简介：Manybiologicalmaterials,suchaswoodandbone,possesshelicoidmicrostructuresatmicroscale,whichcanserveasreinforcingelementstotransferstressbetweencracksurfacesandimprovethefracturetoughnessoftheircomposites.Failureprocesses,suchasfiber/matrixinterfacedebondingandslidingassociatedwithpull-outofhelicalfibers,areresponsiblemainlyforthehighenergydissipationneededforthefracturetoughnessenhancement.Herewepresentsystemicanalysesofthepull-outbehaviorofahelicalfiberfromanelasticmatrixviathefiniteelementmethod(FEM)simulation,withimplicationsregardingtheunderlyingtougheningmechanismofhelicoidmicrostructures.Wefindthat,throughtheiruniformcurvatureandtorsion,helicalfiberscanprovidehighpull-outforceandlargeinterfaceareas,resultinginhighenergydissipationthataccounts,toalargeextent,forthehightoughnessofbiologicalmaterials.Thehelicityoffibershapeintermsofthehelicalanglehassignificanteffectsontheforce-displacementrelationshipsaswellasthecorrespondingenergydissipationduringfiberpull-out.