Deviations from the Fourier Hypothesis, Detected during the Low Frequency Modal Analysis of the Box-Shell

The article presents the results of box-shaped shell tests in the frequency range of 10…50 Hz. According to the Fourier hypothesis, the peaks of the amplitude-frequency characteristics corresponding to different points of the box-like shell are to lie on the same vertical straight line. An analysis of the results of frequency tests revealed significant deviations from the Fourier hypothesis. It is shown that in resonance (of the same tone) different points of the box shell oscillate with different frequencies. Frequency shifts are about 2 Hz.

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