Analytical and experimental studies of beam waveguide absorbers for structural damping

Abstract

The reduction of structural vibrations in ships and submarines is a long standing concern of the Navy. Waveguide absorbers are very effective devices which can be applied to this problem. This study evaluates the increase in vibration damping of a plate structure across a broad frequency range using light weight beam waveguide absorbers. Viscoelastic and constrained layer beam waveguide absorbers were studied both theoretically and experimentally. Impedances of the waveguide absorbers at the attachment point were predicted using both Bernoulli-Euler and Timoshenko beam theory for the viscoelastic beam and using sixth order beam theory for the constrained layer beam. The theoretically predicted impedances were compared with the experimental measurements. Results from random vibration tests of a plate structure showed significant increases in damping over a broad frequency range (100 Hz - 2 KHz) when the waveguide absorbers were attached on the plate.