Bolton, J Stuart

Song, Bryan H.

English

Purdue E-Pubs

Purdue UniversityPurdue e-PubsPublications of the Ray W. Herrick Laboratories School of Mechanical Engineering7-2002The application of the edge-constraint effect tonearly-realistic noise control applicationsJ Stuart BoltonPurdue University, bolton@purdue.eduBryan H. SongNASA-Kennedy Space CenterFollow this and additional works at: http://docs.lib.purdue.edu/herrickThis document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact epubs@purdue.edu foradditional information.Bolton, J Stuart and Song, Bryan H., "The application of the edge-constraint effect to nearly-realistic noise control applications"(2002). Publications of the Ray W. Herrick Laboratories. Paper 77.http://docs.lib.purdue.edu/herrick/77THE APPLICATION OF THE EDGE-CONSTRAINT EFFECT TO NEARLY-REALISTIC NOISE CONTROL APPLICATIONSBryan H. SongNASA-Kennedy Space CenterJ. Stuart Bolton Ray W. Herrick LaboratoriesPurdue UniversityPurdue University Herrick LaboratoriesBackground• Investigation of edge constraint effect on samples placed in a modified standing wave tube (J. S. Bolton et al., SAE 1997; B H Song et al JASA 1999) . .   ., .• Internal constraints may be used to selectively enhance the transmission loss of lining materials at low frequencies (B. H S t l JASA 2001). ong e  a ., .• Enhancement of the barrier performance of porous linings by using internal constraints (B. H. Song et al., submitted for NCEJ 2001).Introduction• Comparison between measured and FE predicted random transmission loss .• Enhancement of transmission loss of barrier system by exploiting the edge-constraint effect at low frequency• Design of low frequency noise control barriers following from constraint of porous lining materials around their edges.Glass Fiber Material inside of Sample HolderFour Microphone MeasurementAnechoic Transmission Loss (3” Sample A in a Small Tube)40      3035Experiment                             Prediction using FEM (Edge constrained)Prediction using FEM (Unconstrained)   25B)Increase in TLShearing mode1520TL (d  due to edge constraint5107 dB102 103 1040Frequency (Hz) Surface Normal Impedance (3” Sample A in a Small Tube)810Experiment                                   46Re(zn)Prediction using FEM (Edge constrained)Prediction using FEM (Unconstrained)   102 103 104025n)0Im(zn102 103 104-5Frequency (Hz)Poroelastic Material Properties used in Calculations  Material Bulk density(Kg/m3)Porosity Tortuosity Flow resistivity(MKS Rayls/m)Shear modulus(Pa)Loss factorSample A 6.73 0.99 1.1 21000 1200 0.35Random Incidence Transmission Loss(27 cm X 27 cm)    Schematic of Experimental Setup for the Random Transmission Loss  R everb era tio nR (210 3)F o am  B arrie rsS am p leso o m   mL o u d sp eaker 1A L T E C  A 7XL o u d sp eaker 2A L T E C  A 7XT ech ro nA m p lifie r 7520D u a l M ic ro p h o n eS u p p ly(B & K  5935 )W ave tek  F ilte r  852W ave tek  F ilte r 852B & KP u lseC o m p u te rR an d o m  N o iseG en era to rG R  1390  AR an d o m  N o iseG en era to rB & K  2032H P  (V ec tra )The Circular Aperture for Random Incidence Transmission Loss (30 cm Diameter)    Axisymmetric and 3-D FE Models(30 cm Diameter Circular Aperture)    Axisymmetric Model3-D ModelInternally-Constrained, 30 cm Diameter SampleMid mid Constrained- -  CaseEdgeMidMid-midMid-mid-midTL for the Various Constraint Cases40Edge constrained (FE prediction)       3035Edge constrained (Measurement)         Mid constrained (FE prediction)        Mid constrained (Measurement)          Mid-mid constrained (FE prediction)    Mid-mid constrained (Measurement)      2025L [dB]Mid-mid-mid constrained (FE prediction)Mid-mid-mid constrained (Measurement)  1015TL5102 1030Frequency [Hz]TL for the Unconstrained FE Predictions40Edge constrained       3035Mid constrained        Mid-mid constrained    Mid-mid-mid constrained2025L (dB)1015TL5102 1030Frequency (Hz)FE Prediction of Random Incidence Transmission Loss (3-D Model)   SPL (1000 Hz)ADX SDXFE Prediction of Random Incidence Transmission Loss (Axisymmetric FE Model)    SPL (1000 Hz)ADX SDXThe Square Aperture for Random Incidence Transmission Loss (27 cm by 27 cm)      Internally-Constrained, 27 cm by 27 cm Sample3-D FE Model (27 cm by 27 cm Square Aperture)    ,  Internally-Constrained Green Sample(Frame Constraint) Glass fiber (3”)B&K Two Microphone Probe7.5 cmTL Increase for the Internally-Constrained Sample A (Frame Constraint)   403035 (a)Measurement (Edge constraint)   Measurement (Frame constraint)  FE prediction (Edge constraint) FE prediction (Frame constraint)2025(dB)1015TL 2 30510 10Frquency [Hz]TL for the Single Panel System Lined with Glass Fiber Material  Limp Panel (0.078”)+Air (1”)+Glass fiber (3”)B&K Two Microphone Probe7.5 cm2.5 cmTL Increase for the Internally-Constrained Sample A (Frame Constraint)   403035 (b)2025L (dB)1015TL102 10305Frquency [Hz]C l iGood agreement between measured and FE predicted random onc us onstransmission losses.Random transmission losses through segmented lining materials were enhanced at low frequencies by the edge constraint effect.  Light and stiff fibrous materials combined with edge and internal constraint mechanisms can be used to design, light, high performance low frequency noise control barriers.

The application of the edge-constraint effect to nearly-realistic noise control applications

https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1079&context=herrick

The application of the edge-constraint effect to nearly-realistic noise control applications

Abstract

Similar works

Full text

Available Versions

Purdue E-Pubs