Ultrasonic material characterization using large-aperture PVDF receivers |
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Authors: | J.C. Adamowski |
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Affiliation: | a Escola Politécnica da Universidade de São Paulo, Av. Prof. Mello Moraes, 2231, 05508-900 São Paulo, SP, Brazil b UNESP - Universidade Estadual Paulista, Dep. Electrical Eng., Av. Brazil, 56, 15385-000 Ilha Solteira, SP, Brazil |
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Abstract: | This work describes the use of a large-aperture PVDF receiver in the measurement of liquid density and composite material elastic constants. The density measurement of several liquids is obtained with accuracy of 0.2% using a conventional NDE emitter transducer and a 70-mm-diameter, 52-μm P(VDF-TrFE) membrane with gold electrodes. The determination of the elastic constants is based on the phase velocity measurement. Diffraction can lead to errors around 1% in velocity measurement when using alternatively the conventional pair of ultrasonic transducers (1-MHz frequency and 19-mm-diameter) operating in through-transmission mode, separated by a distance of 100 mm. This effect is negligible when using a pair of 10-MHz, 19-mm-diameter transducers. Nevertheless, the dispersion at 10 MHz can result in errors of about 0.5%, when measuring the velocity in composite materials. The use of an 80-mm diameter, 52-μm-thick PVDF membrane receiver practically eliminates the diffraction effects in phase velocity measurement. The elastic constants of a carbon fiber reinforced polymer were determined and compared with the values obtained by a tensile test. |
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Keywords: | 43.35.Cg 43.35.Yb 43.20.El |
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