ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Collection
Keywords
Years
  • 1
    facet.materialart.
    Unknown
    Interaction of airborne and structure-borne noise radiated by plates (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The interaction of airborne and structure-borne noise radiated by aircraft structures is studied analytically and experimentally for the case of noise radiating from thin, isotropic, rectangular aluminum plates as a result of fully coherent, combined acoustic and vibrational inputs. Attention is given to the great influence of the relative phase between inputs on the combined noise radiation characteristics of the plates; these phase-dependent effects, which are manifest as cross-terms in both the dynamic and acoustic portions of the analysis, can radically alter the combined sound power radiated by airframe structure plates. Such interactive effects have heretofore been neglected in analyses of results from analytical and experimental studies of propeller-driven aircraft interior noise.
    Keywords: ACOUSTICS
    Type: Journal of Sound and Vibration (ISSN 0022-460X); 115; 387-403
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Phase shift errors in the theory and practice of surface intensity measurements (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The surface acoustical intensity method (sometimes known as the microphone-accelerometer cross-spectral method) is a relatively new noise source/path identification tool. Several researchers have had difficulties implementing this method because of instrumentation phase mis-match. A simple technique for measuring and correcting instrumentation phase mis-match has been developed. This new technique has been tested recently on a noise source identification problem of practical interest. The results of the experiments indicate that the surface acoustic intensity method produces reliable data and can be applied to a variety of noise source/path problems.
    Keywords: ACOUSTICS
    Type: Journal of Sound and Vibration; 82; May 22
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    A new measurement method for separating airborne and structureborne aircraft interior noise (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: It is pointed out that interior noise levels of propeller driven aircraft are substantially higher than levels measured for other types of CTOL aircraft. Reduction of interior noise of such aircraft requires a knowledge of the relative importance of the acoustic and structural noise transmission paths. Noise entering the aircraft interior via an acoustic path is the noise radiated by an external noise source (propellers, exhaust noise), which propagates through the acoustic medium (air) and is then transmitted through the aircraft fuselage. This type of incoming noise is referred to as airborne noise. Noise entering the aircraft interior via a structural path is the noise which has its source in the vibrational energy which has been transmitted through the structure from a remote vibrational energy source (engines, wind flutter). This type of incoming noise is referred to as structureborne noise. A new method for separating airborne and structureborne noise is presented. It is based on two-microphone cross spectral acoustic intensity measurements.
    Keywords: ACOUSTICS
    Type: Noise Control Engineering Journal; 20; Jan
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Studies of noise transmission in advanced composite material structures (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Noise characteristics of advanced composite material fuselages were discussed from the standpoints of applicable research programs and noise transmission theory. Experimental verification of the theory was also included.
    Keywords: COMPOSITE MATERIALS
    Type: ACEE Composite Struct. Technol.; p 161-178
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Interaction of airborne and structureborne noise radiated by plates. Volume 2: Experimental study (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The interaction of airborne and structureborne noise radiated by aircaraft materials was studied. The results corroborate the findings of an earlier analytical study by showing that the noise radiation of vibrating plates due to combined airborne and structureborne inputs possesses a stong synergistic nature. The large influence of the interaction between the airborne and structureborne inputs was hitherto ignored by researchers of aircraft interior noise problems.
    Keywords: ACOUSTICS
    Type: NASA-TM-87747 , NAS 1.15:87747
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    Interaction of airborne and structureborne noise radiated by plates. Volume 1: Analytical study (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The interaction of airborne and structureborne noise radiated by aircraft materials was examined. The theory and results of several computer simulations of the noise radiated by thin, isotropic, rectangular aluminum plates due to fully coherent combined acoustic and vibrational inputs is presented. The most significant finding was the extremely large influence that the relative phase between inputs has on the combined noise radiation of the plates. Phase dependent effects manifest themselves as cross terms in both the dynamic and acoustic portions of the analysis. Computer simulations show that these cross terms can radically alter the combined sound power radiated by plates constructed of aircraft-type materials. The results suggest that airborne-structureborne interactive effects could be responsible for a significant portion of the overall noise radiated by aircraft-type structures in the low frequency regime. This implies that previous analytical and experimental studies may have neglected an important physical phenomenon in the analayses of the interior noise of propeller dirven aircraft.
    Keywords: ACOUSTICS
    Type: NASA-TM-87746 , NAS 1.15:87746
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Separation of airborne and structureborne noise radiated by plates constructed of conventional and composite materials with applications for prediction of interior noise paths in propeller driven aircraft (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The anticipated application of advanced turboprop propulsion systems and use of composite materials in primary structure is expected to increase the interior noise of future aircraft to unacceptability high levels. The absence of technically and economically feasible noise source-path diagnostic tools has been a primer obstacle in the development of efficient noise control treatments for propeller driven aircraft. A new diagnostic method which permits the separation and prediction of the fully coherent airborne and structureborne components of the sound radiated by plates or thin shells has been developed. Analytical and experimental studies of the proposed method were performed on plates constructed of both conventional and composite materials. The results of the study indicate that the proposed method can be applied to a variety of aircraft materials, could be used in flight, and has fewer encumbrances than the other diagnostic tools currently available. The study has also revealed that the noise radiation of vibrating plates in the low frequency regime due to combined airborne and structureborne inputs possesses a strong synergistic nature. The large influence of the interaction between the airborne and structureborne terms has been hitherto ignored by researchers of aircraft interior noise problems.
    Keywords: ACOUSTICS
    Type: NASA-TM-87414 , NAS 1.15:87414
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    A new measurement method for separating airborne and structureborne noise radiated by aircraft type panels (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The theoretical basis for and experimental validation of a measurement method for separating airborne and structure borne noise radiated by aircraft type panels are presented. An extension of the two microphone, cross spectral, acoustic intensity method combined with existing theory of sound radiation of thin shell structures of various designs, is restricted to the frequency range below the coincidence frequency of the structure. Consequently, the method lends itself to low frequency noise problems such as propeller harmonics. Both an aluminum sheet and two built up aircraft panel designs (two aluminum panels with frames and stringers) with and without added damping were measured. Results indicate that the method is quick, reliable, inexpensive, and can be applied to thin shell structures of various designs.
    Keywords: ACOUSTICS
    Type: NASA-TP-2079 , L-15481 , NAS 1.60:2079
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    Noise transmission loss of aircraft panels using acoustic intensity methods (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The two-microphone, cross-spectral, acoustic intensity measurement technique was used to determine the acoustic transmission loss of three different aircraft panels. The study was conducted in the transmission loss apparatus in the Langley aircraft noise reduction laboratory.
    Keywords: ACOUSTICS
    Type: NASA-TP-2046 , L-15306 , NAS 1.60:2046
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    User's guide to noise data acquisition and analysis programs for HP9845: Nicolet analyzers (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A software interface package was written for use with a desktop computer and two models of single channel Fast Fourier analyzers. This software features a portable measurement and analysis system with several options. Two types of interface hardware can alternately be used in conjunction with the software. Either an IEEE-488 Bus interface or a 16-bit parallel system may be used. Two types of storage medium, either tape cartridge or floppy disc can be used with the software. Five types of data may be stored, plotted, and/or printed. The data types include time histories, narrow band power spectra, and narrow band, one-third octave band, or octave band sound pressure level. The data acquisition programming includes a front panel remote control option for the FFT analyzers. Data analysis options include choice of line type and pen color for plotting.
    Keywords: ACOUSTICS
    Type: NASA-TM-83256
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...