Understanding Noise & Vibration Control 噪声与振动控制.pdf

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1、UnderstandingNoise&VibrationControl了解噪声与振动控制TypeofNoise噪声的类型•Thereare2typesofnoise:–Air-bornenoise空气传播的噪音–Structure-bornevibration,whichwillappearasairbornenoiseafterbeingradiatedbyastructure结构传播的振动辐射出了空气噪声ControlofNoise&Vibration噪声与振动控制•NoiseandVibrationcanbecontr

2、olledbyusingfourmethods噪声和振动可以用四种方法控制:–Barrier屏障–Absorption吸收–structuraldamping结构阻尼–vibrationisolation振动隔离ControlofNoise&Vibration噪声与振动控制•Ingeneral,combinedmethodsareusedforeffectivenoisecontrol一般情况下，需用组合方法来达到有效的噪声控制–ControlofAir-borneNoise空气传播噪音控制•usebothbarriersa

3、ndabsorbers使用屏障和吸收方法–ControlofStructure-borneNoise结构噪声的控制•Usebothisolationanddamping使用隔离和阻尼ControlofAir-borneNoise空气噪声的控制BarriersandEnclosures障碍和外壳•asolidmaterialwhich,byvirtueofitsmass,actsasanacousticalreflector固体材料凭借其质量作为声学反射体；•itisnotthestiffnessofthebarriertha

4、tproducesthenoisereduction,butthemass(kg/m2)它不是因为其刚度产生噪声屏障的，是它的质量ControlofAir-borneNoise(cont’)空气噪声的控制BarriersandEnclosures障碍和外壳•usefulinreducingnoise>250Hzdependingonthesurfacemass随其表面质量而定，可降低>250赫兹的噪音•Verylowfrequencynoisecanbeattenuatedonlybyusingverymassivecons

5、tructions非常低频率的噪音，只能通过非常大质量的结构衰减•Generally,openingarearelativetothetotalenclosureareashouldnotexceed10percent.一般来说，壳面如需开孔，开口面积不大於总面积百分之10。ControlofAir-borneNoise(cont’)空气噪声的控制Absorption吸收•Absorptionperformanceincreaseswithincreasingmaterialthickness吸收性能随材料厚度而增加•Abs

6、orptionperformanceincreaseswithincreasingfrequency.吸收性能随着频率的增加而增加•Enclosurewithoutaddedabsorptionhasanamplifyingeffectatlowfrequenciesandlimitedperformanceathighfrequencies(CurveA).不加吸收材料的外壳在低频有放大效应，在高频性能是有限的。•enclosurewithaddedabsorption(CurveB)showsconsiderablybe

7、tterattenuationinthehigherfrequencyrangeandatlowerfrequenciesaswell.加了吸收材料的外壳在高频有很好表现，在低频也不错。ControlofStructure-borneNoise结构噪声的控制StructuralDamping结构阻尼•Structuraldampingreducesbothimpact-generatedandsteady-statenoisesattheirsource.结构阻尼降低冲击所产生的影响和稳态噪声源•Damping,howeve

8、r,suppressesonlyresonantmotion.然而，阻尼仅抑制谐振运动•Forced,nonresonantvibrationisrarelyattenuatedbydamping,althoughapplicationofdampingmaterialssometimes