Shunt Damping Research Articles

Parallel Piezoelectric Shunt Damping of Rotationally Periodic Structures

This paper considers the RL shunt damping of rotationally periodic structures with an array of regularly spaced piezoelectric patches. The technique is targeted to the damping of a specific mode withnnodal diameters. For this particular case, one can take advantage of the shape of the targeted mode to organize the piezoelectric patches as a modal filter (in parallel loops) which reduces the demand on the inductors of the tuned inductive shunt. In the case of a perfectly rotationally periodic structure, it is possible to organize 4npiezoelectric transducers (PZT patches) in two parallel loops of 2npatches each. In this way, the demand on the inductors is reduced by4n2as compared to independent loops, which may allow a fully passive integration of the RL shunt in a turbomachinery application. The method is first illustrated experimentally on a circular plate; it is then applied to a prototype of an industrial bladed drum. The influence of blade mistuning is investigated.

寄生抵抗を考慮した圧電シャント制振のための負性キャパシタ回路の設計法

寄生抵抗を考慮した圧電シャント制振のための負性キャパシタ回路の設計法

シャント制振のための電磁アクチュエータのセンサレスパラメータ推定

Electromagnetic shunt damping is a sensor-less passive damping technique using an electromagnetic actuator. The accurate values of the parameters of the system are essentially required for designing a controller in the damping technique. This paper proposes a parameter estimation method of an electromagnetic actuator attached to a mechanical structure in order to use for electromagnetic shunt damping. The electromagnetic actuator attached to the structure is modeled as the system including the mechanical and electrical systems which are connected by the electromechanical coupling coefficient. This paper points out a remark on the estimation: The frequency response of the electrical admittance especially neighborhood the natural frequency of the mechanical structure shows an electro-mechanically resonant feature, which does not appear in the pure electrical system without the electromechanical coupling. By applying least squares method to the frequency response data of the electrical admittance neighborhood the natural frequency, the parameters of the mechanical system and the electromechanical coupling coefficient as well as the electrical parameters can be estimated. The proposed estimation method requires only measurements of the frequency response of the electrical admittance across the terminals of the electromagnetic actuator. Therefore, both the parameter estimation and the electromagnetic shunt damping are possible to perform without any displacement or velocity sensors, or any additional actuators. In order to verify the effectiveness of the proposed method, the experiments of parameter estimation and of electromagnetic shunt damping are performed. The experimental results show that the proposed method is effective to estimate the parameters of the electromagnetic actuator without use of any other sensors.

Piezoelectric shunt damping by synchronized switching on negative capacitance and adaptive voltage sources

Synchronized switch damping (SSD) techniques have recently been developed for structural vibration control using piezoelectric materials. In these techniques, piezoelectric materials are bonded on the vibrating structure and shunted by a network of electrical elements. These piezoelectric materials are switched according to the amplitude of the excitation force to damp vibration. This paper presents a new SSD technique called 'synchronized switch damping on negative capacitance and adaptive voltage sources' (SSDNCAV). The technique combines the phenomenon of capacitance transient charging and electrical resonance to effectively dampen the structural vibration. Also, the problem of stability observed in the previous SSD techniques is effectively addressed by adapting the voltage on the piezoelectric patch according to the vibration amplitude of the structure. Analytical expressions of vibration attenuation at the resonance frequency are derived, and the effectiveness of this new technique is demonstrated, for the control of a resonant cantilever beam with bonded piezoelectric patches, by comparing with SSDI, SSDVenh, and SSDNC techniques. Theoretical predictions and experimental results show the remarkable vibration damping capability of SSDNCAV technique, which was better than the previous SSD techniques. The broadband vibration control capabilities of SSDNCAV technique are also demonstrated, which exceed those of previous SSD techniques.

Wall-plug efficiency analysis of semi-active piezoelectric shunt damping systems

Analysis of the wall-plug efficiency, i.e. the ratio of reflected and absorbed acoustic power over the total electric input power, of semi-active vibration control devices based on the principle of the active piezoelectric shunt damping is presented. The vibration suppression element in the considered vibration control device consists of a piezoelectric actuator, which is connected to the active synthetic impedance shunt circuit that emulates a negative capacitance. Two types of power amplifiers can be used in the implementation of the synthetic impedance: linear (class B, AB) and switching (class D). Using both implementations of the synthetic impedance, a decrease in the transmissibility of vibration by about 30 dB in narrow frequency ranges around 500 Hz, 700 Hz, 900 Hz, and 1.1 kHz has been achieved. The mechanical input power transferred from the source of vibration to the vibration control system, the electric power flow from the piezoelectric actuator to the active shunt impedance, and the wall-plug input electric power were measured. It was demonstrated that the wall-plug input electric power of the vibration control device can be reduced by more than 90% by implementing the switching power stage in the synthetic impedance. Strengths and weaknesses of the two aforementioned implementations of the synthetic impedance shunt circuit in the semi-active vibration control device are analyzed. The key factor in the analysis is the wall-plug efficiency. Principles that can enhance the wall-plug efficiency of the device are discussed.

Structural multimode vibration absorbing with electromagnetic shunt damping

This paper presents multimode vibration absorbing methods which employ negative resistance (NR) and negative inductance negative resistance (NINR) electromagnetic shunt damping vibration absorbers. The NR and NINR shunts can change the impedance of an electromagnet so as to change the control force of the absorber. The governing equation of the coupling system is established. What is more, some numerical simulations are carried out and the results show that the absorbers with NR or NINR shunt can effectively suppress the multimode vibration. Furthermore, the root locus is analyzed to design the resistance of a shunt.

Vibration Reduction of Mistuned Bladed Disks by Passive Piezoelectric Shunt Damping Techniques

This paper presents a vibration control strategy based on the passive piezoelectric shunt damping technique for mistuned bladed disks. Resonant shunted piezoelectrics are attached onto the disk surface between adjacent blades to dissipate the mechanical energy. This strategy is of engineering interest because piezoelectric transducers are placed outside of the main stream in turbomachinery. This idea is developed based on a lumped-parameter bladed disk model. Both piezoelectric shunt damping and piezoelectric mistuning are introduced to minimize the blade mistuning effect. First, a tuning design is carried out to damp a specified mode for the tuned bladed disk. When blade mistuning is taken into account, a further vibration reduction is achieved by introducing an optimal piezoelectric mistuning pattern obtained by a genetic algorithm. In reality, the blade mistuning pattern is not constant in the long run. Because of various complexities, a perturbation of the blade mistuning pattern might result. In benefitting from the manageability and controllability of piezoelectric shunt circuits, an adaptive control strategy is developed to adjust the “optimal” piezoelectric mistuning pattern according to the perturbation. Numerical simulation reveals that good performance is achieved in terms of reducing the vibration of slowly time-variant, mistuned bladed disks.

Coupled FEM/BEM for control of noise radiation and sound transmission using piezoelectric shunt damping

In this paper, we present a coupled finite element/boundary element method (FEM/BEM) for control of noise radiation and sound transmission of vibrating structure by passive piezoelectric techniques. The system consists of an elastic structure (with surface mounted piezoelectric patches) coupled to external/internal acoustic domains. The passive shunt damping strategy is employed for vibration attenuation in the low frequency range. The originality of the present paper lies in evaluating the classically used FEM/BEM methods for structural–acoustics problems when taking account smart systems at the fluid–structure interfaces.

Scaling of electromagnetic transducers for shunt damping and energy harvesting

Abstract In order for an electromagnetic transducer to operate well as either a mechanical shunt damper or as a vibration energy harvester, it must have good electromechanical coupling. A simple two-port analysis is used to derive a non-dimensional measure of electromechanical coupling, which must be large compared with unity for efficient operation in both of these applications. The two-port parameters for an inertial electromagnetic transducer are derived, from which this non-dimensional coupling parameter can be evaluated. The largest value that this parameter takes is approximately equal to the square of the magnetic flux density times the length of wire in the field, divided by the mechanical damping times the electrical resistance. This parameter is found to be only of the order of one for voice coil devices that weigh approximately 1 kg, and so such devices are generally not efficient, within the definition used here, in either of these applications. The non-dimensional coupling parameter is found to scale in approximate proportion to the device's characteristic length, however, and so although miniaturised devices are less efficient, greater efficiency can be obtained with large devices, such as those used to control civil engineering structures.

セルフチューニング負性キャパシタによる適応圧電シャントダンピング

セルフチューニング負性キャパシタによる適応圧電シャントダンピング

Dynamic analogy between an electromagnetic shunt damper and a tuned mass damper

An electromagnetic shunt damper (EMSD) is composed of an electromagnetic damper connected to one or more RLC shunt circuits. Through a theoretical comparison, this paper reveals the similarity and difference between an EMSD and a tuned mass damper (TMD), both of which are resonant-type vibration absorbers. The equivalent mass, stiffness and damping coefficient of the EMSD are derived based on the transfer functions of structures with a TMD or an EMSD, and the functions of circuit capacitance and inductance are discussed accordingly. The optimal parameters of the RLC circuit in the EMSD are obtained through H∞ optimization. Despite their different optimal parameters, the EMSD and TMD exhibit comparable control performance with the same equivalent mass ratio. The dynamic analogy between these two types of dampers offers a new perspective for understanding novel EMSDs, given that TMDs have previously been extensively studied. The potentials and constraints of the EMSD are further discussed through numerical case studies in which EMSD control performance is examined in different situations.

Dual-Functional Energy-Harvesting and Vibration Control: Electromagnetic Resonant Shunt Series Tuned Mass Dampers.

This paper proposes a novel retrofittable approach for dual-functional energy-harvesting and robust vibration control by integrating the tuned mass damper (TMD) and electromagnetic shunted resonant damping. The viscous dissipative element between the TMD and primary system is replaced by an electromagnetic transducer shunted with a resonant RLC circuit. An efficient gradient based numeric method is presented for the parameter optimization in the control framework for vibration suppression and energy harvesting. A case study is performed based on the Taipei 101 TMD. It is found that by tuning the TMD resonance and circuit resonance close to that of the primary structure, the electromagnetic resonant-shunt TMD achieves the enhanced effectiveness and robustness of double-mass series TMDs, without suffering from the significantly amplified motion stroke. It is also observed that the parameters and performances optimized for vibration suppression are close to those optimized for energy harvesting, and the performance is not sensitive to the resistance of the charging circuit or electrical load.

Development of a Grounded Virtual Admittance Circuit and Piezoelectric Shunt Damping with a Virtual Series LR Elements

Development of a Grounded Virtual Admittance Circuit and Piezoelectric Shunt Damping with a Virtual Series LR Elements

Improving Low Frequency Performance of Double-Wall Structure Using Piezoelectric Transducer/Loudspeaker Shunt Damping Technologies

The potential of piezoelectric transducer (PZT) and loudspeaker shunt damping technologies on improving noise insulation efficiency of double-wall structure at low frequencies is investigated. A semi-active circuit of negative capacitance is introduced to the PZT to achieve noise reduction at all structural resonance frequencies and a passive circuit of purely resistance is introduced to the shunt loudspeaker to add the damping effect of the cavity at cavity dominated frequency. A coupled model, characterizing the interaction among the PZT patched plates, air cavity and shunted loudspeakers, is developed based on modal analysis methods. Numerical results show that PZT shunt damping or the loudspeaker shunt damping is effective to improve the performance at some certain resonant frequencies and the combined PZT/loudspeaker shunt damping model can achieve noise reduction at all coupled and uncoupled structural-acoustic mode frequencies. Finally, experiments are carried out in a laboratory set-up to verify the numerical results roughly.

A survey of control strategies for simultaneous vibration suppression and energy harvesting via piezoceramics

This article presents a summary of passive, semipassive, semiactive, and active control methods for schemes using harvested energy as the main source of energy to suppress vibrations via piezoelectric materials. This concept grew out of the fact that energy dissipation effects resulting from energy harvesting can cause structural damping. First, the existing equivalent electromechanical modeling methods are reviewed for vibration-based energy harvesters using piezoelectric transducers. Modeling of base excitation cantilever beam ranges from lumped to distributed parameter formulations. The commonly used electrical power conditioning circuits and their optimization are also summarized and discussed. The energy dissipation from harvesting induces structural damping, and this leads to the concept of purely passive shunt damping. This article reviews the literature on vibration control laws along the lines of purely passive, semipassive, semiactive, and active control. The classification of pervious results is built on whether external power is supplied to the piezoelectric transducers. The focus is placed on recent articles investigating semipassive and semiactive control strategies derived from synchronized switching damping. However, whether or not the harvested energy is large enough to satisfy a vibration suppression requirement has become an important topic of research but has not yet specifically been addressed in previous studies. Hence, this survey also reviews the possible control methods aiming for less control energy consumption and addresses the potential application for simultaneous vibration control and energy harvesting.

Vibration isolation of a beam via negative resistance electromagnetic shunt dampers

In this study, two novel electromagnetic shunt damping vibration isolators (EMSD-VIs) were developed for the vibration isolation of a beam structure. The proposed isolator utilizes a pair of electromagnetic coils and permanent magnet and a box-shaped spring to generate both variable damping and spring effect. The governing equation of the EMSD-VI-supported beam was established according to Galerkin method. The negative resistance was proposed to improve the performance of the isolator. The stability analysis was investigated to determine the design rules of the shunted negative resistance. The acceleration transmissibility of the beam system was simulated by using passive EMSD-VI control and negative resistance (NR)-EMSD-VI control. The experiment was conducted to verify the theoretical model and the numerical simulation. The experimental results demonstrated that the proposed NR-EMSD-VI is capable of isolating the first-order and the third-order vibrations. Also, a discussion of the resonance frequency shift toward higher value was given.

Measurement of mechanical and electrical energy flows in the semiactive piezoelectric shunt damping system

The analysis of the mechanical and electric energy flows in the semiactive vibration control system, which is made of a piezoelectric actuator shunted by a negative capacitor, is presented. The vibration control system is designed to suppress the vibration transmission in a narrow frequency range. Using a proper adjustment of the electronic circuit elements, the transmissibility of vibrations has been suppressed by 35 dB at the frequency of 1.5 kHz. The results of our measurements indicate that the average apparent electrical power in the electric part of the vibration control device is about 100 times larger than the mechanical power, which is supplied to the system from the source of vibrations. The rules for designing the highly efficient and low-power electronic parts of semiactive vibration control systems are discussed.

A novel multimode negative inductance negative resistance shunted electromagnetic damping and its application on a cantilever plate

Based on the characteristic of the electromagnetic damping, a novel multimode vibration control treatment, negative inductance negative resistance electromagnetic shunt damping (NINR-EMSD), is proposed and employed to control multimode vibration of a cantilever plate. The negative inductance of the shunt impedance can cancel the inherent inductance of the electromagnet, and the impedance of circuit consisted of the coils and shunt will be a pure resistance and the shunt current will be frequency independent when the inductance of the shunt and the electromagnet are equal with each other. The negative resistance cancels the resistance of electromagnet, and as a result the resistance and the current of the closed circuit will change, which make it feasible to control the multimode vibration of the system. Electromechanical coupling coefficient is obtained based on the equivalent current method. The governing equation of the plate with the electromagnetic shunt damping (EMSD) is established according to Hamilton's principle. Multimode vibration control of the system is simulated and experiments are carried out to verify the performance of the NINR-EMSD. The numerical predictions and experimental results agree well with each other and show that: the negative inductance negative resistance (NINR) of the shunt impedance can increase the damping of the structure notably; the decrease of the resistance of shunt impedance have a significant contribution to the improvement of vibration control performance; the first four modes vibration of the plate can be suppressed simultaneously with the NINR-EMSD.

Design and test of a novel isolator with negative resistance electromagnetic shunt damping

This paper proposes a negative resistance electromagnetic shunt damping vibration isolator and investigates the effectiveness of the isolator. The isolator consists of a shunt circuit and a pair of electromagnet and permanent magnets that are pasted onto a box-shaped spring. A kind of negative resistance shunt impedance is proposed to cancel the inherent resistance of the electromagnet. The electromechanical coupling coefficient and the electromagnetic damping force calculation formula are obtained by Biot–Savart’s law and Ampère’s law, respectively. A single degree of freedom system is employed to verify the performance of the proposed isolator. The governing equation is established. The performance of the proposed isolator under a half-cycle sine pulse is investigated and discussed. Experiments were carried out and the results agreed well with the numerical predictions. Both the results demonstrate that the negative resistance electromagnetic shunt damping vibration isolator could suppress vibration transmitted to the structure effectively.

Virtual Piezoelectric Vibration Absorber with LR Parallel Shunt Circuit

A virtual piezoelectric vibration absorber with LR Parallel shunt circuit was developed to emulate the effect of a physical piezoelectric shunt damper. A controller was designed and the feedback structure according to the LR parallel shunt circuit was suggested by using the governing equations of piezoelectric shunt damping system. The inductor L and resistor R only “exist” as numerical representations inside the controller. The virtual piezoelectric vibration absorber can both eliminate the need for large inductor and tune circuit component parameters online to adapt to environmental changes. Therefore the two disadvantages of the physical piezoelectric shunt damper are overcome. The simulation results for a cantilever beam show the effectiveness of the Virtual piezoelectric vibration absorber for vibration suppression.