Multi-axial strain transfer from laminated CFRP composites to embedded Bragg sensor: II. Experimental validation

Abstract

Embedded optical fibre sensors are considered in numerous applications for structural health monitoring purposes. Since the optical fibre and the host material in which it is embedded have different material properties, the strain in both materials will not be equal when external load is applied. Therefore, the strain transfer from the host material to the embedded sensor (optical fibre) was studied in more detail in the first part of the paper. This second part presents an experimental evaluation of the response of uni-axial fibre Bragg grating sensors embedded in small cross-ply composite laminates subjected to out-of-plane transverse loading. This loading case induces high birefringence effects in the core of the optical fibre. Using the numerically determined strain transfer coefficients (Luyckx et al 2010 Smart. Mater. Struct. 19 105017) together with multi-axial strain formulations, the authors were able to measure with reasonable accuracy the total strain field inside a carbon fibre reinforced plastic specimen.

The study of internal structure of woven glass and carbon fiber reinforced composite materials with embedded fiber-optic sensors

“…A similar situation was observed for CFRP specimen. The obtained results on the distortion of the reflected optical signal from FBG sensors embedded into composite materials with a woven reinforcement structure are consistent with well-known studies for unidirectional composites [18,29,30]. This result shows that this problem is common for different types of composite materials and types of reinforcement.…”

Fiber Bragg Grating Sensors in Three Asphalt Pavement Layers

“…An external perturbation (temperature, strain) causes the central Bragg wavelength to shift [6]. FBG is one of the most used technologies in commercial applications in the fields of optical communication and composite materials [7], temperature sensors, and strain sensors due to several inherent advantages over other technologies: accuracy and range, lightweight, small size, self-referencing, multiplexing, immunity to electromagnetic interference, and environmental ruggedness [8]. The tensility or compression of the grating can lead to a period change when the FBG sensor (FBGs) is deformed by outside temperature change or loading.…”

Multi-instrumentation monitoring for the curing process of a composite structure

“…On the optical devices side, micro-structured optical fibres (MOF) [21][22][23][24][25] have been developed in order to maximize the quantification of the light beam perturbation. These recent technologies have been showed efficient diagnosis on the thermal phenomena which occur during composites curing.…”