Determination of the Natural Frequencies of Beams Using Sound Pressure

摘要: This paper presents a method to determine the natural frequencies of transversal bending vibrations of beams and plates by means of time-history analysis. As excitation source the sound pressure produced by a speaker was used; it permits an accurate control of the exciting frequency. The method consists in exciting the beam/plate around the resonance frequency analytically determined and find the frequency value that produces the highest amplitudes of the stabilized system, without inducing the beat phenomena. By departing from that frequency in sense of increasing or decreasing, the amplitude is diminished and signal envelope becomes modulated in amplitude. It can be used in application where contact between the system and the exciter is not possible or permitted.