Ultrasonic low-frequency transducers with dry dot contact and their applications for evaluation of concrete structures

Low-frequency transducers with dry dot contact (or dry point contact (DPC)) allow to overcome the problems of ultrasonic contact in testing of concrete. With the help of these transducers, it is possible to carry out the testing of concrete and other solid materials with longitudinal and shear waves. The principle of operation and device of ultrasonic low-frequency piezoelectric transducers with DPC, which are generating on the surface of solid body normal and tangential oscillatory force are shown. Directional diagrams of acoustic fields of these transducers, waveform of signals and their spectrums are given. Also shown possible areas of application of these transducers, in particular for flaw detection and testing of strength of concrete structures.