Developing Methods and Devices for Ultrasonic Contactless Shadow Testing of Large-Sized Products Made of Polymer Composite Materials

It is shown that in order to increase the sensitivity of ultrasonic contactless shadow testing of products made of polymer composite materials (PCMs), it is necessary to develop highly sensitive low-frequency broadband contactless piezoelectric transducers (PETs). The methods of providing both high sensitivity and a wide band of ultrasonic contactless PET are considered. The ultrasonic contactless high-sensitivity broadband PETs based on the use of mosaic contact PET technology, the choice of optimal matching layers, and the use of various options for the excitation of radiating PETs have been proposed and developed. It is shown that with the help of mosaic low-frequency broadband contactless PETs, one can achieve a high sensitivity of testing and ensure the accuracy of measuring acoustic characteristics (ultrasound velocity, density, etc.) with ultrasonic low-frequency shadow contactless testing of large-sized PCM products.