Passive Damping of Rotationally Periodic Structures with Tuned Piezoelectric Inductive Shunt

Bilal Mokrani,André Preumont,Mihaita Horodinca,Ioan Burda,Renaud Bastaits,Iulian Romanescu

doi:10.3390/act7030041

Abstract

This paper considers the piezoelectric resistive and inductive RL shunt damping applied to rotationally periodic structures equipped with an array of regularly spaced piezoelectric patches. A method for simplifying the hardware, by reducing the size of the inductors and eliminating the use of synthetic inductors, is described. The paper compares two different ways of using the piezoelectric array: independent loops and parallel loops. It shows that, if a specific mode with n nodal diameters is targeted, mounting 4n piezoelectric patches in two parallel loops is as efficient as mounting them in 4n independent loops, while considerably reducing the demand on the inductors, L, (by 4n2). The method takes advantage of the mode shapes of rotationally periodic structures. The proposed method is validated numerically and experimentally on a rotationally periodic circular plate (nearly axisymmetric). The proposed technique is aimed at turbomachinery applications.

Highlights

New materials and new fabrication techniques in turbomachinery lead to structures with extremely low damping which may be responsible for severe vibrations and possible high-cycle fatigue problems
There is a need for systems to increase the damping which may be achieved in various ways, blade friction damping [1], friction ring damper [2], viscoelastic damping treatment or piezoelectric shunt [3,4], to name only a few
The motivation of this study was the simplification of the hardware of the RL shunt damping when applied to rotationally periodic structures by reducing the demand on the inductors

Summary

Introduction

New materials and new fabrication techniques in turbomachinery (e.g., blisks) lead to structures with extremely low damping which may be responsible for severe vibrations and possible high-cycle fatigue problems. The R-shunt involves only a network of resistors; it has limited performance, but it is simple and robust. The RL-shunt involves a set of resistors and inductors, and the electrical network is tuned to the targeted mode. The performances are superior to the R-shunt, but the electrical network needs accurate tuning of the electrical frequency on the targeted mode(s); it does not damp the other modes and, for the targeted ones, it is very sensitive to the variation in natural frequencies. The value of the inductance, L, required to achieve electrical tuning, ( LC )−1/2 ' ωi , is very large, which necessitates the use of synthetic inductors (electronic circuit called gyrator) [11]

Methods

Results

Conclusion