Contact-less and compact Electro-Magnetic Acoustic Transducers with enhanced signals, novel shapes and more flexible operation regimes

• Applicant: Professor Dr.-Ing. Dirk Rüter
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; Measurement Systems ; Microsystems
• Term: from 2018 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 404411918

• Final Report Year: 2022

Final Report Abstract

Novel inductive ultrasonic transducers in compact designs and new modes of operation were raised to a higher level of knowledge and feasibility. Non-contact ultrasonic technology is interesting for the energy- and resource-intensive metal industry. Improved or immediate quality inspection leads to more efficiency and can improve sustainability and competitiveness. Two difficult, fundamentally different and novel application scenarios underlined the practicability. Planned detailed investigations of coupling effects and sound fields were embedded in these scenarios and published therefrom. The first non-contact echo scenario was the axial inspection of the liquid internal volume of thick-walled metal tanks from the outside, notoriously difficult already with contacting transducers. The second non-contact echo scenario was the phase-accurate operation of a particularly compact dual transducer for the alignment of lateral sound fields with interference. The feasibility for novel compact phased arrays is thus near. A pleasant surprise was the "zero field detection" shown, which would enable a non-contact, low energy and practically non-magnetic ultrasonic inspection technique for normal steel as the most important industrial metal.

Publications

• “A compact and powerful EMAT design for contactless detection of inhomogeneities inside the liquid volume of metallic tanks,” tm – Technisches Messen, vol. 87, no. 5, pp. 349–359, 2019
  Rieger, Kai; Erni, Daniel & Rueter, Dirk
  
• “Examination of the liquid volume inside metal tanks using non-contact EMATs from outside,” IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 68, no. 4, 2021
  Rieger, Kai; Erni, Daniel & Rueter, Dirk
  
• “Unidirectional Emission and Detection of Lamb Waves based on a Powerful and Compact Coils-only EMAT”, NDT and E International 122 (2021) 102492
  Rieger, Kai; Erni, Daniel & Rueter, Dirk
  
• “Noncontact reception of ultrasound from soft magnetic mild steel with zero applied bias field EMATs”, NDT and E International 125 (2022) 102569
  Rieger, Kai; Erni, Daniel & Rueter, Dirk