Summary
This paper presents the experimental results of strain measurements made by the fiber Bragg grating sensors embedded into polymer composite materials (PCMs). A series of performed experiments are described to demonstrate the capability of fiber optic sensors to measure strains in the case of their pronounced gradient distribution within the material, under compression and tension, at cyclic variation of strains with time and at different temperatures. A measuring technique is presented, and the results of strain measurements during the process of preparation of PCM including measurements of residual process‐induced strains are discussed.The results of strain measurements made by fiber optic strain sensors (FOSS) are compared with the results of numerical modeling based on the finite element method and independent measurement data obtained with the use of a digital optical system Vic‐3D and other experimental devices. The comparison made shows good agreement between the results obtained by the experimental methods and numerical simulation.The results of numerical computations demonstrate that the embedment of optical fibers in a PCM introduces perturbations in the strain distribution pattern in the vicinity of optical fibers but practically does not cause changes in the value of the strain tensor component measured by the FOSS. The conclusions about applicability range of FOSS embedded into PCM were made based upon the numerical simulation. The interrelation model between Bragg wavelength peak shift and the strain of the optical fiber in the fiber Bragg grating area for the sensor that is not affected by the environment is proposed.
The results of measuring gradient strain fields by embedded or mounted point fiber-optic sensors based on Bragg gratings and distributed fiber-optic sensors based on Rayleigh scattering are discussed. Along with the experiment, the results of numerical modeling of strain measurement errors associated with the assumption of uniaxial stress state in the area of the embedded Bragg grating and measurement errors by distributed fiber-optic sensors associated with gage length are presented. Experimental results are presented for 3D printed samples and samples made of polymer composite material. The geometry of the samples was chosen based on the results of numerical simulations, and provides different variants of non-uniform strain distribution under uniaxial tension, including the variant in which the derivative of the strain distribution function changes its sign. A good agreement of numerical results and experimental data obtained by distributed and point fiber-optic sensors in areas where the derivative of the strain distribution function keeps a sign and an increase in the error of strain measurement results by distributed fiber-optic sensors in areas where this derivative changes sign are demonstrated.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.