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 goal of this work is an analysis of modern technologies and problem definitions of mechanics of composite materials for production of outlet guide vane for new domestic aviation propulsion PD-14, planned for installation on the short-range and mid-range jet aircraft MS-21. Outlet guide vanes (OGV), also called flow straightening vanes, are radially disposed behind the fan to straighten out the airflow to reduce losses in the outer contour of the engine. Considering a large number of vanes in the engine, the weight reduction can be very significant due to using polymer composite materials (PCM) instead of the metal in OGV. It is predicted that the weight reduction of each vane, at certain approach to design, can reach 40 %. The results of literature search of composite materials application in the details of fan for aircraft jet engines of world top manufacturers are presented in this paper. The analysis of advanced techniques for production of composite outlet guide vane, such as prepreg technology with autoclave molding, resin transfer molding (RTM), the use of thermoplastic binders and press-materials was carried out. It was noted that the formulation and solution of complex problems of engineering mechanics of composite materials are necessary for high-rate realization of mechanical properties in constructions and reducing the occurrence of defects. The possible problem definitions of deformable solid body mechanics, describing such processes as filtration, physical and chemical conversion, visco-elastic-plastic deformation in heterogeneous medium, typical for composite materials production cycle were considered. The influence of autoclave molding parameters on the mechanical properties of several types of carbon fiber reinforced plastics (CFRP) was analyzed. Using the equations of mechanics of laminated composite plates and shells we calculated effective elastic and strength properties of quasi-isotropic CFRP. A comparative estimate of the effectiveness of composite materials application in the design of OGV was obtained.

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