Abstract
Despite the extensive body of research on fiber Bragg grating (FBG) sensors, embedding FBGs into composite materials still leaves an important challenge unresolved: improving model accuracy while preserving sensitivity under coupled thermo-mechanical loading. In this work, an integrated mathematical model of an FBG-based fiber-optic sensing subsystem is developed and implemented in MATLAB/Simulink, enabling simultaneous estimation of mechanical action (pressure/strain) and temperature from the Bragg-wavelength shift while explicitly accounting for optical, mechanical, and thermal parameters of the composite host. The model combines Bragg-wavelength shift computation with strain-optic and thermo-optic contributions, a composite stress–strain transfer that maps external pressure to axial fiber strain, transient heat transfer to the grating region, and synthesis of the reflected spectrum and optical power profile for interrogation. A calibration-based decoupling stage is included to separate thermal and mechanical components, and the Simulink workflow supports parameter sweeps and uncertainty analysis. Model outputs agree with reference/experimental data, with a discrepancy not exceeding 4% across the considered operating range. Simulations indicate a pressure sensitivity of 5–15 pm/kPa, a refractive-index sensitivity of up to 500 nm/RIU, and a tunable spectral range of 1530–1570 nm, while remaining stable under simultaneous pressure and temperature variations. The proposed model serves as a practical digital prototype for embedded FBG sensing and supports design optimization, compensation-strategy development, and structural health monitoring scenario evaluation.