Finite-element model calibration of a railway vehicle based on experimental modal parameters

Abstract

This article describes the experimental calibration of a three-dimensional numerical model of an Alfa Pendular train vehicle based on modal parameters. The dynamic tests of the carbody and bogie of the vehicle allowed the determination of the frequencies and modal configurations of 13 vibration modes, by applying the data-driven stochastic subspace identification method. In addition, a dynamic characterisation test of the passenger-seat system was also conducted. The calibration of the model was performed using a submodelling/multistep approach involving two phases, the first one focused on the calibration of the model of the bogie under test conditions and the second one focused on the calibration of the complete model of the vehicle. The calibration was performed through an iterative method based on a genetic algorithm and allowed to obtain optimal values of 17 parameters of the numerical model. For the pairing of the vibration modes, real and complex, a recent technique was used based on the calculation of the modal strain energy. The stability of a significant number of parameters considering different initial populations demonstrated the robustness of the algorithm. The comparison of experimental and numerical responses before and after calibration revealed significant improvements in the numerical model and a very good correlation between the responses obtained with the calibrated model and the experimental responses.

Keywords:

• finite-element model updating
• railway vehicle
• dynamic tests
• modal identification
• mode pairing criteria
• genetic algorithm

Acknowledgements

This work is funded by FEDER funds, through the Operational Programme for Competitiveness Factors – COMPETE, and National Funds, through the Foundation for Science and Technology (FCT), under the project No FCOMP-01-0124-FEDER-007195 (Ref. FCT PTDC/ECM/69697/2006). The first author expresses his gratitude to the FCT for the financial support through the PhD scholarship SFRH/BD/30897/2006. The authors also wish to express their gratitude to Eng. João Pereira, from CP, and Engineers Rui Pereira, Nuno Freitas, Pedro Conceição and Carlos Touret, from EMEF, for their cooperation and provided information about the Alfa Pendular train and for the advantages granted on the performance of the dynamic tests.