A method of using piezoelectric lead zirconate titanate (PZT) transducers to characterize the vibrational modes of ceramic Vehicle Body Armor Support System (VBASS) plates for the purpose of crack detection is presented. By the use of bonded transducers on the VBASS plate, the presence of hairline cracks can be determined by comparing the output voltage waveforms against those of an undamaged plate. The authors have shown how PZT transducers, in a variant of the impact method (Evans, 1985), can be used to characterize the resonant modes of vibration of a ceramic armor plate, and how a single transducer can be used to distinguish damaged from undamaged plates. Two metrics were used to determine if the plates were cracked: the peak-to-peak output voltage versus frequency of the driving voltage, and the total harmonic distortion of the output signal versus the input driving frequency relative to that of the uncracked plate. The peak-to-peak voltage graphs clearly show a shift in the resonant vibration frequency of the plate from 65 to 74 kHz, as well as a reduction in the amplitude of the transmission signal. The total harmonic distortion compliments the peak-to-peak voltage graphs by showing the degree of distortion of the transmitted signal in the cracked plate relative to the uncracked plate. The total harmonic distortion metric may be useful in the future to determine crack depth or severity. The ultimate objective of this work is to develop a device that provides reliable plate assessment in the field. The authors have demonstrated a working prototype of a portable, handheld device to perform this kind of test. Based on the data from the experiments mentioned above, research and development is currently underway to develop more robust versions of the hand-held device for armor crack detection in the field.
Crack detection in armor plates using ultrasonic techniques
Rissnachweis in Verstärkungsplatten mittels Ultraschalltechnik
Materials Evaluation ; 66 , 6 ; 555-559
2008
5 Seiten, 9 Bilder, 1 Tabelle, 7 Quellen
Article (Journal)
English
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