On higher eigenvalues of variational inequalities
On I. Vekua's method in the theory of elastic mixtures.
On identification of critical curves
The paper deals with the problem of finding a curve, going through the interior of the domain , accross which the flux , where is the solution of a mixed elliptic boundary value problem solved in , attains its maximum.
On implicit constitutive theories
In classical constitutive models such as the Navier-Stokes fluid model, and the Hookean or neo-Hookean solid models, the stress is given explicitly in terms of kinematical quantities. Models for viscoelastic and inelastic responses on the other hand are usually implicit relationships between the stress and the kinematical quantities. Another class of problems wherein it would be natural to develop implicit constitutive theories, though seldom resorted to, are models for bodies that are constrained....
On integration of differential equations in elastostatics through determination of the mean stress
On internal constraints in continuum mechanics.
On Ishlinskij's model for non-perfectly elastic bodies
The main goal of the paper is to formulate some new properties of the Ishlinskii hysteresis operator , which characterizes e.g. the relation between the deformation and the stress in a non-perfectly elastic (elastico-plastic) material. We introduce two energy functionals and derive the energy inequalities. As an example we investigate the equation describing the motion of a mass point at the extremity of an elastico-plastic spring.
On Lamb's plane problem in micropolar viscoelastic half-space with stretch.
On linear versus nonlinear flow rules in strain localization analysis
This note contains some remarks on the analysis of bifurcation phenomena, specifically strain localization (onset of a strain rate discontinuity), in small-deformation elastoplasticity. Nonassociative flow rules are allowed for to cover constitutive models frequently adopted for frictional (and softening) materials such as concrete. The conventional derivation of the localization criterion resting on an incrementally linear "comparison material" is critically reviewed and compared to the criterion...
On Lyapunov stability in hypoplasticity
We investigate the Lyapunov stability implying asymptotic behavior of a nonlinear ODE system describing stress paths for a particular hypoplastic constitutive model of the Kolymbas type under proportional, arbitrarily large monotonic coaxial deformations. The attractive stress path is found analytically, and the asymptotic convergence to the attractor depending on the direction of proportional strain paths and material parameters of the model is proved rigorously with the help of a Lyapunov function....
On mixed finite element methods for linear elastodynamics.
On models of long-term behavior of concrete
Long-term behavior of concrete is modeled by several widely accepted models, such as B3, fib MC 2010, or ACI 209 whose input parameters and output values are not identical to each other. Moreover, the input and, consequently, the output values are uncertain. In this paper, fuzzy input parameters are considered in uncertainty quantification of each model response and, finally, the sets of responses are analyzed by elementary tools of evidence theory. That is, belief and plausibility functions are...
On Neumann's problem for a quasilinear differential system of the finite elastostatics type. Local theorems of existence and uniqueness
On numerical approximation of an optimal control problem in linear elasticity.
On numerical solution of a variational inequality of the 4th order by finite element method
The problem of a thin elastic plate, deflection of which is limited below by a rigid obstacle is solved. Using Ahlin's and Ari-Adini's elements on rectangles, the convergence is established and SOR method with constraints is proposed for numerical solution.
On numerical solution of weight minimization of elastic bodies weakly supporting tension
Shape optimization of a two-dimensional elastic body is considered, provided the material is weakly supporting tension. The problem generalizes that of a masonry dam subjected to its weight and to the hydrostatic pressure. A part of the boundary has to be found so as to minimize a given cost functional. The numerical realization using a penalty method and finite element technique is presented. Some typical results are shown.
On one mathematical model of creep in superalloys
In a new micromechanical approach to the prediction of creep flow in composites with perfect matrix/particle interfaces, based on the nonlinear Maxwell viscoelastic model, taking into account a finite number of discrete slip systems in the matrix, has been suggested; high-temperature creep in such composites is conditioned by the dynamic recovery of the dislocation structure due to slip/climb motion of dislocations along the matrix/particle interfaces. In this article the proper formulation of the...
On one type of integro-differential equations.
On Operators with Bounded Imaginary Powers in Banach Spaces.
On periodic homogenization in perfect elasto-plasticity
The limit behavior of a periodic assembly of a finite number of elasto-plastic phases is investigated as the period becomes vanishingly small. A limit quasi-static evolution is derived through two-scale convergence techniques. It can be thermodynamically viewed as an elasto-plastic model, albeit with an infinite number of internal variables.