FLEXURAL VIBRATIONS OF CERTAIN FULL AND ANNULAR COMPOSITE ORTHOTROPIC PLATES

The uncoupled equation of motion for the flexural displacement of an orthotropic composite circular plate having symmetric lamination is presented. A numerical method is employed to calculate the symmetric and nonsymmetric vibrational frequencies of full and annular composite plates subjected to a variety of boundary conditions. Effects produced by lamination interchange and fiber reversal are discussed; in particular, certain laminations are capable of producing a higher fundamental frequency than either of the constituent materials alone can attain. For annular plates it is found that for certain lay-ups the fundamental frequency derives from a nonsymmetric mode. Finally, pinhole-center annuli are examined and, for a free inner edge, a comparison is made with corresponding full-plate frequencies. © 1979, American Association of Physics Teachers. All rights reserved.