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Dynamic characteristics of the structure with viscoelastic dampers combined with inerters and subjected to temperature changes

Pawlak Zdzisław M., Lewandowski Roman

Vibrations in Physical Systems

2020

Vol. 31, nr 2

art. no. 2020222

The purpose of the work is dynamic analysis of passive dampers used in structural systems to reduce excessive vibrations caused by wind or earthquakes. Special systems are considered that contain inerter, i.e. device using rotational inertia, in combination with a viscoelastic damper. The so-called fractional models of viscoelastic dampers describe their dynamic behavior in a wide frequency range using a small number of model parameters. To describe material behavior over a wider frequency range, the time-temperature superposition principle is used. The shifting factor is calculated from the well-known William-Landel-Ferry formula. This allows for determination of damper parameters at any temperature based on the parameters obtained at the reference temperature. Laplace transformation of the derived equations of motion leads to the non-linear eigenproblem, which could be solved using the continuation method. The influence of temperature on the dynamic characteristics of the system is examined.

Temperature influence on non-linear harmonic vibrations Of plates made of viscoelastic materials

Litewka Przemysław, Lewandowski Roman

Engineering Transactions

2020

Vol. 68, iss. 2

159--176

This paper is devoted to the analysis of ambient temperature influence on harmonic vibrations of von Kármán geometrically non-linear plates. The time-temperature superposition and the Williams-Landel-Ferry formula for the horizontal shift are used to modify the viscosity properties in the fractional Zener material model of viscoelasticity. The non-linear amplitude equation is obtained from the time-averaged principle of virtual work and the harmonic balance method. It is then solved after the finite element (FE) discretization using the continuation method to get the response curves in the frequency domain. Several numerical examples are solved and a significant influence of temperature on the resonance properties of the analysed plates is observed.