Numerical simulation for development of methodology of stress-strain state control of composite bulkhead for aviation application with the usage of FBG sensors

Fiber-optic sensors are used to monitor the state of structures in various industries. The best solution for monitoring deformations in the products made of polymer composite materials are fiber Bragg gratings (FBGs). In this paper, we consider the possibility of studying the stress-strain state (SSS), tracking structural changes in the construction with the help of FBGs, using the example of a "U" -shaped composite frame of an aircraft engine. Based on the revealed regularities and peculiarities of the FBGs operation, the main control points have been determined. In the course of the research, we created a three-dimensional computer model of an aircraft propulsion system composite frame which was used for the analysis of the stress-strain state under various loading conditions. The developed model makes it possible to perform a layer-by-layer analysis of the composite frame structure to estimate the normal and shear interlayer stresses, which determine the destruction of the structure. Numerical modeling of this problem was carried out by the finite element method (FEM) in the software package ANSYS Workbench. Numerical results were compared with the experimental data obtained in laboratory tests of a composite frame segment equipped with fiber-optic sensors. The tests were carried out on the equipment of the unique scientific installation "Unique scientific and technological complex of automated computation" using the Zwick servo-hydraulic machine and the Astro X327 interrogator. The results obtained will be used to determine the size of the effective "sensitive zone" for embedding fiber-optic sensors (FOS) based on Bragg gratings into the construction of a composite frame. The main goal of this work is the development of a methodology for detecting and identifying various types of damage and the maximum load during the working lifespan of the structure.