A novel narrowband ultrasonic spectroscopy (NBUS) technique which utilizes specially designed resonance transducers with carefully selected narrow frequency bands is presented. The NBUS is based on sensing electrical impedance of the piezoelectric transducer in the vicinity of its resonance. The paper is focused on optimizing the NBUS setup consisting of a piezoelectric transducer coupled to a multi-layered structure. Variations of the electrical impedance of a piezoelectric transducer caused by variations of parameters of the inspected structure are estimated using an equivalent circuit model. Selected simulation results obtained using the KLM equivalent circuit model, which takes into account mechanical loads on both surfaces of its piezoelectric element are presented. Variations of transducer's electrical impedance resulting from variable acoustical coupling to a multilayered structure are presented in function of frequency. Experimental results obtained from an aluminium sandwich structure and a carbon fibre composite panel are presented. Contrary to common opinions, the presented results show that NBUS inspection of multilayered structures can be efficiently performed using transducers with much lower centre frequencies than those required in pulse-echo inspection of the same structures.
Narrowband ultrasonic spectroscopy for inspecting multilayered aerospace structures
Schmalbandige Ultraschallspektroskopie zur Prüfung von Mehrschicht-Raumfahrtstrukturen
2006
9 Seiten, 8 Bilder, 8 Quellen
Aufsatz (Konferenz)
Datenträger
Englisch
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