Optimizationand mechanism ofultrasonic weldingprocessofCF/PEIcomposite

widelyusedintheaerospacefield. Theefficientbondingtechnologyhasanimportanteffectonthe manufacturingcostand safetyof CFRP components.Inthispaper,carbonfiberreinforcedpolyetherimideresin matrix composites (CF/PEI)wereweldedbyultrasonic weldingtechnology.Theeffectsofultrasonic weldingpressure and weldingtimeonthestrengthofultrasonicweldedjointswerestudiedbysinglelapshearstrength (LSS)test,andthe micro morphologyofsection wascharacterizedbyscanningelectron microscope. Theexperimental data were analyzed bylinear fitting,and the time pressure parameters were optimizedandthejointstrengthwaspredictedbycombiningBPneuralnetworkandgeneticalgorithm. Finally,theinfluencemechanismofholdingtimeonjointstrengthwasstudied.Theresultsshowthat whentheweldingtimeis2.5sandthe weldingpressureis0.45 MPa,the maximum LSSis25.6 MPa,anditisfoundthatthehigher weldingstrengthisduetotheformation ofdenseandstable structureonthejointsurface.Theexperimentaldataarerefined byBP neuralnetwork.The LSS valuesimulated by geneticalgorithm is24.8 MPa,andtheerror betweenthesimulation andthe experimentalresultsisonly3%.Withtheincreaseofthe holdingtime,thestrength ofultrasonic weldingjointincreasesrapidlyfirstandthentendstobestable.Whentheholdingtimeis5s,the moltenresinattheweldinginterfaceisbasicallycuredcompletely,andthePEIresinandcarbonfiber form adensestructure,andthestrengthofultrasonicweldingjointisstable.