EXPERIMENTAL INVESTIGATION OF LAMB WAVE RESPONSE FOR THE SURFACE CORROSION DAMAGE IN PLATES

Because the surface corrosion damage could susceptibly occur in metallic structures for the corrosive environment and fatigue loads, it essential to detect the corrosion timely and precisely before the loss of life and property caused by corrosion. Based on low-frequency Lamb wave technique, the low-frequency A0 Lamb wave, the low-frequency S0 Lamb wave and one-way S0-A0 Lamb mixing wave are experimentally investigated in the thin plates with the early stage damage caused by the surface corrosion, which were made by different times of hydrochloric corrosion. Firstly, it verified that the damage degree of the surface corrosion region increases with the number of corrosion times by the Scanning Electron Microscopy (SEM). Secondly, the linear and nonlinear effect caused by corrosion had been investigated, and the relationship between the characters of the different Lamb waves and the different corrosion damage levels were qualitatively discussed. Especially, the length and the location of the corrosion region were located successfully by one-way S0-A0 Lamb mixing wave. This paper explores experimentally the propagation mechanism of low frequency linear and nonlinear Lamb wave in thin plates with corrosion damage, which can provide an experimental basis for Lamb-wave detection techniques used in the evaluation and location of damages.