A novel exciting method for a sandwich type piezoelectric transducer operating in longitudinal-bending hybrid vibration modes is proposed and discussed, in which the piezoelectric elements for the excitations of the longitudinal and bending vibrations share the same axial location, but correspond to different partitions. Whole-piece type piezoelectric plates with three separated partitions are ...

background and aims. basic periodontal treatment aims at eliminating supra- and sub-gingival plaque and establishing conditions which will allow effective self-performed plaque control. this aim is primarily achieved with sonic and ultrasonic scalers. however, generation of bacterial aerosols during these procedures is of great concern to patients, the dentist and the dental assistant. the aim ...

Active Fiber Composites (AFC) manufactured at EMPA with commercially available piezoelectric ceramic fibers have been investigated for their potential use as Acoustic Emission (AE) sensors. AFC elements have been evaluated with methods derived from AE sensor characterization as well as additional measurements. Some commercial AE sensor types have been evaluated with the same methods for compari...

Submicrometer-structured (Bi(0.5)Na(0.5))(0.94)Ba(0.06)TiO(3) ceramics ((G) < 720 nm) from nanopowders were studied. The real part of the optimum room temperature set of piezoelectric coefficients obtained from resonances of the BNBT6 dense ceramic disks and shear plates [d(31) = (-37 + 1.33i) pC·N(-1), d(15) = (158.3 - 8.31i) pC·N(-1), k(t) = 40.4%, k(p) = 26.8%, and k(15) = 40.2%] and d(33) (...

The propagation of longitudinally polarized acoustic modes along thin piezoelectric plates (BN, ZnO, InN, AlN and GaN) is theoretically studied, aiming at the design of high frequency electroacoustic devices suitable for work in liquid environments. The investigation of the acoustic field profile across the plate revealed the presence of longitudinally polarized Lamb modes, travelling at veloci...

A preliminary study of the feasibility of using piezo-transducer arrays, for detecting flaws in flat aluminum plates and steel tubing, is being performed at The University of Tennessee. The sensor arrays are designed for embedding in aluminum plates and brass tubes. Various forms of defects are placed on the test specimens. Preliminary experiments are carried out using both flat aluminum plate ...

For all processes in industry where liquids are intermediate or end products, there is a demand for online measurements of physical liquid properties, like density, viscosity and speed of sound. The continuous monitoring of those quantities is important for quality control and for enhancing productivity. In this paper layered resonant piezoelectric sensors for liquids are investigated and it is...