Advanced micro structuring and joining technologies for direct integration of piezo fibers into metallic materials
A technology for the direct integration of lead-zirconate-titanate (PZT) fiber arrays into micro structured aluminum sheets is presented. The permanent clamping between the micro structured carrier material and the piezoceramic is achieved using a joining by forming process. Potential applications for produced piezo-metal composites are structural health monitoring, active noise reduction, or smart structures. The manufacturing steps of the piezometal-module are explained in detail. In order to reduce the necessary forming force for the micro structuring of the aluminum sheets, a warm micro forming process is investigated and the influences upon the achieved geometric precision and the necessary forming force are discussed. During the joining process, impedance spectroscopy is utilized as in situ method for process control and failure mode detection. For the joining process, the tool is equipped with miniaturized test probes to temporarily contact the piezo transducer. As a result, the joining process can be monitored and controlled based on the inherent sensor function of the piezoceramics. Moreover, the final capsuling of the active elements with thin aluminum foils through ultrasonic welding is described to protect the piezoceramics against mechanical loads and contact.