Nonlinear Elastic Waves Spectroscopy (NEWS) for non-destructive inspection and detection of the subsurface cracks and flaws

The objective of the proposed research is to develop a new technology, based on the principles of nonlinear acoustics that will provide an accurate detection of subsurface crack and flaws in materials used in aircraft. Existing theoretical and experimental data demonstrate that the detection of microcracks and other defects that accumulate in material due to fatigue and external damage is enhanced by orders of magnitude with the use of nonlinear acoustic techniques. In the proposed work we will apply two novel techniques of nonlinear acoustic nondestructive evaluation (NA NDE) for evaluation of the material damage. The first technique exploits modulation of ultrasound by low-frequency vibrations and the second is called nonlinear time reversal acoustic (NTRA). Both techniques have a great potential for microcracks detection and localization, even if taken separately. We, however, propose to develop a combined NEWS technique, which will take the advantages of both methods. The Phase I research effort will demonstrate the feasibility of the proposed nonlinear acoustics techniques and supporting models. We will also produce first generation instrumentation and data processing techniques that will become the foundation of a cost effective and “field-friendly” product for the nondestructive inspection (NDI) of aircraft materials.