ACOUSTIC DEVICE FOR LOCALIZED CONTACTLESS MEASUREMENT OF ELASTIC AND DISSIPATIVE NON-LINEARITIES AND VISCOELASTICITY

摘要

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).