Proceedings of 41st Danubia-Adria Symposium Advances in Experimental Mechanics (pp. 71-74)
АУТОР(И) / AUTHOR(S): Dragan Rakić 
, Slobodan Radovanović , Miroslav Živković
Download Full Pdf 
DOI: 10.46793/41DAS2025.071R
УВОД / INTRODUCTION:
For reliable stability analysis of geotechnical structures, accurate calibration of constitutive model parameters is essential. These parameters govern the simulated material response under load, and any uncertainty can lead to significant deviations in predicted behavior.
Conventional parameter determination relies on experimental testing of soil samples, whereby stress–strain measurements are used to infer individual model parameters according to their constitutive definitions. However, this manual fitting process is complex and time-consuming, particularly for soils, which exhibit highly nonlinear behavior.
To address these challenges, we propose an automated parameter identification procedure for constitutive models. The methodology is developed for the Modified Cam-Clay model (MCC), a widely adopted framework for simulating the mechanical response of soft clays and normally consolidated soils.
The first part of this paper presents the theoretical foundations and the implicit stress integration algorithm for the MCC model, implemented within the PAK finite element software. For automated identification, the same integration scheme is translated into Python and applied at the level of single integration point. This point-wise approach is justified for homogeneous stress states, such as those encountered in standard laboratory tests (e.g., oedometer and triaxial tests).
In the second part of the paper, we describe the parameter identification program, which interfaces with the Python integration routine to perform optimization against experimental data. Finally, the developed identification algorithm is verified through a comparison of parameter estimates obtained from the PAK-based finite element implementation and those produced by the automated procedure.
КЉУЧНЕ РЕЧИ / KEYWORDS:
ПРОЈЕКАТ / ACKNOWLEDGEMENT:
This research was supported by the Science Fund of the Republic of Serbia, #GRANT No 7475, Prediction of damage evolution in engineering structures – PROMINENT and by the Ministry of Science, Technological Development and Innovation, Republic of Serbia, Agreement No. 451-03-137/2025-03/200107.
ЛИТЕРАТУРА / REFERENCES:
- Živković, M., Kojić, M., Slavković, R., Grujović, N., Rakić, D., Dunić, V. PAK-S, Program for FE Structural Analysis of Solids and Structures, University of Kragujevac, Faculty of Engineering, Kragujevac, 2019.
- Furukawa, T., Sugata, T., Yoshimura, S., Hoffman, M. An automated system for simulation and parameter identification of inelastic constitutive models, Computer Methods in Applied Mechanics and Engineering, 2002, 191(21-22), 2235-2260.
- Borja, R. I., Lee, S. R, Cam-clay plasticity, part 1: implicit integration of elasto-plastic, Computer Methods in Applied Mechanics and Engineering, 1990, 78(1), 49-72.
- Bathe K.J, Finite element procedures, USA: Massachusetts Institute of Technology, 1996.