Contact problems for elastic bodies with initial stresses (rigid punches)

Conclusions In this work, the results are presented of investigations into contact problems for prestressed solids with special reference to rigid punches. It should be mentioned that in the last 5–6 years further investigations into the contact problems for solids with inifial stresses with special reference to elastic punches using the formulation of the second approach, i. e., in the general united form for compressible and incompressible solids with elastic potentials of the arbitrary structure, were also carried out by the authors of this article.The authors believe that further progress in the development of the mechanics of contact interaction of prestressed solids (both for rigid and elastic punches) is determined by examination of more complicated problem groups (for elastic, viscoelastic, and plastic solids), and by carrying out experiments to determine the strength of the effect of the initial stresses on the main characteristics of contact interaction of the structural material. It is also evident that, from the practical viewpoint, it is interesting to carry out these investigations for nonhomogeneous initial states. However, this is associated with considerable mathematical problems, even in theoretical developments and, these problems are even greater in application in practice.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Khmel'nitsk Technological Institute of Household Maintenance. Translated from Prikladnaya Mekhanika, Vol. 25, No. 8, pp. 3–18, August, 1989.     

Analogies between linearized and linear problems for compressible elastic bodies

International Applied Mechanics -     

Some three-dimensional problems for an elastic medium with isolated rigid inclusions

Problems of determining stresses in isolated ellipsoidal rigid inclusions contained in an isotropic elastic space subjected to uniformly distributed loading at infinity are considered. A solution in a closed form is constructed for inclusions shaped as ellipsoids of revolution.     

Some problems in plane elastic dielectrics

Representations of Galerkin type are obtained for the displacement vector, polarization vector and the potential fields in the static plane theory of elastic dielectrics using the method of associated matrices. Fundamental matrix solutions of an infinite elastic dielectric plane subjected to a concentrated body force, electric force and charge density are derived from the singular solutions of harmonic, biharmonic and Helmholtz equations. Using boundary operatorsY, Z, M, the fundamental matrix solutions, and Betti's formulae, a matrix (x, y) is constructed and an integral representation for (u ₁,u ₂,P ₁,P ₂, ) is obtained. Discontinuity theorems are stated for the double layer potential andQ operator of the single layer potential. By means of these theorems, the solutions of interior and exterior boundary value problems are reduced to the solution of a system of five singular integral equations. The index of one of the systems is shown to be zero and it is concluded that Fredholm theorems and its alternatives hold.

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Zusammenfassung Durch Anwendung der Assoziativ-Matrizen-Methode werden Galerkinische Darstellungen für den Verschiebungsvektor, den Polarisierungsvektor und die potentiellen Prüffelder einer statischen ebenen Theorie des elastischen Dielektrikums entwickelt. Von den singulären Lösungen der harmonischen, biharmonischen und Helmholtz-Gleichungen werden grundlegende Matrizenlösungen für das unendliche, ebene und elastische Dielektrikum, das durch konzentrierte Raumkräfte, elektrische Kräfte und Ladungsdichte beansprucht wird, abgeleitet. Unter Verwendung der Randwert-OperatorenY, Z, M, der grundlegenden Matrizen-Lösungen und Betti's Formel, wird eine Spezial-Matrize (x, y) konstruiert und eine Integraldarstellung für (u ₁,u ₂,P ₁,P ₂, ) erhalten. Unstetigkeitssätze werden für das Doppelschicht-Potential und denQ-Operator eines einschichtigen Potentials angeführt. Durch Anwendung dieser Sätze werden die Lösungen der inneren und äusseren Grenzwertprobleme zur Lösung eines Systems von fünf singulären Integralgleichungen reduziert. Der Index eines der Systeme wird als Null bewiesen und es wird die Schlussfolgerung gezogen, dass der Fredholmsche Satz und seine Alternativen fur diese Theorie anwendbar sind.

     

Some axisymmetric problems for an elastic inhomogeneous thick-walled tube

An equilibrium differential equation for an axisymmetric problem is reduced to an integrable form under the assumption that the shear modulus is continuously differentiable and Poisson’s ratio is constant. A procedure of successive approximations is proposed for the case of a compressible material, and the Lamé problem is solved exactly for the case of an incompressible material. A piecewise continuous variation of the Lamé parameter as a function of radius is considered. Several examples of determining the stress-tensor components are given for various cases of inhomogeneity.     

Some dynamic problems for elastic materials with functional inhomogeneities: anti-plane deformations

The paper considers two dynamical problems for an isotropic elastic media with spatially varying functional inhomogeneity, the propagation of surface anti-plane shear SH waves, and the stress deformation state of an anti-plane vibrating medium with a semi-infinite crack. These problems are considered for five different types of inhomogeneity. It is shown that the propagation of surface anti-plane shear waves is possible in all these cases. The existence conditions and the speed of propagation of surface waves have been found. In the section devoted to the investigation of the stress deformation state of a vibrating medium with a semi-infinite crack, Fourier transforms along with the Wiener Hopf technique are employed to solve the equations of motion. The asymptotic expression for the stress near the crack tip is analyzed, which leads to a closed form solution of the dynamic stress intensity factor (DSIF). Here also the problem is considered for five different functional inhomogeneities. From the formulae for DSIF thus obtained one can see that the inhomogeneity can have both a quantitative and qualitative impact on the character of the stress distribution near the crack.Received: 25 July 2002, Accepted: 3 April 2003, Published online: 27 June 2003PACS: 83.20.Lr, 83.50.Tq, 83.50.Vr, 46.30.Nz     

On three-dimensional elastic problems of one-dimensional hexagonal quasicrystal bodies

Based on rigorous operator theory, a general solution of the three-dimensional elasticity equations of equilibrium for 1D hexagonal quasicrystals is obtained. The solution is expressed in terms of four quasiharmonic functions, which is very simple and useful. The point phonon (phason) force solution of an infinite 1D hexagonal quasicrystal body is derived, all in terms of elementary functions. They can play an important role in numerical simulations such as boundary element method.     

Domain decomposition methods applied to solve frictionless-contact problems for multilayer elastic bodies

A parallel Dirichlet–Dirichlet domain-decomposition algorithm for solving frictionless-contact problems for elastic bodies made of composite materials is proposed and justified. Numerical results that demonstrate the effectiveness of the approach and its software implementation are presented