PSI - Issue 73

Marek Kawulok et al. / Procedia Structural Integrity 73 (2025) 51–57 Marek Kawulok et al. / Structural Integrity Procedia 00 (20 2 5) 000 – 000

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For the surface with rubber tubing, the situation is much clearer. The friction model achieves not only a higher R² value (0.99) but also a significantly lower RMSE (0.98 compared to 1.92), confirming a better fit to the data. This is consistent with the graphical representation, where the response amplitudes closely follow the line characteristic of friction damping. The initial amplitude predicted by the friction model (31.73) also appears to be more realistic than the overestimated value predicted by the viscous model (39.52). These results confirm that, while a combined model may be appropriate for a smooth surface, friction damping alone best describes the damping on the surface with the tubing. 5. Conclusion This contribution focusses on the experimental investigation of damping in the motion of a ball absorber, with particular attention to the influence of the surface material on the damping characteristics. Two surface conditions were analysed, one without modification and the other with rubber tubing attached to the track surface. The main goal was to determine which mathematical damping model best describes the observed decay in the oscillation amplitude of the absorber. In the case of the surface without tubing, it was not possible to clearly determine whether the primary damping mechanism was viscous or frictional, as the results indicated a combination of both. However, the damping behaviour showed a slightly stronger alignment with the friction model. For the surface with rubber tubing, the correspondence with the friction model was even more evident, while the contribution of viscous damping appeared negligible. The results provide a starting point for a deeper analysis, demonstrating that surface treatment significantly influences damping behaviour. To clearly identify the dominant damping mechanism, further investigation is needed, taking into account possible experimental uncertainties, such as potential surface irregularities of the track or geometric imperfections in the shape of the ball, among other possible factors. Acknowledgements The financial support of the grant programme financed by the Ministry of Education, Youth and Sports of the Czech Republic through VSB–TUO SGS SP2025/067 and from the budget for conceptual development of science, research and innovations is highly acknowledged. References Náprstek, J., Fischer, C., Pirner, M., Fischer, O., 2013. Non-linear Model of a Ball Vibration Absorber. In: Papadrakakis, M., Fragiadakis, M., Plevris, V. (eds) Computational Methods in Earthquake Engineering. Computational Methods in Applied Sciences 30. Springer, Dordrecht. https://doi.org/10.1007/978-94-007-6573-3_18 Náprstek, J., Fischer, C., 2020. Stable and unstable solutions in auto-parametric resonance zone of a non-holonomic system. Nonlinear Dynamics 99, 299–312. https://doi.org/10.1007/s11071-019-04948-0 Kawulok, M., Čermák, M., Pospíšil, S., Juračka, D., 2024. Numerical Procedure for Solving the Nonlinear Behaviour of a Spheri cal Absorber. Periodica Polytechnica Civil Engineering 68 (4), 1367–1377. https://pp.bme.hu/ci/article/view/25903 Chopra, A. K., 1995. Dynamics of Structures: Theory and Applications to Earthquake Engineering. Ed. 1. New Jersey: Prentice Hall College Div. Pospíšil, S., Fischer, C., Náprstek, J., 2014. Experimental analysis of the influence of damping on the resonance behavior of a spherical pendulum. Nonlinear Dynamics 78 (1), 371-390. https://doi.org/10.1007/s11071-014-1446-6 MathWorks, 2025. Help Center " Computer Vision Toolbox: Design and test computer vision systems", [online] URL https://www.mathworks.com/products/computer-vision.html (Accessed: 05.18.2025) Duda, R. O., Hart, P. E., 1972. Use of the Hough transformation to detect lines and curves in pictures. Communications of the ACM 15 (1), 11-15. https://doi.org/10.1145/361237.361242 Schafer, R., 2011. What Is a Savitzky-Golay Filter? [Lecture Notes]. IEEE Signal Processing Magazine 28 (4), 111-117. https://doi.org/10.1109/MSP.2011.941097 Al-Hababi, T., Cao, M., Saleh, B., Alkayem, N. F., Xu, H., 2020. A Critical Review of Nonlinear Damping Identification in Structural Dynamics: Methods, Applications, and Challenges. Sensors 20(24):7303. https://doi.org/10.3390/s20247303 Elias, S., Matsagar, V., 2017. Research developments in vibration control of structures using passive tuned mass dampers. Annual Reviews in Control 44, 129-156. https://doi.org/10.1016/j.arcontrol.2017.09.015