A. A. Sinitsyn

Development of a broadband low-frequency mosaic ultrasonic piezoelectric transducer with a limited aperture

Broadband low-frequency mosaic ultrasonic piezoelectric transducers with apertures comparable with acoustic wavelengths, which are designed as sets of acoustically coupled piezoelectric elements of different heights, are considered. Examples of small-aperture broadband mosaic transducers and their production technology are presented.

Choosing parameters of space-time signal processing in ultrasonic structuroscopy of cast-iron molds subjected to thermal cycling

It is shown that in order to improve the accuracy of measuring the speed of ultrasonic vibrations in cast-iron products by echo-pulse method, one should use noise-immune space-time echosignal processing methods that improve signal–to–pattern-noise ratio. Signal parameters should also be adapted for characteristics of the test object. Requirements for the choice of probing-signal parameters have been established as well as optimum displacement step of a double-crystal transducer. The value of the speed of ultrasound at a time moment that precedes the destruction of cast-iron mold has been determined.

Adaptive instruments for ultrasonic nondestructive testing of large objects with complex structures

An ultrasonic multifunctional adaptive measuring complex, which is built on the basis of a personal computer and algorithmically generates various simple and complexly modulated probing signals, is described. This system implements various radio-engineering algorithms for processing echo signals (storage, optimal filtering, synchronous detection, etc.) and provides adaptation of the signal parameters to the characteristics of inspected objects. Using the example of a frequency-modulated signal, it is shown that an adaptive measuring complex can increase the testing reliability and provide high sensitivity and high resolution owing to both the adaptive adjustment of the parameters of a probing signal and the compensation for distortions in the received signal in the electroacoustic path.

Comparison of the features of composite and mosaic piezotransducers for the ultrasonic testing of products with a high attenuation level of ultrasonic signals

The problem of the creation of stacked (mosaic and composite) broadband transducers that simultaneously provide a broad band and a high electroacoustic transduction efficiency is analyzed. The mosaic technology is shown to be optimal for the practical implementation of ultrasonic broadband low-frequency electroacoustic transducers. Being functionally flexible, the mosaic technology allows the development of numerous variants of electroacoustic transducers for the solution of different ultrasonic testing problems and, first of all, for the undistorted transduction of signals.

Using antenna arrays for reference-free measurement of speed of ultrasound and thickness of concrete articles

A reference-free method is considered for concurrent measurement of the speed of ultrasonic vibrations and the thickness of concrete constructional products with ultrasonic antenna arrays that use the “focusing to a plane” algorithm.

Spatiotemporal characteristics of broadband ultrasonic transducers

It is shown that the quality of transformation of ultrasonic signals in a broadband transducer is affected by not only the amplitude-frequency but also the spatial characteristics of broadband probes. To evaluate the quality of transformation of ultrasonic broadband signals, integral spatiotemporal characteristics of a broadband probe are introduced, viz., the correlation field distribution and the correlation directivity characteristic. The experimental correlation spatiotemporal characteristics of a mosaic low-frequency broadband transducer are presented.