Opracowanie czujników światłowodowych opartych na mikrorezonatorach pieśrścieniowych do monitorwania stanu technicznego konstrukcji w opraciu o propagację fal

Guided waves (GW) based monitoring is seen as one of the most promising structural health monitoring (SHM) techniques for damage detection in plate-like structures. In the frame of Opus 17 and Sonata 16 projects, application of fiber Bragg grating (FBG) sensors for GW measurements was studied. Some interesting phenomena and sensor capabilities were reported but also some shortcomings of the sensors were revealed. The motivation of this project is to overcome the shortcoming by leveraging novel developments in the field of photonics and manufacture of photonic devices. The project aims to develop novel optical fiber sensors based on micro-ring resonators (MRR) for GW sensing. The MRR are 100 times smaller and show better sensing performance. But these sensors are not commercially available. So multi-disciplinary research in the design of specialty optical fibers, then micro-fabrication and optimization of the sensors needs to be done. Once that is carried out, their performance for GW sensing will be assessed. The expected better performance can then be leveraged for better SHM using GW based techniques.

Key Objectives (8 out of total 13):
O1. Develop different geometries for the specialty optical fibers to fulfill different application demands (multi-core, D shaped) (Task 1)
O2. Study different geometries and configurations for the MRR to achieve improved sensitivity (Task 2)
O3. Study the influence of different process parameters on the optical performance of the MRR. (Task 2)
O4. Study & Benchmark the sensitivity of the MRR to GW with piezo based sensors and FBGs. (Task 3)
O5. Study the influence of ambient conditions (loading, temperature etc.) on the MRR (Task 3).
O6. Study factors affecting the sensitivity and utilization (Task 3)
O7. Develop new metrics and signal processing strategies based on the results from Task 3 (Task 4)
O8. Optimize the sensor placement location for improved performance of the SHM network (Task 4)

Methodology:
This project aims at developing a novel sensor system which is better for GW based SHM. The project proposes a three stage intervention to achieve this. The interventions will be development of specialty optical fibers to allow better GW coupling and allow in-fiber micro-fabrication of the MRR. The design of the optical fiber will be optimized for better optical and structural performance at sensor and system level. The task 2 deals with design, and micro fabrication of MRR. This will be done for better sensitivity to GW and robustness. Task 3 deals with studying and characterizing the MRR performance for GW sensing. All different sensitivity studies will be carried out. Novel configurations will be studied as well. The scope of the study is both numerical and experimental. Once the performance is benchmarked, the new features offered by the MRR (high frequency bandwidth, better sensitivity, isotropic sensitivity) will be leveraged for improving damage detection and localization in structures. Both metallic and composite structures will be studied. The project employs iterative approach where experience from the other tasks will be used to improve the entire system in all other tasks iteratively.

Key Innovations (5 out of total 9):
I1. Use of MRR for GW sensing (Tasks 1, 2,3)
I2. Development of novel optical fiber architecture for fulfilling the application demands (optical, mechanical and functional. (Tasks 1, 2, 3, 4)
I3. Improved understanding of the MRR response to incident guided wave (Task 3)
I4. Identification and quantification of the factor influencing the fiber-wave coupling including specimen material, bond type, bond length etc. (Task 3)
I5. Customization of GW based damage detection and isolation technique using MRR including damage sensitive metrics (Task 4)

Impact
a) Novel sensor system (100 time smaller).
b) Higher coupling of wave to fiber (3 times better).
c) Higher bandwidth (100% more) of sensing allows better reference-free SHM which improves applicability.
d) Reduction of number of sensors used and instrumentation cost (50%).
e) Improved sensitivity potentially (500%).