多孔金屬材料吸聲性能測試系統(tǒng)設(shè)計與實現(xiàn).pdf

1、獨創(chuàng)性聲明本人聲明所呈交的論文是我個人在導(dǎo)師指導(dǎo)下進(jìn)行的研究工作及取得的研究成果。盡我所知，除了文中特別加以標(biāo)注和致謝的地方外，論文中不包含其他人已經(jīng)發(fā)表或撰寫過的研究成果，也不包含為獲得寧夏大學(xué)或其它教育機(jī)構(gòu)的學(xué)位或證書而使用過的材料。與我一同工作的同志對本研究所做的任何貢獻(xiàn)均己在論文中作了明確的說明并表示了謝意。研究生簽名：I對IM：弘J3年鄉(xiāng)月2，蘆關(guān)于論文使用授權(quán)的說明本人完全了解寧夏大學(xué)有關(guān)保留、使用學(xué)位論文的規(guī)定，即：學(xué)校有

2、權(quán)保留送交論文的復(fù)印件和磁盤，允許論文被查閱和借閱，可以采用影印、縮印或掃描等復(fù)制手段保存、匯編學(xué)位論文。同意寧夏大學(xué)可以用不同方式在不同媒體上發(fā)表、傳播學(xué)位論文的全部或部分內(nèi)容。(保密的學(xué)位論文在解密后應(yīng)遵守此協(xié)議)研究生簽名：導(dǎo)師簽名：了齒一時間：2／Dl≥時間：加R吖月2)日年兮月2之B／AbstractPorousmetalisanewtypeofstructuralmaterialhavingmultifunctionalpr

3、operties，CallbeusedincuttingedgetechnologyandextremeconditionsTheacousticcharacteristicsoftheporousmetalmaterialincludingtheabsorptioncoefficient，andtransmissionloss，thesurfaceacousticimpedance，thecharacteristicimpedance

4、，thecomplexwavenumbertheeffectivedensityandvolumemodulusetcExistingstandardizedtestingsystemisusedtotesttheabsorptioncoefficient，transmissionlossandsurfaceacousticimpedanceThispaperfocusesontheacousticcharacteristicsofth

5、eporousmetalmaterial，aimstoapplythetwomicrophonetransferfunctionmethodtodesignandbuildaacousticmaterialperformancetestsystemFirst，thispaperdetailsbasicknowledgeaboutthetestsystelnandthederivationofaformulaofmaterialacous

6、ticperformanceinimpedancetube，includingtheacousticsandacousticmeasuring，theparametersaboutacousticperformance，acousticmodel，theplanewavetheorybasedonimpedancetube，thecomplexreflectioncoefficient，thesurfaceacousticimpedan

7、ce，thesoundabsorptioncoefficientandtheserlsorexchangetechnologySecond，theconstructionoftheacousticperformancetestsystemundertheordinarysoundpressurelevel(SPL)andhiighSPLconditionsisdetailed，includingthedesignofimpedancet

8、ube，thecollocationstudyofthepoweramplifierandthespeaker，thetypeofmicrophoneandchoice，bymeansofthehighpoweredspeakersandpoweramplifiertoenhanceSPL，devisedahorn—typeloudspeakertoimprovetheemissivitySpecificmeasurementsteps

9、areintroducedandtheproblemsarisingfromthemeasurementprocessisproposed，choosingastandardporousmetalmaterialassampleofthemeasurement，achievingitsalgorithmbasedonMATLAB，theanalysisresultsofthesystemisthesarfleasB&Kequipment

10、，provestheaccuracyofthemeasurementsystemThird，thestudyofthecharacteristicimpedanceandthecomplexwavenumberarebasedonthepresentsystemTheformulaefurmeasuringthecharacteristicimpedanceandcomplexwavenumberofporousmaterialshav

11、ebeenmadeadetailedderivationinthispaperTheporousmetalmaterialswdieusedtoaSSeSStheusefulnessofthepresentmethodTheacousticalcharacteristicsaremeasuredunderlowandhigh—frequencylevelsThemeasuredvaluesofeffectivedensitybulkmo

12、dulus，surfaceimpedanceandsoundabsorptioncoefficientwerederivedfromthecharacteristicimpedanceandthecomplexwavenumberandwerecomparedwiththecalculatedvaluesbytheJohnsonAllardmodelasafunctionoffrequencyatlowfrequenciesandthe

13、DelanyandBazleymodelathighfrequenciesAdditionallytheerrorSOUrCeSbetweentwovaluesareanalyzedinthispaperThegoodagreementbetweenthetheoryandexperimentaldataprovidesconvincingevidencethattheapparatusandmethodhasbeenshowntobe

14、extremelyusefulforstudiesoffundamentalpropertiesinporousmaterialandbythecharacteristicimpedance，wecanknowntheabsorptioncoefficientofanylayerofairKeywords：Porousmetalmaterials，acousticcharacteristic，testsystem，transferfun