A simulation study on migration technique for damage imaging based on mindlin plate theory

Currently, structural health monitoring (SHM) is one ofthe most promising directions in the research field of smart materials andstructures. However, up to now, most of the developed methods can onlydetect and localize the damage, quantitatively identify the extent of thedamage, especially for multiple damages, remain a challenge task. This paperproposed a migration approach for identification of multiple damages inplate-like structure in real time using scattered Lamb waves. Based onMindlin plate theory, the fast frequency-wavenumber domain migrationtechnique for dispersive flexural wave was deduced for the first time.According to the Huygens' Principle, damages were imaged by applying atime-coincidence imaging condition after extrapolating the excited andscattered wave fields. Numerical simulation study employed a Mindlin platetheory-based finite difference method to generate synthetic scattered wavefields with damages of different shapes and sizes in the structure. Imagingresults for the synthetic wave fields have demonstrated that the proposedmethod has the capability of not only localizing multiple damages but alsoidentifying their extent; its advantage of fast calculation meets therequirement of real-time damage identification for an on-line structuralhealth monitoring system.