This paper describes the calibratio

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 cali-
bration 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.