Frequency separation of signals and interferences in noise-immune ultrasonic testing of articles manufactured from complexly structured materials (original) (raw)
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Measurement Techniques, 2012
Problems of ultrasonic noise-immune testing of complexly structured cast-iron articles are considered. It is shown that the extraction of informative echo signals from noise and interference requires, in addition to the fulfillment of optimal signal-filtering conditions, the use of flexible multifunctional equipment for ultrasonic testing that allows formation of various signals, flexible variation of their parameters, and application of numerous radio-engineering operations to signals for adapting the parameters of the instrumentation to the characteristics of a tested object.
Physics Procedia, 2015
Some technical aspects of two Spanish cooperation projects, funded by DPI and Innpacto Programs of the R&D National Plan, are discussed. The objective is to analyze the common belief about than the ultrasonic testing in MHz range is not a tool utilizable to detect internal flaws in highly attenuating pieces made of coarse-grained steel. In fact high-strength steels, used in some safe industrial infrastructures of energy & transport sectors, are difficult to be inspected using the conventional "state of the art" in ultrasonic technology, due to their internal microstructures are very attenuating and coarse-grained. It is studied if this inspection difficulty could be overcome by finding intense interrogating pulses and advanced signal processing of the acquired echoes. A possible solution would depend on drastically improving signal-to-noise-ratios, by applying new advances on: ultrasonic transduction, HV electronics for intense pulsed driving of the testing probes, and an "ad-hoc" digital processing or focusing of the received noisy signals, in function of each material to be inspected. To attain this challenging aim on robust steel pieces would open the possibility of obtaining improvements in inspecting critical industrial components made of highly attenuating & dispersive materials, as new composites in aeronautic and motorway bridges, or new metallic alloys in nuclear area, where additional testing limitations often appear.
Russian Journal of Nondestructive Testing
Problems of ultrasonic noise-immune testing of complexly structured cast-iron articles are considered. It is shown that the extraction of informative echo signals from noise and interference requires, in addition to the fulfillment of optimal signal-filtering conditions, the use of flexible multifunctional equipment for ultrasonic testing that allows formation of various signals, flexible variation of their parameters, and application of numerous radio-engineering operations to signals for adapting the parameters of the instrumentation to the characteristics of a tested object.
Russian Journal of Nondestructive Testing
These and subsequent articles present the results of the studies of interference resistant methods and devices for ultrasonic testing of extended items made of complexly structured materials. The presented results are based on the radio-engineering R & D that have been conducted for over 30 years by the Department of Electronic Devices of the Moscow Power Engineering Institute. The studies are concurrently focused on the development of methods for separating echo signals from white and structural noise, on the application of complexly modulated signals, on the development of spatial and temporal methods for processing signals, on the development of broadband mosaic transducers, and on the design of multifunctional devices for ultrasonic testing. The necessity of such a comprehensive approach to ultrasonic testing is substantiated in this article by analysis of the problems of ultrasonic testing of complexly structured items with strong integral attenuation of ultrasound.
Calibration of Ultrasonic Testing for Faults Detection in Stone Masonry
2012
Building preservation is a complex problem to deal with, especially for building of historical relevance so as inspection and monitoring of structural conditions is an essential part of proper management of buildings rehabilitation. In the field of assessment methodologies, particular importance is given to Non-Destructive Testing Techniques (NDTs) that aspire to achieve the highest number of information about materials and structures without altering their condition. Among NDTs, Ultrasonic Testing (UT) exploits the transmission and reflection characteristics of mechanical waves with appropriate frequencies passing through the investigated item [1]. Elastic waves propagate in different manner through solid materials and cavities, thus enabling fault detection. When a signal passes through a specific item, certain frequency components are altered, the item behaving like a filter. The frequency attenuation increments with the frequency of the signal, meaning that the higher frequencie...
Features of applying complexly modulated signals in ultrasonic flaw detection
Russian Journal of Nondestructive Testing - RUSS J NONDESTRUCT T-ENGL TR, 2007
The use of complexly modulated signals during ultrasonic testing of articles with high integral ultrasonic attenuation is substantiated. On the basis of concepts of the optimal-filtering theory, phase-manipulated and frequency-modulated signals most suitable for ultrasonic testing are chosen and the main characteristics of various complexly modulated signals are analyzed. The advantage of using phase-manipulated and frequency-modulated signals in ultrasonic flaw detection for ensuring a high testing resolution and a high sensitivity is shown. It has been revealed that the application of state-of-the-art circuitry components allows the use of various properties of complexly modulated signals and creation of new ultrasonic methods and devices on this basis.
Journal of Vlsi Signal Processing Systems for Signal Image and Video Technology, 2004
Sinusoidal interferences are found in ultrasonic signals when we try to characterize a material, as for example interferences coming from PC cards. We are interested in obtaining a robust method that cancels these interferences preserving the waveform of the signal. A Blind Source Separation method to extract these sinusoids is presented in this paper. We will get so many linear mixtures of the backscattering echo of the material and the sinusoids as we need from different pulse responses of the material.