Study on the Influence of Mechanical Noise on the Impact Identification Performance of an FBG Accelerometer

The influence of mechanical noise on impact identification using fiber Bragg grating (FBG) accelerometers in complex environments remains insufficiently explored and quantitatively characterized. This study investigates how the intensity and propagation path of mechanical noise affect the output stability and impact-detection capability of a self-developed FBG accelerometer. A quantitative evaluation approach is established using wavelength-variation statistics, impact-response amplitude, and signal-to-noise ratio (SNR). Experimental results show that mechanical noise markedly increased the background wavelength fluctuation, with the maximum standard deviation reaching 16.71 pm, approximately 11 times the no-additional-noise value. By contrast, the RMS of the target impact response increased only slightly, from 0.0300 nm to 0.0353 nm, indicating that mechanical noise primarily affects baseline stability rather than the amplitude of the target impact response. Under the highest-intensity disturbance tested, the SNR remained at 22.98 dB, and the impact event remained distinguishable. The proposed multi-indicator approach provides a quantitative characterization of the FBG accelerometer response under different mechanical-noise conditions. A commercial 941B accelerometer was used as an external reference for sensitivity calibration, and its measurements were not used for direct performance comparison with the FBG accelerometer. The results provide experimental evidence of the impact-identification behavior of the proposed sensor under the investigated mechanical-noise conditions.