Determination of dynamic parameters of a tram wheel parts in a numerical and experimental modal analysis

The analysis of dynamic parameters finds effective application in processes related to the assessment of the technical condition of machines. Mass transport vehicles are particularly sensitive to maintaining an appropriate level of traffic safety through relevant design and diagnostics. The combination of numerical and experimental methods increases the efficiency of modal properties investigations, which can be used as diagnostic parameters. During the research, the authors performed a numerical model of a system composed of a rim and an inner disc of a wheel fitted in a Konstal 105Na tram, widely used in many polish cities and frequently subjected to repair and renovation processes. The Time Response analysis in SOLIDWORKS (also called Modal Time History) was then conducted, resulting in obtaining information about object vibration response in time domain to the impulsive excitation at given points. These signals were then processed in MATLAB aiming at determining the frequencies of natural vibration and damping ratios. The processing parameters in MATLAB were corresponding to the analysis settings of the experimental measurement, carried out within the BK Connect environment, with an impact modal hammer and piezoelectric transducers. When analyzing the experimental measurements, the authors applied Fast Fourier Transformation, Frequency Response Function and Complex Mode Indicator Function (the theoretical basis of which and practical sense of application were also presented in the paper). Finally, the results of the experiment were compared with simulation outcomes. This comparison allowed the obtainment of frequency characteristics of the vibration response to the impact and the determination of the dynamic parameters of the actual object. Six frequencies of natural vibrations were determined in the frequency range of 0 to 3000 Hz, as well as their damping ratios and autocorrelation indicators between modes. Similarities and potential sources of differences between the numerical and the experimental results were identified and explained, followed by conclusions on the practical application of the presented research methodology in the industry.