Fiber Bragg grating-based shear strain sensors for adhesive bond monitoring

Abstract

The application of shear stress sensors in structural health monitoring remains limited because current sensors are either difficult to implement, they feature a low measurement resolution or the interrogation of the output signal is complex. We propose to use fiber Bragg grating-based sensors fabricated in dedicated highly birefringent microstructured optical fibers. When embedded in a host material, the orientation angle of the fiber should be chosen such that their polarization axes are aligned parallel with the direction of maximum shear stress when the host is mechanically loaded. We present experimental results of sensors embedded in the adhesive layer of single lap and double lap structural joints. These tests demonstrate that when the joints are tension loaded, the embedded sensors have a shear stress sensitivity of around 60 pm/MPa. We study the influence of the adhesive material on the sensor response, as well as the influence of sensor orientation and location in the bond line. Finally, we demonstrate the minimal thermal cross-sensitivity of the shear stress sensitivity of this sensor.

Sensors for the measurement of shear stress and shear strain-a review on materials, fabrication, devices, and applications

“…The recorded shear force sensitivity was 60 picometer (pm)/MPa for these different configurations. A small change in environmental temperature affects the measured value and the sensitivity of this sensor was dependent on the temperature [76]. Müller et al focused on the numerical integration of the four coupled-mode equations which is the requirement of FBG sensors.…”

Internal strain monitoring in composite materials with embedded photonic crystal fiber Bragg gratings

“…mbedded such a shear loaded of the Bragg ivity of abou fringent fibers show that by sensing or for sensor [28]. will nearly remain constant, independently of the loading level.…”