Self-sensing of damage in carbon fiber polymer-matrix structural composites by electrical measurement
MetadataShow full item record
This thesis assesses the ability of carbon fiber polymer-matrix structural composites to sense their own damage. The self-sensing involved electrical measurement. The damage was inflicted by impact at controlled energy levels. The study encompassed damage sensitivity determination, data precision analysis, specimen dimension effects and electrical contact configuration design. The resistance of the segment of the specimen containing the impact point increased upon impact. The resistance obtained by using the four-probe method is a more sensitive, more accurate and more precise (less data scatter) indicator of impact damage than that obtained by using two-probe method. The two-dimensional electric potential/resistance method is much less sensitive than the one-dimensional resistance method. In the two-dimensional method, the resistance method is more sensitive than the potential method. The sensitivity of the potential method is enhanced when the potential gradient line is close to the current line. The electric potential method is effective for damage sensing in carbon fiber polymer-matrix composite when the distance between the current line and potential gradient line is sufficiently small, such as 1.0 mm in the through-thickness direction; it is ineffective when this distance is 2.1 mm or more. The resistance method has no thickness limitation, but it suffers from current path distortion upon damage and consequent reduced sensitivity.