Microstructural Influence on Deformation and Fatigue Life of Composites Using the Generalized Method of Cells

:Afully!coupleddeformationanddamage!approachtomodeling!the!response!of!composite!materials!and!composite!laminates!is!presented.!!It!is!based!on!the!semi9analytical!generalized!method!of!cells!(GMC)!micromechanics!model!as!well!as!its!higher!fidelity!counterpart,!HFGMC,!bothof!which!provide!closed9form!constitutive!equations!forcomposite!materials!as!well!as!the!micro!scale!stress!and!strain!fieldsin!the!composite!phases.!!The!provided!constitutive!equationsallow!GMC!and!HFGMC!to!function!within!a!higherscale!structural!analysis!(e.g.,!finite!elementanalysis!or!laminationtheory)!torepresenta!composite!material!point,!while!the!availability!ofthe!micro!fields!allow!the!incorporation!oflower! scale! sub9models! to! represent! local! phenomena! in! the! fiber! and! matrix.! !Further,! GMC’s!formulation!performs!averaging!when!applying!certain!governing!equations!such!that!some!degree!of!microscale!field!accuracy!issurrendered!in!favor!of!extreme!computational!efficiency,!rendering!the!method!quite!attractive!as!the!centerpiece!in!a!integrated!computationalmaterialengineering!(ICME)!structural! analysis;! whereas HFGMC!retains!this! microscale! field! accuracy,!but! at! the! price! of!significantly!slower!computational!speed.!Herein,!the!sensitivity!of!deformationandthe!fatigue!life!of!graphite/epoxy!PMC! composites, with! both! ordered! and! disordered! microstructures,!has! beeninvestigated!using!this!coupled!deformation!and!damage!micromechanics!based!approach.!!Thelocal!effects!of!fiberbreakage!and!fatiguedamage!areincluded!as!sub9models!that!operate!onthe!microscale!forthe!individual!composite!phases.!!Foranalysis!of!laminates,!classical!lamination!theory!is!employed!as!theglobal!or!structural!scalemodel,!whileGMC/HFGMC!is!embedded!to!operateon!themicroscale!to!simulate!the!behavior!of!the!composite!material!withineachlaminate!layer.!!Akey!outcome!of!this!study!isthe!statistical!influence!of!microstructure!and!micromechanics!idealization!(GMC!or!HFGMC)!on!the!overall!accuracy!of!unidirectional!andlaminatedcomposite!deformation!and!fatigue!response.!!