Latesttechnology.NoisereductionTheauthorhasconductedfournoisemeasurementsintotalatthePWRItestingcoursetoimprovethenoisereductioneffectofPERS,includingthefirstonedescribedabove.Thesecondnoisemeasurementinwasfocusedontheinfluenceofporosityonnoisereduction.FigureshowsthatnoisereductionofPERSisalmostsaturatedattheporosityofandover.Inthethirdnoisemeasurementof,amajorissuewastheeffectofPERSthicknessonnoisereduction.TheoptimalPERSnoisereductionlevelsforpassengercars,lighttrucks,andheavytrucksare-dB(A),-dB(A),and-dB(A),respectively.FigurerevealsthatthenoisereductionofPERSbecomesamaximumatthethicknessofcm.ConsideringtherelativelysmalldifferenceofnoisereductionbetweencmthicknessofPERSandcmthicknessofPERS,andmaterialcostreduction,theoptimalthicknessofPERSseemstoexistbetweencmandcm.TheoptimalPERSnoisereductionlevelsforpassengercars,lighttrucks,andheavytrucksare-dB(者不得不牺牲客车降噪同时,提高湿摩擦。
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