A Modal Expansion Analysis of Noise Transmission Through Circular Cylindrical Shell Structures With Blocking Masses

Gardonio, Paolo; Ferguson, N.S.; Fahy, F.J.

doi:10.1006/jsvi.2000.3456

Cited by 28 publications

(10 citation statements)

References 21 publications

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“…In this section we present the main sound transmission mechanisms in agreement with the detailed study by Gardonio et al 4 The coupling between the external field and the structural modes characterizes the excitation of the cylinder. This external acoustic-structural coupling is represented by the external modal force F n s m s ext , which, after integration of Eq.…”

Section: A Bare Cylinder Response To Incident Acoustic Fieldsupporting

confidence: 69%

“…For broadband applications it becomes difficult to reduce the structural acoustic coupling using lightweight treatment as decoupling at one frequency tends to increase coupling at another. Gardonio et al 4 had some success achieving this using blocking masses placed on the structure but had to assume some knowledge of the angle of the incident noise field. Jolly and Sun 5 used vibration absorbers to reduce the radiation of broadband noise from a vibrating panel and Nagaya and Li 6 examined the optimization of an absorbers treatment applied to a radiating plate using neural network but neither considered radiation into a cavity.…”

Section: Introductionmentioning

confidence: 99%

“…Multiple optimally damped distributed vibration absorbers ͑DVAs͒ and HRs are applied to control the sound transmission in a cylindrical enclosure over a broad frequency range containing many structural and acoustic resonances. A conventional modal expansion method 4 is used to describe the behavior of the cylindrical shell, excited by an external acoustic plane wave, and its acoustic cavity. The optimization of the DVA treatment based on the studies by Johnson et al 10,11 is extended by analogy to the HR treatment.…”

Section: Introductionmentioning

confidence: 99%

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Reduction of sound transmission into a circular cylindrical shell using distributed vibration absorbers and Helmholtz resonators

Estève

Johnson

2002

The Journal of the Acoustical Society of America

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A modal expansion method is used to model a cylindrical enclosure excited by an external plane wave. A set of distributed vibration absorbers ͑DVAs͒ and Helmholtz resonators ͑HRs͒ 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.

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Section: A Bare Cylinder Response To Incident Acoustic Fieldsupporting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reduction of sound transmission into a circular cylindrical shell using distributed vibration absorbers and Helmholtz resonators

Estève

Johnson

2002

The Journal of the Acoustical Society of America

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“…Other researchers have considered the acoustic loading as plane waves striking the fairing at an oblique angle [30,[51][52][53], or encapsulating the fairing in a reverberant acoustic field [54,55]. The focus of the work presented here is to illustrate the trends that occur with the addition of passive absorbers to vibro-acoustic systems, and not to discuss the merits of each type of loading.…”

Section: Acoustic Loading On the Fairingmentioning

confidence: 98%

Vibro-acoustic noise control treatments for payload bays of launch vehicles: Discrete to fuzzy solutions

2005

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“…Gardonio et al [14] provide an excellent analytical analysis of structural-acoustic transmission for a cylinder that is very much applicable to the fairing noise problem. Their paper presented the development and application of a modal-interaction analysis to investigate plane-wave transmission of external noise into a representative model of a cylindrical, sandwich composite fairing.…”

Section: Theory a Fairing Noise Transmission Dynamicsmentioning

confidence: 99%

Chamber Core Structures for Fairing Acoustic Mitigation

Lane

Henderson

Williams

et al. 2007

Journal of Spacecraft and Rockets

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information AFRL-VS-PS-JA-2007-1013 SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)AFRL/VSSV SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION / AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. ‡ SUPPLEMENTARY NOTESPublished in the Journal of Spacecraft and Rockets, Vol. 44, No. 1, Jan -Feb 2007 ‡No public affairs clearance on file (DTIC Codes 1,20). ABSTRACTThe U.S. Air Force Research Laboratory is pursuing an innovative composite structure design called chamber core for constructing launch vehicle payload fairings. A composite chamber core fairing consists of many axial tubes sandwiched between face sheets, tubes that can be used as acoustic dampers to reduce low-frequency interior noise with virtually no added mass. This paper presents the results of experimental studies of noise transmission through a 1.51 m diameter x 1.42 m tall chamber core cylinder. It was tested in a semireverberant acoustics laboratory using band-limited random noise at sound pressure levels up to 110 dB. The bare cylinder provided approximately 12.7 dB of attenuation over the 0-500 Hz bandwidth and 15.3 dB over 0-2000 Hz. The noise reduction increased to over 18 dB for both bandwidths with the axial tubes acting as acoustic dampers. Narrowband reductions in excess of 15 dB were measured around specific acoustic resonances. This was accomplished with virtually no added mass to the composite cylinder. Results were compared with the performance provided by a 2.5 cm acoustic blanket treatment. The acoustic dampers were as effective as the acoustic blanket at low frequency, but not at higher frequencies. The acoustic dampers were better able to couple with and damp the low-frequency acoustic modes. Together, the acoustic blanket and dampers provided over 10 dB more noise reduction over the 2000 Hz bandwidth than the bare cylinder. The U.S. Air Force Research Laboratory is pursuing an innovative composite structure design called chamber core for constructing launch vehicle payload fairings. A composite chamber core fairing consists of many axial tubes sandwiched between face sheets, tubes that can be used as acoustic dampers to reduce low-frequency interior noise with virtually no added mass. This paper presents the results of experimental studies of noise transmission through a 1:51 m diameter 1:42 m tall chamber core cylinder. It was tested in a semireverberant acoustics laboratory using band-limited random noise at sound pressure levels up to 110 dB. The bare cylinder ...

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A Modal Expansion Analysis of Noise Transmission Through Circular Cylindrical Shell Structures With Blocking Masses

Cited by 28 publications

References 21 publications

Reduction of sound transmission into a circular cylindrical shell using distributed vibration absorbers and Helmholtz resonators

Reduction of sound transmission into a circular cylindrical shell using distributed vibration absorbers and Helmholtz resonators

Vibro-acoustic noise control treatments for payload bays of launch vehicles: Discrete to fuzzy solutions

Chamber Core Structures for Fairing Acoustic Mitigation

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