Measurement kit for tortuosity testing (Tortuosity_MAA)
The tortuosity is an important parameter which intervenes in the description of the complexity of the path of the sound wave propagating within a material. Tortuosity_MAA allows to determine the tortuosity by using an ultrasonic method based on determination of the high frequency limit for the complex phase velocity. The kit is provided with hardware, transducers and software.
Parameters
Tortuosity
Technical specifications
Method: high frequency limit for the ratio between the sound speed in air and the real part of complex phase velocity within the porous material.
Measurement chain:
- Electrostatic transducers (20-100 kHz) used as source and receiver;
- Power amplifier;
- Microphone preamplifier and signal conditioner;
- Audio sound card (sampling frequency >200 kHz);
- Software developed in Labview ®.
Measurement procedures: Impulse responses obtained by using convolution of exponential sine sweep.
Applications
The tortuosity value can be used both to understand the internal structure of a porous media and to make possible the use of adavanced predition models for the determination of complex acoustical parameters when these are not experimentally measured.
References
P. Bonfiglio, F. Pompoli, Misura sperimentale della tortuosità di materiali a cella aperta con tecnica ad ultrasuoni, ATTI 34° Convegno AIA, Firenze 13-15 Giugno 2007.
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P. Bonfiglio, F. Pompoli, Frequency dependent tortuosity measurement by means of ultrasonic tests, Proceedings of ICSV14, Cairns July 9-12 2007.
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