Multi-frequency Approach to Imaging Damage in Stiffened Structures Exhibiting Multi-path Reflections

Reflections of guided waves by features in structures of complex geometry, such as panels with stiffeners, present a significant difficulty for locating and quantifying damage. In specific cases where the damage is far away from the reflecting boundary or substructure, time-gating techniques may be applied to remove reflections. In this work we examine the effectiveness of multi-frequency method to address multi-path reflections using the time-reversal and diffraction tomography techniques. Imaging results show excellent reconstruction quality and estimation of damage size and severity. This new method enables practical implementation of quantitative damage assessment in complex structures using minimal number of sensors. doi: 10.12783/SHM2015/239