Second-Harmonic Properties of Horizontally Polarized Shear Modes in an Isotropic Plate

概要

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The second harmonics of SH modes that occur within an isotropic plate with two free boundaries are investigated by applying second-order perturbation theory. The results show that the second harmonics include two types of waves. One is driven waves produced by the fundamental waves due to the nonlinearity of an elastic medium, and the other is free waves introduced to satisfy the second-harmonic boundary conditions. It is also found that the second-harmonic field patterns are symmetric, and the second-harmonic amplitudes are independent of propagation distance and one of the third-order elastic constants, C. The second-harmonic resonant phenomena occur and the second harmonics possess the characteristics of two-dimensional spatial accumulation once the phase velocities of SH modes equal the longitudinal velocity of the elastic medium. Moreover, the analytical expressions of the second harmonics are obtained. Numerical results show the distortions of the second-harmonic field patterns.
社団法人応用物理学会の論文
1996-07-15