Non-destructive evaluation of healing of bone fracture using acoustic emission (AE)

Acoustic Emission (AE) is a Nondestructive Testing (NDT) technique based on observation and analysis of ultrasonic waves propagated by failure mechanisms in a material under stresses. This technique provides real-time monitoring of the structural discontinuities of tissues in order to assess and characterize the bone fracture healing process. The goals of this study are to investigate the compatibility and usefulness of AE technique in the evaluation of fracture healing phases of the bone and to develop an NDT methodology for the monitoring of crack initiation and propagation in bones. The experiments depended on "in vitro" techniques using bovine tibia models. The test samples were subjected to tensile loading until fracture using a mechanical testing machine. During the mechanical tests, AE signals were captured and recorded via AE system processor equipped with two wideband piezoelectric sensors fixed to the surfaces of both ends of test samples. AE activities were observed by superposing force versus time and cumulative AE versus time diagrams. In experiments, the cumulative AE number for each period of time rose up exponentially with the incremental tensile load. Load for AE initiation demonstrated a convincing linear interaction with AE event generation. Each major change on AE event curve coincided with a significant increase of AE hit number, Amplitude (dB), Absolute Energy (ae), Energy (EU) and Peak Frequency (Hz) of the recorded signals. Keywords: Acoustic Emission (AE), Non-Destructive Testing (NDT), Crack Initiation and Propagation, Fracture Healing, Bovine Tibia.