Strain sensing characteristics using piezoresistivity of semi-conductive silicon carbide fibers

Abstract

Conductive fibers having piezoresistive characteristics such as carbon fibers can be used as a sensing component as well as a load bearing component in composite materials by weaving them together with reinforcing fibers or embedding the fibers into composite materials. Silicon carbide (SiC) fibers with semi-conductive grade can have outstanding piezoresitive properties due to the inherent characteristics of semi-conductive materials, so the fibers have potential as a strain sensor with a high gauge factor (GF). In this study, the strain sensing characteristics of semi-conductive SiC fibers were investigated and the electrical sensing properties of the SiC fibers were evaluated. The SiC fibers were embedded into unidirectional glass/epoxy composites and the resistance change of the SiC fibers was measured according to the applied mechanical strain. Static loading and cyclic loading were applied to the SiC fiber embedded composite specimens and the electrical sensing characteristics of the SiC fiber piezoresistivity were evaluated for sensitivity, linearity, measurement repeatability, and noise level. As a result, the piezoresistivity of the SiC fibers showed outstanding strain sensitivity with an average GF of 8.25 and excellent linearity up to the strain range of 1.36%. The measurement was consistently repeated within the maximum coefficient of variation (CV) of 1.13%, and the average noise level was 5.75 Finally, by comparing the strain sensing performance of the SiC fibers to that of carbon fibers, the potential of the SiC fibers as a strain sensor for composite materials was assessed.