Reduction of sound transmission into a circular cylindrical shell using distributed vibration absorbers and Helmholtz resonators
Esteve, Simon J.
Johnson, Martin E.
MetadataShow full item record
A modal expansion method is used to model a cylindrical enclosure excited by an external plane wave. A set of distributed vibration absorbers (DVAs) and Helmholtz resonators (HRs) are applied to the structure to control the interior acoustic levels. Using an impedance matching method, the structure, the acoustic cavity, and the noise reduction devices are fully coupled to yield an analytical formulation of the structural kinetic energy and acoustic potential energy of a treated cylindrical cavity. Lightweight DVAs and small HRs tuned to the natural frequencies of the targeted structural and acoustic modes, respectively, result in significant acoustic and structural attenuation when the devices are optimally damped. Simulations show that significant interior noise reduction can only be achieved by adding damping to both structural and acoustic modes, which are resonant in the frequency bandwidth of interest. In order to be independent of the azimuth angle of the excitation and to avoid unwanted modal interactions, the devices are distributed evenly around the cylinder in rings. This treatment can only achieve good performance if the structure and the acoustic cavity are lightly damped.
Showing items related by title, author, creator and subject.
Clark, Robert L.; Fuller, Chris R. (Acoustical Society of America, 1992-09-01)A model reference active structural acoustic control (ASAC) approach is investigated as a method for replacing microphone error sensors located in the acoustic field with accelerometers located on the structure. The suggested ...
Thompson, Charles (Acoustical Society of America, 1984-01-01)An analysis of acoustic streaming in a two-dimensional waveguide having slowly varying height is presented. Special attention is paid to waveguides with cross sections that are small compared to the acoustic and/or wall ...
Development of a new standard laboratory protocol for estimating the field attenuation of hearing protection devices. Part III. the validity of using subject-fit data Berger, Elliott H.; Franks, John R.; Behar, Alberto; Casali, John G.; Dixon-Ernst, Christine; Kieper, Ronald W.; Merry, Carol J.; Mozo, Ben T.; Nixon, Charles W.; Ohlin, Doug; Royster, Julia D.; Royster, Larry H. (Acoustical Society of America, 1998-02-01)The mandate of ASA Working Group S12/WG11 has been to develop "laboratory and/or field procedure(s) that yield useful estimates of field performance" of hearing protection devices (HPDs). A real-ear attenuation at threshold ...