction; Multiaxial load; Stress strain; Modeling; Transformation induced plasticity; Combined load; Finite element method; Shear stress
• ISSN: 0014-4851; 1741-2765
• DOI: 10.1007/s11340-007-9053-9

This paper deals with the development of a new experimental technique for the multi-axial testing of flat sheets and its application to advanced high strength steels. In close analogy with the traditional tension-torsion test for bulk materials, the sheet material is subject to combined tension and shear loading. Using a custom-made dual actuator hydraulic testing machine, combinations of normal and tangential loading are applied to the boundaries of a flat sheet metal specimen. The specimen shape is optimized to provide uniform stress and strain fields within its gage section. Finite element simulations are carried out to verify the approximate formulas for the shear and normal stress components at the specimen center. The corresponding strain fields are determined from digital image correlation. Two test series are performed on a TRIP-assisted steel sheet. The experimental results demonstrate that this new experimental technique can be used to investigate the large deformation behavior of advanced high strength steel sheets. The evolution of the yield surface of the TRIP700 steel is determined for both radial and non-proportional loading paths.