Thermoacoustic phased-array radiators – Theory, characteristics, and applications

Autor: Daniel Hufschläger, Dirk Gohlke, Matthias Weise, Klaas Bente, Mate Gaal
Jazyk: German<br />English<br />Spanish; Castilian<br />French
Rok vydání: 2023
Předmět:
Zdroj: Research and Review Journal of Nondestructive Testing, Vol 1, Iss 1 (2023)
Druh dokumentu: article
ISSN: 2941-4989
DOI: 10.58286/28064
Popis: Standard non-invasive acoustic non-destructive testing (NDT) methods like testing in contact or using immersion tank arrangements are limited since the probes need to be in direct contact with the test piece or using a fluid as coupling media. Air-coupled ultrasonic testing avoids these limitations and enables new testing methods. Two up-and-coming transducer technologies are recognized as promising: transducers using ferroelectrets and transmitters based on the thermoacoustic principle. Thermoacoustic radiators based on thin-film technology offer a resonant-free generation of ultrasound. The resonance-free operation enables the wideband generation of acoustics waves and promises advantages for existing NDT methods. Using specially shaped substrates and electrodes enables the fabrication of planar and focused thermoacoustic radiators. This contribution presents the latest results of our ongoing research regarding thermoacoustic radiators, which is the thermoacoustic phased-array. Phased-array transducers offer the on-the-fly change of the steering angle and the position of the focal point without moving or modifying the transducer itself. Combining both technologies, thermoacoustic emitter and the phasedarray principle broaden the spectrum of classical NDT applications and modern approaches like the excitation of guided waves or structural health monitoring. In detail, we modelled the sound field of a self-fabricated thermoacoustic phased-array radiator, characterised the emitter elementwise and tested several application scenarios (e.g., transmission, beam steering, focusing and the excitation of guided waves).
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