Paper number 379


Joung-Man Park1, Sang-Il Lee1, Young-Min Kim1, Ki-Won Kim2, and Dong-Jin Yoon 3

1Dept. of Polymer Science & Engineering,
Regional Research Center for Aircraft Technology,
Gyeongsang National University, Chinju 660-701, Korea
2Dept. of Metallurgical Materials Engineering,
Gyeongsang National University, Chinju 660-701, Korea
3Failure Prevention Research Center,
Korea Research Institute of Standards and Science,
Taedok Science Town, Taejon 305-306, Korea

Summary Using electromechanical technique, various conductive carbon fibers and graphite and steel filaments/epoxy micro-composites were evaluated by measuring electrical resistivity to investigate the interfacial properties including the microfailure modes and inter-fiber distance effect with a aid of acoustic emission (AE). Micromechanical techniques, such as pull-out and fragmentation tests, and electrodeposition (ED) as a surface treatment method were combined. Testing micro-specimens were kept to be contacted electrically using silver paste with very thin copper wire on the conductive fibers. While tensile loading applied, the change of electrical resistivity was detected by fiber breakage and microfailure in micro-composites. In electro-pullout test, electrical resistivity was correlated to interfacial shear strength (IFSS) in a steel filament/epoxy composite by detecting maximum pull-out load and the increment mode of resistivity. Electro-micromechanical test was sensitive effectively to detect microfailure events and inter-fiber distance effect in graphite and carbon multi-fibers/epoxy composites. There were the correspondance between a fiber breakage and a sudden increment of electrical resistivity. AE was applied to correlate the microfailure occurrence from fiber break and matrix cracking and while testing for the untreated and ED treated speciemens. By extending electro-micromechanical technique to 1-ply unidirectional carbon fiber/epoxy laminar under tensile load, electrical resistivity showed different microfailure trends for two narrow and wide specimens.
Keywords electro-micromechanical technique, electrical resistivity, electrodeposition (ED), multi-fiber composites, pull-out test, fragmentation test, interfacial shear strength (IFSS), acoustic emission (AE).

Theme : Interface and Interphase ; Mechanical Properties

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