Resonant defects: A new approach to highly-sensitive defect-selective ultrasonic imaging

In this paper, a consistent way to enhance acoustic, optical and thermal defect responses is suggested by using selective ultrasonic activation of defects based on the concept of Local Defect Resonance (LDR). A straightforward phenomenology and the finite element simulation are developed to evaluate various order LDR frequencies. The LDR provides a selective excitation of a defect that results in a high local vibration amplitude and enhancement of the defect ultrasonic, thermal and optical responses readily measurable even for a few mW of acoustic input. This proposes LDR application as an efficient and highly-sensitive mode for ultrasonic, thermosonic and optical defect-selective imaging in NDT.