Version of the linear elasticity theory with a structural parameter

It is shown that, in the planar case, the system of constitutive equations of the linear elasticity theory should contain five independent equations. In the classical theory, only three equations are formulated, while the other two are contained in implicit form in the postulate of diffeomorphism, which is the assumption of smoothness of the displacement field. A closed elasticity model is constructed without the assumption of diffeomorphism, and it contains a structural parameter having a dimension of length. It is shown that, in a static version, macrodeformations depend on stresses and second derivatives of stresses with respect to the coordinates, while there is dispersion of longitudinal and transverse waves in the dynamics.     

Equations of the linear theory of elasticity of anisotropic materials,reduced to three independent wave equations

Novosibirsk. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 6, pp. 143–150, November–December, 1994.     

Solving the three-dimensional equations of the linear theory of elasticity

The three-dimensional Lamé equations are solved using Cartesian and curvilinear orthogonal coordinates. It is proved that the solution includes only three independent harmonic functions. The general solution of equations of elasticity for stresses is found. The stress tensor is expressed in both coordinate systems in terms of three harmonic functions. The general solution of the problem of elasticity in cylindrical coordinates is presented as an example. The three-dimensional stress–strain state of an elastic cylinder subjected, on the lateral surface, to arbitrary forces represented by a series of eigenfunctions is determined. An axisymmetric problem for a finite cylinder is solved numerically     

Impulsive stress analysis of plates at the concentrated impact loading point by the three-dimensional dynamic theory of elasticity

In this paper, a method of stress analysis is proposed to analyze impulsive stresses at an impact loading point, since use of the classical plate theory cannot lead to a convergent result. In particular, under these impact conditions (regardless of mass of impactor, velocity of impactor, stiffness of plate, etc.), we used the three-dimensional dynamic theory of elasticity and potential theory of displacement to analyze the impulsive strains at an impact loading point. Also, by using Hertzian contact theory to account for local deformation, the impact loading could be analyzed, and this loading was applied to the impulsive stress analysis by allowing the impact loading to be approximated to an analyzable function. In the numerical analysis, we used a fast Fourier transform (FFT) algorithm and applied the numerical inverse Laplace transformation.     

On Saint-Venant's principle in the two-dimensional linear theory of elasticity

Archive for Rational Mechanics and Analysis -     

Affine transformations of the equations of the linear theory of elasticity

This paper deals with the general formulas of affine transformations that preserve invariance of the static equations of the linear theory of elasticity in the case of arbitrary anisotropic materials. The invariance of the equations with respect to affine transformations allows one to model a given anisotropic material by another material. All anisotropic materials are divided into classes of mutually congruent materials. The congruency conditions are obtained for orthotropic and isotropic materials and for orthotropic and transversely isotropic materials. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 4, pp. 124–134, July–August, 2006.     

Construction of eigentensor columns in the linear micropolar theory of elasticity

The internal structure of the block tensor matrix of the elastic modulus tensors is studied for the case of micropolar theory. In particular, the problem of finding the eigenvalues and eigentensor columns of block tensor matrices is considered. The complete orthonormal system of eigentensor columns for a block tensor matrix is constructed. A number of definitions and theorems are formulated. Several newly introduced terms are used to propose various representations of the specific strain energy and the corresponding constitutive relations.     

Love solutions in the linear inhomogeneous transversely isotropic theory of elasticity

A general Love solution for the inhomogeneous transversely isotropic theory of elasticity with the elastic constants dependent on the coordinate z is proposed. This result may be considered as a generalization of the Love solutions we recently derived for the inhomogeneous isotropic theory of elasticity. The key steps of deriving the Love solution for the classical linear homogeneous transversely isotropic theory of elasticity are described for further use of the derivation procedure, which is then generalized to the inhomogeneous transversely isotropic case. Some particular cases of inhomogeneity traditionally used in the theory of elasticity are also examined. The significance of the derived solutions and their importance for the modeling of functionally graded materials are briefly discussed     

Effective characteristics of fiber composites in the linear moment theory of elasticity

A special boundary value problem whose solution is used to determine the effective characteristics in the linear moment theory of elasticity is considered. A procedure of finding the effective characteristics is proposed by the example of a fiber composite whose matrix and inclusions are isotropic. The boundary effects of structure functions are also discussed.     

General love solution in the linear isotropic inhomogeneous theory of radius-dependent elasticity

A general Love solution for the inhomogeneous linear isotropic theory of elasticity with the elastic constants dependent on the coordinate r is proposed. The axisymmetric case is analyzed and cylindrical coordinates are used. This is the fourth publication in the series on general solutions in the inhomogeneous theory of elasticity. The new results are promising for the modern theory of functionally graded materials. The key steps of deriving the Love solutions are described for further use of the derivation procedure. The procedure of generalizing the Love solutions to the inhomogeneous theory of elasticity is detailed. The results obtained are discussed     

Stress retardation versus stress relaxation in linear viscoelasticity

We present a preliminary examination of a new approach to a long-standing problem in non-Newtonian fluid mechanics. First, we summarize how a general implicit functional relation between stress and rate of strain of a continuum with memory is reduced to the well-known linear differential constitutive relations that account for “relaxation” and “retardation.” Then, we show that relaxation and retardation are asymptotically equivalent for small Deborah numbers, whence causal pure relaxation models necessarily correspond to ill-posed pure retardation models. We suggest that this dichotomy could be a possible way to reconcile the discrepancy between the theory of and certain experiments on viscoelastic liquids that are conjectured to exhibit only stress retardation.     

Compatibility conditions and equations of motion in the linear micropolar theory of elasticity

An analog of Cesàro’s formula and several compatibility conditions are given for the three-dimensional and two-dimensional linear micropolar theory of elasticity in the form different from that used in the literature. A number of formulas are obtained to determine the antisymmetric part of the strain (stress) tensor in terms of the symmetric part of the strain tensor and the symmetric part of the bending-torsion (stress and couple-stress) tensor and to determine the antisymmetric part of the bending-torsion (couple-stress) tensor in terms of the symmetric part of the bending-torsion (couplestress) tensor. Some integro-differential equations of motion expressed in terms of the symmetric parts of the stress and couple-stress tensors are proposed for the micropolar theory of elasticity.     

Symmetry operators and general solutions of the equations of the linear theory of elasticity

Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 36, No. 5, pp. 98–104, September–October, 1995.