Second-Harmonic Generation of Lamb Waves in a Solid Layer on a Half Space

摘要

This work develops an effective approach for studying second-harmonic generation of Lamb waves in the composite structure consisting of a solid layer on a half space. Using a second-order perturbation approximation and a modal expansion analysis approach for waveguide excitation, an effective theoretical model has been established. The fields of second harmonics of Lamb waves can be regarded as superpositions of a finite series of normal Double Frequency Lamb Waves (DFLWs). Despite the strongly dispersive nature of Lamb waves, it is found that a DFLW can grow.with, propagation distance down the composite structure when the DFLW phase velocity equals that of the primary Lamb wave.