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Determination of third order elastic constants using a simple ultrasonic apparatus
The difficulty in measuring third order elastic constants has been always in the design of the complex apparatus needed to generate both compressional and shear waves under uniaxial and hydrostatic pressures. Parameters, such as the angle of incidence have to be determined with accuracy using expensive devices. The apparatus described in this paper leaves just one variable to be determined with accuracy, namely, the time of flight of ultrasonic waves within the specimen under test. A variety of materials could be tested in this way, including rock specimens and concrete, thus enabling the evaluation of stresses in-situ within buildings and structures. This research provides initial measurements related to the characterization of the non-linear elastic properties of materials using a simple ultrasonic apparatus. These will provide the basis for studying the relationships between non-linear properties and the more important engineering properties such as ultimate strength, residual strength after impact, and fatigue loading. The results related to second order elastic constants were obtained from the computation of both longitudinal and shear wave velocities using a single formula with just one variable: the transit-time of ultrasonic pulses. There is the potential of making high precision transit-time measurements using digital signal processing techniques, such as cross-correlation. There is also the exciting prospect of exploiting shear wave birefringence present within the specimen, which would provide additional information about internal fractures and pore structure of materials.
Determination of third order elastic constants using a simple ultrasonic apparatus
The difficulty in measuring third order elastic constants has been always in the design of the complex apparatus needed to generate both compressional and shear waves under uniaxial and hydrostatic pressures. Parameters, such as the angle of incidence have to be determined with accuracy using expensive devices. The apparatus described in this paper leaves just one variable to be determined with accuracy, namely, the time of flight of ultrasonic waves within the specimen under test. A variety of materials could be tested in this way, including rock specimens and concrete, thus enabling the evaluation of stresses in-situ within buildings and structures. This research provides initial measurements related to the characterization of the non-linear elastic properties of materials using a simple ultrasonic apparatus. These will provide the basis for studying the relationships between non-linear properties and the more important engineering properties such as ultimate strength, residual strength after impact, and fatigue loading. The results related to second order elastic constants were obtained from the computation of both longitudinal and shear wave velocities using a single formula with just one variable: the transit-time of ultrasonic pulses. There is the potential of making high precision transit-time measurements using digital signal processing techniques, such as cross-correlation. There is also the exciting prospect of exploiting shear wave birefringence present within the specimen, which would provide additional information about internal fractures and pore structure of materials.
Determination of third order elastic constants using a simple ultrasonic apparatus
Bestimmung der Elastizitätskonstante dritter Ordnung mittels einfacher Ultraschallgeräte
Bohhadjera, A. (author)
2003
7 Seiten, 5 Bilder, 1 Tabelle, 10 Quellen
(Nicht paginiert)
Conference paper
Storage medium
English
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