Propagation of Quasi-Lamb Waves in an Elastic Layer Interacting with a Viscous Liquid Half-Space

International Applied Mechanics - The propagating of quasi-Lamb waves in an elastic layer that interacts with a half-space of a viscous compressible fluid is studied. The three-dimensional...     

Effect of the Initial Stresses on Waves in the System Consisting of a Viscous Fluid Layer and a Compressible Elastic Half-Space

International Applied Mechanics - The problem of acoustic wave propagation in a prestrained compressible elastic half-space that interacts with a layer of viscous compressible fluid is solved using...     

Dispersion of Surface Waves in a Periodically Laminated Piezoelectric Half-Space with Liquid Upper Layer

An approach is proposed to set up the dispersion equations for surface waves propagating through a periodically laminated piezoelectric medium, with the upper layer being a perfect compressible fluid. The approach is based on the formalism of Hamiltonian periodic systems. The dispersion equations derived are valid for an arbitrary law of variation in properties with periodicity coordinate. The influence of the liquid layer and inhomogeneity of the piezoelectric medium on the dispersion spectra of surface waves is studied__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 3, pp. 55–61, March 2005.     

Instabilities in Dynamic Anti-plane Sliding of an Elastic Layer on a Dissimilar Elastic Half-Space

The stability of dynamic anti-plane sliding at an interface between an elastic layer and an elastic half-space with dissimilar elastic properties is studied. Friction at the interface is assumed to follow a rate- and state-dependent law, with a positive instantaneous dependence on slip velocity and a rate weakening behavior in the steady state. The perturbations at the interface are of the form exp(ikx ₁+pt), where k is the wavenumber, x ₁ is the coordinate along the interface, p is the time response to the perturbation and t is time. A key feature of the problem is that interfacial waves both in freely slipping contact as well as in bonded contact exist for the problem. Attention is focused on the role of the interfacial waves on slip stability. Instabilities are plotted in the $\operatorname{Re} (pL/V_{o})$ versus $\operatorname{Im} (p/|k|c_{s})$ plane, where L is a length scale in the friction law, V _o is the unperturbed slip velocity and c _s is the shear wave speed of the layer. Stability of both rapid and slow slip is studied. The results show one mechanism by which instabilities occur is the destabilization by friction of the interfacial waves in freely slipping contact/bonded contact. This occurs even in slow sliding, thus confirming that the quasi-static approximation is not valid for slow sliding. The effect of material properties and layer thickness on the stability results is studied.     

Surface Forces Driven Wrinkling of an Elastic Half-Space Coated with a Thin Stiff Surface Layer

This paper studies surface instability of a coated semi-infinite linear elastic body interacting with another flat rigid body through surface van der Waals (vdW) forces under plane strain conditions. The emphasis is on the effect of the surface coating layer on the wavelength of surface wrinkling. It is shown that the surface of the coated elastic half-plane is always unstable even in the presence of a very stiff coating layer. However, the numerical results show that the stiff coating layer has a significant effect on the wavelength of the surface instability mode and can effectively prevent the surface from short-wavelength wrinkling. In particular, the surface tangential displacement associated with the surface instability vanishes when the elastic half-plane is incompressible. In this case, the in-plane rigidity of the coating layer has no effect on surface instability while the bending stiffness of the coating layer has an effect on the wave-length of the surface instability mode. Furthermore, the Poisson’s ratio of elastic half-plane has a significant role in the surface instability and the associated wave-length. C. Q. Ru is on leave from the University of Alberta, Edmonton, T6G. 2G8, Canada.     

梯度介质半空间Rayleigh面波传播性能研究

对剪切弹性模量沿深度以指数函数变化的非均质半空间，本文用摄动法得到了Rayleigh面波的波函数解答及相速度方程。以不同金属与陶瓷复合而成的几种梯度材料为例，用数值方法求解了相速度方程，给出了相应的波的弥散曲线，结果表明，梯度介质半空间自由表面附近的Rayleigh波通常有两种不同的弥散形式，即正常弥散和非正常弥散。     

Propagation of Coupled Waves Interacting with an Electromagnetic Field in Periodically Inhomogeneous Media

The paper is concerned with coupled (electroelastic, electromagnetoelastic, and magnetoelastic) waves in inhomogeneous media     

Propagation of Elastic Waves in Periodically Inhomogeneous Media

The structural theory of waves and vibrations in periodically inhomogeneous media is set out. Relevant research results are presented. Emphasis is on the principles of the theory, surface waves, and other surface effects     

Propagation of Harmonic Waves in an Orthotropic Cylindrical Shell on Elastic Foundation

An equation is derived, using Timoshenko shell theory, to analyze axisymmetric strain fields in an orthotropic cylindrical shell on an elastic foundation. Also a dispersion equation is derived to study the natural harmonic waves in a shell depending on the properties of the elastic foundation. The wave velocities computed by the numerical method proposed are in agreement with the analytical solutions, which confirms the reliability of the results     

Surface Waves in a Stratified Periodic Medium with a Liquid Upper Layer

An approach is proposed to set up the dispersion equations for surface waves in a periodically stratified half-space contacting with a layer of a perfect compressible liquid. The approach is based on the formalism of periodic Hamiltonian systems. The dispersion equations derived are valid for an arbitrary law of variation in the properties with respect to the coordinate of periodicity. The effects of the liquid layer and the inhomogeneity of the elastic medium on the dispersion spectra of surface waves are studied     

Pressure of a Narrow Band-Like Punch Upon an Elastic Half-Space

An asymptotic solution is obtained to the contact problem of a band-like punch acting upon an elastic half-space. The method of joined asymptotic expansions is used. The results of numerical calculations are presented. The efficiency of the approach is tested by comparing it with another method     

Numerical Simulation of the Stress Concentration in an Elastic Half-Space with a Two-Layer Inclusion

The stress concentration around a two-layered spherical inclusion located near the surface of an elastic half-space under uniform compression is considered. A numerical solution algorithm is elaborated, application software is created, and numerical experiments demonstrating the capabilities of the approach proposed are conducted.