Remarks concerning the flexure of a compressible nonlinearly elastic rectangular block

Under consideration is the problem of flexure of compressible nonlinearly elastic rectangular blocks. The discussion is confined to deformations describing the bending of a rectangular block into a sector of a circular cylindrical tube. The predictions based upon the well-known semilinear material model are investigated. Addressed, in particular, are some problems concerning the existence, uniqueness and stability of solutions to specific boundary value problems.     

Theory of stability of compressible elastoplastic ground

Based on the three-dimensional linearized equations of stability, the deformation process of compressible elastoplastic ground is investigated in the case of small subcritical deformations. In the case of a homogeneous subcritical state, the general solutions of the equations of stability are constructed similarly to [1].Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 148–153, September–October, 1977.     

A bifurcation problem for a compressible nonlinearly elastic medium: growth of a micro-void

In this paper, we carry out an explicit analysis of a bifurcation problem for a solid circular cylinder composed of a particularcompressible nonlinearly elastic material. This problem is concerned with the bifurcation of a solid body into a configuration involving an internal cavity. A discussion of its physical interpretation is then carried out. In particular, it is shown that this model may be used to describe the nucleation of a void from apre-existing micro-void.     

Axisymmetric oscillations of two spherical shells in a compressible fluid

To find the interaction between spherical shells at the frequency of their free oscillations in a fluid, we examine the problem of axisymmetric oscillations of two identical spherical shells under the assumption that the shell centers of curvature do not coincide. The solution is found for the cases of a compressible and an incompressible fluid by the series method with reduction to an infinite system of linear equations. A mathematical justification of the method used is presented.     

The stress state of a laminated nonlinearly elastic thick-walled spherical shell

This paper deals with spatial axisymmetric boundary-value problems of the physically nonlinear theory of elasticity for piecewise-homogeneous spherical bodies. The passage to dimensionless characteristics of the stress-strain state allows us to extract a physical dimensionless small parameter in the nonlinear state equations. The solution of nonlinear equilibrium equations and boundary-value problems is searched for in the form of series in positive degrees of the small parameter. This approach allows reducing the stated physically nonlinear boundary-value problem to a sequence of corresponding linear nonhomogeneous problems. A specific analytical solution and numerical results are obtained for a two-layer nonlinearly elastic spherical shell under bilateral pressure. S. P. Timoshenko Institute of Mechanics, National Academy of Sciences of Ukraine, Kiev. Translated from Prikladnaya Mekhanika, Vol. 35, No. 12, pp. 26–32, December, 1999.     

Inflation and bifurcation of compressible spherical membranes

The inflation and bifurcation of spherical membranes is considered. The membrane material is assumed to be isotropic and hyperelastic but may be arbitrarily compressible. Qualitatively the behaviour of compressible membranes is shown to be the same as that of incompressible membranes but specific forms of strain-energy functions are chosen to illustrate possible quantitative differences.     

Nonaxisymmetric elastoplastic impact of a parabolic body on a spherical shell

A method is proposed to calculate a spherical shell under nonaxisymmetric impact of a massive body. The motion of the shell is described by momentless equations, which are solved using the Laplace transformation and an asymptotic expansion of the required quantities in a small parameter. The contact interaction force P(t) was determined for the elastoplastic model of local bearing deformation for a parabolic impactor. Plots of the solution are given. The validity of the results is confirmed by good agreement between the solution and the limiting cases — an axisymmetric impact and an impact on a half-space.Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 1, pp. 181–186, January–February, 2005.     

Bifurcation phenomena of a biphasic compressible hyperelastic spherical continuum

A basic linear bifurcation problem is solved for a representative biphasic composite spherical cell. Setting is that of an internal inclusion that expends with an external shell made of a different material. Exact rate equations are derived in the framework of hyperelastic continuum mechanics. Sample examples are solved numerically revealing sensitivity of critical strain levels and bifurcated mode pattern to strength differential between both phases. Mathematical framework can be adapted to other types of constitutive responses.     

Oblique wave propagation in a compressible general magnetoplasma

Summary The refractive index equation has been derived for arbitrarily directed oblique waves in compressible general magnetoplasma with arbitrarily directed magneto-static field. The q factor obeys a general sixth order algebraic equation. Booker's quartic equation and Seshadri's result are found as particular cases and other particular cases have been discussed. The general result is checked by using tensor analysis methods and transformation of coordinates.Any views expressed in this paper are those of the author. They should not be interpreted as reflecting the views of The RAND Corporation or the official opinion or policy of any of its governmental or private research sponsors.Consultant to The RAND Corporation, Santa Monica, California; affiliated with the Electrical Engineering Department, University of Kansas, Lawrence, Kansas, U.S.A.     

Inflation and eversion of spherical shells of a special compressible material

A study is made of the qualitative features of the inflation of a shell of the so-called material of type II. This material has a strain energy function which is linear in i ₁, i ₃ and arbitrary in i ₂, where i ₁, i ₂ and i ₃ are the three principal invariants of the stretch tensors. For a specific form of the arbitrary function, a closed-form solution to the equations of equilibrium describing spherical eversion can also be found. By using this solution, a comparison can be made between the qualitative features of the regular and everted shells under internal pressure. It is found that the stress distribution in both cases is different and that a larger pressure can be sustained by the everted shell. However eversion has no effect on the other features studied.     

Quasi-static cylindrical cavity expansion in an elastoplastic compressible Mises solid

The self-similar elastoplastic field induced by quasi-static expansion of a pressurized cylindrical cavity is investigated for Mises solids under the assumption of plane-strain. Material behavior is modeled by the elastoplastic J₂ flow theory with the standard hypoelastic version. The theory accounts for elastic-compressibility and allows for arbitrary strain-hardening (or softening) in the plastic range. A formulation of the exact governing equations is presented and analyzed in detail for the remote elastic field and for asymptotic plastic behavior near the cavity wall, along with numerical investigations for the entire deformation zone. An analytical solution was obtained under the axially-hydrostatic assumption (axial stress coincides with hydrostatic stress) within an error of about 2% or less as compared to the exact, numerically evaluated, value of cavitation pressure. Two ad-hoc compressibility approximations for cavitation pressure are suggested. These relations, which give very accurate results, appear to provide tight lower and upper bounds on the exact value of cavitation pressure within an error of less than 0.5%.