Date of Award
Mechanical, Automotive, and Materials Engineering
D. E. Green
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The focus of this research was to determine the yielding and work hardening behaviour of two anisotropic steel sheets (DP600 and HSLA). Uniaxial tension and compression tests were performed in the rolling and transverse directions and at 45 degrees to the rolling direction for each sheet. Plane-strain tension tests were carried out along the rolling and transverse directions. Digital image correlation was used to determine the strain distribution throughout the gauge region.
The stress-strain response of the plane-strain tension specimen was estimated through a comparison of the experimental and numerically predicted load-strain response.
Yield stresses in uniaxial tension were obtained for various yield offsets, and R-values were obtained, allowing for the anisotropy of each steel sheet to be determined. Yield data was also obtained in plane-strain and equibiaxial tension, pure shear, and uniaxial compression for corresponding values of plastic work per unit volume from the stress-strain response.
Hill's 1948 R-based and stress-based yield criteria, Hill's 1979 planar-isotropic yield criterion and Barlat's Yld2000-2d yield function were evaluated at each value of plastic work per unit volume, and compared against the experimental yield data obtained.
A low degree of anisotropy was noted for both materials. While all yield functions provided similar results for DP600, it was noted that Hill's 1948 R-based criterion and Hill's 1979 yield criterion were unable to accurately predict material behaviour for all yield offsets for HSLA. It was found that Barlat's Yld2000-2d provided the most accurate representation of the experimental data.
Turton, Neil D., "Experimental determination of the yield locus of anisotropic metal sheets using digital image correlation" (2009). Electronic Theses and Dissertations. 7930.