Analysis of Reliability of Strain Measurements Made with the Fiber Bragg Grating Sensor Rosettes Embedded in a Polymer Composite Material

Abstract

The results of strain measuring experiments, with the help of rosettes consisting of fiber Bragg grating sensors (FBG) embedded at the manufacturing stage in a polymer composite material are considered in this paper. The samples were made by the direct pressing method from fiberglass prepregs. A cross-shaped sample was tested under loading conditions corresponding to a complex stress state. A variant of strain calculations based on experimental data is discussed. The calculations were performed under the assumption of a uniaxial stress state in an optical fiber embedded in the material. The obtained results provide a reasonable explanation of the absence in the conducted experiment of two peaks in the reflected optical spectrum, the presence of which follows from the known theoretical principles. The experimental result with two peaks in the reflected optical spectrum was obtained for the same sample under a different loading scheme. The proposed variant of the numerical model of the experiment and the results of numerical simulation made for FBG rosettes embedded in the material allowed to estimate error in the strain values calculated on the assumption of the uniaxial stress state in the optical fiber and in the presence of two peaks in the reflected optical spectrum.

Enhancing the Distributed Acoustic Sensors’ (DAS) Performance by the Simple Noise Reduction Algorithms Sequential Application

“…Many of these technologies are adapted to perceive both static and dynamic external impacts on optical fiber, such as sound and other mechanical vibrations, temperature variations, and mechanical stress. Over the last few Algorithms 2023, 16, 217 2 of 15 decades, acoustic monitoring has gained great popularity in many industries such as oil and gas production [22], processing [23], transportation [24], geophysics and mineral deposits exploration [25], protection of territories [26], and structural integrity monitoring of vital engineering constructions [27][28][29]. At the moment, such monitoring is usually performed by fiber optic DASs (due to their intrinsic advantages) using phase-sensitive technology (ϕ-DAS) implemented with the use of high-coherence light sources and direct or hybrid backscattering detection, since conventional OTDR is not sensitive to dynamic deformations, has a higher noise level, and requires additional time for the obtained data averaging.…”

Model of the Temperature Influence on Additively Manufactured Carbon Fibre Reinforced Polymer Samples with Embedded Fibre Bragg Grating Sensors

“…Meanwhile, since composite materials are subjected to different mechanical and/or thermal loading, which decreases the structural performance, it has been essential to develop a reliable and precise real-time monitoring method in order to obtain information on the structural state of material to improve the performance of composite products [ 7 , 8 , 9 ]. Surface mounted optical fibre sensors have obtained remarkable attention in the field of experimental stress analysis and health monitoring of composite structures [ 10 ].…”