Laurence J. Jacobs

GATech · company speakers →

Taking nonlinear ultrasound from the lab to the field – the importance of developing reliable standards and benchmark problems. Abstract: Predictive health monitoring of structural components requires the development of advanced sensing techniques capable of providing quantitative information on the damage state of macroscale structural systems. Nonlinear ultrasound (NLU) can measure absolute, strength based material parameters which can be coupled with uncertainty models to enable accurate and quantitative life prediction. These second harmonic techniques are acoustic wave based, so component interrogation can be performed in situ using either bulk, surface and guided waves. Since the underlying material physics is independent of the choice of ultrasonic wave, it is possible to interrogate a variety of different structural systems for microscale defects. Recent studies have demonstrated that NLU is sensitive to nano- and microscale changes in microstructure due to a variety of damage mechanisms such as thermal, sensitization and fatigue damage. Although linear ultrasonic methods are effective in detecting macroscopic flaws such as cracks, they are often not capable of assessing damage in its early states. In contrast, NLU is sensitive to damage mechanisms associated with nanoscale changes in microstructure, such as dislocations and precipitates. This talk will examine the steps needed to take NLU from being a valuable laboratory characterization technique to a reliable, field qualified tool

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