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某机载雷达天馈伺系统随机振动分析.docx

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某机载雷达天馈伺系统随机振动分析 I.Introduction Randomvibrationsareacommonandsignificantissueinaerospacesystems,astheycannotonlyresultinreducedperformanceandoperationefficiencybutalsocausefatiguefailureandevencatastrophicaccidents.Theantennasystemofanairborneradar,asoneofthecrucialcomponentsforobservationandcommunication,issusceptibletorandomvibrationsinducedbyvarioussources,suchasturbulence,enginevibration,andstructuralresonance.Therefore,thestudyofrandomvibrationanalysisoftheantennasystemisofgreatimportanceforensuringthesafetyandreliabilityoftheaircraftandtheperformanceoftheradar. Inthispaper,wepresentastudyoftherandomvibrationanalysisoftheairborneradarantennasystem.Specifically,wefocusontheanalysisoftheantennafeedsystem,whichconsistsofthefeedhorn,waveguide,andarray.Theanalysisincludesthecalculationofthepowerspectraldensity(PSD)ofvibrationacceleration,theestimationofthenaturalfrequenciesanddampingratiosofthefeedsystem,andtheevaluationofthesystemresponseusingthefiniteelementmethod(FEM).Theeffectsofvariousparameters,suchasthelocation,intensity,andfrequencyoftheexcitationsources,andthematerialandgeometryofthestructuralcomponents,areinvestigated. II.RandomVibrationAnalysis A.Powerspectraldensity ThePSDisastatisticalmeasurementofthedistributionofthepowerofasignaloverfrequency.Itisafundamentaltoolforanalyzingthecharacteristicsofrandomvibration,asitdescribestheamplitudeofvibrationaccelerationasafunctionoffrequency.ThePSDiscalculatedbytakingtheFouriertransformoftheautocorrelationfunctionofthevibrationacceleration. ThePSDoftheantennasystemcanbeestimatedbymeasuringthevibrationaccelerationatthemountingpointoftheantennaandthenprocessingthedatausingasuitablealgorithm.Alternatively,thePSDcanbeobtainedbynumericalsimulationusingamathematicalmodelofthesystem. B.Naturalfrequenciesanddampingratios Thenaturalfrequenciesanddampingratiosofthefeedsystemareimportantparametersthatdeterminetheresponseofthesystemtorandomvibration.Thenaturalfrequenciesarethefrequenciesatwhichthesystemvibratesinafreemode,i.e