FatiguecrackpropagationtestingusingsubsizedrotatingbendingspecimensOriginalResearchArticle

Inmanyindustrialapplications,mechanicalpropertiescharacterizationisneededyetsufficientamountofmaterialforstandardsizedspecimensisnotavailable.Miniaturizedspecimentestingtechniquehastobeemployed.Currentlytherearealotofeffortindevelopingsubsizedspecimentechniqueforimpact,fracturetoughnessandtensileproperties.Workonfatiguepropertiestestingislimitedandlargelyconfinedtostress/strainlifetests.Inthecurrentwork,evaluationoffatiguecrackpropagationbehaviourusingsurfacecrackgrowthinarotatingbendingrodhasbeenattempted.Ninedifferentrodgeometrieshavebeentested.Theresultingfatiguecrackpropagationdataismoresensitivetoroddiameterthantorodlength.Differenceincrackgrowthbehaviourcanlargelybeunderstoodwhencrackclosureistakenintoaccount.Allinall,thecrackpropagationdataobtainedfromthesesmallsizedrodsagreewellwiththoseobtainedfromstandardtestingemployingcompacttensionspecimens.Amoreprecisepictureaboutthecrackgrowthbehaviourcanbeobtainedifcrackclosureisconsidered.Ifcrackclosureisnotmonitored,rodswithlongerlengthandsmallerdiameteraremorelikelytogivetheconservativeupperboundfatiguecrackpropagationbehaviour.