Torsional oscillation of rigid disk in infinite transversely isotropic elastic cylinder

In the present analysis torsional oscillation of a rigid disk in an infinite transversely isotropic elastic cylinder is considered. The effects of anisotropy in the stress intensity factor are shown graphically.     

Finite elastic deformations of an infinite plate perforated by two circular holes under biaxial tension

Summary Based on the theory of finite deformations and by the use of a given reference frame in undeformed body, stresses of an incompressible isotropic infinite plate with two circular holes subjected to biaxial tension at infinity are investigated. The material is assumed to be in the state of finite plane strain. The method of successive approximation is used in connection with the complex variable method of plane elasticity. Numerical results due to the second-order approximation theory are given for stresses, and compared with those predicted by classical theory of elasticity.

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Übersicht Es werden die Spannungen in einer unendlich ausgedehnten Platte mit zwei kreisförmigen Löchern nach der Theorie endlicher Verformungen und unter Verwendung eines im unverformten Körper festgelegten Bezugsgerüstes untersucht. Die Platte besteht aus inkompressiblem isotropen Material und wird einer im Unendlichen zweiachsialen Verzerrung ausgesetzt. Der Verzerrungszustand wird als eben angenommen. Bei den Untersuchungen werden die komplexen Methoden der ebenen Elastizitätstheorie in Verbindung mit schrittweisen Näherungen angewendet. Aufgrund einer Annäherung zweiter Ordnung werden die Spannungen numerisch ausgerechnet und mit den Werten verglichen, die von der klassischen Elastizitätstheorie vorausgesagt werden.

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The author wishes to express his hearty thanks to Osamu Tamate, Professor of Tohoku University, for directing the work.     

Poromechanical response of a finite elastic cylinder under axisymmetric loading

Drained or undrained cylindrical specimens under axisymmetric loading are commonly used in laboratory testing of soils and rocks. Poroelastic cylindrical elements are also encountered in applications related to bioengineering and advanced materials. This paper presents an analytical solution for an axisymmetrically-loaded solid poroelastic cylinder of finite length with permeable (drained) or impermeable (undrained) hydraulic boundary conditions. The general solutions are derived by first applying Laplace transforms with respect to the time and then solving the resulting governing equations in terms of Fourier–Bessel series, which involve trigonometric and hyperbolic functions with respect to the z-coordinate and Bessel functions with respect to the r-coordinate. Several time-dependent boundary-value problems are solved to demonstrate the application of the general solution to practical situations. Accuracy of the numerical solution is confirmed by comparing with the existing solutions for the limiting cases of a finite elastic cylinder and a poroelastic cylinder under plane strain conditions. Selected numerical results are presented for different cylinder aspect ratios, loading and hydraulic boundary conditions to demonstrate the key features of the coupled poroelastic response.     

Stress concentration in a transversely isotropic spherical shell with two circular rigid inclusions

The refined Timoshenko-type theory that takes into account the transverse shear strains is used to find an analytic solution for the stress state of transversely isotropic shallow spherical shell with two circular rigid inclusions. The case of a shell with closely spaced rigid inclusions of unequal radii under internal pressure is analyzed numerically. The stresses in the shell increase considerably with decrease in the distance between the inclusions and increase in the transverse shear parameter     

The electro-elastic field of the infinite piezoelectric medium with two piezoelectric circular cylindrical inclusions

The electro-elastic field of the infinite piezoelectric medium with two piezoelectric circular cylindrical inclusions is derived under the antiplane shear stresses and inplane electric fields. The analytical solution is obtained. The proposed method is based upon the use of conformal mapping and the theorem of analytic continuation. From the results obtained, it can be found that the electro-elastic field depends on the material constants of individual phases, the geometric parameters of the system and the applied antiplane shear stresses and electric fields at infinity. In addition, the specific cases when two circular cylindrical inclusions are tangent to each other and they are holes and/or rigid ones, are also studied in this paper. The project supported by the National Natural Science Foundation of China (19872023) and the Foundation of the Ministry of Education for trans-century outstanding scholars     

Electroelastic response of a piezoelectric cylinder with D∞ symmetry under axisymmetric mechanical loading

To understand the electroelastic field in fibers made of biodegradable polymers such as poly-l-lactic acid, we theoretically analyze the axisymmetric electroelastic field in a solid and infinitely long cylinder with D_∞ symmetry, when subjected to a combined pressure and torsional shear stress. By introducing two kinds of displacement potential functions and an electric potential function and applying a Fourier transform technique, we derive the formulae for the electroelastic field quantities inside the body. Moreover, by performing numerical calculations, we elucidate the field both qualitatively and quantitatively, and investigate the possibility of using fibers made of poly-l-lactic acid for medical engineering applications.     

Anti-plane dynamic problem of an electroelastic cylinder with thin rigid inclusions excited by a system of surface electrodes

Summary The anti-plane mixed boundary problem of electroelasticity for vibrations of an infinite piezoceramic cylinder with a thin rigid inclusion is considered. Using the developed integral representation of the solution, the boundary problem is reduced to a system of singular integro-differential equations of the second kind with resolvent kernels. Calculations yeild the amplitude-frequency characteristics of the piecewise homogeneous cylinder. The behaviour of electroelastic fields, both within the cylinder and on its boundary, is given.     

Axisymmetric smooth contact for an elastic isotropic infinite hollow cylinder compressed by an outer rigid ring with circular profile

A contact problem for an infinitely long hollow cylinder is considered. The cylinder is compressed by an outer rigid ring with a circular profile. The material of the cylinder is linearly elastic and isotropic. The extent of the contact region and the pressure distribution are sought. Governing equations of the elasticity theory for the axisymmetric problem in cylindrical coordinates are solved by Fourier transforms and general expressions for the displacements are obtained. Using the boundary conditions, the formulation is reduced to a singular integral equation. This equation is solved by using the Gaussian quadrature. Then the pressure distribution on the contact region is determined. Numerical results for the contact pressure and the distance characterizing the contact area are given in graphical form. The English text was polished by Yunming Chen     

Stability and fracture of plates with two edge cracks under tension

The paper presents experimental results on the deformation, local buckling, and fracture of D16AT plates with two parallel edge cracks under tension. The distribution of strains and deflections over typical cross-sections and buckling modes are determined. The influence of the crack length and the distance between the cracks on the local buckling stresses and breaking stresses is studied. The effect of local buckling on the strength of the plate is evaluated __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 11, pp. 121–125, November 2006.     

PRESSURE AND PRESSURE GRADIENT IN AN AXISYMMETRIC RIGID VESSEL WITH STENOSIS

Based on an improvement of the Karman-Pohlhausen's method, using nonlinear polynomial fitting and numerical integral, the axial distributions of pressure and its gradient in an axisymmetric rigid vessel with stenosis were obtained, and the distributions related to Reynolds number and the geometry of stenotic vessel were discussed. It shows that with the increasing of stenotic degree or Reynolds number, the fluctuation of pressure and its gradient in stenotic area is intense rapidly, and negative pressure occurs subsequently in the diverging part of stenotic area. Especially when the axial range of stenosis extends, the flow of blood in the diverging part will be more obviously changed. In higher Reynolds number or heavy stenosis, theoretical calculation is mainly in accordance with nast experiments.     

轴对称横观各向同性热弹性圆柱的分解

为了得到精确的应力场、位移场、温度场,将扭转圆轴的精化理论研究方法推广到轴对称横观各向同性热弹性圆柱。利用Bessel函数以及轴对称横观各向同性热弹性圆柱的通解,给出了轴对称横观各向同性热弹性圆柱的分解定理。根据柱面齐次边界条件获得了精确的精化方程,精化方程可以分解为一阶方程、超越方程、温度方程,从而将横观各向同性热弹性圆柱的轴对称问题分解为轴向拉压问题、超越问题、热-应力耦合问题。超越部分对应端部自平衡情况,可以清晰地了解到端部应力分布对内部应力场的影响,热-应力耦合部分对应无外加应力场时圆柱内部因温度变化引起的热应力。     

Contact with friction of a rigid cylinder with an elastic half-space

An exact solution to the problem of indentation with friction of a rigid cylinder into an elastic half-space is presented. The corresponding boundary-value problem is formulated in planar bipolar coordinates, and reduced to a singular integral equation with respect to the unknown normal stress in the slip zones. An exact analytical solution of this equation is constructed using the Wiener-Hopf technique, which allowed for a detailed analysis of the contact stresses, strain, displacement, and relative slip zone sizes. Also, a simple analytical solution is furnished in the limiting case of full stick between the cylinder and half-space.     

A crack of arbitrary shape inside an infinite transversely isotropic cylinder under arbitrary load

Summary  In the first part of the article an infinite circular cylinder is considered, made of transversely isotropic elastic material and weakened by a plane crack perpendicular to its axis O z. The crack is opened by an arbitrary normal stress. The second part is devoted to the same crack loaded by an arbitrary tangential stress. The complete solution in both cases is presented as a sum of the solution of a similar problem of a crack in an infinite space and an integral transform term, the parameters of which are determined from a set of linear algebraic equations derived from the boundary conditions. Governing integral equations with respect to the yet unknown crack displacement discontinuities are obtained. In the case of a circular crack, these equations can be inverted and solved by the method of consecutive interations. Received 30 November 2000; accepted for publication 3 May 2001     

Collision of an elastic finite-length cylinder with a rigid barrier

The paper proposes an approximate solution describing a collision of an elastic finite-length cylinder with a rigid barrier when the lateral boundary conditions of the first fundamental problem of elasticity are satisfied. A finite-difference approach with respect to time and the integral transform method are used to reduce the original initial-boundary-value problem to a one-dimensional one. It is solved using the matrix Green’s function. The final expressions for displacements are obtained by solving a singular integral equation by the orthogonal-polynomial method. The values of displacements and strains are analyzed for short periods of time __________ Translated from Prikladnaya Mekhanika, Vol. 43, No. 9, pp. 74–82, September 2007.     

Nonstationary axisymmetric problem of electroelasticity for a piezoceramic cylinder with circular polarization

This paper considers the problem of the propagation of forced electroelastic axisymmetric torsional waves in a hollow piezoceramic cylinder of finite dimensions, whose curvilinear electroded surfaces are subjected to shear stresses or an electrical potential. A new closed solution is constructed by expansion in vector eigenfunctions using the structural algorithm of finite integral transforms, which makes it possible to determine vibration eigenfrequencies, the stress-strain state of the element, and the potential and intensity of the induced electrical field. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 1, pp. 12–21, January–February, 2009.