V. V. Shiryaev

Thermal (infrared) tomography: Terminology, principal procedures, and application to nondestructive testing of composite materials

The methods of infrared (thermal) tomography are reviewed. Approaches to the dynamic thermal tomography of composite materials are described, which are based on the analysis of changes in the surface temperature with time. Most experimental illustrations refer to thermal testing of fiber reinforced plastic as the typical material used in the air- and spacecraft industry.

Processing of active thermal nondestructive testing results by the method of wavelet analysis

Wavelet transforms can be used for active thermal nondestructive testing for the identification of flaws that are located at different depths and produce Gaussian-like signals characterized by a time shift on a heated surface. The results of the application of scalar and complex wavelet analysis for increasing the signal/noise ratio in the active thermal inspection of flaws in composite materials and thermal-barrier coatings, as well as also for revealing the corrosion in metals, are described. Parent Morlét, Paul, and Mexican-hat wavelets were used.

Application of principal component analysis in dynamic thermal testing data processing

The principles and features of the application of statistical principal component analysis (PCA) in active thermal testing are considered. A comparison between PCA and Fourier analysis in finding defects in composite materials, detecting corrosion in aluminum, and determining moisture content in construction materials is performed. It is concluded that, generally, images of principal components increase the signal-to-noise ratio and are close in performance to phase diagrams; nevertheless, the results of this method are poorly predictable and require further analysis.

Active Thermal Detection of Water in Cellular Aircraft Structures

The paper describes the technique and instrumentation for active thermal detection of water in cellular structures fabricated from aluminum, glass-enforced plastic, and carbon-fiber plastic. Results of modeling and experimental tests are given. Limiting characteristics of the method are discussed.

IR thermographic evaluation of thermal diffusivity anisotropy: comparative analysis of some algorithms

Theoretical and experimental results for determining thermal diffusivity components in anisotropic Carbon Fiber Reinforced Plastic laminates up to 5 mm thick are presented. The effectiveness of the theory is evaluated by using a 3D numerical model. IR thermographic implementation of the Parkers technique has been used for determining transverse diffusivity. Both spot- and slit-mask techniques have been applied for analyzing thermal diffusivity components.

An apparatus for the active thermal testing of corrosion in steel cylindrical containers and test results

An apparatus that works on the thermal-testing principle involving infrared thermal imagers of different types and optical and convective heating devices is described. The main purpose of the apparatus is to detect hidden corrosion in 1- to 2-mm-thick steel containers that are intended for temporary storage of radioactive wastes.

Transient thermal nondestructive testing (NDT) of defects in aluminum panels

This paper describes results of the inspection of aluminum specimens by transient infrared thermography. The inspected specimens contain various defects: internal and external corrosion, delaminations and water between two sheets. The accent is made on comparison between scanning IR radiometer and FPA camera, verification of theoretical data by experiment, discrimination between different defects and simple inversion method for corrosion data.

A novel data processing algorithm in thermal property measurement and defect detection by using one-sided active infrared thermography

The proposed algorithm is based on the analysis of an artificial front-surface pixel-based function which includes temperature and time. This function experiences certain extremums, and the corresponding times can be used for determining thermal diffusivity by the formula similar to the known Parker expression. In thermal NDT, such approach being applied to defect areas, provides diffusivity variations which can be used for the evaluation of defect severity in a particular specimen. In this study, both the theoretical basis and the some experimental implementations of the proposed data processing algorithm have been explored to illustrate its validity in thermal properties measurement and thermal NDT, including thermal tomography.

Trends in Using Passive Thermal Imaging Diagnostics in Power Engineering and Industry

The regions of application of thermal imaging technique for testing the heat shielding of building structures, diagnostics of smoke pipes, boilers, cooling ponds, and thermal service lines are described.

Advanced IR sensing technology research in the city of Tomsk, USSR

Some large scientific organisations in the city of Tomsk, Siberia, USSR are involved into the researchings on the advanced IR sensing technology. They are Polytechnic Institute founded in 1896, Uriiversity of Tomsk founded in 1888, Institute of Atmospheres Optics, Academy of Sciences arid Institute of Automatized Control Systems and Radio electronics. Main fields are as follows: 1) thermal (IR) nondestructive testing of materials, machines and systems; 2) optoelectronics; 3) laser optics, transmission of infrared through the atmosphere and investigation of energy distribution in laser beams. Researching equipment includes Western and Russian industrial thermovisers, lasers, personal computers, IR detectors etc and some borne-made devices and components. There are optical arid JR detectors Lndustry in Tomsk that allows i.e produce spheric and aspheric mirrors and lenses, JR filters, cadmium-mercury-teilur and indium anlymonide T1 receivers arid to develop the scanning and measuring devices on the base mentioned above. Seine projects to develop the specific Tomsk thermoviser so far have nOt come true so the main accent was made onto the computerized thermographic systems suitable for solution of particular scientific problems.