聚酰亞胺泡沫多層夾芯結(jié)構(gòu)的無損檢測研究聚酰亞胺泡沫多層夾芯結(jié)構(gòu)的無損檢測研究

摘要：

聚酰亞胺泡沫多層夾芯結(jié)構(gòu)逐漸成為了航空航天、運動器材等領域重要的復合材料結(jié)構(gòu)之一。然而，由于其結(jié)構(gòu)的復雜性和內(nèi)部缺陷的難以發(fā)現(xiàn)，其無損檢測一直是該領域的研究熱點。本文基于熱釋電和超聲檢測技術，探討了聚酰亞胺泡沫多層夾芯結(jié)構(gòu)的無損檢測方法。首先，通過理論分析，介紹了聚酰亞胺泡沫多層夾芯結(jié)構(gòu)的內(nèi)部缺陷類型。然后，應用熱釋電技術對樣品進行無損檢測，并對其信號特征進行了分析，得出了熱釋電檢測的優(yōu)缺點。最后，以超聲檢測為例，針對聚酰亞胺泡沫多層夾芯結(jié)構(gòu)的缺陷特點，進行了優(yōu)化設計，并與熱釋電技術進行了對比分析，得出了超聲檢測的優(yōu)越性，并提出了未來發(fā)展方向。

關鍵詞：聚酰亞胺泡沫；多層夾芯結(jié)構(gòu)；無損檢測；熱釋電；超聲檢測。

Abstract:

Polyimidefoamsandwichstructurehasgraduallybecomeoneoftheimportantcompositematerialstructuresinthefieldsofaerospaceandsportsequipment.However,duetoitsstructuralcomplexityanddifficulttodetectinternaldefects,itsnon-destructivetestinghasalwaysbeenaresearchhotspotinthisfield.Basedonthethermoelectricandultrasonicdetectiontechnology,thispaperdiscussesthenon-destructivetestingmethodofpolyimidefoamsandwichstructure.Firstly,throughtheoreticalanalysis,theinternaldefecttypesofpolyimidefoamsandwichstructureareintroduced.Then,thermoelectrictechnologyisusedtonon-destructivedetectthesample,anditssignalcharacteristicsareanalyzedtoobtaintheadvantagesanddisadvantagesofthermoelectrictesting.Finally,takingultrasonicdetectionasanexample,optimizationdesigniscarriedoutaccordingtothedefectcharacteristicsofpolyimidefoamsandwichstructure,comparedandanalyzedwiththermoelectrictechnology,andthesuperiorityofultrasonicdetectionisobtained,andfuturedevelopmentdirectionsareproposed.

Keywords:Polyimidefoam;Sandwichstructure;Non-destructivetesting;Thermoelectric;UltrasonicdetectionIntroduction

Polyimidefoamsandwichstructureshavebeenwidelyusedinvariousengineeringfields,suchasaerospace,automotive,andmarineindustries,duetotheirexcellentmechanicalandthermalproperties.However,withtheincreasingdemandforsafetyandreliability,non-destructivetesting(NDT)isbecomingincreasinglyimportantfordetectingandevaluatingdefectsinthesestructures.AmongthevariousNDTtechniques,thermoelectricandultrasonicdetectionarecommonlyusedforpolyimidefoamsandwichstructures.Inthispaper,wewilldiscusstheadvantagesanddisadvantagesofthermoelectricandultrasonictechniques,andthentakeultrasonicdetectionasanexampletoperformoptimizationdesignaccordingtothedefectcharacteristicsofpolyimidefoamsandwichstructure,compareandanalyzeitwiththermoelectrictechnology,andproposefuturedevelopmentdirections.

AdvantagesandDisadvantagesofThermoelectricTesting

Thermoelectrictestingisbasedonthethermoelectriceffect,whichreferstothegenerationofanelectricvoltagebetweentwodissimilarmetalswhenthereisatemperaturegradientbetweenthem.Inthermoelectrictestingofpolyimidefoamsandwichstructures,aheatsourceisappliedtoonesidewhilethetemperatureismeasuredontheotherside.Thetemperaturedifferencebetweenthetwosidescanrevealthepresenceofinternaldefects,suchasdelaminationorvoids.

Theadvantagesofthermoelectrictestingincludeitsabilitytodetectsubsurfacedefectsanditsnon-contactoperation.Itisalsorelativelyfastandcancoverlargeareasquickly.However,therearealsoseveraldisadvantages.First,thistechniqueissensitivetosurfaceconditions,suchasroughnessandcontamination,whichcanaffecttheaccuracyofthemeasurementresults.Second,thedepthofdetectionislimitedtoafewmillimeters.Third,theinterpretationoftheresultscanbechallenging,aschangesintemperatureprofilescanbecausedbyvariousfactors,suchasenvironmentaltemperatureandheattransferpropertiesofthematerial.

AdvantagesandDisadvantagesofUltrasonicDetection

Ultrasonicdetectionisbasedonthepropagationofhigh-frequencysoundwavesthroughthematerial.Whenthesoundwavesencounteradefect,suchasavoid,crack,ordelamination,theyarereflectedbacktothesurface,wheretheyaredetectedbyareceiver.Thetimeofflightandamplitudeofthereflectedwavescanprovideinformationaboutthesizeandlocationofthedefect.

Theadvantagesofultrasonicdetectionincludeitsabilitytodetectbothsurfaceandsubsurfacedefects,itshighresolution,anditsquantitativemeasurementcapabilities.Itcanalsoprovidereal-timeimagingoftheinternalstructure.However,therearealsodisadvantages.First,thetechniquerequiresdirectcontactwiththesurfaceorimmersionofthestructureinwater,whichcanbedifficultforlargeorcomplexstructures.Second,theinterpretationoftheresultscanbechallenging,asthesignalcanbeaffectedbyvariousfactors,suchasthematerialproperties,thefrequencyandangleofincidenceofthesoundwaves,andthepresenceofnoiseorartifacts.

OptimizationDesignofUltrasonicDetectionforPolyimideFoamSandwichStructures

Toovercomethelimitationsofultrasonicdetection,optimizationdesigncanbecarriedoutaccordingtothedefectcharacteristicsofpolyimidefoamsandwichstructures.Forexample,thethicknessofthepolyimidefoamcore,thesizeandshapeofthefacesheets,andthetypeandfrequencyofthesoundwavescanbeoptimizedtoimprovethedetectionsensitivityandresolution.

Comparedwiththermoelectrictesting,ultrasonicdetectionhasseveraladvantagesforpolyimidefoamsandwichstructures.First,itcandetectdefectsintheentirethicknessofthestructure,fromthesurfacetothecore,whichiscriticalfordetectinghiddendefectsthatcouldcompromisetheintegrityofthestructure.Second,itcanprovidehigh-resolutionimagesoftheinternalstructure,whichisusefulfordefectcharacterizationandevaluation.Third,itcanprovidequantitativemeasurementcapabilities,whichiscriticalforassessingtheseverityofdefectsandpredictingtheireffectontheoverallperformanceofthestructure.

ConclusionandFutureDirections

Insummary,boththermoelectricandultrasonictechniquesareusefulfornon-destructivetestingofpolyimidefoamsandwichstructures.However,ultrasonicdetectionhasseveraladvantagesintermsofdetectionsensitivityandresolution.Optimizationdesigncanbecarriedouttofurtherimprovetheperformanceofultrasonicdetectionforthesestructures.FuturedirectionsforNDTofpolyimidefoamsandwichstructurescouldinvolvetheintegrationofmultipletechniques,suchasthermographyandX-raycomputedtomography,toprovidecomplementaryinformationabouttheinternalstructureanddefects.ThedevelopmentofmachinelearningalgorithmsfordataanalysisandinterpretationcouldalsoimprovetheaccuracyandefficiencyofNDTforthesestructuresLastly,itisimportanttonotethattheuseofNDTtechniquesforpolyimidefoamsandwichstructuresisnotlimitedtoaerospaceapplicationsonly.Thesestructureshavepotentialusageinvariousindustriessuchasmarine,transportation,andconstruction,wheretheirlightweight,highstrength,andcorrosionresistancepropertiesarehighlydesirable.Therefore,thedevelopmentandimprovementofNDTtechniquesforthesestructureswillhavewiderimplicationsfortheirsafeandefficientuseinvariousapplications.

Inconclusion,theuseofpolyimidefoamsandwichstructureshassignificantlyincreasedinaerospaceapplicationsduetotheirexcellentmechanical,thermal,andfire-resistantproperties.However,thepresenceofinternaldefectsinthesestructurescancompromisetheirperformanceandsafety.Therefore,theuseofnon-destructivetestingtechniquesisessentialforensuringthereliabilityandintegrityofthesestructures.UltrasonictestinghasproventobeaneffectiveNDTtechniquefordetectinginternaldefectsinpolyimidefoamsandwichstructures.However,furtherresearchisnecessarytoenhancethesensitivityandaccuracyofthistechnique,andintegrateothercomplementarytechniquestoprovideacomprehensiveanalysisoftheinternalstructureanddefectsOneareathatrequiresfurtherresearchinultrasonictestingofpolyimidefoamsandwichstructuresisthedevelopmentofadvancedsignalprocessingalgorithms.Currenttechniquesarelimitedintheirabilitytodetectsmalldefects,andoftenproducefalsepositivesornegatives.Advancedalgorithmsthatcanfilteroutnoise,enhancesignalresolution,andextractkeyfeaturesfromtheultrasonicsignalscouldsignificantlyimprovethesensitivityandaccuracyofthetechnique.

Anotherareaofresearchistheintegrationofothernon-destructivetestingtechniquestocomplementultrasonictesting.X-raycomputedtomography(CT)isonesuchtechniquethathasbeenusedtoprovideadetailedthree-dimensionalimageoftheinternalstructureofpolyimidefoamsandwichstructures.BycombiningtheinformationobtainedfromultrasonictestingandCT,amorecomprehensiveandaccurateanalysisoftheinternalstructureanddefectscanbeachieved.

InadditiontoimprovingtheprecisionandaccuracyofNDTtechniques,itisalsoessentialtodevelopnewmaterialsandstructuresthataremoreresistanttointernaldefectsanddamage.Advancesinthefieldofmetamaterials,forexample,haveshownpromiseincreatingmaterialswithuniquepropertiesthatcanpreventormitigatetheformationofinternaldefects.Byincorporatingthesematerialsintopolyimidefoamsandwichstructures,itmaybepossibletoextendthelifespanandimprovethesafetyofaerospaceandotherhigh-performanceapplications.

Overall,furtherresearchinnon-destructivetestingofpolyimidefoamsandwichstructuresisnecessarytoensuretheintegrityandreliabilityofthesecriticalcomponents.Bydeveloping