Experimental modal analysis and modal updating of flexible beam using least square rational function method
Zahedi Mesgar, Sepideh (2024)
Diplomityö
2024
School of Energy Systems, Konetekniikka
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe20241220106135
https://urn.fi/URN:NBN:fi-fe20241220106135
Tiivistelmä
Flexible beam structures are widely used in modern engineering applications where experimental modal analysis (EMA) is an essential methodology for characterizing dynamic behaviours and verifying structure integrity for a given operational condition. In structural applications, improper dynamics can cause premature wear, noise, and eventual failure. In this thesis work the application of EMA for determining natural frequencies, mode shapes and dynamic responses of flexible beams using Peak Picking (PP) and Least Squares Rational Fraction (LSRF) techniques is explored.
By using impact excitation with an impact hammer and measuring the responses through accelerometers, frequency response functions (FRF) are obtained. While the peak-picking method gave some qualitative hints, the LSRF gave a much better estimate especially when the data are noisy, or many modes are close together. Experimental Results Comparison with Finite Element Analysis (FEA) and Laser Vibrometer for validation and the possible discrepancy in boundary condition and material properties were investigated.
The results validated the effectiveness of EMA in capturing essential dynamic parameters that define the vibrational characteristics of beams. The consistency of the modal parameters with theoretical predictions reinforces the reliability of the employed methods. This thesis contributes to the field of structural dynamics by offering a robust methodological foundation for analysing beam structures and emphasizes the potential for further refinement of EMA techniques for broader engineering applications.
By using impact excitation with an impact hammer and measuring the responses through accelerometers, frequency response functions (FRF) are obtained. While the peak-picking method gave some qualitative hints, the LSRF gave a much better estimate especially when the data are noisy, or many modes are close together. Experimental Results Comparison with Finite Element Analysis (FEA) and Laser Vibrometer for validation and the possible discrepancy in boundary condition and material properties were investigated.
The results validated the effectiveness of EMA in capturing essential dynamic parameters that define the vibrational characteristics of beams. The consistency of the modal parameters with theoretical predictions reinforces the reliability of the employed methods. This thesis contributes to the field of structural dynamics by offering a robust methodological foundation for analysing beam structures and emphasizes the potential for further refinement of EMA techniques for broader engineering applications.