Non-deterministic Calibration of Crystal Plasticity Model Parameters

Crystal plasticity constitutive models are frequently used with finite elements for modeling metallic grain-scale phenomena. The accuracy of these models is directly a function of the calibrated parameters, which fully define a crystal plasticity model. A number of techniques exist for the calibration of these parameters. In the current study, a comparison of results using deterministic and non-deterministic calibration methods is made. Additionally, the effect of the type of measured data on calibrated material parameters, global (homogenized) or local, is also presented. Included in the study is a new approach to parameter calibration based on combined digital image correlation and high angular resolution electron backscatter diffraction. Utilizing data from these experimental techniques allows for local evaluation of both strain and relative stress: essentially giving stress-strain curves from numerous point locations in a single coupon. The overall result is that calibration based on sub-grain-scale measurements is preferable when sub-grain-scale phenomena are of primary interest.