Vol 52, No 5 (2017)

We consider two problems of elasticity, namely, the Boussinesq problem about the action of a lumped force on a half-space and the related problem about the interaction of the half-space with a cylindrical rigid punch with plane base. In the classical statement, these problems have singular solutions. In the Boussinesq problem, the displacement under the action of the force is infinitely large, and in the punch problem, the infinitely large variable is the pressure on the punch boundary. In the present paper, these problems are solved with the use of relations of generalized elasticity derived regarding a medium element of small but finite dimensions rather than a traditional infinitesimal element. The structure parameter of the medium contained in the solutions can be determined experimentally. The obtained generalized solutions of the problems under study are regular.

The problem of centrally symmetric deformation of a multilayer elastoplastic ball in the process of successive accretion of preheated layers to its outer surface is considered in the framework of small elastoplastic deformations. The problems of residual stress formation in the elastoplastic ball with an inclusion and a cavity are solved under various mechanical boundary conditions on the inner surface and for prescribed thermal compression distributions. The graphs of residual stress and displacement fields are constructed.

The problem of extension of a plate with symmetric edge notches of different shape is numerically solved on the basis of the theory of plane stress state of an ideally plastic body under the von Mises plasticity condition. The discontinuities of the tangential and normal components of the velocity along the rigid-plastic boundaries, which result in the plastic strain localization in the neck and the material fracture, are calculated. The obtained results are of practical interest for estimating the limit extension force for a plate with edge notches of different shape and the limit strain of a thin sheet in inhomogeneous biaxial extension.

We study the processes of additive formation of spherically shaped rigid bodies due to the uniform accretion of additional matter to their surface in an arbitrary centrally symmetric force field. A special case of such a field can be the gravitational or electrostatic force field. We consider the elastic deformation of the formed body. The body is assumed to be isotropic with elasticmoduli arbitrarily varying along the radial coordinate.We assume that arbitrary initial circular stresses can arise in the additional material added to the body in the process of its formation. In the framework of linear mechanics of growing bodies, the mathematical model of the processes under study is constructed in the quasistatic approximation. The boundary value problems describing the development of stress–strain state of the object under study before the beginning of the process and during the entire process of its formation are posed. The closed analytic solutions of the posed problems are constructed by quadratures for some general types of material inhomogeneity. Important typical characteristics of the mechanical behavior of spherical bodies additively formed in the central force field are revealed. These characteristics substantially distinguish such bodies from the already completely composed bodies similar in dimensions and properties which are placed in the force field and are described by problems of mechanics of deformable solids in the classical statement disregarding the mechanical aspects of additive processes.

The paper is dedicated to Professor N. F. Morozov on the occasion of his 85th birthday. In the paper, we consider new dispersive properties of elastic flexural waves in periodic structures with rotational inertia. The structure is represented as a lattice with elementary bonds of Rayleightype beams. Although such beams in the semiclassical regime react as the classical Euler–Bernoulli beams, they exhibit new interesting characteristics as the dispersion frequency of flexural waves increases. Special attention is paid to degenerate cases related to the so-called Dirac cones on dispersion surfaces and to the directed anisotropy for the doubly periodic lattice. A comparative analysis accompanied by numerical simulation is carried out for the Floquet–Bloch waves propagating in periodic flexible lattices of different geometry.

The postbuckling of rods loaded by a compressive force P in an elastic medium is considered. The resolving nonlinear equation is obtained, and a method for solving this equation is given. It is shown that, for large lengths, in contrast to the case without elastic medium, the deflection increases as the force P decreases after the loss of stability. Several simple finite-element models, namely, the problems of compression of multilink rods with links connected by springs, are considered to confirm this effect.

There are well-known methods and algorithms for determining the film adhesion to a plane substrate, which have their own advantages and drawbacks and the applicability ranges. The substrates can have a good initial shape (spherical, cylindrical, etc,) covered, for example, by a thin film layer. But there are practically no studies of the film adhesion to a substrate with a nonplane surface. A two-dimensional approach to determining the film adhesion to a plane or a nonplane substate is developed, which permits increasing the accuracy of determining the adhesion and decreasing the scattering of the obtained results. An example is considered.