简介：Theuniaxialratchetingbehaviorofapolyetherimide(PEI)polymer'TECAPEI'wasstudiedusingstress-controlledcyclicloadingatroomtemperature,includingbothcyclictension-compressionwithnon-zerotensilemeanstressandtension-unloadingtests.Theexperimentalobservationswerefocusedonthetime-dependentratchetingofthePEIpolymerrevealedincyclictestsatdiversestressratesandwithdifferentpeakstressholdingtimes.TheresultsshowedthatthePEIpolymershowsobviousratchetingdeformation;i.e.,theratchetingstrainaccumulatesprogressivelyinthetensiledirectionduringstress-controlledcyclictestswithnon-zeromeanstress.Theratchetingishighlydependentontheappliedmeanstressandstressam-plitude,andisalsocharacterizedbyastrongtime-dependencyduringthecyclicstressingatdiversestressratesandwithdifferentpeakstressholdingtimes.Thetime-dependentratchetingofthePEIpolymeriscausedmainlybyitsremarkableviscosity.AcomparisonoftheratchetingoccurringbeforeandbeyondtheultimatestresspointofthePEIpolymershowedthattheratchetingbeyondtheultimatestresspointismoresignificantthanthatoccurringbeforethatpoint.