Ultrasonic testing of an ice specimen by the dry point contact transducers

Acoustic methods of nondestructive testing (NDT) occupy an important place among mostly developed methods and tools for practical evaluation of materials and structures. However, there are a number of problems that are not yet solved. One of them is connected with the transducer design for testing of rough and irregular surfaces. There are rocks, stones, ice etc. among materials with such surface. The problems lye in creation of a reliable acoustic contract of sensors with the testing surface as well as in necessity of high repeatability of the testing conditions. These problems are of special concern when it is necessary to make a fine classification and identification of materials with similar characteristics. Generally used sensors introduce a considerable "noise" into registered data. That makes it difficult and sometimes impossible to correctly analyze the testing results. Ultrasonic transducers inherited all the problems of other acoustic sensors. A special generation of ultrasonic transducers, i.e. the dry point contact (DPC) transducers, allows to facilitate ultrasonic testing conditions for rough and irregular surfaces. One of the applications of the DPC transducers to ultrasonic testing of ice is described in this work. The transducer design and the equipment set-up are given. Some experimental data of ultrasonic testing of ice by the DPC transducers are shown. An analysis of other publications devoted to applications of the DPC transducers as well as an attempt to forecast further development of investigation of ice using the DPC transducers will be given in the oral presentation.