Abstract
This paper addresses a sensitive strain monitoring composite as compared with carbon fiber reinforced polymer composites (CFRP). Carbon fibers in CFRP can be used as sensors to detect fiber fracture and strain of composites using electrical resistance change. However, the sensitivity is not sufficient because of the electrical conduction between neighboring fibers. In this study, surface oxidized SiC fibers were applied to prevent electrical conduction due to contacts between neighboring fibers. Model specimens were fabricated by embedding as-received or oxidized SiC fibers into epoxy resin, and electrical changes were measured under monotonic and loading-unloading tensile tests. As a result, electrical resistance of oxidized SiC fiber specimens increased remarkably with increasing strain as compared to as-received SiC fiber specimens. 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 difference of electrical resistance behavior about two kinds of specimens with different effective gage length was also indicated.
