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1.
V. T. Grinchenko 《International Applied Mechanics》2005,41(9):988-994
Dynamic effects characteristic of elastic bodies and associated with local disturbances in finite elastic bodies and inhomogeneous
waveguides are analyzed and systematized. The physical causes of such disturbances are analyzed. It is shown that these disturbances
are due to energy transfer from longitudinal to transverse waves and back, when they are reflected from the free surface of
an elastic body
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Translated from Prikladnaya Mekhanika, Vol. 41, No. 9, pp. 38–45, September 2005. 相似文献
2.
International Applied Mechanics - The propagation of quasi-Lamb waves in a prestrained compressible elastic layer that interacts with a half-space of a compressible ideal fluid and in a prestrained... 相似文献
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N. A. Shul'ga 《International Applied Mechanics》2002,38(12):1440-1458
Waves in anisotropic homogeneous and piecewise-homogeneous piezoelectric cylinders are investigated for various types of anisotropy, boundary conditions, and interaction with the ambient acoustic medium and electromagnetic field 相似文献
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The dispersive propagation of axisymmetric and nonaxisymmetric waves in piezoceramic homogeneous cylinders is studied for various prepolarization directions. 相似文献
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The results of a theoretical investigation into ultrasonic linear normal wavefields in anisotropic three-dimensional bodies with mechanical orthorhombic symmetry are presented. A detailed study is made of the dispersion dependencies for higher normal wave modes in a single-layered orthorhombic plate-type waveguide. Moreover, the distribution of complex branches corresponding to the edge standing wave modes is studied and their role in the transformation of the entire spectrum upon a change in the travel direction in the waveguide plane is analyzed. A new type of localization of the higher modes of high-frequency short-range normal waves in a crystal layer is described. An efficient method is developed for studying the spectrum of ultrasonic normal waves in a circular cylindrical waveguide made of an orthorhombic monocrystal 相似文献
6.
Esben Byskov 《基于设计的结构力学与机械力学》2013,41(4):413-435
ABSTRACT ABSTRACT In some cases, asymptotic methods present an appealing alternative to full nonlinear analyses. In other cases, the value of an asymptotic analysis may merely be that, in a qualitative way, it can characterize the behavior of a structure. Whether an asymptotic method is applied for one or the other purpose it is of interest to attempt an estimation of its range of validity. The present paper addresses this question for an asymptotic method to predict imperfection sensitivity of elastic structures with mode interaction. The particular structure that is investigated possesses an infinity of nearly simultaneous local buckling modes. It is found that very few of these modes need to be taken into account. 相似文献
7.
This paper considers an ideal nonthermal elastic medium described by a stored-energy function W. It studies time-dependent configurations with subsonically moving phase boundaries across which, in addition to the jump
relations (of Rankine–Hugoniot type) expressing conservation, some kinetic rule g acts as a two-sided boundary condition. The paper establishes a concise version of a normal-modes determinant that characterizes
the local-in-time linear and nonlinear (in)stability of such patterns. Specific attention is given to the case where W has two local minimizers U
A
,U
B
which can coexist via a static planar phase boundary. Being dynamic perturbations of such interesting configurations, this
paper shows that the stability behaviour of corresponding almost-static phase boundaries is uniformly controlled by an explicit
expression that can be determined from derivatives of W and g at U
A
and U
B
. 相似文献
8.
Dynamic analysis of a two-layered elasto-piezoelectric composite hollow sphere under spherically symmetric deformation is developed. An unknown function of time is first introduced in terms of the charge equation of electrostatics and then the governing equations of piezoelectric layer, in which the unknown function of time is involved, are derived. By the method of superposition, the dynamic solution for elastic and piezoelectric layers is divided into quasi-static and dynamic parts. The quasi-static part is treated independently by the state space method and the dynamic part is obtained by the separation of variables method. By virtue of the obtained quasi-static and dynamic parts, a Volterra integral equation of the second kind with respect to the unknown function of time is derived by using the electric boundary conditions for piezoelectric layer. Interpolation method is employed to solve the integral equation efficiently. The transient responses for elastic and electric fields are finally determined. Numerical results are presented and discussed. 相似文献
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纤维排列方式对单向纤维加强复合材料弹性常数的影响 总被引:3,自引:0,他引:3
本文应用GMC方法计算了纤维在规则排列和随机排列时单向纤维加强复合材料的总体弹性系数,结果表明,在一定纤维体积比范围内,虽然纵向弹性模量不受纤维排列方式的影响,但是复合材料的横向弹性模量和横向剪切模量受纤维排列方式的影响较大,所以,在考察复合材料的横向弹性常数时,应该考虑纤维排列方式的影响,在相同纤维比的情况下,正方形排列和正方形对角排列所得的弹性常数是上下界,而六角形排列和随机排列的结果位于以上两者之间,当纤维比较小时(小于20%),纤维的排列方式对各弹性常数均无明显影响,本文的结果在工程应用中有指导意义。 相似文献
13.
弹性波作用下压电体摩擦接触界面滑移特性分析 总被引:1,自引:0,他引:1
弹性波与压电体摩擦接触界面相互作用会引起界面滑移或分离,滑移和分离位置的分布与外加压力、剪力、电场及入射波的条件有关。应用Fourier分析及matlab软件给出了滑移范围的解,给出了粘着、滑移或分离的判定条件,通过算例分析了滑移和分离出现的影响因素和条件,为工程应用提供了理论依据。 相似文献
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Postnova and Craster (Wave Motion, 45, 2008, pp. 565-579) describe a method for determining the frequency of trapped modes in slowly-varying elastic plates, and ocean and quantum waveguides. The purpose of the present note is to show that the accuracy of the frequency estimates for ocean waveguides can be significantly increased by taking into account the fact that, as posed, the ocean waveguide problem is not self-adjoint. For an example where the asymptotic problem has an exact solution, comparison with a numerical solution of the full problem shows that the correction to the asymptotically determined frequency is of order the fourth power of the ratio of the shelf width to the scale for longshore variations in the shelf. An explicit simple formula is also given for the trapped mode frequency of an arbitrarily, but extremely weakly and positively, curving coast. 相似文献
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We investigate the existence of trapped modes in elastic rods of constant circular cross-section that possess bends of arbitrary curvature and straighten out at infinity; such trapped modes consist of finite energy localized in regions of maximal curvature. An asymptotic model assuming smallness of dimensionless curvature is developed to describe the trapping. Existence conditions depending on Poisson’s ratio are offered, and the equations from which they derive are numerically validated. A physical explanation of why trapped modes should be expected is also given. 相似文献
18.
We show that twisting of an infinite straight three-dimensional tube with non-circular cross-section gives rise to a Hardy-type
inequality for the associated Dirichlet Laplacian. As an application we prove certain stability of the spectrum of the Dirichlet
Laplacian in locally and mildly bent tubes. Namely, it is known that any local bending, no matter how small, generates eigenvalues
below the essential spectrum of the Laplacian in the tubes with arbitrary cross-sections rotated along a reference curve in
an appropriate way. In the present paper we show that for any other rotation some critical strength of the bending is needed
in order to induce a non-empty discrete spectrum. 相似文献
19.
A new group of wavelets that have the form of solitary waves and are the solutions of the wave equations for dispersive media is proposed to call elastic wavelets. That this group includes well-known Mexican-hat wavelets is proved. It is proposed to use elastic wavelets to study local features of the profile evolution of a solitary wave in an elastic dispersive medium 相似文献
20.
We present the small-amplitude vibrations of a circular elastic ring with periodic and clamped boundary conditions. We model the rod as an inextensible, isotropic, naturally straight Kirchhoff elastic rod and obtain the vibrational modes of the ring analytically for periodic boundary conditions and numerically for clamped boundary conditions. Of particular interest are the dependence of the vibrational modes on the torsional stress in the ring and the influence of the rotational inertia of the rod on the mode frequencies and amplitudes. In rescaling the Kirchhoff equations, we introduce a parameter inversely proportional to the aspect ratio of the rod. This parameter makes it possible to capture the influence of the rotational inertia of the rod. We find that the rotational inertia has a minor influence on the vibrational modes with the exception of a specific category of modes corresponding to high-frequency twisting deformations in the ring. Moreover, some of the vibrational modes over or undertwist the elastic rod depending on the imposed torsional stress in the ring. 相似文献