Existence and uniqueness of solutions of integral and integrodifferential equations of Volterra type in the theory of viscoelasticity

The conditions of existence and uniqueness of solutions of certain classes of nonlinear integral and integrodifferential equations of Volterra type are found.V. I. Lenin Higher Mechanical and Electrical Engineering Institute, Sofia. Medical Academy, Sofia. Translated from Mekhanika Polimerov, No. 1, pp. 161–162, January–February, 1976.     

Initial-boundary problem for a nonlinear integrodifferential system

Theorems of existence and uniqueness of a generalized solution are established for an initial-boundary problem for a nonlinear integrodifferential system of equations.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 2, pp. 187–194, February, 1990.     

On some new integral inequalities for non-self-adjoint hyperbolic partial integrodifferential equations

The aim of this paper is to establish some new partial integral inequalities in two independent variables which can be used in the analysis of a class of nonlinear non-self-adjoint hyperbolic partial integrodifferential equations. An elementary method of reducing the integral inequality to a second-order partial differential inequality and then integrating it by Riemann's method is used to establish our results.     

Stability of solutions of Volterra integrodifferential equations

Systems with past memory (or after-effect), the state of which is given by nonlinear Volterra- type integrodifferential equations with small perturbations, are investigated. The equations depend on functionals in integral form and, in particular, on analytic functionals represented by Fréchet series. The integral kernels can allow for singularities with Abel’s kernel. The stability under persistent disturbances, and the structure of the general solution, are investigated in the neighborhood of zero for an equation with holomorphic nonlinearity assuming asymptotic stability of the trivial solution of the linearized unperturbed equation. Stability in the critical cases (in Lyapunov’s sense) of a single zero root and of pairs of pure imaginary roots for the unperturbed equation is analyzed.     

On existence problems for the optimal control of certain nonlinear integral equations of Urysohn type

In Refs. 1–3, existence results have been obtained for optimal control problems whose state equations are described by certain nonlinear integral equations of Urysohn type. We generalize and synthesize these results by formulating a general lower closure result from which the results of Refs. 1–3 are shown to follow. In the course of this, we also present a novel and rather abstract treatment of existence problems for variable-time optimal control, quite in the spirit of Ref. 4.     

Method of solving nonlinear dynamic problems in viscoelasticity

The authors propose a method of solving Volterra's system of nonlinear integrodifferential equations. This method is based on the use of a power series. As an illustration, the authors consider the vibration of flexible viscoelastic cylindrical shells under impulsive and periodic loads.Institute of Cybernetics and Computer Center, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Mekhanika Polimerov, Vol. 9, No. 3, pp. 554–558, May–June, 1973.     

Iterative calculation of strongly nonlinear self-vibrating viscoelastic mechanical systems

We consider self-excited vibrations of strongly nonlinear mechanical systems obeying the hereditary theory of viscoelasticity. using the Bubnov-Galerkin method, the problem is reduced to a system of ordinary nonlinear integrodifferential equations. The normal modes of vibration of nonlinear conservative elastic systems are chosen as the unperturbed solutions. Self-vibrating solutions are found by iteration to any degree of accuracy. The process converges for certain restrictions on the unperturbed functions and on the small parameter of the problem.Translated from Dinamicheskie Sistemy, No. 5, pp. 86–90, 1986.     

Existence and uniqueness of Sobolev type integrodifferential equations

An imbedding method for nonlinear Fredholm integral equations gives rise to a Sobolev type integrodifferential equation. For such equations, sufficient conditions are given to guarantee local existence and uniqueness of solutions. A Picard type theorem utilizing a Lipschitz condition is obtained.     

A nonlinear variation of constants method for integro differential and integral equations

A variation of constants technique is utilized to obtain representation formulas for solutions of perturbed nonlinear integrodifferential and integral equations. These representations are used to analyze boundedness and stability properties of perturbed integral equations. Questions on the existence of the inverse of the fundamental matrix as well on the existence of the semigroup property of the fundamental matrix are discussed.     

The Solvability for a Class of Nonlinear Integrodifferential Equations of Parabolic Type

In this paper we consider the well-posedness for a class of nonlinear integrodifferential equations of parabolic type. We use integral estimates to deduce an a priori estimate in the classical space C^{2+α,1+\frac{α}{2}}. The existence of the solution is established by means of the continuity method which is similar to a parabolic initial and boundary value problem. Moreover, the continuous dependence upon the data and the uniqueness of the solution are obtained. Finally, the results are generalized into a class of nonlinear integrodifferential systems.     

Numerical computation of weak solutions of nonlinear motion equations of stiffened cylindrical shells

An algorithm is presented for the numerical solution of nonlinear equations of motion of stiffened cylindrical shells described by a Timoshenko-type theory. This algorithm is constructed using a weak solution of nonlinear motion equations of stiffened cylindrical shells. A difference scheme is constructed using the approximation of integral identities. A dependence was found between the steps of the time and space variables for the linearized difference scheme.Presented at the Ninth International Conference on the Mechanics of Composite Materials, Riga, Latvia, October, 1995.Translated from Mekhanika Kompozitnykh Materialov, Vol. 31, No. 6. pp. 808–815, November–December, 1995.     

Logarithmic corrections in a quantization rule. The polaron spectrum

A nonlinear integrodifferential equation that arises in polaron theory is considered. The integral nonlinearity is given by a convolution with the Coulomb potential. Radially symmetric solutions are sought. In the semiclassical limit, an equation for the self-consistent potential is found and studied. The potential has a logarithmic singularity at the origin, and also a turning point at 1. The phase shifts at these points are determined. The quantization rule that takes into account the logarithmic corrections gives a simple asymptotic formula for the polaron spectrum. Global semiclassical solutions of the original nonlinear equation are constructed.Moscow Institute of Electronic Engineering; Moscow Power Institute. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 97, No. 1, pp. 78–93, October, 1993.     

ON CERTAIN BOUNDARY VALUE PROBLEMS FOR NONLINEAR INTEGRODIFFERENTIAL EQUATIONS

ＯＮＣＥＲＴＡＩＮＢＯＵＮＤＡＲＹＶＡＬＵＥＰＲＯＢＬＥＭＳＦＯＲＮＯＮＬＩＮＥＡＲＩＮＴＥＧＲＯＤＩＦＦＥＲＥＮＴＩＡＬＥＱＵＡＴＩＯＮＳＤ．Ｇ．Ｐａｃｈｐａｔｔｅ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓａｎｄＳｔａｔｉｓｉｃｓＭａｒａｔｈ...     

Integral manifolds of systems of autonomous nonlinear difference equations

Sufficient conditions for the existence of one-sided integral manifolds of solutions of systems of nonlinear difference equations are obtained. One-sided nonlinear projections, defining these manifolds, are constructed.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 44, No. 1, pp. 132–134, January, 1992.     

Numerical-analytical algorithm to solve the equation of particle transport in plane geometry

We describe a numerical-analytical algorithm to solve the boundary-value problem for the integrodifferential equation of particle transport in a plane homogeneous medium. The general scheme of approximate solution of this problem is based on its reduction to the solution of some integral equation by summator operators of function approximation theory. Solvability conditions are established for the approximate equations and the algorithm errors are estimated. Working formulas are presented for the algorithm implemented in the form of a computer program. The summator operators in this algorithm are the algebraic interpolation operators with nodes at the extremal points of Chebyshev polynomials of first kind.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 62, pp. 69–76, 1987.     

On minimal nonlinearities which permit bifurcation from the continuous spectrum

Bifurcation from the continuous spectrum of a linearized operator is of interest in many physical problems. For example it occurs in the nonlinear Klein-Gordon equation and in nonlinear integrodifferential equations as the Choquard problem; it further appears in nonlinear integral equations of the convolution type. A general theory enclosing all these problems is not yet known. To understand the basic phenomena, we therefore consider monotone differential operators whose linearisations have a purely continuous spectrum. It is shown that in fact the lowest point of the continuous spectrum is a bifurcation point, if the nonlinearity grows sufficiently strong.     

Instability in the critical case of pair of pure imaginary roots for a class of systems with aftereffect

The stability of a system described by Volterra integrodifferential equations is investigated in the critical case when the characteristic equation has a pair of pure imaginery roots. Conditions for instability, analogous to the well-known conditions from the theory of differential equations [1], are derived. (A similar result was established previously in [2] for integrodifferential equations of simpler structure with integral kernels of exponential-polynomial type). For the proof, several manipulations are used to simplify the original equation and, in particular, to reduce the linearized equation to the form of a differential equation with constant diagonal matrix. (An analogous approach was used to analyse instability for Volterra integrodifferential equations in the critical case of zero root in [3, 4]). As an example, the sign of the Lyapunov constant in the problem of the rotational motion of a rigid body with viscoelastic supports is calculated.     

Forced axisymmetric oscillations of a viscoelastic cylindrical shell

The variational problem of forced oscillations of a cylindrical shell is reduced to a system of linear integrodifferential equations for which a periodic solution is constructed.Moscow Institute of Electronic Machinery. Translated from Mekhanika Polimerov, No. 6, pp. 1111–1114, November–December, 1975.     

Well-defined solvability and spectral analysis of abstract hyperbolic integrodifferential equations

The authors study integrodifferential equations in Hilbert space. The coefficients of the equations are unbounded and the principal part is an abstract hyperbolic equation perturbed by terms with Volterra integral operators. Such equations can be regarded as an abstract generalization of the Gurtin–Pipkin integrodifferential equation that describes heat transfer in materials with memory and has a number of other applications. Well-defined solvability of initial boundary value problems for such equations is established in weighted Sobolev spaces on the positive semi-axis. The authors examine spectral problems for operator-valued functions representing the symbols of the said equations and study the spectrum of the abstract Gurtin–Pipkin integrodifferential equation.     

Asymptotic stability of impulsive stochastic partial integrodifferential equations with delays

In this paper, we study the existence and asymptotic stability in the p-th moment of mild solutions of nonlinear impulsive stochastic partial functional integrodifferential equations with delays. We suppose that the linear part possesses a resolvent operator in the sense given in Grimmer [R. Grimmer, Resolvent operators for integral equations in a Banach space, Trans. Am. Math. Soc. 273(1) (1982), 333–349] and the nonlinear terms are assumed to be Lipschitz continuous. A fixed point approach is employed for achieving the required result. An example is provided to illustrate the results of this work.