Vibration modes and random response of a multi-bay panel system using finite elements

Vibration modes and random response of a multi-bay panel system using finite elements

Lindberg, G.M.
Olson, M.D.

National Research Council Canada, National Aeronautical Establishment, Structures and Materials Section

1967-12-31

A finite e lement approach ta the dynamic analysis of continuous skin- stringer panels is presented. The methodl is illustrated in the calculation of vibration modes and random response of a five-bay stringer-stifffened panel with all outer edges clamped.The panel skin is represented by finite plate elements and tbc stringers , which are assumed infinitely stiff in bending , are represented by beam torsional elements . Results are presented for tbe first 35 panel vibration modes. These modes oecur in distinct groups withfive similar modes in each, the numberfive corresponding to the number of panel bays. The response of the panel to plane wave propagation of acoustic noise (propagating norrmal to the stringers) is a150 calculated. The resulting response power spectral densities were found to be fundamentally different from those associated with single span panels. These power spectra did not have widely separated peaks, but rather the peaks tended to be squeezed into groups corresponding to the groupings of natural frequenc ies for the panel.

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National Research Council Canada

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National Research Council Aeronautical Report LR 492

Aerospace Engineering Reports

report

(c)1967 National Research Council Canada