Shunt Damping Research Articles

Hybrid Electromagnetic Shunt Damper for Vibration Control

Abstract It has been shown that shunting electromagnetic devices with electrical networks can be used to damp vibrations. These absorbers have however limitations that restrict the control performance, i.e., the total damping of the system and robustness versus parameter variations. On the other hand, the electromagnetic devices are widely used in active control techniques as an actuator. The major difficulty that arises in practical implementation of these techniques is the power consumption required for conditioners and control units. In this study, robust hybrid control system is designed to combine the passive electromagnetic shunt damper with an active control in order to improve the performance with low power consumption. Two different active control laws, based on an active voltage source and an active current source, are proposed and compared. The control law of the active voltage source is the direct velocity feedback. However, the control law of the active current source is a revisited direct velocity feedback. The method of maximum damping, i.e., maximizing the exponential time-decay rate of the response subjected to the external impulse forcing function, is employed to optimize the parameters of the passive and the hybrid control systems. The advantage of using the hybrid control configuration in comparison with purely active control system is also investigated in terms of the power consumption. Besides these assets, it is demonstrated that the hybrid control system can tolerate a much higher level of uncertainty than the purely passive control systems.

Enhancement of a dynamic vibration absorber by means of an electromagnetic shunt

In this study, we address the reduction of structural vibrations by means of an electromagnetic shunt damper (EMSD) combined with a mechanical dynamic vibration absorber (DVA). Two architectures, that differs in the placement of the EMSD with respect to the DVA, are tested, showing that one of them enhances the vibration control. In parallel, three shunt architecture are tested: a resistive shunt, a resonant conservative shunt and a resonant dissipative shunt. Optimal values of the EMSD and DVA parameters are obtained; then, the performances of all architecture, according to relevant criteria, are estimated and compared to a single DVA or a single EMSD. The case of a conservative DVA, that creates an anti-resonance, is particularly targeted. It is shown that the performances rely on two free parameters only: the mass ratio for the DVA and the electromagnetic coupling factor for the EMSD, thus giving generic abacuses that can be applied to any practical cases. Finally, experiments are proposed and a good agreement with the theoretical results is obtained, thus validating them.

A study on shunt damping performance, current response, and energy analysis of voice coil motor

Electromagnetic shunt damping is a method of damping by connecting a shunt circuit to the terminals of the voice coil motor (VCM). When controlling the VCM current using an amplifier, the control law has a function equivalent to that of a shunt circuit. In this paper, we propose a new method that analyzes not only the performance of conventional shunt vibration control, but also the response performance of generated force and energy consumption for current controlled VCM.

Acoustic Radiation Suppression of a Truss Core Sandwich Panel Using Decentralized Resonant Shunt Damping

The aim of the present work was to suppress the free space acoustic radiation of a truss-cored sandwich panel through the use of the decentralized resonant shunt method. First, the finite element model of the structure was established and its sound radiation characteristics were studied using the elemental radiators decomposition method. Then the decentralized modal piezoelectric shunt vibration control strategy of the Kagome sandwich panel was described in detail. In this approach, a small number of rods in the bottom truss of the sandwich panel were replaced by a piezoelectric stack transducer; each transducer was connected to a single resonant shunt which was tuned to suppress the vibration of a specific mode. The biggest advantage of the independent modal resonant shunt method is that the circuits of each mode are independent of each other; thus the large-scale parameter optimization can be decomposed into small-scale optimization problems. The results of the numerical simulation have shown that the approach that has been proposed in this paper is very effective in controlling the sound radiation of the examined structure at its resonant frequency. The results of this study can be useful in the study of the sound radiation suppression of a sandwich panel.

Nonlinear damping and mass effects of electromagnetic shunt damping for enhanced nonlinear vibration isolation

This paper investigates the nonlinear mass and damping effects of nonlinear electromagnetic shunt damping (N-EMSD) for vibration isolation performance enhancement of a permanent magnets (PMs) based nonlinear vibration isolator (NVI). An electromagnetic structure composing of two coils and two PMs is designed to realize equivalent nonlinear damping and mass. The nonlinear mechanic-electromagnetic coupling coefficient is analyzed and modeled. The voltage frequency of the circuit is twice the displacement frequency that is totally different with that of the linear electromagnetic shunt damping (L-EMSD). The amplitude frequency response function of the NVI with N-EMSD is theoretically derived via the harmonic balance method (HBM) and the stability is judged with Jacobian matrix. Then the equivalent nonlinear damping and nonlinear mass of the N-EMSD is derived. The numerical predictions agree with the experimental results, which demonstrate that the use of inductance in shunt circuit can change the equivalent nonlinear mass and the “jump” frequency of the NVI. Large value of inductance deteriorates the vibration isolation performance and the optimal inductance is slightly smaller than zero. Furthermore, N-EMSD can realize nonlinear damping to achieve wide band vibration isolation of the NVI. The optimal negative resistance is discussed.

Consistent frequency-matching calibration procedure for electromechanical shunt absorbers

Electromagnetic and piezoelectric shunt damping can be represented by an equivalent mechanical vibration absorber with a spring, dashpot, and inerter in series. A common calibration procedure for multiple electromechanical shunt absorbers is obtained by this equivalence, including a correction for the influence from residual vibration modes by additional modal terms, whose coefficients are consistently identified by frequency matching for the system with rigid absorber dashpots. The accuracy and robustness of the calibration procedure are verified numerically for an unsupported truss structure with rigid body modes.

Electromagnetic shunt damping for shock isolation of nonlinear vibration isolators

Electromagnetic shunt damping (EMSD) can effectively suppress structural vibrations of linear systems. However, the effects of EMSD on shock isolation for either linear or nonlinear vibration systems have not been studied deeply. This paper investigates the shock isolation of nonlinear vibration isolators (NVIs) with negative resistance electromagnetic shunt damping (NR-EMSD). An NVI that is capable of realizing linear and nonlinear characteristics is constructed. The coupled governing equations of the NVI with NR-EMSD are derived. Shock acceleration ratio (SAR), shock displacement ratio (SDR) and relative displacement ratio (RDR) are employed to evaluate the shock isolation performance of linear vibration isolators (LVIs) and NVIs. Both the numerical simulations and experiments are performed. The results demonstrate that with the increase of negative resistance SDR and RDR decrease in a wide frequency band, SAR decreases in the shock amplification region but increases in the shock isolation region. A higher value of inductance leads to the decrease of the period and is harmful to shock isolation. The shock isolation performance of the NVI with NR-EMSD is better than that of the LVI with NR-EMSD, which demonstrates that a properly designed nonlinear stiffness is beneficial to shock isolation. NR-EMSD could increase damping to improve the shock isolation performance for both linear and nonlinear systems.

Optimal passive shunted damping configurations for noise reduction in sandwich panels

This article addresses the issue of vibration and noise reduction in laminated sandwich plates using piezoelectric patches with passive shunted damping. A finite element implementation of a laminated sandwich plate with viscoelastic core and surface bonded piezoelectric patches is used to obtain the frequency response of the panels. The sound transmission characteristics of the panels are evaluated by computing their radiated sound power using the Rayleigh integral method. Resistor and inductor shunt damping circuits are used to add damping to the sandwich panels. The optimal location of the surface-bonded piezoelectric patches is then obtained, along with the resistor and inductor circuits resistance and inductance, using direct multisearch optimization to minimize added weight, number of patches, and noise radiation. Trade-off Pareto optimal fronts and the respective optimal patch configurations are obtained.

Estimation and measurement of effective line mobility on a non-deterministic thin plate excited by a piezoelectric patch

This paper derived the expression to estimate the effective line moment mobility of a non-deterministic thin plate under moment excitation by a piezoelectric patch actuator. The piezoelectric patch actuator is assumed to generate purely line moments at each of its edges and regarded as a finite number of point moments acting on an infinite plate, which is achieved by integration method. The theoretical model is validated using MATLAB simulation and compared with experimental measurements on a randomized thin plate. The derived effective line moment mobility managed to closely estimate high-frequency response while cutting significant computational time and resource. Results from this study can be used in many applications ranging from vibration isolation where power transmission between the isolator with an area distribution and its host structure can be determined more accurately, and to design the optimal shunt circuit of a piezoelectric shunt damper for maximum power dissipation in order to reduce vibration of a non-deterministic thin plate.

On the design of nonlinear damping with electromagnetic shunt damping

Traditional linear electromagnetic shunt damping (L-EMSD) has been studied deeply, however, the vibration isolation performance becomes worse with the increase of linear damping in the isolation region. To overcome the limitation of L-EMSD, this paper proposes two types of nonlinear electromagnetic shunt damping (N-EMSD) to develop nonlinear damping for the broadband vibration isolation of linear vibration isolators (LVIs). Both the two types of N-EMSD consist of two permanent magnets (PMs) and coils, however, the ways to connect to the external shunt circuits and the configurations between the PMs and coils are different. Nonlinear electromagnetic coupling coefficients are analyzed theoretically. The theoretical transmissibility of the LVI with N-EMSD is derived via the harmonic balance method (HBM). Numerical simulations and experiments are conducted to verify nonlinear damping performance of N-EMSD. The results demonstrate that compared to L-EMSD the proposed N-EMSD have similar vibration suppression performance in the resonance region, but are more effective in the isolation region.

Theoretical modeling and experimental analysis of nonlinear electromagnetic shunt damping

Linear electromagnetic shunt damping (L-EMSD) has been investigated deeply for vibration control in previous studies. This paper proposes nonlinear electromagnetic shunt damping (N-EMSD) for vibration isolation enhancement of linear vibration isolators (LVIs), which has not been discussed in existing literature. N-EMSD composes of a pair of the permanent magnets (PMs) and a pair of the coils, where the two coils are wound in opposite direction and connected in series. The nonlinear electromagnetic coupling coefficient is derived. The coupling governing equations of a LVI with N-EMSD are established and the amplitude-frequency relationship is theoretically derived using the harmonic balance method (HBM). Both the simulations and experiments are carried out to verify the nonlinear damping characteristic of N-EMSD. The results demonstrate that the LVI with N-EMSD can effectively reduce the vibration in the resonance region without affecting the vibration isolation performance in the isolation region compared with the traditional L-EMSD. It is also found in both simulation and experiment for the two coils configuration that the frequency of the induced voltage is twice the frequency of the displacement. Furthermore, the transmissibility of the LVI with N-EMSD reduces with the increase of the input amplitude in the resonance region, which demonstrates the nonlinearity of N-EMSD. The natural frequency slightly decreases with the decrease of the peak transmissibility. This paper extends the electromagnetic shunt damping (EMSD) technique from linear to nonlinear fields and provides a guideline to design nonlinear damping.

Numerical Analysis of Amplitude Reduction Using Electromagnetic Shunt Damper with an LCR Parallel Circuit in a Superconducting Magnetic Levitation System

An electromagnetic shunt damper is a type of a dynamic vibration absorber; however, the subsystem consists of an LCR series circuit instead of a supporting mass. When this is utilized to a superconductive levitation system, the optimal value of the resistance within the circuit is quite small. The value is difficult to be precise in practice, hence there are chances that the damper will be ineffective. However, there are possibilities that the restriction due to the optimal resistance value can be eased by using an LCR circuit where the resistance and the capacitance is parallel. In this study, the authors studied the vibration characteristics of a levitating magnet with an electromagnetic damper. The theoretical frequency responses of the amplitude were derived for both conditions: the system with a series circuit and a parallel circuit. Numerical calculations were also performed to confirm the effectiveness of the damper.

Evaluation of optimal analysis, design, and testing of electromagnetic shunt damper for vibration control of a civil structure

Evaluation of optimal analysis, design, and testing of electromagnetic shunt damper for vibration control of a civil structure

Analysis and Numerical Evaluation of H∞ and H2 Optimal Design Schemes for an Electromagnetic Shunt Damper

Abstract The electromagnetic coupling effect can generate electromagnetic damping to suppress disturbance, which can be utilized for vibration serviceability control in civil engineering structures. An electrodynamic actuator is used as a passive electromagnetic damper (EMD). Ideally, the EMD is assumed to be attached between the ground and the structure. The kinetic energy of the vibrating structure can be converted to electrical energy to activate the electromagnetic damping. To induce appropriate damping, the two terminals of the damper need to be closed and cascaded with a resonant shunt circuit as an electromagnetic shunt damper (EMSD). In this study, an resistance–inductance–capacitance (RLC) oscillating circuit is chosen. For determination of optimal circuit components and comparing against the tuned mass damper (TMD), existing H∞ design formulae are applied. This work extends this with a detailed development of an H2 robust optimization technique. The dynamic properties of a footbridge structure are then selected and used to verify the EMSD optimal design numerically. The vibration suppression performance is analytically equivalent to the dynamic characteristic of the TMD and has feasible installation and better damping enhancement. To further evaluate the potential application of the EMSD, multi-vibration mode manipulation via connecting multiple RLC resonant shunt circuits is adopted. The multiple RLC shunt circuit connecting to EMD is an alternative to the single mode control of a traditional TMD. Therefore, the EMSD can, in principle, effectively achieve suppression of single and multiple vibration modes.

A novel ring-shaped vibration damper based on piezoelectric shunt damping: Theoretical analysis and experiments

In this paper, a novel ring-shaped piezoelectric damper is proposed; meanwhile, vibration control on a single-DOF system is performed by using it. This damper, called vibration ring, may be used for vibration control of rotating machinery. It has the appearance of a metal ring and can be installed between supporting structure and bearing house. Damping is achieved using piezoelectric stack connected with series resonant RL shunts as fundamental element. Surrounding the stack is a metal structure, which squeezes the stack along its poled axis when the damper is excited by radial forces. Due to its unique configuration, this damper is stiffer than traditional damping devices and can protect stacks very well. In order to analyze and demonstrate the performance of such damper, the electromechanical coupling equation of this damper is firstly derived. Next, the force transmissibility between simplified rotor/shaft and supporting structure is obtained from the foregoing equation in Laplace form. Then the optimum inductance value of shunt circuit is determined. Finally, the performance of vibration ring is demonstrated through simulations and experiment based on a test rig. The experimental results show that the force transmissibility is reduced about 57.75% at resonant frequency.

A bistable vibration isolator with nonlinear electromagnetic shunt damping

Abstract This paper presents a bistable vibration isolator (BVI) with several ring permanent magnets (PMs) and utilizes nonlinear electromagnetic shunt damping (N-EMSD) to improve the vibration isolation performance of the BVI. The theoretical model of N-EMSD is established. The harmonic balance method (HBM) is employed to derive the transmissibility of the BVI with N-EMSD. The analytical, numerical and experimental efforts are performed to investigate the vibration isolation performance of the BVI with N-EMSD. The results demonstrate that when the BVI is in the interwell oscillation, two peaks appear in the transmissibility curve and the transmissibility could be smaller than 1 between the two peaks. With the increase of the negative resistance, the motion of the BVI changes from the aperiodic/chaotic interwell oscillation to intrawell oscillation, resulting in the increase of the isolation band and the improved vibration isolation performance. The effects of the nonlinear electromagnetic coupling coefficient and the negative resistance are also investigated. The BVI with N-EMSD provides a feasible approach to study the vibration isolation characteristic of bistable structures.

Voltage-Controlled Synthetic Inductors for Resonant Piezoelectric Shunt Damping: A Comparative Analysis

In this paper, the design, simulations, and experimental results related to new analog circuits for voltage controlled synthetic inductors (VCSI) are presented. The new circuits based on a generalized impedance converter (GIC) are proposed for adaptive resonant piezoelectric shunt damping. The VCSIs are implemented using (1) an analog multiplier and (2) an operational transconductance amplifier (OTA) as voltage-controlled resistor. The simulation and experimental results for the new proposed VCSIs are presented and a comparative analysis follows. The proposed VCSIs work in a stable manner in parallel with negative impedance converters (NIC) to enhance structural damping in resonant piezoelectric resistive-inductive shunt applications. The behavior of the synthetic inductor is identical to a real inductor only in a specific frequency range and this situation can explain the reported spreading performance in the literature for resonant piezoelectric shunt damping. The simulation results are validated by a group of experimental investigations that confirm the improved stability and linearity of the new circuits proposed as VCSIs. Experimental results show that the VCSI based on an analog multiplier have an enhanced linearity in comparison with the OTA version in a limited voltage control range.

Improvement on sound transmission loss through a double-plate structure by using electromagnetic shunt damper

It is well-known that the acoustic sound performance of double-plate structures deteriorates rapidly around the mass-air-mass resonance frequency. In this study, a electromagnetic shunt damper (EMSD) connected between incident and radiating plate is used to improve the sound transmission loss at low frequency ranges. The EMSD consists of a coil, a permanent magnet, and a specially designed shunt circuit. First, a full structural-acoustic coupling modal model is developed to analyze the vibration and acoustical behaviour of the double-plate structures with EMSD system. Then two EMSD shunt circuit configurations, namely negative resistance (NR) and negative resistance series with capacitance (NR-C), are proposed to control the sound transmission. The control performance of the EMSD is investigated based on different parameters of the shunt circuits. Finally, the experiment was performed to verify the proposed theoretical model of EMSD. The numerical and experimental results show that, the sound transmission loss around the mass-air-mass resonance frequency can be improved significantly by using the EMSD with NR or NR-C shunt circuit. However, EMSD cannot control the first in-phase mode of the double-plate structure.

Damping of piezoelectric space instruments: application to an active optics deformable mirror

This paper presents the shunt damping of a unimorph piezoelectric mirror intended to be used as an active secondary corrector in future space telescopes. We propose to take advantage of the actuation capability of the piezoelectric mirror, to increase its natural damping during the critical launch phase of the spacecraft. The piezoelectric actuators, intended to be used for active optics, are shunted on a passive resistive and inductive RL circuit during the launch operation. The proposed concept is verified numerically and experimentally on a piezoelectric deformable mirror prototype, developed on behalf of the European Space Agency. We show that the shunt damping significantly reduces the response of the most critical mode of the mirror (− 23 dB) as well as the stress in the mirror when subjected to a typical vibro-acoustic launch load. This reduces the risk of damaging the mirror during the delicate launch phase, without increasing the complexity of the design.

Edgewise vibration reduction of small size wind turbine blades using shunt damping

Edgewise vibration in wind turbine blades is one of the important factors that results in reducing the performance of wind turbines. Therefore, control or reduction of the mentioned vibrations can be of great help in increasing the efficiency of wind turbines. In this paper, the shunt damping method is proposed to reduce the edgewise blade vibration of horizontal axis wind turbines. For this purpose, partial differential equations governing dynamics of the system are derived using the Lagrange method. These equations are completely nonlinear and linearization is not performed to avoid possible errors in the analysis. In order to evaluate the effectiveness of the proposed shunt damping method in vibration reduction of the wind turbine blade, obtained results by applying shunt damping method are compared with corresponding results obtained by employing a conventional method known as a tuned mass damper (TMD). For better comparison, by considering proper cost functions, the shunt damper and TMD parameters are optimized using a genetic algorithm. Finally, the effectiveness of optimized shunt damper in vibration reduction of the blade is compared with optimized TMD by presenting simulation results.