Carsten Unverzagt

Computer-assisted design of transducers for ultrasonic sensor systems

In this contribution, possibilities and methods for computer-assisted design of ultrasound transducers are described. These transducers are essential for an ultrasonic sensor design, e.g. for continuous non-invasive determination of quantities that are important in process technology. To achieve technical reliability and robustness, the precise determination of all acoustic properties of the used sensor materials is of great importance. Problem-oriented modeling, numerical simulation, special optimization algorithms and improved methods for the visualization of propagating waves offer new and promising possibilities for developing ultrasonic transducers with enhanced properties.

Sensitivitätssteigerung bei der inversenMaterialparameterbestimmung für Piezokeramiken

Zusammenfassung Für eine realitätsnahe Finite-Elemente-Simulation von Piezokeramiken ist es notwendig, dass deren Materialparameter präzise bekannt sind. Zur Bestimmung werden zunehmend numerische Verfahren auf Basis inverser Methoden eingesetzt, die einen Einfluss aller Materialparameter auf den als Messgröße genutzten Impedanzverlauf voraussetzen. Dieser kann durch die Nutzung einer segmentierten Elektrode in Kombination mit einem elektrischen Vornetzwerk vergrößert werden, wodurch die Sensitivität erhöht und die Bestimmung aller relevanter Materialparameter an einer einzelnen Probe ermöglicht wird.

4.1 - Sensitivitätssteigerung im Rahmen eines inversen Ansatzes zur Materialparameterbestimmung für Piezokeramiken durch Elektrodenmodifikationen

Simulationen mittels der Finiten Element Methode (FEM) sind heute ein fester Bestandteil im Entwicklungsprozess von Ultraschallsystemen. Durch die simulative Ermittlung der transienten Schwingungsvorgange konnen Optimierungen bezuglich gewunschter Zielkriterien vorgenommen werden. Hierdurch lassen sich die aufwendige Prototypenfertigung reduzieren und gunstige Entwurfspunkte schneller ermitteln.

Finite element simulation of single ultrasonic transducer with segmented electrodes to adjust the directional characteristic

For many applications like level measurement and industry robotics it is of advantage if the directional characteristic of an ultrasonic transducer is changeable or adaptable for the improvement of spatial resolution. Often this goal is reached with the use of ultrasonic transducer arrays, which elements are driven with phase shifted excitation signals. One disadvantage of these solutions is the great effort for building such an array and the multi-channel sensor electronics. In this contribution the directional characteristic of a single air transducer with segmented electrodes is analyzed. Therefore a variable script based finite element model is used to discover the influence of different electrode configurations on the directional characteristic of a single piezoceramic transducer. Especially the influence on the angle of beam and the near field length are evaluated. The used variable model permits an optimization of the configuration with regards to the mentioned criteria. The findings will be used f...

P1G-7 Optimization of Ultrasound Reflecting Mirrors

In many different ultrasound applications mirrors are often used to deflect ultrasonic waves. The dimensions of the mirror and the applied materials have an essential influence on the output signal characteristics and the obtained measuring quantities. The extension of mirror geometry is not necessarily associated with a higher reflection coefficient. This can be explained with the aid of coincidence condition. A second criterion aims at the avoidance of the mirror resonance. This two conditions lead to an optimal dimensioning of mirror geometry with given material properties and operation mode, as exemplified for a rectangular mirror