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THE RESPONSE OF A MODEL STRUCTURE TO NOISE. PART II CURVED PANEL.
SOUTHAMPTON UNIV (ENGLAND)
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A model structure consisting of a curved sheet of area 4 ft x 6 ft and radius 4 ft, subdivided into small regular panels by frames and stringers, has been excited by discrete frequency sound. The response of a row of panels between two frames has been studied in detail and the stringer twisting and bending modes have been identified. These form respectively the lower and upper bounds of a group of modes. Polar plots of the response vector relative to the exciting pressure have been used to identify the intermediate modes which have significant response to acoustic plane wave excitation. Many such modes, close together in frequency, have been shown to exist. A theoretical analysis based on the energy method and using the mode shapes derived for the flat panel gives a reasonable approxi mation to the upper and lower bounds of the group of modes. An estimation of the stress in the upper bounding mode gives an order of magnitude agreement with the experimental results. Author
APPROVED FOR PUBLIC RELEASE