Generation of finite-amplitude Lamb modes in a layered planar structure

In this article a technique for analyzing the generation of finite-amplitude Lamb modes in a layered planar structure has been developed. The focus here is on weakly nonlinear wave motion, for which the successive approximation can be adopted. The analysis is based on the assumptions that the material of each layer is isotropic and homogeneous with no attenuation and no dispersion, and that the higher harmonic energy is much less than that of the fundamental. On the basis of these assumptions and partial plane wave approach, a theoretical model for nonlinear generation of finite-amplitude Lamb modes in a layered planar structure has been established. This model reveals some interesting features of the physics of the second harmonics with the cumulative growth effects.