Dr.-Ing. Jens Twiefel
Leibniz Universität Hannover
The presentation will provide an overview on the topics and recent findings of the Piezoelectric and Ultrasonic Technology Lab of the Institute of Dynamics and Vibration Research at the Leibniz Universität Hannover. The lab is working a lot on power ultrasonic systems for actuation in the frequency range from 20 kHz to 100 kHz. The ultrasonic systems are covered from the power plug to the process, both theoretically and practically/experimentally. Currently, the lab is focusing on four main areas/groups. First, ultrasonic wave propagation in solids and fluids. The topics include ultrasonic assisted casting and laser welding but also the characterization of wave fields for sensing applications. The second main topic is the area of electromechanically coupled structural dynamics covering the optimization and evaluation of complex transducer structures and systems under various time dependent boundary conditions. Additionally, broadband vibration energy harvesting techniques are under investigation. The third group focuses on the control of dynamic systems. Therefore, a µC-based standalone control and measurement unit has been developed and implemented, that is capable of measuring the instable branches in the frequency response of non-linear transducers. The fourth area works on various interface and vibro-impact processes including the ultrasonic transportation and drives, interface processes in ultrasonic wire bonding as well as a novel tactile display providing a tactile impression of virtual surfaces. Bio.: Jens Twiefel obtained his diploma in computer engineering with major in mechanical engineering from Universität Paderborn. Back then he started to work in the area of ultrasonic systems. In his doctoral thesis he was working on piezoelectric standing wave motors, with this graduated at Leibniz Universität Hannover. He was a visiting scholar at Virginia Tech, USA and a visiting researcher at The Tokyo University. Today, he is in charge of the Piezoelectric and Ultrasonic Technology Lab of the Institute of Dynamics and Vibration Research at the Leibniz Universität Hannover since 2008. Within his group various topics in the fields of power ultrasonics, non-linear vibration, vibration energy harvesting, wave propagation and control of dynamic systems are covered. Currently 16 PhD candidates are working and studying in his lab under his co-supervision.