In-situprocess and condition monitoring of advanced fibre-reinforced composite materials using optical fibre sensors

Abstract

This paper presents a general overview of a number of optical fibre sensor systems which have been developed and used in advanced fibre-reinforced composites for in-situ process and condition monitoring. The in-situ process monitoring techniques were optical-fibre-based evanescent wave spectroscopy, transmission near-infrared spectroscopy and refractive index monitoring. The optical fibre sensors were successful in tracking the cure reaction. The condition monitoring of advanced fibre-reinforced composites was carried out using two intensity-based optical fibre sensor systems: an extrinsic multi-mode Fabry-P érot sensor and Bragg gratings. In addition to this, the feasibility of using the reinforcing fibre as a light guide was demonstrated. These sensor systems were evaluated under quasi-static, impact and fatigue loading. The test specimens consisted of prepreg-based carbon-fibre-reinforced epoxy and glass-fibre-reinforced epoxy filament-wound tubes. Excellent correlation was obtained between surface-mounted strain gauges and the embedded optical fibre sensors. The feasibility of using these sensor systems for the detection of impact damage and stiffness reduction in the composite due to fatigue damage was successfully demonstrated.

Cure monitoring of carbon–epoxy composites by optical fiber-based distributed strain–temperature sensing system

“…Therefore, quality assurance of large-scale composite structures is necessary, and there is an urgent need to develop effective cure monitoring techniques for composite materials since the quality of the materials is very dependent on their cure processes [1][2][3]. Several cure monitoring techniques are utilized for composite materials, such as differential scanning calorimetry [4], dielectrometry [5], and point type optical fiber sensors including extrinsic Fabry-Perot type sensors [6,7], Raman spectroscopy [8], and fiber Bragg grating (FBG) sensors [9][10][11]. Among these techniques, optical fiber sensors are very useful for strain and temperature monitoring of composite materials.…”

Fatigue Crack Length Measurement of Sputtered Metal Film for RFID-based Smart Stress Memory Patch

“…However, a RFID sensor tag to evaluate the accumulation of fatigue damage has not been presented because it is difficult to combine the RFID system and traditional fatigue assessment techniques, such as continuous strain monitoring by strain gage or FBG (Fiber Bragg Grating) sensor. [11][12][13] The estimation of fatigue damage of structures is very important to avoid fractures due to their aging degradation. Therefore, RFID-type fatigue sensor is strongly required for this sensor network.…”

On the feasibility of optical fibre sensors for strain monitoring in thermoplastic composites under fatigue loading conditions

“…It was even concluded that optical fibre Bragg sensors were more reliable than classical strain gauges [1]. Doyle et al [3] experimented on the use of fibre optic sensors for tracking the cure reaction of a fibre reinforced epoxy, with success. They also successfully demonstrated the feasibility of these sensors for monitoring the stiffness reduction due to fatigue damage, but for thermosetting matrix.…”