Resonant Ultrasonic Activation of Damage: Application for Diagnostic Imaging

Defects induced in materials are accompanied by a local decrease of stiffness in the damaged area, which manifests in their characteristic frequencies and a possibility of resonant activation by a driving acoustic wave. Such Local Defect Resonance (LDR) enables to reliably detect and visualize the defect as soon as the driving acoustic frequency is matched to damage characteristic frequency. This also provides a high frequency selectivity of the LDR-based imaging, i.e., an opportunity of detecting a certain defect among a multitude of other defects in material. In this article, the benefits of the resonant approach are demonstrated via multiple case studies for nonlinear, optical, and thermosonic frequency-selective imaging of defects in lightweight materials and components.