Logowanie do System sprawozdań KDM

Badania układów czujników światłowodowych na potrzeby monitorowania falami prowadzonymi stanu technicznego konstrukcji

Kierownik projektu: Rohan N. Soman

Instytut Maszyn Przepływowych PAN w Gdańsku

Gdańsk

Streszczenie projektu

Context: 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 as it allows inspection of large areas with few number of sensors. The fiber optic (FO) sensors have several advantages such as immunity to magnetic and electric fields, small size low weight etc. But their use for GW sensing was limited due to their low sensitivity. But the use of edge filtering approach and the remote bonding of the fiber Bragg grating (FBG) sensors it is possible to obtain good sensitivity thus paving the way for their use in structures. In order to use these sensors in the structure the physics of the measurement and interaction of the fiber with the wave as well as the material, bonding etc. needs to be studied. Also the existing GW based SHM techniques need to be customized for the use with the new sensing technique. Lastly to ensure that the performance of the method is comparable to other methods optimization of the methodology is required and hence is identified as the goal of the proposed project.

Objectives:

O1. Study of the coupling between the specimen and the fiber and its effect on the wave propagation.

O2. Study of the variables such as bond type, bond length, excitation frequency, direction of the incident wave etc. on the coupling of the waves in the fiber.

O3. Implementation of damage detection and isolation algorithm based on multiplexed FBG sensor arrays in plate like structures.

O4. Development of optimization of placement for FBG sensors for improved damage assessment

Methodology: This project aims at studying the phenomena of wave coupling between the fiber and the sample. The different factors affecting the coupling will be studied quantitatively and qualitatively through experimental as well as numerical studies. The scope of the sensitivity studies will include different sample and fibre materials, different orientation of fibres, different bond types and lengths. The wave coupling phenomenon on embedded fibres will be studied as well. Analytical models will be developed for estimation the effect of the coupling under real conditions. The analytical models then will be applied for compensating the effects of the coupling for locating the damage using the ellipse and hyperbola based approach for GW.

For the improved performance of the SHM technique using GW, optimization of sensor placement will be carried for the application of FBG sensors which show directional sensitivity. The anisotropic sensitivity makes it imperative to develop a real encoded genetic algorithm for the application as well as new cost functions based on application demands and functional constraints imposed by the FBG sensors.

Innovation:

I1. Improved understanding of the fiber-wave coupling and the directionality of propagation

I2. Identification and quantification of the factor influencing the fiber-wave coupling including specimen material, bond type, bond length etc.

I3. Customization of GW based damage detection and isolation technique using FBG based sensors

I4. Optimization of sensor placement for GW based SHM using FBG sensors taking into consideration the constraints and advantages of the FBG

I5. Development of a two-step optimization strategy for controlling the problem size to ensure thorough search of the search-space

Impact

? Better understanding of the wave coupling phenomena and quantification of the factors affecting the coupling.

? Development of definitive methodology for damage detection using GW based on FBG sensors.

? An optimization methodology useful for sensors with directional sensitivity as well as based on the functional constraints of the FBG sensors.

? A better understanding of the wave coupling phenomena in embedded fibres.