Effectiveness of line type and cross type piezoelectric patches on active vibration control of a flexible rectangular plate

In the present work, vibration control of a simply supported plate with line type and cross type piezoelectric (PZT) patches are investigated with and without actuation voltage. The plate is modeled under the assumption of Kirchhoff’s Plate theory. The mass of PZT patches remain constant in all cases. In case of actuation, applied voltage considered are 1, 2 and 3 mV. The external excitation to the plate is in the form of harmonically varying point load of 1 mN. It is noticed that cross type PZT patch is more effective in deflection suppression of plate than that of line type PZT patch at 3 mV of actuation at patch thickness of 0.75 μm. Suppression of central deflection of plate for line type and cross type PZT patches are obtained in different frequency bands of (175–185 Hz) and (870–880 Hz) respectively.

Modelling of sound radiation from a beam-stiffened plate and a clamped rectangular plate based on a modal method

The farfield acoustic radiation efficiency and power of a flexible rectangular plate coupled to a relatively stiffer beam are investigated. A numerical model based on a modal method that consists of a plate with sliding edges surrounded by four stiff beams is studied. Assuming that each beam is a heavy mass, a plate with clamped edges is realised, and this model is verified. This model is then extended to a beam-stiffened plate. If the bending stiffness of the excited beam is large, the radiation efficiency increases in the corner- and edge-mode frequency regions and is higher than that of the clamped plate in terms of the averaged response for randomly selected excitations. The reason for this effect is that the corner and edge areas that radiate sound are broader because the behaviour of the plate is governed by the motion of the stiff beam. This is explained in terms of the wavenumber and the wavelength of a stiff beam and a flexible plate. It is shown that this is true only when the excitation is applied to the beam, and the radiation efficiency is similar if the plate is excited. In addition, it was found that the radiation power decreases with increasing beam stiffness because the vibration of the plate actually decreases. In addition, it was shown that the variation in the radiation efficiency of the beam-stiffened plate is smaller when the beam is excited than when the plate is excited.

Effects of Sway Motion and Flow-Induced Vibration on Vortex Structure Behind Flexible Rectangular Plate

Vortex structure behind a flexible rectangular plate with sway motion and flow-induced vibration was experimentally investigated by wind tunnel experiment by using Particle Image Velocimetry (PIV). The flexible rectangular plate, which was made of a polyurethane block, was cantilevered on a flat plate. On the opposite end, top free end showed a sway motion in the downstream direction. Increasing sway angle, the top free end involved the flow-induced in-line vibration which has a small amplitude. This is a typical example of fluid-structure interaction problem. However more experimental research for the effects of the sway motion and the flow-induced vibration on vortex structure behind the rectangular plate is required. In this paper, we focus attention on the phase-averaged vortex structure when the amplitude of vibration is the largest and smallest case. PIV measurement was conducted to clarify the phase-averaged and the instantaneous vortex structure behind the swaying plate. We discussed the effect of sway motion and flow-induced vibration on vortex structure.

A Proposal of Advanced Modeling for Motion and Vibration in Flexible Structures

This paper proposes a modeling technique for motion and vibration in flexible structures. We call this technique ‘extended reduced order physical model’. Because vibration is generally influenced by motion, it is necessary to analyze vibration together with motion. New modeling technique can be used to represent both motion and vibration. Effectiveness of this technique is confirmed by characteristics of vibration of a flexible rectangular plate with free support through simulation in this study. Target modes, the first bending and the first torsional modes of the structure reappeared.

Response of a Flexible Printed Circuit Board to Periodic Shock Loads Applied to its Support Contour

Treating a printed circuit board (PCB) as a thin flexible rectangular plate, we evaluate its dynamic response to periodic shock loads applied to the support contour. The effect of the load periodicity on the amplitudes, accelerations, and stresses is analyzed for transient and steady-state damped linear vibrations, as well as for steady-state undamped nonlinear vibrations. It is shown that the transient nonresonant linear response can exceed the steady-state response by up to two times, and that the linear approach can be misleading in the case of a nondeformable support contour and intense loading. The obtained results can be of help when evaluating the accelerations, experienced by surface mounted electronic components and devices, and the dynamic stresses in a PCB of the given type, dimensions, and support conditions.

A Flexible Rectangular Plate on an Elastic Layer: Large Area Contact

The unbonded frictionless receding contact problem of a symmetrically loaded thin rectangular plate resting on an elastic layer is solved in this paper. The contact is assumed to be tensionless. The problem is transformed into the solution of three coupled two-dimensional singular integral equations. The possible contact pressure singularities along the plate edges and at the corners are treated using adaptive discretization. The contact regions are found iteratively since the problem is nonlinear. Contact regions and numerical values of displacements and contact pressures are presented to illustrate the influences of uplift, layer depth, aspect ratio, stiffness ratio, Poisson’s ratio, and other quantities.