A nonlinear theory of elastic shells of the Kirch hoff-Love type with continuously distributed disloca tions is proposed. For the principal unknowns in the set of solving equations, we accepted the components of the distortion tensor for a deforming surface. The set of equations includes the incompatibility equations in which the density of dislocations is assumed as a set function of coordinates on the surface and the equilib rium equations with given external load density. The problems of torsion and bending of a circular cylindri cal shell with dislocations were considered. These problems are reduced either to ordinary differential equations or to algebraic equations. Without external loads, we found several exact solutions on isometric deformations of shells with dislocations. It is shown that the cylindrical shell with dislocations can be twisted or bent with no resistance, i.e., without the occurrence of stresses. We also investigated the infla tion of a closed elastic sphere and the buckling of a flat membrane with dislocations.Defects of the dislocation type play a significant role in the mechanical behavior of surface crystals, nanotubes, nanofilms, and other two dimensional physical systems [1]. The distributions of dislocations can be used for modeling various other defects in the indicated systems.
DENSITY OF DISLOCATIONS IN SHELLSLet σ be the elastic shell surface considered as a two dimensional material continuum in the reference configuration, i.e., in an undeformed state. We desig nate the radius vector of a point on σ as r and the Gaussian coordinates as q α (α = 1, 2). We introduce the vectors r α of the principal basis and the vectors of the mutual basis r β , as well as the gradient operator on σ:(1)Here, n is the unit vector of the normal to the surface σ. We designate the radius vector of the deformed surface Σ referred to the same curvilinear coordinates q α as R and the vectors of the principal basis, the mutual basis, and the unit normal to Σ as R α , R β , and N, respectively. Assuming that the surface distortion tensor [2, 3] F = gradR = r α ⊗ R α is a single valued and continuously differentiable function of coordinates q α , we consider the problem of determining the field of shell displace ments u = R -r from the field of the tensor F set in the multiply connected region. The vector field u(r) is determined in this case, generally speaking, ambigu ously, which assumes the presence of translational dis locations in the shell, each of which is characterized by the Burgers vector. Assuming that the number of dislo cations on a limited portion of the shell is high and fol lowing the method of [4], we pass from the discrete set of dislocations to their continuous distribution. Let us determine the dislocation density α as the vector field, the integral of which over an arbitrary region on σ is equal to the summary Burgers vector for all disloca tions contained in this region. The indicated defini tion results in the following equation with respect to the distortion:(2)Here, E is the three...