It has been shown theoretically that a loss in the acoustic contact affects the properties of Stoneley acoustic waves at the interface between two solid half-spaces. The dispersion equation is presented in a form that allows the necessary and sufficient conditions for the existence of a boundary wave to be obtained for various combinations of parameters of the bordering media.
1 January 2018 in Russian Journal of Nondestructive Testing
The pulsed operation mode of an emission–reception system consisting of two immersion piezoelectric transducers separated by a liquid (glycerine) layer has been studied. Identical piezoceramic plates...
This paper theoretically and experimentally considers the pulsed mode of operation of the radiation-receiving system. The system contains two identical piezoceramic plates separated by a layer of immersion liquid (glycerin). The emitter was excited by the complex electrical signal of the special shape, which consisted of two half-cycles of the sine wave (exciting and compensating) on the natural frequency of the piezoplates. The forms of these signals were calculated by the authors and described in their previous papers using the d’Alembert method. The length of the electrical signal was estimated at the output of the piezoelectric receiver. The problem was solved theoretically using the finite element method. The acoustical system was simulated with the help of the COMSOL Multiphysics modeling environment. A comparative study of the theoretical and experimental results is carried out. The form of the signal at the output of the system was calculated by the d’Alembert method, and the simulated form by the finite element method was in good coincidence with the results of experimental and full-scale modeling. It is shown that the usage of complex waveforms allows achieving a significant pulse duration reduction of the electrical voltage at the output of the receiver.
1 July 2017 in Russian Journal of Nondestructive Testing
The properties of TBC-3 and PZT-23 piezoelectric ceramics have been studied by the method of loaded three-element complex oscillator. Changes in the higher-order (up to fifth) parameters are considered for large mechanical (0–120 MPa) and electric (0–600 kV/m) loads. Results of studying the longitudinal flexibility s11E, piezoelectric modulus d31, and dielectric permittivity ε33σ are presented within a frequency range of 20–200 kHz, where the frequency dispersion of dielectric as well as piezoelectric and elastic parameters is observed.
The results of a study on the geometric shape of the damper on the efficiency of the ultrasonic piezoelectric transducer are presented. In particular, a damper in the form of a truncated cone is considered, the generatrix of which has an inclination angle α relative to the diameter of the piezoceramic plate. The shape of the damper in the form of a truncated cone is chosen based on the a priori assumption that this helps to increase the path of the wave in the damper material due to numerous reflections in it. A criterion for the efficiency of damper operation is proposed. The optimal (from the point of view of the damper efficiency) value of the angle α was determined theoretically and experimentally. The technology of its production is described. Satisfactory agreement between the results of theoretical and experimental studies was noted.
1 March 2020 in Optoelectronics, Instrumentation and Data Processing
This paper presents the results of experimental studies and digital methods for recording of holograms using spatial light modulators. The use of holograph