Abstract: For the purpose of long-term real-time health monitoring for GFRP structures, composite made of short-cut carbon fiber mat and epoxy resin was applied as a smart layer for deformation measuring. The piezoresistivity of the smart layer was studied by cyclical tension test, and it was applied on a three point bending beam. The stable VA characteristic and piezoresistivity were confirmed in CFRP smart layer. Under cyclical tension, the resistance of CFRP smart layer was observed to increase linearly and reversibly with stability. Based on its piezoresisitivity, the resistance of the CFRP smart layer is able to reflect the bending deformation of the GFRP beam whether it is on the tension side or compression side. Furthermore, the results reveal that such a method can be affected by electrode configuration: the resistance responses of four-probe method are more stable, but the gauge factors are comparatively low, which is 5.9 for four-end probe method and 7.3 for four-surface probe method; two-probe method can improve the gauge factor to 13.1, but is inferior to four-probe method in stability.

Key words: GFRP, CFRP, piezoresisitivity, deformation monitoring