Modeling Folded Beam Waveguide Absorber Behavior Using Translational and Rotational Degree of Freedom Frequency Response Function Coupling

摘要

Folded beam waveguide absorbers (WGAs) have been shown to effectively provide low frequencydamping for thick-walled vibrating structures. Although it is relatively straightforward to measure thedamping provided by WGAs, current analytical prediction techniques have been found to underestimate themeasured damping. As current prediction techniques rely solely on translational degrees-of-freedom(TDOF), it has been suggested that losses due to rotational motion may be the source of additionaldamping. In this study, the damping provided to a thick rectangular plate by a WGA is predicted using theFrequency Domain Substructure Synthesis (FDSS) technique. Rotational degree-of-freedom frequencyresponse functions (RDOF FRFs) for use with this technique are estimated using the Finite-DifferenceMethod (FDM). FDSS predictions using only TDOF FRFs as well as FDSS predictions using both TDOFand RDOF FRFs are compared to measured data. For coupling at a single point on the plate, FDSSpredictions using both TDOF and RDOF FRFs were substantially better than those which used only TDOFFRFs. However, it is shown that FDSS predictions using only TDOF FRFs can be substantially improvedwhen several attachment points on the plate are considered.