In-process monitoring of joining operations for piezoceramic elementsDonnerstag (06.07.2017) 17:00 - 17:20 Uhr Bestandteil von:
The direct integration of piezo elements into micro structured aluminium sheets is a new approach for adaptronics and lightweight constructions. With the integration of the active piezoceramic elements the aluminium sheets gain sensor and actuator functionalities. Due to the absence of any adhesive layers during the joining process of the both materials, a high stiffness and a low damping ratio can be achieved for the material compound. In contrast to adhesively bonded sensors, which are placed on top of the structural element, the piezoceramic elements and the aluminium sheets are joined using a forming process to generate form fit and interference fit. The mechanical interconnections and the preload of the piezoceramic elements is an important issue for the sensor and actuator capability of the later smart material. State of the art are post-process inspection methods to characterise the mechanical interconnection of the joining partners and the performance of the transducer after the joining operation. Scope of the paper is the development of a novel in-process monitoring method that utilizes the piezoceramic transducer as inherent sensor for failure mode detection and preload evaluation during the joining by forming operation. As demonstrated in previous researches, the method was proven and showed its feasibility on single piezoceramic elements. Within this study, results of forming experiments with array batches of interconnected piezoceramic elements are presented. The piezoceramic batches are electrically contacted inside the joining tool and are utilized as material inherent sensor during joining by forming experiments. Test samples are characterised by impedance spectroscopy during the joining operation. Furthermore, cracks or defects are detected by optical microscopy inspection. Based on the results, a novel in-process-monitoring method utilizing the piezoceramic joining partners as inherent sensor is outlined.