Vibration Of Flexible Plate Research Articles

Flexural vibrations of plates by the moire method

The reflected image moire method was used to yield the vibration modes of plates. Interference of the reflection of a reference grating from the specularly polished surface of a vibrating plate with a second similar grating created a moire pattern consisting of straight equidistant lines corresponding to the nodal regions of the plate. The moire pattern produced when the plate was illuminated by a continuous parallel light beam yielded the nodal configuration of the vibrating plate. When the vibrating plate was illuminated by a stroboscopic light source the moire pattern showed the contour map of partial slopes of the plate at the instant of illumination. While the first technique, with continuous illumination, yielded the exact form and location of the nodes and antinodes of a vibrating plate at its natural frequencies, the second technique, with intermittent light, gave the local amplitude and phase distribution of the plate.

Damping of Composite Structures by Viscoelastic Interlayers

Previous work on damping of plate flexural vibrations by constrained viscoelastic layers is generalized to apply to beam-like structures. A previously presented “structural parameter” is redefined so as to permit a unified analysis of damping obtained in systems consisting of two elastic structures with a viscoelastic interlayer. Such systems include: sandwich plates, plates with attached damping tapes, beams with inserts, and two beams mounted flange-to-flange. Design optimization with respect to this structural parameter is discussed in conjunction with other design considerations. Some of the effects of end constraints and discontinuities of the main structure or the constraining member are presented. (Results presented in part grew out of studies supported by the U. S. Air Force, Wright Air Development Division, and the U. S. Navy, Bureau of Ships.)

Flexural Vibration of Plates on Uniform Elastic Foundations

The flexural vibration of uniform plates on uniform elastic foundations is of interest in connection with fatigue and sound intensity studies.