Evaluation of the Fiber/Matrix Interfacial Strength in CFRTP by Push-out Test Technique Using Nanoindenter

: The fiber/matrix interfacial strength in discontinuous carbon fiber reinforced thermo-plastics was evaluated by a push-out test using a nanoindenter. Two types of composites were prepared.Theyweremolded using polypropylenereinforced bydiscontinuous carbon fibers using differentsurfacetreatments.Thinpolishedspecimenswithathicknessof20μmwereprepared.The load-displacement curves wereobtained byextruding carbon fiberwith a custom-madeflat-ended push rod attached to thenanoindenter.Theprocess ofinterfacialdebonding fracturewasnumeri-callysimulated bythecohesivezonemodel,using themixed-modecriticalenergyreleaserateasa criterion. In addition, interfacial shear strengths were evaluated using the feature points of the measured load-displacement curve.It can beconcluded from the results that the higher the interfacial shear strength, the higher the macroscopic tensile strength. Subsequently, Kelly-Tysonʼs theorywasused to predict themacroscopictensilestrengths.Thepredictedtensilestrengthsofthe composites werealmost consistent with thepracticalvalues. る上で重要な信頼性を支配する要因の一つは，繊維と樹