A7.4 - Estimation of Material Degradation by Backscattered Ultrasonic Tomography

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings SENSOR 2011
A7 - Ultrasonic Sensors II
R. Romanyshyn, V. Koshovy, I. Romanyshyn, R. Sharamaga - National Academy of Sciences of Ukraine, Lviv (Ukraine)
177 - 180


A new aproach to the estimation of degradation of material in the bulk of product based on backscattered ultrasonic tomography is presented in the paper.
The proposed approach is based on the physical assumption that material degradation leads to the increase of structure heterogeneities of material and increase of the variation of physicomechanical properties of material. That’s why the estimation of degradation degree consists in the estimation of the chaoticy of scattering property tomographical images.
Methods to assess of the operative degradation based on tomographic images of thick-walled cylindrical objects are reduced to:

- ultrasound scanning of the product with registration of the scattered ultrasonic signal in the form of A-scans, processing of registered A-scans and the formation of spherical projection;
- 3D-tomographic reconstruction of the scattering in the bulk of material;
- the estimation of metal degradation degree in the bulk of the product can be carried out with the usage of statistical processing of scattering coefficient tomographical images. In particular the chaotic of the tomographical images can be calculated.

For the quantitative characteristics of the chaotic distribution of scattering coefficient a parameter similar to the signal to noise ratio when compared the standard image with an etalon is proposed to use.
SNR decreases while degradation increase. The results of experimental verification of the proposed technologies on steel thick feedwater lines in Rovno nuclear powerplant have confirmed the effectiveness of this approach.