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Electrical design and oscillation states of directly integrated piezoelectric sensors and actuators in metal sheets

Presentation held at Wissenschaftliches Symposium "Leichtbau durch Funktionsintegration", 27./28.03.2018, Chemnitz
Elektrischer Aufbau und Schwingungsmoden direkt integrierter piezoelektrischer Sensoren in Blechen
: Schmidt, Marek; Schubert, Andreas; Koriath, Hans-Joachim; Wittstock, Volker; Müller, Benedikt; Pierer, Alexander

presentation urn:nbn:de:0011-n-4940275 (1.4 MByte PDF)
MD5 Fingerprint: 6bf5c51450e1eb3375e085a7c4d62d58
Created on: 9.5.2018

2018, 14 Folien
Wissenschaftliches Symposium "Leichtbau durch Funktionsintegration" <6, 2018, Chemnitz>
Presentation, Electronic Publication
Fraunhofer IWU ()
piezoceramic; vibration mode; micro manufacturing

Material savings in production and design of lightweight structures can take place until the structural stiffness reaches certain limits, which show up in an endangering stability of components and structural safety. Extending the limits can be achieved by integration of functional materials such piezoceramic. For instance, piezoelectric transducers, in the form of piezo-patches, are commonly bonded with an adhesive onto a component surface and can be used as a sensor or an actuator. Structural health monitoring and active vibration control are examples for usage. The structural integration of piezoceramics in metal parts with the technique joining by forming is an alternative approach. However, this method avoids damping materials like adhesives or other polymer interlayers between the piezoceramic and the metallic structure. Piezoceramic fibers with rectangular cross-section are assembled in locally microstructured metal sheets. Due to the following joining by forming process a force-fit and form-fit connection is achieved and enable undamped acoustic coupling. The article is focused on the electrical side of the joining operation and deals with the arrangement, selection and coating method of electrode and insulation layers. The arrangement determines the useable piezoelectric effects, which are subdivided into transverse, longitudinal or shear mode. For all modes, two opposite sides have to be coated with an electrode layer. One electrical side serves as the signal line for the actuator or sensor function and has to be insulated from the metal sheet. The other electrode side acts as the ground connection and requires electrical contact to the metal sheet. The layer selection as well as the coating method are selected by the specific requirements for a large scale joining operation. In laboratory, prototypes with different arrangements of the coatings were produced in order to obtain all three mentioned piezoelectric effects. Functions of the prototypes were tested in a micro-tensile-compression testing machine (ElectroForce 3220). The realization of the three piezoelectric effects could be demonstrated. Since the longitudinal mode has the largest surface to be insulated, the experiment showed an increased signal failure for this piezoelectric effect. For the avoidance of a large insulating area, a modified design for the piezo-metal connection is proposed for the longitudinal mode.