Electrical sensing properties of carbon fiber reinforced plastic strips for detecting low-level strains

In this work, the electrical sensing properties of carbon fiber reinforced plastic (CFRP) strips under tension strains were studied. The electrical resistance change ratio of a CFRP strip responds to the applied axial and transverse strain. Under 500 microstrain, the strain sensing properties of CFRP strips with different width–length ( w / l ) ratios vary significantly. The experimental results showed that the nonlinear transverse effect was reduced as the w / l ratio of CFRP strips increased. For a CFRP strip with gauge length equal to or larger than 500 mm (i.e. w / l ≤ 0.0012), the magnitude of the transverse effect was greatly reduced. The gauge factor for the 500 mm long CFRP strip with a linear relationship to the applied strain was determined. The long gauge length CFRP strip can provide more reliable signal behavior, even at a low strain level of 200 microstrain or a high strain level of 1000 microstrain. Based on the results of a long-term cycle tension test, the cycle-ability and the possible noise range of CFRP strips are quantitatively discussed. Finally, the sensing properties of an effective CFRP strip on low-level strains are summarized.