Prediction of mechanical properties of healing fractures using acoustic emission

Abstract

The objective of this study was to develop a non-destructive method for monitoring fracture healing with acoustic emission (AE). Experimentally produced fractures of the rat femur were tested in tension and in torsion at 4,6,8 and 12 weeks after fracture. AE signals were monitored during these mechanical tests. The values for load and torque at the initiation of the AE signal were defined as new mechanical parameters. The apparent density and ash density of the fracture site were also measured at each time period. Tensile strength, tensile stiffness, maximum torque and torsional stiffness of the fracture site increased with time. The AE signal was detected before complete specimen failure. Load and torque for initiation of AE increased proportionally with increasing mechanical properties. The mineral density, however, reached a plateau at 8 weeks, when callus mechanical strength was approximately 50% of control. Load for initiation of AE was strongly correlated with the strength (I = 0.98), stiffness (I = 0.88). and failure strain ( Y = -0.63) of the callus. Torque for initiation of AE was highly correlated with the maximum torque (I = 0.95) and torsional stiffness (I = 0.93) of the callus. The findings of the present study indicated that some mechanical properties of healing fractures could be estimated by monitoring AE signals.

Fracture of fiber-reinforced composites analyzed <i>via</i> acoustic emission

“…This agreed with previous studies which indicated that plastic deformation of the matrix and fibers produced continuous signals of low amplitudes; on the other hand, cracking of the resin matrix or reinforcing fibers or debonding of the fibers generated burst-type signals of higher amplitudes 41) . Watanabe et al 20) found a positive linear relationship between AE activity, in terms of cumulative counts and load for initiation of acoustic signals, and the final failure load. In the present study, AE amplitude was analyzed instead of signal counts.…”

“…It can detect failure initiation, the initial site of damage, damage propagation, accurately measure the maximum strength of a material and detect the mechanism of failure at multiple sites -even nonvisible subsurface ones. It provides early warnings of failure and is regarded as having high sensitivity since it can register even small cracks 15,19,20) . Dental composite structures often exhibit local failures before rupture into two or more pieces.…”

Monitoring the Mechanical Properties of Healing Bone

“…The use of acoustic emission to determine the mechanical status of a healing bone was investigated by Watanabe et al [44]. They found that under increasing loading, the acoustic emission signal from the fracture site could be detected prior to the failure and that the load required to initiate the acoustic emission increased proportionately with the increasing mechanical properties of the healing fracture.…”

A paradigm shift for bone quality in dentistry: A literature review

“…Correlation and multiple regression analyses revealed that the degree of BAp c-axis orientation had a more significant contribution to Young's modulus than BMD [21]. This finding explains one of the reasons for the reported dissociation between BMD and bone strength; that is, bone strength improved without increased bone density in the later phase of bone regeneration [81,82]. Because of the intrinsic mechanical anisotropy of BAp and collagen, their directional arrangement generates anisotropy in bone mechanical property [21].…”