Standard Test Method for Measuring Damage Resistance of Fiber-Reinforced Polymer-Matrix Composite to Concentrated Quasi-Static Indentation Force

boththecenterofthe xture’sopeningandthecenterlineoftheindenter.Fortherigidlybackedcon guration,placethespeci-mendirectlyonthe atrigidsupportsuchthatthespecimen’scenterisalignedwiththecenterlineoftheindenter.Thedistancebetweenthecenterlineoftheindenterandcentersofthespecimenandsupport xtureshallnotexceed1.0mm(0.04in.).Ifasinglespecimenisgoingtobeloadedinintervals,alignmentmarksshouldbemadeonthe xturessuchthattheoriginalalignmentcanbemaintained.

11.6Applyloadtothespecimenindisplacementcontrolataconstantcrosshead(orservohydraulicram)displacementrate.Thedisplacementrateshouldbeselectedsoastoreachthemaximumforcewithin1to10min.RecordtheloadversusdisplacementtraceonanX-Ychartrecorderorotherappropri-aterecordingdevice.

11.7Asloadisincreased,theindenterwillpressintothespecimenformingalocaldepressionand,forthesimplysupportedcon guration, exingthespecimen.Observedam-agecharacteristics.ExamplesofatypicalF/dcurveforthesimplysupportedcon gurationandfortherigidlybackedcon gurationareshowninFigs.3and4.

11.8Whenadesiredmilestone,suchasFmaxorthedesiredcontactforceorthedesireddamagestate,hasbeenreached,thespecimenshallbeunloadedandthetestmachinestopped.Loadanddisplacementshallberecordedthroughoutthetestinclud-ingtheunloadingcycle.Theunloadingrateshallbethesameastheloadingrate.

11.9Dentdepth(d)isafunctionofcontactforcebutcannotbeobtainedfromaloadedspecimen.Therefore,thespecimenmustbeunloadedtoperformthismeasurement.Forexample,toobtaindatcontactforceF8,loadspecimentoF=F8>0;unloadtoF=0;performmeasurementtoobtaind(F8).Centerthespecimenonthe xtureagainaccordingtothealignmentmarksandloadthespecimentothenexthigherload,F=F9>

F8.Thedentdepth,asde nedin3.2.4,shallbemeasuredusingasuitabledentdepthindicatorasde nedin7.8.Thedentshallbemeasuredimmediatelyaftertheloadisremovedfromthespecimen.Ifdistancesaremeasuredrelativetoa xedpoint,thedentdepthwillbethedifferencebetweenthelowestpointinthedentandtheplatesurface.Thedistancetotheplaneofthespecimen’ssurfaceshallbetheaverageoffourmeasure-mentsspaced90°apartandatleast25mmfromtheindentationpointtoprovideasufficientdistanceawayfromthedenttonotin uencethemeasurement.Ifthedepthismeasureddirectlybyusingadepthgage,thedepthshallbetheaverageoftwomeasurementswiththegagerotated90°betweenmeasure-ments.Thebaseofthedepthgageshallbeatleast50mmandsufficientlylargetospanovertheregionaffectedbythedent.Thedentdepthshallbemeasuredtothenearest0.01mm(0.001in.).

11.10TheF1forceandmaximumforce,Fmax,canbedeterminedfromthecontactforce/indenterdisplacement(F/d)curve(s)afterthetest.F1andFmaxmaynotexistfortherigidlybackedcon guration.12.Report

12.1Reportthefollowinginformation,orreferencespoint-ingtootherdocumentationcontainingthisinformation,tothemaximumextentapplicable.Reportingofitemsbeyondthecontrolofagiventestinglaboratory,suchasmightoccurwithmaterialdetailsorpanelfabricationparameters,shallbetheresponsibilityoftherequester.

12.1.1Therevisionlevelordateofissueofthistestmethod.12.1.2Thedate(s)andlocation(s)ofthetest.12.1.3Thename(s)ofthetestoperator(s).

12.1.4Anyvariationstothistestmethod,anomaliesnoticedduringtesting,orequipmentproblemsoccurringduring

testing.

FIG.3TypicalF/dResponsefortheSimplySupported

Con guration