A detailed experimental modal analysis of a clamped circular plate

摘要

A detailed study has been made of the natural frequencies and modal shapes of a thin steel disc that is clamped at the edges by two steel flanges. The aim was to determine how accurately numerical modeling could be used to predict the results and to investigate the possibility of any new experimental observations even for this simple structure. A mechanical shaker and impact hammer were used to excite the plate to obtain the frequency response function of the structure. The first eight modal shapes at each of the resonant frequencies were then measured using laser scanning vibrometry. These results were compared with theoretical results obtained analytically and numerically using PAFEC. While part of the existing understanding of the plate vibration was confirmed, significant differences were found in the values of the modal frequencies. The experimental data also demonstrated a dependence of the mode shape orientations and splitting of degenerated natural frequencies on the shaker position and properties of the flanges. This paper will report on some interesting effects that need to be considered when doing such measurements and illustrate the risks of using numerical modeling without the use of experimental comparison.