Effects of installations on the low frequency vibration response of specimens in acoustic fatigue tests

In acoustic fatigue tests, it is often considered that the vibration response of a specimen in a progressive tube or in a reverberation rcom depends only on the dynamic characteristics and the boundary condition of the specimen, and has nothing to do with the test setup which couples the specimen to the corresponding sound field. By using the experimental results and the analysis of the acoustic-induced vibration of a boundary clamped rectangular thin plate with a currentlp used test setup in a progressive tube and in a re verberation room, this paper stresses that the effects of the setup on the low frequency vibration modes must not be neglected in some cases. In the theoretical explanation of the experimental results, the Rayleigh-Ritz method is firstly used to give several natural frequencies of low order; the an approach of electro-mechano-acoustical analogous circuit is introduced to yield the other resonant and anti-resonant frequencies in the response spectra. This approach can be applied to estimate the attribution of various parameters of a given test setup to the vibration response quantitatively, and it supplies a rational layout of acoustic fatigue tests with a theoretical basis and means.