Abstract
his paper reports the design, fabrication, and experimental validation of smart tilted fiber Bragg grating (TFBG) sensors embedded within the internal structure of wooden beams for real-time strain and deflection monitoring. Pine and oak specimens were instrumented with five multiplexed FBGs distributed along the span and tested under a constant end load to capture the strain field during bending. To mitigate temperature-induced bias in the deflection analysis, a dedicated reference FBG was placed in a non-deflecting zone and used to compensate the individual temperature response of each sensing element. The optical transducers were encapsulated in epoxy-impregnated carbon fabric to ensure reliable strain transfer, mechanical protection, and long-term stability without compromising the host material. Wavelength-shift demodulation and in-situ calibration provided separate estimates of strain and temperature, enabling accurate reconstruction of the beam shape. The temperature-compensated measurements showed close agreement with Euler–Bernoulli beam predictions for both wood species, with correlation coefficients exceeding 0.87 across all trials. The sensing system exhibited repeatable behavior and low hysteresis, while the embedded configuration preserved the structural integrity and allowed unobtrusive installation. Overall, the results demonstrate that smart TFBG sensors are a practical and effective solution for embedded structural health monitoring of timber members, offering high accuracy, electromagnetic immunity, and seamless integration into load-bearing components. The approach is readily scalable to multi-sensor arrays and mixed materials, paving the way for continuous monitoring of civil and architectural wooden structures.