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1

Nonlinear surface elastic waves in materials

Rushchitsky J.

Vibrations in Physical Systems

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2014

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Vol. 26

33--40

EN

This paper is devoted to analysis of the surface nonlinear elastic harmonic waves of four types (Rayleigh and Stoneley harmonic waves within the framework of plane strain state; Love and Mozhaev harmonic wave within the framework of anti-plane strain state). The nonlinear model is based on introducing the Murnaghan elastic potential, which includes both geometrical and physical nonlinearities. Each type of surface waves is discussed in four steps: statement of the problem, nonlinear wave equations, approximate solution (first two approximations), so-me conclusions. A nonlinear analysis of waves required many novelties: new variants of the Murnaghan potential, new nonlinear wave equations and new nonlinear boundary conditions. The nonlinear wave equations were solved by the method of successive approximations. A new approach to analyze the boundary conditions is offered. Some new nonlinear wave effects are observed theoretically: a wave picture is reached by the 2nd harmonic and becomes changing in time of propagation, the wave numbers become depending on the initial amplitude.

2

Love waves in pre-stressed Yeoh materials

Kosińska A., Kosiński S.

Vibrations in Physical Systems

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2010

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Vol. 24

233--238

EN

The paper is concerned with the effect of pre-stress on the propagation of Love waves in incompressible nonlinear rubberlike materials with the representation for the strain energy function derived by Yeoh. The special initial deformations in the form of the large static homogeneous pure strains are assumed in the half space and in the layer of the waveguide. It is considered the wave propagation along a principal axis and the dispersion equation for Love waves along a principal axis of the underlying deformation in respect of a selected strain energy function is analyzed in details. For two types of homogeneous equibiaxial deformations the numerical results are obtained. They are quite different as in linear theory, because the equibiaxial static deformations can lead to reduction or increase of the cut-off frequency of the waveguide. The standard procedure for the linearization of equations of motion was used. This approach bases on the assumption that, small time depending motions are superimposed on large static deformation.

PL

W pracy rozpatrzono zlinearyzowane zagadnienie brzegowe dla fal Love’a. Założono, że półprzestrzeń sprężysta i spoczywająca na niej cienka warstwa o grubości h wykonane są z różnych materiałów Yeoha i poddane są jednorodnej statycznej deformacji wstępnej, identycznej w obu obszarach. Dla materiału Yeoha funkcja energii odkształcenia W zależy jedynie od pierwszego niezmiennika tensora deformacji tj. W =W(I1). Ta szczególna zależność może powodować w zależności od typu deformacji wstępnej występowanie dużych lub nieistotnych różnic jakościowych między liniowym i zlinearyzowanym podejściem do propagacji fal Love’a w nieściśliwych materiałach sprężystych.

3

Shear velocity inversion procedure for love waves

Zaman F. D., Masod K.

Journal of Technical Physics

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2003

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Vol. 44, no 3

295-301

EN

An inverse solution is presented to the seismic inverse problem for one-dimensional shear velocity variations. The Love waves, travelling in a layer overlying a half-space incident upon delta-function potential, are considered. The equation of motion for Love waves is transformed to the Schrodinger equation and then the potential is recovered by applying Gelfand-Levitan and Marchenko procedure.