Papers by Keyword: Carbon Fiber Smart Layer

Abstract: The paper deals with the temperature sensitivity of a new type strain sensor named carbon fiber smart layer (CFSL) made of epoxy-matrix composites with short carbon fiber mats. The experiment result indicated that the epoxy matrix CFSL is sensitive to temperature variation. It exhibits NTC effect in -5°C~25°C and exhibits PTC effect in 25°C~50°C. The NTC effect is relatively gentle and the PTC effect is relatively dramatic. The mechanism of both NTC effect and PTC effect is discussed based on the temperature sensitivities of carbon fiber itself and the fiber to fiber interface. Further experiment demonstrated its temperature sensing properties in the temperature scale in which the NTC effect or PTC effect exhibits individually.

Abstract: The paper makes a comprehensive study on the sensitivity of a new type strain sensor named polymer-matrix carbon fiber smart layer. The sensitivity to tensile strain was gained by a uniaxial tension test. By a three-point bending test on a FRP bar stuck by the smart layer, the sensitivity to compressive strain was revealed and a lower gauge factor was obtained compared to the sensitivity to tensile strain. In addition, a pure shearing test was designed, revealing the sensitivity to shear strain.

Abstract: Based on the piezoresistive function character and the conductivity of carbon fiber smart layer (CFSL), a novel electrical resistance tomography (ERT) system of spherical and cylindrical CFSL has been developed for global health monitoring. Based on the background of the third generation nuclear containment vessel, CFSL is stuck on the surface of the structure, and the effectiveness of the ERT system is verified by virtual experiment. The image reconstruction results show that CFSL on two-dimensional curved surface has good sensing characteristics in the complex strain state. Compared with structural volumetric strain in the monitoring area, it indicates that the high electrical resistance of CFSL is distributed in the high strain area of structures, and the low electrical resistance of CFSL is just distributed in the low strain area of structures. Therefore the resistivity’s distribution of CFSL can reflect qualitatively the structural volumetric strain field.

Abstract: With epoxy reinforced by short carbon fiber mats, a skin-like strain sensor, polymer-matrix smart layer was developed, which can continuously cover the structural surface to sense strain for the whole filed. The smart layer was proved to be an effective strain sensor for tensile strain up to 0.8% by a monotonic tension experiment, exceeding this limit cause nonlinearity in the resistance response. The damage sensitivity of the smart layer was revealed by the monitoring for a FRP beam with prefabricated defect. Based on its sensitivities, the smart layers was applied in the health monitoring for a concrete beam under three-point bending, the result showed a good correlation between the resistance change of the smart layer and the load applied on the structure. The emergency of structure damage can be monitored by the turning point on the resistance-deflection curve of the smart layer.