Corrosion degradation monitoring of ship stiffened plates using guided wave phase velocity and constrained convex optimization method.

The study presents an experimental investigation on the corrosion degradation level assessment using nondestructive wave-based methods. The degradation level of ship structural elements has been assessed in two different ways. The first one is based on the spectral decomposition and zero-crossing incorporated reconstruction of the dispersion curve approach of the antisymmetric Lamb wave mode and the best matching of the theoretical solution. The second approach was based on searching for a solution to the convex optimization problem. In the first case, the plate thickness is assumed to be constant and the phase velocity reconstructed curve is fitted to match the best solution in the all considered frequency domain. In the second case, the assumption about the varying plate thickness is set and the optimal thickness distribution resulting in any times of wave flight is defined. • Wave-based methods for the corrosion degradation level assessment are employed. • Plate thickness reduction is assessed using phase velocity curve reconstruction. • The constrained convex optimization in thickness reduction estimation is used. [ABSTRACT FROM AUTHOR]