Nonlinear guided waves-based localization of out-of-sight damage through local wave-direction estimation

Scanning laser Doppler vibrometry (SLDV) is a great full-field measurement technique for guided waves’ based SHM and NDT. However, the required time and effort for scanning large structural components, and the need for accessing the entire surface, limits its industrial application. To tackle this limitation, a novel wave processing algorithm, “local wave-direction estimation (LWDE)”, is introduced for localization of damage by only partially scanning the surface of a component. LWDE is a baseline-free imag-ing method which is based on the presence of nonlinear guided waves originat-ing from the damage location. Angular bandpass filters are applied and the local nonlinear wave direction is estimated as the trajectory along which nonlinear wave energy is the highest. The local wave direction map is then converted to an error map which indicates the damage locations (i.e. sources of nonlinear re-sponse) as local minima. The performance of LWDE is demonstrated on an aircraft composite plate with a disbond at one of the backside stiffeners. It is shown how the technique can be used for localization of the disbonded area without any prior information about material properties and layup, even when the disbond is not in the field-of-view of the SLDV measurement area.

Publication year:2022

Accessibility:Open