Validation of Uniaxial Data Beyond Uniform Elongation
Mark A. Iadicola
Uniaxial testing is one of the simplest methods used to determining mechanical properties for sheet metals, but the classic test does not determine properties to sufficiently high strain levels for use in models of very large deformations such as forming operations. This limitation is primarily due to the classical test requiring uniform deformation in the gage length. Full-field optical techniques are now being used to extend the applicable strain range of uniaxial testing to strains beyond uniform elongation and well into diffuse necking, but assumptions must be made as to the multi-axial state of stress in this regime. In order to determine if such assumptions are correct, uniaxial experiments are performed combined with a unique combination of digital image correlation to measure plastic strains and stress tensor measurement through X-ray diffraction methods. The combination of metrology permits determination of the true stress - true strain response to strains four times uniform elongation and the associated multi-axial stresses at the highest strain levels. The results show that typical assumptions to extend the uniaxial data beyond uniform elongation are appropriate for a limited portion of the extended strain measured, but are inappropriate at higher strain levels near localized necking.
Numisheet 2011, Proceedings of the 8th International Conference and Workshop on Numerical Simulation of 3D Sheet Metal Forming Processes
Validation of Uniaxial Data Beyond Uniform Elongation, Numisheet 2011, Proceedings of the 8th International Conference and Workshop on Numerical Simulation of 3D Sheet Metal Forming Processes, Seoul, -1, [online], https://doi.org/10.1063/1.3623680
(Accessed December 10, 2023)