This paper addressed a new sensitive strain monitoring system in SiC fiber reinforced plastic composite in comparison with that of in carbon fiber reinforcement. Carbon fibers in CFRP can be used as sensors to detect fiber elongation and fiber breaks for the electrical resistance changes. However, in low strain range (<1%), the electrical resistance change derived from fiber breaks is relatively less than expected that from fiber elongation because of the electrical conduction between neighboring fibers. In this study, surface oxidized SiC fibers were applied to prevent the electrical conduction between neighboring fibers. Model specimens were made by embedding as-received or oxidized SiC fibers into epoxy resin, and the electrical resistance changes were measured under tensile tests. As a result, electrical resistance of an oxidized SiC fiber composite increased remarkably with increasing strain as compared to an as-received SiC fiber composite. Cumulative fracture probabilities of oxidized fibers embedded in the model specimens were predicted from measured electrical resistance change, and the strength distributions were analyzed based on Weibull statistics. The effect of effective gage length on electrical resistance behaviors was discussed using the experimental result on single fiber fragmentation tests.
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