Discontinuous constrained layer damping treatments applied to a vibrating free‐free beam.

Abstract

The vibration response to application of discontinuous constrained layer damping (CLD) patches to varied portions of a free‐free beam was studied. Since neither closed‐form solutions nor finite element methods can be readily implemented for CLD analysis with partial coverage of a structure under broadband excitation [C. T. Sun and Y. P. Lu, Vibration Damping of Structural Elements (Prentice‐Hall, Englewood Cliffs, NJ, 1995), pp. 318–362], an empirical approach was taken. The test object was a 26.5‐ × 1‐ × 1/8‐in. steel beam, and was subjected to a chirp. The aim was to quantify the relative effectiveness of varied lengths and positions of CLD patches in reducing the response of the first five resonant modes of the beam. Assessment of the potential for strain energy dissipation was made based on the net displacement of the beam (appropriately phased mode summation), with relative phase of the summed modes specific to the input force signal. Attempts were made to correlate the effect of CLD on each mode to the time‐averaged percentage of strain energy for that mode under the treatment patch, coupled with the percentage of the beam’s strain energy under the patch. [Work supported by NSF.]