Garrison M. Hommer¹, Ashley N. Bucsek², Harshad Paranjape¹, Zachary Brunson¹, Jinesh Dahal¹, Aaron Stebner¹; ¹Colorado School of Mines, ²University of Michigan

Researchers have been challenged for nearly a century to directly measure the multiaxial nature of the thermomechanical constitutive relationships of crystalline materials. Recently, a new planar-biaxial experimental platform has been developed to meet these challenges. Coupling with far-field high-energy diffraction microscopy enables the direct assessment of elastic vs. inelastic deformation of the gauge sections of cruciform specimens subjected to plane stress loadings, without any a priori assumptions of the form of constitutive relationships. Results using this platform to answer two long-standing mechanics questions will be presented: 1) Why does dwell fatigue of alpha-titanium subjected to multiaxial loads not follow our best constitutive relationships derived from uniaxial tests? and 2) What is the mechanistic origin of path-dependence in superelastic nickel-titanium? Concluding remarks will be given to show the connections between the experimental data and multiple micromechanical and continuum modeling frameworks.