Experimental and numerical investigations of nonlinear interaction of counter-propagating Lamb waves

The nonlinear interaction of Lamb waves has attracted considerable attention because of its potential for localizing micro-damage in plate-like structures. Most recent studies have focused on the nonlinear mixing of Lamb waves propagating in the same direction, but this makes it difficult to determine the exact position of micro-damage because of the relatively large mixing zone. To overcome these shortcomings, we consider the nonlinear interaction of counter-propagating Lamb waves in this letter, An obvious resonance phenomenon is first observed in both experiments and simulations, which agrees well with our previous theoretical analysis [Li et al, J. Appl. Phys. 124, 044901 (2018)]. Also, analyzing the time-domain signal shows that the precision of damage localization is a function of the frequencies, the number of cycles, and the phase and group velocities of the primary waves. Published under license by AIP Publishing.