Parametric vibrations of piezoelectric viscoelastic cylindrical panels taking into account transverse shear deformations

The paper presents a numerical-analytical approach to solving problems of parametric vibrations of layered hinged piezoelectric viscoelastic cylindrical panels under electromechanical harmonic loading. The mathematical model is constructed using mechanical hypotheses about layer-by-layer approximation of shear deformations by quadratic functions on the thickness of panel, which are supplemented by adequate hypotheses on the distribution of electric field quantities when the components of the electric field strength vector and the normal component of the electric induction vector are different from zero. The dissipative properties of materials are taken into account on the basis of the theory of linear viscoelectric elasticity. To solve the problems, a technique based on the use of the variation principle and the representation of the required quantities in the form of decomposition into double trigonometric series has been developed. This makes it possible to reduce the considered problems to Mathieu-Hill-type equations taking into account energy dissipation, which are solved by the method of harmonic linearization, which allows to determine the boundaries of the regions of dynamic instability.

Parametric vibrations of graphene sheets based on the double mode model and the nonlocal elasticity theory

Parametric vibrations of the single-layered graphene sheet (SLGS) are studied in the presented work. The equations of motion govern geometrically nonlinear oscillations. The appearance of small effects is analysed due to the application of the nonlocal elasticity theory. The approach is developed for rectangular simply supported small-scale plate and it employs the Bubnov–Galerkin method with a double mode model, which reduces the problem to investigation of the system of the second-order ordinary differential equations (ODEs). The dynamic behaviour of the micro/nanoplate with varying excitation parameter is analysed to determine the chaotic regimes. As well the influence of small-scale effects to change the nature of vibrations is studied. The bifurcation diagrams, phase plots, Poincaré sections and the largest Lyapunov exponent are constructed and analysed. It is established that the use of nonlocal equations in the dynamic analysis of graphene sheets leads to a significant alteration in the character of oscillations, including the appearance of chaotic attractors.

Dynamic analysis of an orthotropic viscoelastic cylindrical panel of variable thickness

The intensive development of the modern industry is associated with the emergence of a variety of new composite materials. Plates, panels, and shells of variable thickness made of such materials are widely used in engineering and machine building. Modern technology for the manufacture of thin-walled structures of any configuration makes it possible to obtain structures with a given thickness variation law. Such thin-walled structures are subjected to various loads, including periodic ones. Nonlinear parametric vibrations of an orthotropic viscoelastic cylindrical panel of variable thickness are investigated without considering the elastic wave propagation. To derive a mathematical model of the problem, the Kirchhoff-Love theory is used in a geometrically nonlinear setting. The viscoelastic properties of a cylindrical panel are described by the hereditary Boltzmann-Volterra theory with a three-parameter Koltunov-Rzhanitsyn relaxation kernel. The problem is solved by the Bubnov-Galerkin method in combination with the numerical method. For the numerical implementation of the problem, an algorithm and a computer program were developed in the Delphi algorithmic language. Nonlinear parametric vibrations of orthotropic viscoelastic cylindrical panels under external periodic load were investigated. The influence of various physical, mechanical, and geometric parameters on the panel behavior, such as the thickness, viscoelastic and inhomogeneous properties of the material, external periodic load, were studied.

Imitative simulation of parametric beam vibrations

This paper discusses two approaches to the investigation of parametric vibrations for beam structures: the approximate approach also known as VKB method (phase integrals) and the iterative algorithm basically simulating the process of vibration. The study compares the results yielded by these two approaches for a compressed freely supported beam and a ring under external compression load. The problem was solved through graphic programming in PVISSIM environment.

Liquid Vibrations in Cylindrical Tanks with and Without Baffles Under Lateral and Longitudinal Excitations

The paper is devoted to issues of estimating free surface elevations in rigid cylindrical fluid-filled tanks under external loadings. The possibility of baffles installation is provided. The liquid vibrations caused by lateral and longitudinal harmonic loadings are under consideration. Free, forced and parametrical vibrations are examined. Modes of the free liquid vibrations are considered as basic functions for the analysis of forced and parametric vibrations. The modes of the free liquid vibrations in baffled and un-baffled cylindrical tanks are received by using single-domain and multi-domain boundary element methods. Effects of baffle installation are studied. The problems of forced vibrations are reduced to solving the systems of second order ordinary differential equations. For parametric vibrations the system of Mathieu equations is obtained. The numerical simulation of free surface elevations at different loadings and baffle configurations is accomplished. Beat phenomena effects are considered under lateral harmonic excitations. The phenomenon of parametric resonance is examined under longitudinal harmonic excitations.