COMPARISONS OF EXPERIMENTAL, AND THEORETICAL FREQUENCIES FOR RECTANGULAR-PLATES WITH VARIOUS BOUNDARY-CONDITIONS AND ADDED MASSES

This paper is concerned with a vibration analysis of rectangular plate s with masses mounted on various locations. The edges of the plates ma y either be clamped or simply supported. The study is particularly use ful in the understanding of the vibration of printed circuit boards us ed in the electronics industry. An energy method is developed to obtai n analytical frequencies of the plates with various edge support condi tions. The analytical procedure using the Rayleigh-Ritz approach is ad opted in which each of single and multiple trigonometric series terms is used to represent the shape function. Two experimental methods, a s pectrum analyser and a TV-holographic system, are used to study the be haviour of the plate vibrations. The holographic image produced at the corresponding mode frequencies by using the TV-holography technique h as been applied to verify the frequency spectra obtained from the spec trum analyser. The experimental results have been used to illustrate t he validity of the analytical model. The comparisons show that the ana lytical model predicts natural frequencies reasonably well, in which t he EM 100-term model is suggested for vibration plates with higher mod es or heavier loads. (C) 1998 Elsevier Science Ltd. All rights reserve d.