Computational Methods of the Identification of Chaboche Isotropic-Kinematic Hardening Model Parameters Derived from the Cyclic Loading Tests

The Chaboche-Lemaitre combined isotropic -kinematic hardening model (CKIH) gives an overall information about the material behaviour under cyclic loading. The identification of hardening parameters is a difficult and time-consuming problem. The procedure of the parameters identification using the experimental hysteresis curve obtained in a cyclic loading test under strain control is presented in details here for a S235JR construction steel. The last stabilized cycle extracted from the hysteresis curve is required for the identification of hardening parameters. The model with three backstresses is tested here. The optimization algorithm is also used for the improvement of the agreement between experimental and numerical data. In order to include some uncertainty of experiment and the identification procedure, the authorial algorithm written on the basis of the fuzzy logic soft -computing method is applied here. The results obtained show that the identification procedure presented in this paper ensures the good agreement between the experimental tests and numerical calculations. The correct selection of parameters associated with the hardening is essential for the right description of material behaviour subject to loading in different engineering problems, including in metal forming processes.