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Accueil du site > Séminaires, conférences > Séminaires du LIP > Séminaires en 2005 > Ultrasonic identification of structure and mechanical properties of cancellous bone.

Ultrasonic identification of structure and mechanical properties of cancellous bone.

Date : 25/02/2005 à 14h00

Intervenant :
- Michal PAKULA

Résumé : Ultrasonic studies in vitro of cancellous bones prove that both phases : solid and fluid may play a significant role in the wave propagation phenomena in the materials. In particular the methods show existence of two longitudinal wave modes and sensitivity of the wave parameters (phase velocity, attenuation coefficient) to kind of fluid filling pores of bone.

Commonly used to interpratation of the ultrasonic data for saturated porous materials the macroscopic Biot’s model is well verified for many lower porosity materials (rocks, sintered materials), while in the case of cancellous bones, which porosity ranges between 50 to 90 percent (sometimes even higher), the model is less powerful to predict the observed behaviour of waves.

The studies develops microscopically based cellular model (CM) of wave motion in cancellous bones assuming propagation of plane wave in the main direction of trabecular network. As the result the effect of scattering is not present in the model and no limit is imposed on the applied wavelengths.

The wave parameters calculated from the proposed CM are compared with the experimental data from the ultrasonic studies and the wave parameters predicted by Biot’s theory. It was shown that only for the long wave range (low frequencies) the predictions of both considered models coincide. Moreover, the results obtained from the cellular model are in good qualitative agreement with the experimental data received from ultrasonic measurements.

It is considered potential use of the proposed model to solve inverse problems - evaluation of material characteristics from the measured ultrasonic parameters in the wide frequency range.