Comparing thermal stimulation techniques in infrared thermographic inspection of corrosion in steel

Remote detection of corrosion in metals is a developing application area of active thermal nondestructive testing. In this study, emphasis is made on the optimization of heating techniques that is of a major interest in practical surveys. Some popular data processing techniques, such as Fourier transform, correlation and principal component analysis, are also quantitatively compared in application to corrosion detection in 1-2 mm thick steel by applying a criterion of signal-to-noise ratio. The best inspection results have been obtained by using powerful halogen lamps and air blowers. Material loss of about 25 % with lateral dimensions greater than 10x10 mm can be reliably identified in practical tests. The use of Xenon flash tubes is inefficient because of significant steel thickness. LED panels have not provided expected results due to low absorption of LED quasi-monochromatic radiation

Hardware and Software for Thermal Nondestructive Testing of Metallic and Composite Materials

Modeling and processing software, as well as experimental units, developed at Tomsk Polytechnic University for the last decade in the field of thermal/infrared nondestructive testing, are shortly described in this paper along with some illustrations of using this technique in the detection of impact damage in composites and corrosion in metals

Inspecting aviation composites at the stage of airplane manufacturing by applying 'classical' active thermal NDT, ultrasonic thermography and laser vibrometry

The results of applying three nondestructive testing techniques to the inspection of parts of a new Russian TVS-2DTS airplane made of carbon fiber reinforced plastic are presented. A basic technique implemented in workshop conditions implements optical stimulation of inspected parts. The usefulness of ultrasonic infrared thermography combined with laser vibrometry in the evaluation of parts with complicated geometry is illustrated. Samples with artificial and real defects have been tested in workshop conditions

Defining the Thermal Features of Sub-Surface Reinforcing Fibres in Non-Polluting Thermo–Acoustic Insulating Panels: A Numerical–Thermographic–Segmentation Approach

Natural fibres present ozone-friendly solutions in the field of construction. The attenuation of the sound and heat losses is an important feature in such type of materials above all, when used in non-woven fabrics and fibre-reinforced composites. Hemp fibres show robust insulation performance; this research work should be considered beneficial to the development of a non-destructive thermographic methodology, which can address the thermal barrier (typically applied on multi-layer panel) effects. The intent is to assess the integrity of the sub-surface reinforcing glass fibres; such integrity state will help confer the rigidity and the resistance to mechanical stresses. The testing proposed in this study can be further developed in a laboratory right after the manufacturing process of similar type of components. The testing needs preliminary numerical simulations to help guide the selection of the appropriate pre- and post-processing algorithms combined with or without segmentation operators. A set of numerical and experimental tests were performed through controlled thermal stimulation while recording the thermal responses. The study also highlights the advantages, disadvantages, and future development of the presented technique and methodologies