Ultrasonic detection and characterization of delaminations in thin composite plates using signal processing techniques

It is shown that a piezoelectric element vibrating in an extensional or shear mode can be modeled rigorously by systematic use of the transmission line analogy and the superposition theorem. A schematic representation of such an element which is in a way more intuitive than others representations is introduced. The stresses on the electroded faces are considered as sources of stress applied at the two ends of an acoustic transmission line, since the acoustical perturbations may be considered as originating on these faces. Using transmission line theory, a complete set of expressions is found for electrical impedance, acoustic stresses, and velocities. Computed results are exactly the same as those given by the classical method, even if the computation sequence is almost entirely different. An intuitive graphical model for a piezoelectric element is proposed. It is also shown that the acoustic velocities on opposite faces of an asymmetrical loaded piezoelectric plate are exactly equal at the antiresonance frequency when internal losses are neglected. The programs developed can be used efficiently for practical multilayered transducer design. >

New transmission line analogy applied to single and multilayered piezoelectric transducers

A unidimensional, linear systems, block diagram model of a two-layer thickness mode piezoelectric transducer is presented. The layers are subject to opposing piezoelectric polarization and the device is assumed to be loaded by semi-infinite isotropic media at the two principal faces. Block diagram representations of the transducer acting as both a generator and a receiver of ultrasound are developed in conjunction with the equivalent model of the electrical admittance. When expressed in this manner, the underlying cause and effect relationships are identified, with the important contribution of the piezoelectric boundary highlighted. Comparisons with the conventional single-layer transducer are made throughout and the major physical differences in terms of transduction performance are discussed. The new model is compared with finite element analysis and good agreement is also demonstrated with experimental data. A key aspect of the methodology is the provision of a more intuitive understanding of such device behavior. Accordingly, emphasis has been placed on the physical relationships and this is considered a major contribution of the work

A block diagram model of the thickness mode piezoelectric transducer containing dual oppositely polarized piezoelectric zones

An Intuitive Multilayered Transducer Model with Losses Based on Transmission Line Theory

It is shown that a piezoelectric element vibrating in an extensional or shear mode can be modeled rigorously in a novel way by systematic use of the transmission line analogy and the superposition theorem. A novel schematic representation of such an element that is somewhat more intuitive that other representations, particularly Mason's model, is introduced. The stresses on the electrode faces are considered as sources applied at the ends of an acoustic transmission line, since the acoustic perturbations may be considered as originating on these faces. Using transmission line theory, a complete set of expressions is found for electrical impedance, acoustic stresses, and velocities. Computed results are exactly the same as those given by the classical method, even if the computation sequence is almost entirely different. >

https://ieeexplore.ieee.org/iel2/169/4424/00171391.pdf

A. Lukoševičius

Papers

Optimization of the piezoelectric transducer response by means of electrical correcting circuits