Calibration of fracture locus in scope of uncoupled elastic–plastic-ductile fracture material models

• We performed uncoupled elastic–plastic - damage material calibration.
• We used custom design specimens and testing devices to perform all experiments.
• We calibrated fracture locus according to Bai and Wierzbicki.
• We outlined calibration alternative based on target function variants.
• Experiments with excessive stress concentration showed limitations of used approach.

This paper describes the calibration process for the uncoupled material model of ductile damage designed by Bai and Wierzbicki. This problem has been investigated within the project “Identification of ductile damage parameters for nuclear facilities”. The project includes material experiments, designing the shape of the samples, and using the samples for calibrating the material constants of selected ductile damage models. The calibration process for the Bai–Wierzbicki material model is based on fifteen tested samples corresponding with the literature. In this paper, we discuss some promising modifications of basic calibration approaches for uncoupled models. These modifications are based on variants in the formulation of the target function expressing the calibration error. The result of the calibration process was verified through FE simulation of a comparison of each specimen with experimental data. A material model with a description of the ductile damage in a wide range of stress states was searched within the project. For this purpose, the model was tested on some other specimens which exhibit higher stress concentration and showed the limitations of the Bai and Wierzbicki uncoupled model.