Enhanced evaluation of interfacial properties in fiber reinforced plastic via a modified tow fragmentation method

초록

A reliable evaluation method for interfacial properties in fiber-reinforced composites is continuously required. In this study, the interfacial properties of carbon fiber/epoxy composites were evaluated using a tow fragmentation (TF) test combined with an acoustic emission (AE) technique, and the effects of different desizing conditions on interfacial behavior were analyzed. AE signals obtained from fiber, epoxy, and single-fiber fragmentation tests were analyzed using fast Fourier transform, enabling clear discrimination of damage modes associated with fiber fracture, matrix fracture, and interfacial slip. Acetone desizing exhibited superior interfacial load-transfer characteristics while minimizing fiber damage compared with thermal desizing. The TF test revealed a proportional relationship between the number of fiber fracture events and mechanical strength, allowing quantitative determination of tow shear stress (TSS). The TSS was governed primarily by interfacial load transfer rather than interfacial area, and showed a consistent trend with interfacial shear strength obtained from the microdroplet test. Finite element analyses further confirmed that the proposed TSS-based framework appropriately represents tow-scale interfacial load-transfer behavior. These results demonstrate that the AE-assisted TF test provides an effective and physically meaningful approach for quantitative evaluation of interfacial load-transfer behavior under conditions representative of actual composite structures.

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