Analyzing the effect of adhered metal electrodes on piezoelectric elements using different types of adhesives

Modeling and simulation play a key-role in computer-assisted design of ultrasonic sensors. The accuracy of those numerical or analytical models highly depends on the material dataset chosen as well as on the digitized simplified geometry. Thus, researchers worked on techniques how to measure material datasets of piezoceramics or passive materials (i.e. polymers) for use in simulation [1] [2]. Most computer models neglect the influence of adhesive bonds between those active and passive material components used to form a complete ultrasonic transducer and thus imply perfect interface layers. To gain a more accurate model one need to go further and consider non-perfect interface layers between assembly parts. Because adhesive bonds are neither necessarily isotropic nor homogeneous and their geometric dimensions are very small, we need to define effective material datasets dependent on the model used in simulation. In this contribution the indicator under study is the electric impedance of the active element. We will show the influence of different adhesives used to adhere metal electrodes on piezoceramic discs. The experimental results will be compared to simulation results using a standard FEM-Tool and assuming an ideal interface between piezoceramic disk and metal electrode.