AUTHORS:

Soman R., Rahman W., Filipkowski A., Anuszkiewicz A., Kasztelanic R., Osuch T., Buczynski R., Peters K.

ABSTRACT:

Structural health monitoring (SHM) based on guided waves (GW) have received great interest in last few years particularly for thin-walled structures. The GW are especially attractive as they can inspect large areas with a few discrete sensors and are sensitive to barely-visible structural damages. The utilization of the fiber Bragg grating (FBG) sensors for GW sensing is gaining attention. The FBG sensors have shown some unique abilities such as remote sensing, acoustic coupling, mode filtering etc. But their use has been limited for the GW sensing due to its limited sensitivity. One of the challenges with improving the sensitivity, and ensuring repeatability with the FBG sensors is the uncertainty in the bond quality. This is especially important due to the small area of contact between the fiber and the structure. A solution to this is the use of a D-shaped optical fiber which increase the area in contact. This paper for the first time investigates the coupling efficiency and attenuation of GW in D-shaped fibers using numerical and experimental analysis. For the experimental analysis scanning laser Doppler vibrometer (SLDV) and FBG in edge filtering configuration have been utilized. The experimental results are supported by numerical simulations. The results indicate that the coupling efficiency for the D-shaped fiber improved by 50% as compared to the standard single mode fiber (ssmf) while the attenuation characteristics are comparable. The improved coupling efficiency can allow more widespread utilization of the D-shaped fibers for GW based SHM.

Measurement, 2026, vol. 273, art. 121093, doi: 10.1016/j.measurement.2026.121093