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JOURNALS // Teoreticheskaya i Matematicheskaya Fizika // Archive

TMF, 2025 Volume 224, Number 1, Pages 78–92 (Mi tmf10978)

Constructing a solution of an initial boundary value problem for a functional-differential equation arising in mechanics of discrete-distributed systems

E. P. Kubyshkin, V. D. Romanov

Demidov Yaroslavl State University, Yaroslavl, Russia

Abstract: We consider a three-point initial boundary value problem for a nonlinear functional partial differential equation with an infinite (integral) delay in the argument. The boundary conditions contain a delay in the argument and the highest derivative with respect to time. The initial boundary value problem is a mathematical model of the dynamics of a distributed rotating ideal shaft (rotor) of constant cross section with an ideal rigid circular disk mounted on the shaft. The axes of the shaft and disk coincide, the ends of the shaft rest on bearings. It is assumed that the shaft material obeys a nonlinear rheological model of a hereditarily elastic body. A definition of a solution of the initial boundary value problem is given based on the variational principle. Function spaces for the initial conditions and solutions are introduced, the phase space of the initial boundary value problem is defined. The existence theorem is proved for a solution, as is its uniqueness and continuous dependence on the initial conditions and parameters of the initial boundary value problem in the norm of the phase space. Thus, we demonstrate the well-posedness of the considered initial boundary value problem.

Keywords: nonlinear functional partial differential equations, construction of a solution of a partial differential equation with a delay in the argument, mathematical model of the dynamics of a distributed rotor with a disk.

MSC: 00A69 37N20

Received: 11.03.2025
Revised: 28.04.2025

DOI: 10.4213/tmf10978


 English version:
Theoretical and Mathematical Physics, 2025, 224:1, 1167–1179

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© Steklov Math. Inst. of RAS, 2026