Acoustic device for localized contactless measurement of elastic and dissipative non-linearities and viscoelasticity

Abstract

The invention relates to an acoustic method and device for localized, contactless, measurement of elastic and dissipative non-linearities and dynamic non-linear viscoelasticity in a medium subjected to a low-frequency acoustic stress and probed by ultrasonic pulses or wave trains. For this purpose, the invention relates to an acoustic, localized and contactless device for measuring elastic and dissipative nonlinearities and viscoelasticity of a specimen (2), characterized in that it comprises: means (10, 20, 22, 24) for transmitting a low-frequency acoustic wave (24a) and means (26, 34, 30) for receiving said low-frequency acoustic wave, which means are capable of creating a low-frequency periodic variation of the hydrostatic pressure in the specimen (2); means (10, 12, 14) for generating high-frequency ultrasonic pulses (14a) and means (16, 28, 30) for receiving said pulses; and an analysis unit (32) that includes a model for calculating the modulations in the time of flight and in the amplitude of the ultrasonic pulses (14a) that are induced by the low-frequency acoustic wave (24a) passing through the specimen (2), so as to quantify the elastic and dissipative non-linearities and the non-linear viscoelasticity of the specimen (2).

Description

technical field [0001] The invention relates to an acoustic method and device for the local and non-contact measurement of elastic and dissipative nonlinear and nonlinear viscoelastic properties in a medium subjected to low-frequency acoustic stress and probed by pulses or ultrasonic trains. [0002] The invention relates to the technical field of detection and quantification of microdamages (microcracks) in industrial or biological materials, in particular in bone tissue. [0003] The invention also relates to the technical field of characterization of other complex media, such as solidified or non-solidified granular media (rock, sand, concrete, etc.), complex fluid media (cosmetics, processed agricultural products) or two-phase fluid media (polymers, petroleum) . Background technique [0004] Several documents are known in the art describing acoustically nonlinear measurement systems. These publications describe methods for measuring the effects of acoustic nonlinearity...

AI Technical Summary

Problems solved by technology

[0019] Using a contact mechanical device for changing the stress in the sample, using the mechanical resonance of the sample, a deformation frequency of tens of kHz can be achieved, however, the mechanical resonance frequency is limited by the geometric size and physical properties of the sample

[0020] The method of varying the hydrostatic pressure step by step and requiring the test sample to be enclosed in a fluid-filled enclosure is relatively complex to design and use

[0021] Simultaneous compression and tension (or compression and decompression) tests are difficult to perform without using low-frequency sound waves to create stress changes

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