关于平面问题分类的再探讨

关于平面问题分类的再探讨张雷顺（郑州工学院，郑州４５０００２）由于平面问题比较简单，所以在弹性力学教材中，对平面问题给出了较多的篇幅，也列举了较多的例题．在工程中，相当多的问题也都近似为平面问题处理．但在认定平面问题和进行平面问题分类方面，作者发现时...     

各向异性材料界面共线刚性线夹杂的反平面问题

研究两种各向异性材料焊接界面含共线刚性线夹杂的反平面问题,导出了一般问题的公式和几个典型问题的封闭形式解,求出了刚性线尖端的应力分布,从文中解答的特殊情况,直接导出各向性材料界面与均匀各向异性介质中相应问题的公式与结果,并与有关文献相一致。     

具有孔洞的双周期热弹性平面问题的复势

首先论述了针对调和变温场的热弹性平面问题的复变函数方法，给出了受调和变温时有限 多连通域中复势的一般表达式. 然后基于已知实部的双周期解析函数及其原函数的表示和多 值性分析，导出了双周期调和变温下具有双周期分布孔洞物体平面弹性问题的两个复势函数 的一般公式，由此论证了两种特殊情形下物体的温度应力为零.     

三向应力Mohr圆的真实构成及剪应力作用方向的确定

三向应力Mohr圆的构成在传统上是借助公式推证而得，并以平面图形来表示，缺乏三维的真实感和直观性。在应力应变分析中，对于平面应力问题，可以通过平面应力摩尔圆确定过一点不同斜面上的应力分量及其作用方向。对于三维问题，利用摩尔圆图解法可以确定某一斜面上的正应力和剪应力的数值，但不能表示剪应力的作用方向。剪应力的作用方向需要通过另外的图解方法来确定。本文分别从坐标系旋转和数值计算的角度解释了三向应力Mohr圆的构成过程，形象地说明了Mohr圆的物理本质。针对三向应力Mohr圆不能表示剪应力作用方向的问题，通过矢量运算，给出了剪应力作用方向的确定公式。     

考虑损伤时带微孔粘弹性体的应力分布

本文根据粘弹性理论和带空沿材料的线性理论，利用Laplace变换及其逆变换，给出了粘弹性损伤材料的一种本构模型。应用这种本构关系。讨论了带损伤的圆环形板或圆筒体在内外压力作用下的平面问题，得到了圆孔边缘附近的应力场和损伤增量场的分布情况，同时根据Laplace变换的终值定理，得到圆环或圆筒的终态应力和损伤增量的分布，并分析了工程中的一个典型的例子。得到了最终损伤的一种近似分布。可为工程设计提供一定的参考。     

断裂问题特征根的重根探讨

利用特征矩阵的秩与特征根所对应的子特征函数空间维数之间的关系。确定了反平面断裂问题和平面断裂问题的特征根可能出现的最大重根数．利用Reissner型板特征根与反平面和平面断裂问题特征根的关系确定其可能出现的最大重根数．得到了反平面断裂问题、平面断裂问题和Reissner板断裂问题可能出现的最大重根数分别为1,2,3．     

多材料反平面断裂问题特征值的超逆幂迭代求解

从反平面切口问题的特征方程入手，采用换元逆幂迭代法并利用特征函数解析表达式已知及一些有效技巧研究了可以精确有效地求解具有任意张角、多种不同材料及不同边界条件的反平面切口问题的完备特征解的求解方法。     

弹性力学平面问题位移函数的研究

本文推导出各向同性弹性力学平面问题位移的完备通解，该位移通解的导出，使求解任何边界条件的平面问题成为现实     

一种求解方管稳定性问题的简化方法

采用材料力学中的平面弯曲理论、以及弹性理论中平面应力问题和平面应变问题的转换关系，分析方管在均匀外压作用下的变形、临界压力和应力，得到了方管最大变形、临界压力和最大应力的求解公式．运用有限元分析软件Marc建立有限元模型，分析了方管在外压作用下的变形、临界压力和应力情况．分析结果表明，最大应力出现在凹角处，最大位移出现在各面的中截面处，并将有限元解与本文解作比较，从而验证文本解的正确性．     

等参数正交异性板平面问题的解法

关于文中指出了现有文献中具有等值复参数正交异性板的平面问题的一些错误，给出了相应正确的应力场和位移场表达式；并提出一种以各向同性板平面问题比拟正交异性板平面问题的方法。     

Determination of the Inhomogeneous Preliminary Stress–Strain State in a Piezoelectric Disk

The problem of steady radial vibrations of a thin electroelastic hollow disk in the presence of a preliminary inhomogeneous plane stress–strain state is solved. Vibrations are induced by applying a potential difference across the electrodes placed on the end surfaces of the disk. Equations of the vibrations and boundary conditions are formulated. The preliminary stress state corresponding to the solution of the Lam´e problem was investigated. The direct problem of determining the displacement function is solved numerically by the shooting method. The inverse problem of determining a pre-stress parameter from the change in the natural frequency of the disk is formulated and solved. The accuracy of determining the prestressed state for initial data specified with an error is analyzed.     

Von Kàrmàn problem for a rotating permeable disk

The von Kàrmàn problem of steady viscous incompressible flow in a half-space beneath a permeable, porous disk of infinite radius, uniformly rotating it its own plane, is considered. The Bevers-Joseph condition which takes account for viscous fluid slip relative to the plane disk is taken for the boundary condition for the tangential velocity component. This makes it possible to consider the flow only outside the porous disk. The disk permeability effect on the boundary layer is studied, in particular, its influence on the dependence of the moment of viscous forces distributed over the disk about the axis of rotation on the permeability and the pressure difference.     

Contribution to the determination of the global minimum time for the brachistochronic motion of a holonomic mechanical system

The problem of the brachistochronic motion of a holonomic scleronomic mechanical system is analyzed. The system moves in an arbitrary field of known potential forces. The problem is formulated as an optimal control task, where generalized speeds are taken as control variables. The problem considered is reduced to solving the corresponding two-point boundary-value problem (TPBVP). In order to determine the global minimal solution of the TPBVP, an appropriate numerical procedure based on the shooting method is presented. The global minimal solution represents the solution with the minimum time of motion. The procedure is illustrated by an example of determining the brachistochronic motion of a disk that performs plane motion in a vertical plane in a homogeneous field of gravity.     

ANALYSIS OF SYMMETRIC LAMINATED RECTANGULAR PLATES IN PLANE STRESS

Symmetric laminated plates used usually are anisotropic plates. Based on the fundamental equation for anisotropic rectangular plates in plane stress problem, a general analytical solution is established accurately by method of stress function. Therefore the general formula of stress and displacement in plane is given. The integral constants in general formula can be determined by boundary conditions. This general solution is composed of solutions made by trigonometric function and hyperbolic function, which can satisfy the problem of arbitrary boundary conditions along four edges, and the algebraic polynomial solutions which can satisfy the problem of boundary conditions at four corners. Consequently this general solution can be used to solve the plane stress problem with arbitrary boundary conditions. For example, a symmetric laminated square plate acted with uniform normal load, tangential load and nonuniform normal load on four edges is calculated and analyzed.     

Integrability of the motion of a rolling disk of finite thickness on a rough plane

In this article an analytical solution of equations of motion of a rigid disk of finite thickness rolling on its edge on a perfectly rough horizontal plane under the action of gravity is given. The solution is given in terms of Gauss hypergeometric functions. The integrability results are used to construct various bifurcation diagrams of the steady motion of the disk. The bifurcations of the steady motion of a disk on a rough plane complements the author's bifurcation analysis of the steady motion of the disk on a smooth plane ( [M. Batista, Steady motion of a rigid disk of finite thickness on a horizontal plane, Int. J. Non-Linear Mech. 41 (4) (2006) 605–621]).     

Jeffery solution for an elastic disk containing a sliding eccentric circular inclusion assembled by interference fit

An analytic solution is presented for stresses induced in an elastic and isotropic disk by an eccentric press-fitted circular inclusion. The disk is also subject to uniform normal stress applied at its outer border. The inclusion is assumed to be of the same material as the annular disk and both elements are in a plane stress or plane strain state. A frictionless contact condition is assumed between the two members. The solution is obtained by using the general expression for a biharmonic stress function in bipolar coordinates. The results show that the maximum of the von Mises effective stress due to the inclusion interference occurs in the ligament for large eccentricity, but it deviates from the symmetry axis for small eccentricity. Moreover, along the border of the circular inclusion the hoop stress locally coincides with the contact pressure, in agreement with a similar classical result valid for a half plane.     

Stokes flow of a rotating sphere around the axis of a circular orifice or a circular disk

This paper presents an infinite series solution to the creeping flow equations for the axisymmetric motion of a sphere of arbitrary size rotating in a quiescent fluid around the axis of a circular orifice or a circular disk whose diameters are either larger or smaller than that of the sphere. Numerical tests of the convergence are passed and the comparison with the exact solution and other computational results shows an agreement to five significant figures for the torque coefficients in both cases. The torque coefficients are obtained for the sphere located up to a position tangent to the wall plane containing either the orifice or the disk. It is concluded that the torque coefficients of the sphere and the disk are monotonically increasing with the decrease of the distance from the disk or the orifice plane in both cases.     

Electromagnetic diffraction by a thin conducting circular disk placed at the plane interface of two different media

In this paper, the problem of diffraction of time harmonic, electromagnetic waves by a thin ideally conducting disk lying at the plane interface of two different media is considered. In this analysis, the incident wave is a plane wave travelling in a direction perpendicular to the plane interface of the two media. A Hertz vector formulation is applied to reduce our electromagnetic diffraction problem to a system of two scalar problems which are solved by the help of two pairs of Fredholm integral equations of the second kind. Low frequency approximations to the tangential components of the magnetic intensity associated with the diffracted field at the surfaces of the disk, the induced surface current density on the disk and the scattering cross section are obtained.     

Analytical solution to continuous contact problem for a functionally graded layer loaded through two dissimilar rigid punches

A continuous contact problem of functionally graded layer resting on an elastic semi-infinite plane, which is loaded with through two different blocks is addressed in this study. The elasticity theory and integral transformation techniques are used in solution of the problem. The problem is reduced to a system of singular integral equations, and solved numerically by the aid of appropriate Gauss–Chebyshev integration formula. It is assumed that the elastic semi-infinite homogeneous plane is isotropic and all surfaces are frictionless and continuous. The shear modulus and the mass density of the FG layer vary exponentially along the thickness direction.     

Thermoelastic stresses in a cylinder or disk with cubic anisotropy

The thermoelastic stresses in a crystal in the shape of a circular cylinder or disk are considered. The crystal is a cubically-orthotropic linear elastic solid, with three independent elastic properties. The cubic anisotropy renders the problem asymmetric, despite the axisymmetry of the geometry and thermal loading. This problem is motivated by a thermoelastic model used for certain crystal growth processes. Two simplifying assumptions are made here: (a) the problem is two-dimensional with plane strain or plain stress conditions, and (b) the elastic properties do not depend on the temperature. A new Fourier-type perturbation method is devised and an analytic asymptotic solution of a closed form is obtained, based on the weak cubic anisotropy of the crystal as a perturbation parameter. A general solution technique is described which yields the asymptotic solution up to a desired order. Numerical results are presented for typical parameter values.