Narrow Results

A more general two-dimensional wave motion equation with consideration of attenuation and nonlinearity is proposed to describe propagating nonlinear Rayleigh waves of finite amplitude. Based on the quasilinear theory, the numerical solutions for the sound beams of fundamental and second harmonic waves are constructed with Green’s function method. Compared with solutions from the parabolic approximate equation, results from the general equation have more accuracy in both the near distance of the propagation direction and the far distance of the transverse direction, as quasiplane waves are used and non-paraxial Green’s functions are obtained. It is more effective to obtain the nonlinear Rayleigh sound beam distributions accurately with the proposed general equation and solutions. Brief consideration is given to the measurement of nonlinear parameter using nonlinear Rayleigh waves.

This work deals with the extension of the partition of unity finite element method (PUFEM) "(Comput. Meth. Appl. Mech. Eng.139 (1996) pp. 289–314; Int. J. Numer. Math. Eng.40 (1997) 727–758)" to solve wave problems involving propagation, transmission and reflection in layered elastic media. The proposed method consists of applying the plane wave basis decomposition to the elastic wave equation in each layer of the elastic medium and then enforce necessary continuity conditions at the interfaces through the use of Lagrange multipliers. The accuracy and effectiveness of the proposed technique is determined by comparing results for selected problems with known analytical solutions. Complementary results dealing with the modeling of pure Rayleigh waves are also presented where the PUFEM model incorporates information about the pressure and shear waves rather than the Rayleigh wave itself.

The problem of Rayleigh waves polarized in a plane of symmetry of an anisotropic linear elastic medium is investigated in terms of displacements. The implicit secular equation is derived and subsequently rearranged into a system of three polynomial equations, which is convenient for further analysis of the problem. Next, a new straightforward procedure based on Vieta’s formulas is developed to reduce the system into a single explicit quartic secular equation. Numerical examples describing both approaches are presented for two monoclinic materials “diopside” and “microcline”.

The construction of a high-frequency asymptotic solution describing the propagation of Rayleigh waves along the curved free boundary of an inhomogeneous hyperelastic medium is given. A dispersion formula for the Rayleigh waves is derived.