Application of active piezoelectric patches in controlling the dynamic response of a thin rectangular plate under a moving mass

The governing differential equation of motion for an undamped thin rectangular plate with a number of bonded piezoelectric patches on its surface and arbitrary boundary conditions is derived using Hamilton’s principle. A moving mass traveling on an arbitrary trajectory acts as an external excitation for the system. The effect of the moving mass inertia is considered using all the out-of-plane translational acceleration components. The method of eigenfunction expansion is used to transform the equation of motion into a number of coupled ordinary differential equations. A classical closed-loop optimal control algorithm is employed to suppress the dynamic response of the system, determining the required voltage of each piezoactuator at any time interval. In a numerical example for a simply supported square plate under two different loading paths, the effect of the mass velocity and mass weight of the moving load on the dynamic behavior of the uncontrolled system is investigated. The results show that, depending on the path of the moving mass, the inertia effect is very important, causing different behaviors of the system. In addition, the number of vibrational modes involved in determining the dynamic response of the system is crucial. The inertia effect is more important for an orbiting mass loading case compared to the case in which the moving mass is traversing the plate on a straight line. A number of equally spaced piezo patches are used on the lower surface of the plate to control the displacement of the center point of the plate. The implemented control mechanism proves to be very efficient in suppressing the near resonant dynamic response of the system, requiring fairly low levels of voltage for each patch. Increasing the area of the employed piezo patches would reduce the required maximum voltage for controlling the response of the system.     

DYNAMIC BEHAVIOR OF THIN RECTANGULAR PLATE ATTACHED TO MOVING RIGID

A nonlinear dynamic model of a thin rectangular plate attached to a moving rigid was established by employing the general Hamilton's variational principle. Based on the new model, it is proved theoretically that both phenomena of dynamic stiffening and dynamic softening can occur in the plate when the rigid undergoes different large overall motions including overall translational and rotary motions. It was also proved that dynamic softening effect even can make the trivial equilibrium of the plate lose its stability through bifurcation. Assumed modes method was employed to validate the theoretical result and analyze the approximately critical bifurcation value and the post-buckling equilibria.     

Flutter of a rectangular plate

We address theoretically the linear stability of a variable aspect ratio, rectangular plate in a uniform and incompressible axial flow. The flutter modes are assumed to be two-dimensional but the potential flow is calculated in three dimensions. For different values of aspect ratio, two boundary conditions are studied: a clamped-free plate and a pinned-free plate. We assume that the fluid viscosity and the plate viscoelastic damping are negligible. In this limit, the flutter instability arises from a competition between the destabilising fluid pressure and the stabilising flexural rigidity of the plate. Using a Galerkin method and Fourier transforms, we are able to predict the flutter modes, their frequencies and growth rates. The critical flow velocity is calculated as a function of the mass ratio and the aspect ratio of the plate. A new result is demonstrated: a plate of finite span is more stable than a plate of infinite span.     

Electromechanical control of vibration on a plate submitted to a non-ideal excitation

This paper deals with the enhancement of electromechanical control of vibration on a thin plate submitted to non-ideal excitation. Modelling of the systems displays the non-ideal source used as external excitation above the structure on a particular surface and control force acting at specific points under the structure. The electromechanical device is composed by a RL circuit with a saturated inductance and stings connected to the plate is used as connection between the structure and the controller. Routh–Hurwitz criteria are used to obtain the stability condition of the controlled system and some dynamics exploration leads us to the condition for which the amplitude of vibration is reduced in the mechanical structure.     

Impact of a rectangular plate on a liquid half-space

The potential flow of an ideal incompressible fluid occupying a half-space resulting from the impact of a rectangular plate on its surface is considered. Outside the plate the surface of the fluid is free. An integral equation of the first kind is obtained for the impulsive pressure beneath a flexible plate. It is solved on a computer by the power series method for the particular case of a rigid nondeformable plate. The accuracy of the method is estimated. The theoretical dependence of the virtual mass and virtual moment of inertia coefficients of a rigid nondeformable plate on the plate geometry is constructed and compared with the experimental data and with empirical formulas [1-3] not directly related with the solution of the Laplace equation.Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.5, pp. 120–126, September–October, 1992.     

High-frequency flutter of a rectangular plate

In our recent study of strip plate flutter, two flutter types, low-and high-frequency, were revealed. The first arises due to interaction of the oscillation modes and has been investigated in detail in numerous studies using an approximate piston theory. The high-frequency flutter, detected for the first time, is a consequence of the presence of negative aerodynamic damping and cannot be obtained using the piston theory. In the present study, the high-frequency flutter of a rectangular plate is investigated.     

Stress systems in a rectangular plate

In this paper, the problem of a rectangular plate under general self-equilibrant edge tractions is solved by the method of images. The edge tractions are decomposed into four systems. When the boundary conditions in each system are satisfied, the solution is reduced to a set of linear equations, which can be solved by the method of successive approximations. Finally, the solution is illustrated by numerical examples. The effect of truncation of the set of equations is also investigated.     

Analyses of dynamic characteristics of a fluid-filled thin rectangular porous plate with various boundary conditions

Based on the classical theory of thin plate and Biot theory, a precise model of the transverse vibrations of a thin rectangular porous plate is proposed. The first order differential equations of the porous plate are derived in the frequency domain. By considering the coupling effect between the solid phase and the fluid phase and without any hypothesis for the fluid displacement, the model presented here is rigorous and close to the real materials. Owing to the use of extended homogeneous capacity precision integration method and precise element method, the model can be applied in higher frequency range than pure numerical methods. This model also easily adapts to various boundary conditions. Numerical results are given for two different porous plates under different excitations and boundary conditions.     

Bending vibrations of a rectangular poroelastic plate

This paper presents the equations of motion of an air saturated rectangular porous plate. The model is based on a mixed displacement–pressure formulation of the Biot–Allard theory [1]. We obtain a system of equations which describe the coupling beetween the solid and fluid phases of the plate. This system is solved by applying the Galerkin method.     

Free vibrations of a thin rectangular plate

An asympototic method developed by V.V. Kucherenko and the author is applied to the problem of free vibrations of a thin plate strip in a state of a plane strain. The first few terms of an asymptotic expansion of the natural frequencies are calculated. The results are compared with those obtained by using the classical and refined theories.     

Bending of a partially clamped rectangular plate

Summary The present study deals with the bending of a rectangular plate with two opposite simply-supported edges and other two free edges having any portion, clamped in such a way that the slope is zero. The solution is obtained by means of a superposition proposed by Kurata and Hatano [3]. The case of a square plate under a uniform load or a point load has been studied in detail.

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Übersicht Es wird die Biegung einer rechteckigen Platte untersucht, von der zwei Ränder einfach unterstützt sind, während die anderen Ränder zum Teil frei sind, zum Teil so eingespannt, daß die Neigung verschwindet. Die Lösung wird mit Hilfe einer Superposition erhalten, die von Kurata und Hatano [3] vorgeschlagen wurde. Für den Fall einer quadratischen Platte unter einer gleichförmigen Last oder einer Einzellast werden die Berechnungen weiter ausgeführt.

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This paper is a part of author's Ph. D. thesis submitted to the Indian Institute of Technology, Kharagpur in 1965.     

Stability of a rectangular plate beyond the elastic limit

Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 105–110, September–October, 1990.     

The effective installation of an inclined plate for the enhancement of forced convection over rectangular sources

This paper investigates the unsteady flow and heat transfer characteristics of rectangular sources with and without an inclined plate in a channel. The results show that the installation of an inclined plate above an upstream source results in a periodically unsteady flow and it can effectively enhance the heat transfer performance. Moreover, the inclined angle of the plate is changed under different Reynolds numbers to study the heat transfer performance in the channel. Received on 18 June 1997