Highly-Sensitive Defect-Selective Imaging and NDT via Resonant Nonlinearity of Defects

In this paper, it is proposed to use a combination of mechanical resonance and nonlinearity of defects to enhance substantially the
efficiency of input-output frequency conversion in nonlinear NDT. The concept of a defect as a nonlinear oscillator brings about
new dynamic and frequency scenarios characteristic of nonlinear and parametric oscillations. The experiments confirm transition
to resonant modes of nonlinear vibrations in simulated and realistic defects. All resonant nonlinear modes are strongly localised
in the defect area that provides a background for high-contrast highly-sensitive defect- and frequency-selective imaging.