• Polyzos, Dimosthenis
• Louis, Olivia
• Strantza, Maria
• Van Hemelrijck, Danny
• Aggelis, Dimitrios G.
• Boulpaep, Frans

Abstract

Cortical bone is a highly heterogeneous material at the microscale and has one<br/>of the most complex structures among materials. Application of elastic wave techniques to <br/>this material is thus very challenging. In such media the initial excitation energy goes into<br/>the formation of elastic waves of different modes. Due to "dispersion", these modes tend to<br/>separate according to the velocities of the frequency components. This work demonstrates<br/>elastic wave measurements on human femur specimens. The aim of the study is to measure<br/>parameters like wave velocity, dispersion and attenuation by using broadband acoustic<br/>emission sensors. First, four sensors were placed at small intervals on the surface of the<br/>bone to record the response after pencil lead break excitations. Next, the results were<br/>compared to measurements on a bulk steel block which does not exhibit heterogeneity at<br/>the same wave lengths. It can be concluded that the microstructure of the tissue imposes<br/>a dispersive behavior for frequencies below 1 MHz and care should be taken for<br/>interpretation of the signals. Of particular interest are waveform parameters like the<br/>duration, rise time and average frequency, since in the next stage of research the bone<br/>specimens will be fractured with concurrent monitoring of acoustic emission.

Topics

• impedance spectroscopy
• dispersion
• surface
• steel
• acoustic emission