Strain monitoring of laminated composites using novel hybrid nanofibrous sensors

Abstract

Structural Health Monitoring (SHM) of composite structures necessitates developing robust and resilient sensors which operate in harsh environments with high degree of sensitivity, and are easily integrable in structural components. Electrospinning has been explored in the past for the fabrication of nanofibers whereas electrospraying has been exploited for the deposition of electrosprayed clusters. In this paper, a hybrid manufacturing technique is proposed for manufacturing nanofibrous webs from conductive polymer composite (CPC) solutions. The degree of shear thinning of the solutions is compared by rheological analysis, which shows that the solution with a 2% w/v is effective for electrospray, with a greater degree of shear thinning behavior than a 10% w/v solution. These webs gain their structural integrity and provide multiple sensing mechanisms when nano-sprayed clusters of the same CPC solution weld the fibers obtained through electrospinning together on a polycarbonate substrate. These laminates are then cut into strips and pasted on glass fiber-reinforced polymer (GFRP) composites for strain monitoring with an aim for SHM. Electrochemical impedance spectroscopy is used to characterize the sensing capability using the electrolyte/interface and surface reactions. The thermogravimetric analysis was conducted to study the suitable temperature range for the developed sensor. The measured gauge factor is 2.5. The sensor is tested up to 2000 cycles while the maximum linearity error and maximum hysteresis error of the sensor are calculated as 0.893 and 1.168. This proves the sensor’s effectiveness for quasistatic as well as dynamic loading scenarios. The fractographic analysis also shows that the sensors can follow various failure modes with the applied load