Ultrasonic probes simultaneously producing one longitudinal and two shear waves and their potential applications

Rekuvienė

2012

ultra

In this article review of density and viscosity measurement methods is presented, including ultrasonic pulse echo methods, which are capable to measure these properties of polymer melts. The methods are presented according to measurement principles, methodology, accuracy and possibility to measure density and viscosity of polymer melts on-line during extrusion process. Such measurements are very important for process automation, process monitoring and control. The ultrasonic pulse echo methods are separated from other methods, because very often they are superior to other techniques. The advantage of this technique is that at the same time sound velocity and attenuation in a plastic melt may be measured, what gives more information. For this purpose polarized shear waves as well as longitudinal, torsional and other types of waves in a wide frequency range may be employed.

Section: Measuring Density and Viscosity In Polymer Meltmentioning

confidence: 99%

Viscosity and density measurement methods for polymer melts

Rekuvienė

2012

ultra

“…Extensive investigations in the field of hightemperature integrated ultrasonic shear and longitudinal wave probes are known [1,[14][15][16][17][18]. In these metallic (aluminium) probes shear waves are generated due to mode conversion from longitudinal to shear waves because of reflection inside the metallic substrate having a specific shape (64.6º angle).…”

Section: Mode Conversionmentioning

confidence: 99%

“…The same idea of mode conversion was used by same authors in making screws as axial load and temperature probes using an integrated ultrasonic transducer [2,17]. In order to propagate L wave along the axial direction of the screw back and forth a 45º reflection (steel/air) was used.…”

Section: Mode Conversionmentioning

confidence: 99%

See 1 more Smart Citation

Simultaneous generation of longitudinal and shear ultrasonic waves: knowledge summary, PZT piezoelements manufacturing and experiments

Voleišis

Voleišienė

et al. 2011

ultra

Known ultrasonic transducers for simultaneous generation of longitudinal and shear waves are reviewed: quartz and lithium niobate crystals tilted CdS and ZnO films. A special attention is devoted to the rotated cuts of PZT piezoceramics, literature data theoretical background conclusions are analysed. Manufacturing technology of dual mode PZT transducers with different cut angles and thickness was developed. Reliable electrodes suitable for soldering are made chemically in electroless nickel (EN) plating bath. Nickel electrodes are additionally dectroplated with silver. Various types of PZT ceramics were successfully used. From impedance measurements longitudinal and shear resonances were determined for typical thicknesses 45-100 μm. The cut angle 36º for equal efficiency of both waves was experimentally determined. Operation of transducers soldered to the steel rods and measurement bodies of the certain geometry was investigated. Measurements were provided in a temperature range 20-160 ºC. Axial load experiments up to 234 MPa were provided and corresponding linear dependencies were determined. Experiments showed good performance of developed dual mode PZT ultrasonic transducers.

“…transducers. Shear waves are generated by mode conversion when longitudinal wave is reflected from the boundary with acoustic impedance discontinuity, when appropriate angle is chosen carefully [1], [2], [8], [9].…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Influence of Temperature on Propagation of Ultrasonic Waves in Waveguides with Mode Conversion

Jasiūnienė

Žukauskas

2012

ElAEE

Abstract-In the case of the objects with a high temperature the measurements are often performed using waveguides in order to protect the ultrasonic piezoelectric transducers from a high temperature. In some cases, for measurement of specific properties of materials, shear waves are used. Shear waves can be generated exploiting mode conversion phenomenon using a longitudinal wave transducer and a waveguide with deflected front surface. However, the deflection angle has to be carefully selected, when it is required that the shear waves would propagate parallel to the waveguide axis. The proper deflection angle depends on material used for the waveguide properties. When the temperature changes, the properties of the material (as ultrasonic velocity) change as well, causing the change of the reflection angle and the propagation path. A numerical investigation was performed in order to evaluate how the change of the temperature will influence the reflection angle of the ultrasonic waves and the propagation path. It is shown that the change of the temperature influences the reflection angle and propagation path of ultrasonic waves and should be taken into account.