Modal actuators and sensors

Panel flutter suppression by exact state transformations and feedback control using piezoelectric actuation is presented. A nonlinear control system is formulated for the nonlinear partial differential equation governing the dynamics of a simply supported rectangular panel with bonded piezoelectric layers based on the von Karman large-deflection plate theory. Distributed piezoelectric actuators and sensors connected to processing networks are used as modal actuators and sensors to actively control panel vibrations. The control inputs are given by the electric fields required to drive the actuators based on piezoelectric actuation. Nonlinear feedback control laws are formulated through a transformation of the nonlinear system into an equivalent controllable linear system. The simulated results show that the resulting closed-loop system based on feedback linearized controllers effectively suppress panel flutter limit-cycle motions.Copyright © 2009 by ASME

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A Feedback Linearization Approach for Panel Flutter Suppression With Piezoelectric Actuation

It is significant for the two freedom degree optical switch to study its mechanical characteristics and structural optimum
design to improve its dynamic stiffness. Based on the finite element analysis and optimization calculation, a group of
optimized structure parameters of optical switch is obtained. The validity simulation of the results is verified by the
analyses of the random vibration, harmonic response and fatigue life. It proves that the optimization method adopted in
this article is effective to improve the mechanical performance of the two freedom degree optical switch.

Optimal design for the two degrees-of-freedom optical switch

A robust and high efficient optimization solution for optical switch is proposed in this article. The results of the structure modal analysis are obtained by ANSYS and the optimal dimension is determined aiming at maximizing the dynamic stiffness of the structure. The simulation analyses including random vibration, harmonic response and fatigue life are implemented to demonstrate that the mechanical characteristic of the optical switch is enhanced greatly by the presented optimization method here. Keywords-Optimal Design; Optical Switch; modal analysis; finite element analysis

Optimal Design for the Optical Switch

The application of the principle of orthogonality of the vibration mode shapes of a structure to the design of shaped modal sensors, which detect the vibrational response of the structure for the mode for which they are designed, is presented. The principle was applied in the design of shaped polyvinylidene fluoride (PVDF) modal sensors for detecting the first and second modes of the bending vibration of a simply-supported beam. These sensors, which are designed as the mode 1 and the mode 2 sensors, respectively, were bonded to the same surface of a simply-supported steel beam. The beam was subjected to random vibration by an electromagnetic exciter connected to the opposite surface of the beam. The vibrational responses of the beam measured by the distributed mode 1 and mode 2 PVDF shaped sensors are compared with the vibrational responses measured using an accelerometer. It is shown that the distributed sensors produce maximum voltage output for modes 1 and 2, respectively, for which they were designed. Furthermore, is shown that by dividing the mode 1 and mode 2 sensors into two separate halves and adding or subtracting the output signals of these halves, the mode 1 sensor can be used to detect the second mode of vibration of the beam while the mode 2 sensor can be used to detect the first mode of vibration of the beam.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

M. Solook

Papers

Selective modal sensing of vibrating beams using piezoelectric films