Shunt Damping Research Articles

Enhanced lever-type vibration isolator via electromagnetic shunt damping

Considering the damping limitation of traditional lever-type vibration isolators (LVIs) in the low-frequency range, electromagnetic shunt damping (EMSD) utilising a lever to amplify the damping force is introduced in this study to improve the vibration isolation performance of LVIs. Negative resistance (NR) and NR resonant shunts were used to compensate for inherent resistance to improve the effect of LVI with EMSD (LVI-EMSD). A theoretical model of LVI-EMSD was established, and displacement transmissibility was derived. The optimal parameters of the NR resonant shunt were derived according to the fixed-point theorem. The effects of the lever ratio, negative resistance, and resonant frequency of the circuit on the vibration isolation performance of the LVI-EMSD were numerically and experimentally analysed. The lever structure can simultaneously tune the natural frequency and damping to improve the vibration isolation performance of the LVI-EMSD. Both the NR and NR resonant shunts effectively produce a considerable damping effect, and the NR resonant shunt outperforms the NR shunt in the low-frequency region. The NR shunt could produce a mass effect when the negative resistance was carefully designed. This study provides guidelines for the design, modelling, and optimisation of LVI-EMSD.

LCR並列型電磁シャントダンパを有する超電導磁気浮上系の非古典的モード解析

LCR並列型電磁シャントダンパを有する超電導磁気浮上系の非古典的モード解析

A Low-Power Direct Adaptive SSDV Piezoelectric Vibration Control Circuit

Piezoelectric shunt damping is promising in vibration suppression of thin structures. A Low-power direct adaptive synchronized switch damping on voltage (LDA-SSDV) circuit is designed to solve the stability problem of the SSDV without additional vibration strength monitoring devices. Based on the linear relationship between the maximum piezovoltage and the values of series voltage sources, we use simple envelope detectors and resistive voltage dividers to control the voltage sources. And the voltage sources are activated during the switching events for saving energy. The experimental results show that the LDA-SSDV circuit has a stable operation and similar vibration suppression level compared to SSDV.

Influence of Electromagnetic Shunt Damper on Nonlinear Vibration of HTS Maglev System

The levitation force in the high temperature superconducting (HTS) maglev system has obvious nonlinear characteristics. When the excitation frequency and amplitude meet certain conditions, nonlinear vibration phenomena such as period-doubling bifurcation would appear. Nonlinear vibration will bring difficulties to dynamic analysis and even affect the safety and comfort of driving. While an electromagnetic shunt damper (EMSD) can effectively reduce the vibration amplitude. This paper analyzes the influence of EMSD on the nonlinear vibration of HTS maglev systems from the perspective of experiments and simulations. Firstly, free vibration and forced vibrations in the resonance interval are tested. Secondly, based on numerical simulations, the vibration response under various excitation was analyzed. The results show that the EMSD can effectively suppress its nonlinear vibration. This research has reference value for the detailed understanding of the dynamic characteristics of the HTS maglev and further vehicle design.

Low-frequency broadband absorption of semi-active composite anechoic coating with subwavelength piezoelectric arrays in hydrostatic environments

Considering the influence of hydrostatic pressure on geometric parameters of a lining, this paper first proposes a complete global four-terminal acoustic theoretical prediction method based on phenomenological theory for a semi-active composite coating with subwavelength piezoelectric arrays in deep-sea environment, aiming at exploring the energy dissipation mechanisms and broadening the low-frequency sound-absorbing bandwidth. The Neo-Hookean material model is incorporated into the phenomenological theory to analyze the finite deformation of rubber layers under hydrostatic load. Then, the global acoustic model is established by combining the effective medium method, shunt damping technique, and wave propagation theory in layered media. Moreover, the degraded validations are developed by FE simulation and hydroacoustic impedance tube experiment, and the influences of submergence depth and shunt circuit on the absorption characteristics are explored theoretically. It is expected to break the lower limit frequency of low-frequency sound-absorbing from 500 Hz to 200 Hz, and to expand the upper limit frequency thanks to the multi-modal resonant energy consumption mechanism of distributed circuits.

On the Performance of Wavy Dry Friction and Piezoelectric Hybrid Flexible Dampers

Abstract This paper proposes a flexible dry friction plate to mitigate the vibration of thin-walled structures for one resonance crossing. Based on a cantilever beam–friction damper finite element model, the geometry and material parameters of the friction plate are optimized numerically through steady-state response analyses by the widely used multiharmonic balance method (MHBM). In order to further improve the damping effect, piezoelectric material is distributed to the flexible damper, and two types of dry friction and piezoelectric hybrid dampers are explored, namely, semi-active and passive, respectively. For semi-active hybrid dampers, piezoelectric material is used as an actuator to adjust the normal load applied to the friction interface in real-time, so that the friction damping is improved. For passive ones, piezoelectric material is used as a transducer, which dissipates the strain energy stored in the wavy plate by the shunting circuit, additional shunted piezoelectric damping contributes to the total output damping accordingly. Better damping effect compared with the friction baseline is realized for the two types ideally. This damping module has a simple structure and avoids the problem of installation and maintenance of piezoelectric material which is generally bonded to the host structure. Technical challenges are the semi-active type requires excessive voltage applied to the piezoelectric actuator, while the passive one needs to connect a programable synthetic circuit.

Grey based multi-objective optimization of machining performance in boring of aluminium alloy 6061 through piezoelectric shunt damping

Chatter instability contributes to the poor texture of the surface, abridged tool life, and productivity. In orthogonal cutting, chatter decreases with an increase in damping which consequently increases stability limits. This work addresses the chatter reduction by employing piezoelectric transducers on the overhang length of a boring bar with a shunt circuit. The stability of the boring process is significantly affected by the function of frequency retort on the cutting edge. Cutting tests are performed by selecting vibration amplitude, average surface roughness as response parameters and machining characteristics are evaluated by piezoelectric shunt dynamic response. It is experimentally concluded that, compared to the no damping condition, mean vibrational amplitude and surface roughness decreases considerably using piezoelectric damping. Grey relational methodology has been utilized for multi-attribute decision-making for depicting the optimal internal turning parameters.

Theoretical analysis of a parametrically excited rotor system with electromechanically coupled boundary condition

In this paper, the dynamic behavior of a rotor system with electromechanically coupled boundary condition under periodic axial load is studied, where the boundary condition is derived from a ring-shaped piezoelectric damper which is developed for vibration control of rotor system. This damper is based on the piezoelectric shunt damping technique, which can produce much or little damping performance depends on the selection of shunt circuit parameters. By using assumed mode method and Lagrange equation, the equations of motion are derived. Actually these equations can also be derived from a general forced parametrically excited gyroscopic system. Thus, to analyze such system, a method of multiple scales is developed firstly, where a general procedure is proposed to establish solvability conditions. Subsequently, this procedure is applied to obtain the analytical instability boundaries and forced vibration responses. The analytical results show that the additional combination instability regions are created due to the introduction of shunt circuit. When the parametrically excited eccentric rotor is rotating, the parametric vibrations are superimposed on the unbalanced responses. As the resistance value of shunt circuit is increasing, both parametric vibrations and unbalance vibrations can be significantly suppressed. For the unbalanced responses, both the resonance and anti-resonance phenomena can be observed; whereas for the parametric vibrations, only the resonance phenomena exist. These phenomena indicate that we may achieve great vibration control performance for the rotor parametric vibrations by introducing the piezoelectric shunt damping, as long as the circuit parameters are well adjusted. To validate the obtained analytical expressions, the numerical methods are applied. Specifically, the discrete state transition matrix method (DSTM) is applied to validate the analytical instability boundaries and the Runge-Kutta method is conducted to verify the analytical frequency response functions.

Analysis of the Vibration Suppression of Double-Beam System via Nonlinear Switching Piezoelectric Network

In this paper, a method to suppress the vibration of a double-beam system with nonlinear synchronized switch damping on the inductor via a network (SSDI-net) is proposed. Unlike the classical linear piezoelectric shunt damping, SSDI-net is a nonlinear piezoelectric damping. A double-beam system with SSDI-net was simplified to a lumped parameter electromechanical coupling model and analyzed by using the multi-harmonic balance method, at first with alternating frequency–time techniques (MHBM/AFT). Then, a new lower-power autonomous switching control circuit board was designed, based on SSD technique, and vibration control experiments using a double-beam system with an SSDI network are conducted, to verify the validity of the proposed analysis method and its calculation results. The nonlinear switching piezoelectric network proposed in this article can increase the voltage inversion factor. Furthermore, future applications of this switching piezoelectric network technology in the vibration suppression of bladed-disk structures in aero engines can reduce the number of switches by at least half and obtain almost the same damping effect.

Strongly coupled partitioned iterative method for the structure–piezoelectric–circuit interaction using hierarchical decomposition

The key to the design of advanced micro electro–mechanical devices is an accurate evaluation of the circuit-integrated piezoelectric oscillator that accounts for its complicated configuration. Here, the direct numerical modeling of this oscillator leads to a general formulation as a structure–piezoelectric–circuit interaction. Hence, this study developed a strongly coupled partitioned iterative method for the structure–piezoelectric–circuit interaction. The proposed method was constructed using hierarchical decomposition, the partitioned iterative method for two coupled fields, and loop union. That is, the whole system of the coupled multiphysics is hierarchically decomposed into coupled two-field subsystems, partitioned iterative algorithms for two coupled fields are applied to these subsystems, and the coupling algorithms for these subsystems are reduced to a single coupling algorithm. In the proposed method, three distinct direct piezoelectric, inverse piezoelectric, and circuit solvers are strongly coupled with each other. The inverse piezoelectric solver uses shell finite elements to analyze the response of the thin oscillator efficiently, while the direct piezoelectric solver uses solid finite elements to accurately describe the three-dimensional distribution of the electric potential in the piezoelectric continuum. The proposed method can accurately analyze coupling phenomena in the RC circuit, piezoelectric shunt damping, and piezoelectric energy harvesting.

Advanced vibration isolation technique using versatile electromagnetic shunt damper with tunable behavior

Electromagnetic shunt damper (EMSD) is an emerging damper type capable of mimicking conventional mechanical dampers using their electrical circuit counterparts. Damping, stiffness, and inertance within mechanical domain can be emulated by resistance, inductance, and capacitance from electrical domain, respectively. In particular, four representative conventional damper types, namely, viscous fluid damper (VFD), viscoelastic damper (VED), inerter damper (ID), and tuned inerter damper (TID), are emulated by an EMSD in this paper, thereby forming EMSD-VFD, EMSD-VED, EMSD-ID and EMSD-TID, respectively. Their control performances when installed in a vibration isolation system are subsequently studied both analytically and experimentally. The behavior of EMSD can be easily tuned by changing the external circuits connected to the electromagnetic damper. Moreover, these four types of EMSDs possess complementary isolation performances across the frequency spectrum, which implies that different optimal circuits should be selected in different frequency bands to achieve the best isolation performance. A broadband vibration isolation technique by automatically switching among sub-circuits integrated in a single circuit board will be a promising future research direction.

Vibroacoustical Performance Analysis of a Rigid Device Casing with Piezoelectric Shunt Damping.

Noise and vibration are common issues that may have a negative impact on human’s’ health. To minimize their consequences, several vibroacoustical methods may be employed. One well-known method is Piezoelectric Shunt Damping (PSD). Over the years, many approaches have been investigated, from passive, state switching circuits to active pulse-switching. In this paper, the authors propose three PSD implementations—passive Synchronized Switch Damping on Inductor (SSDI), semi-active SSDI and active Synchronized Switch Damping on Voltage source (SSDV)—for a single-panel structure mounted on a rigid-frame casing. The nine Macro Fiber Composite (MFC) elements were mounted on the plate based on preliminary simulations in FreeFEM. Then, the theoretical results were validated by an identification experiment. The main research is concentrated on the Sound Pressure Level (SPL) and structural vibrations reduction for selected frequencies. The active method provided the highest reduction of vibration—up to 5.5 dB for maximal possible loudspeaker level without overdrive and up to 7.5 dB for lower excitation levels.

Investigation of broadband sound absorption of smart micro-perforated panel (MPP) absorber

A smart micro-perforated panel (MPP) is investigated in order to enhance sound absorption performance of MPP absorbers, especially at low frequencies. The smart MPP consists of a conventional MPP and a surface-bonded piezoelectric ceramic (PZT) shunted with single- or multiple-resonance circuit. A three-dimensional (3D) finite element model is used to investigate the coupling effects between MPP and the shunted PZT. The numerical results demonstrate three energy-dissipation mechanisms: mechanical damping, electrical shunt damping, and Helmholtz resonance of the MPP. The effects of different multimode shunt design methods are explored so as to intensify the panel vibration and hence improve sound absorption. A low-frequency broadband sound absorber can then be constructed based on the strong coupling among the acoustical, electrical, and mechanical domains. Several absorption peaks induced by electromechanical coupling are found in the frequencies lower than the Helmholtz resonance frequency of MPP. The electrical and mechanical responses of the proposed absorber are investigated in detail. In the experiment, the transfer function of the shunt circuit of the proposed absorber is tested with a network analyser, and the sound absorption coefficients are measured in the impedance tube based on the two-microphone transfer function method. Fair agreement between experimental and numerical results is obtained.

Optimal piezoelectric shunt dampers for non-deterministic substructure vibration control: estimation and parametric investigation

Piezoelectric (PZT) shunt damping is an effective method to dissipate energy from a vibrating structure; however, most of the applications focus on targeting specific modes for structures vibrating at low-frequency range, i.e. deterministic substructure (DS). To optimally attenuate structures vibrating at high-frequency range, i.e. non-deterministic substructure (Non-DS) using a PZT shunt damper, it is found that the impedance of the PZT patch’s terminal needs to be the complex conjugate of its inherent capacitance paralleled with the impedance ‘faced’ by its non-deterministic host structure underline moment actuation. The latter was derived in terms of estimation of the effective line moment mobility of a PZT patch on a Non-DS plate by integrating the expression of driving point moment mobility of an infinite thin plate. This paper conducts a parametric investigation to study the effect of changing the size, quantity and configuration of the PZT patch to the performance of the optimal PZT shunt dampers in dissipating the energy of its non-deterministic host structure. Results are shown in terms of energy reduction ratio of the thin plate when attached with optimal PZT shunt damper(s).

An Inerter-Based Dynamic Vibration Absorber With Concurrently Enhanced Energy Harvesting and Motion Control Performances Under Broadband Stochastic Excitation Via Inertance Amplification

Abstract This paper examines the performance of a regenerative dynamic vibration absorber, dubbed energy harvesting-enabled tuned mass-damper-inerter (EH-TMDI), for simultaneous vibration suppression and energy harvesting in white-noise-excited damped linear primary structures. Both single-degree-of-freedom (SDOF) structures under force and base excitations and multi-degrees-of-freedom (MDOF) structures under correlated random forces are studied. The EH-TMDI includes an electromagnetic motor (EM), assumed to behave as a shunt damper, sandwiched between a secondary mass and an inerter element connected in series. The latter element resists relative acceleration at its ends through a constant termed inertance known to be readily scalable in actual inerter device implementations. In this regard, attention is herein focused on gauging the available energy for harvesting at the EM and the displacement variance of the primary structure as the inertance increases through comprehensive parametric investigations. This is supported by adopting simplified inertance-dependent tuning formulae for the EH-TMDI stiffness and damping properties and deriving in closed-form the response of white-noise-excited EH-TMDI-equipped SDOF and MDOF systems through linear random vibration analyses. It is found that lightweight EH-TMDIs, having 1% the mass of the primary structure, achieve improved vibration suppression and energy harvesting performance as inertance amplifies. For SDOF structures with grounded inerter, the rate of improvement is higher as the inherent structural damping reduces and the EM shunt damping increases. For MDOF structures with nongrounded inerter, improvement rate is higher as the primary structure flexibility between the two EH-TMDI attachment points increases.

Advanced seating comfort: suppression of vibration using multi-mode piezoelectric shunt damping

The transmission of seat structural vibration to the human body contributes to vibration discomfort particularly near the resonant frequencies (> 10 Hz). The conventional methods of controlling vehicle seat vibration may no longer be used on lightweight seat structures efficiently. Here, a new control method derived from multi-mode shunt damping using piezoelectric patches is proposed and is implemented on a vehicle seat to suppress the transmission of seat vibration to the occupant's body by controlling the seat foam vibration. The results indicate that the proposed method is effective for controlling seat vibration at the resonant frequencies of the seat. The application of the piezoelectric shunt damping system holds some promise for the future development of lightweight vehicle seats with enhanced ride comfort.

Application of Electromagnetic Shunt Damper to Subharmonic Resonance of Superconducting Magnetic Levitation System

This study investigates the effectiveness of the electromagnetic shunt damper for reducing the amplitude of nonlinear resonance of a superconducting magnetic levitation system by numerical calculation. An electromagnetic shunt damper, a type of dynamic vibration absorber, can suppress mechanical vibration of the main system by converting a part of its vibration energy into electric energy of a subsystem consisting of an electric circuit. Since the electromagnetic force caused by superconductors has nonlinearity, complicated nonlinear resonance can occur in the superconducting magnetic levitation system in addition to its main resonance. This study especially focuses on 1/2-order subharmonic resonance, which can generate a larger vibration component at half the excitation frequency. Numerical calculations were carried out to examine how two types of electromagnetic shunt dampers consisting of LCR series and parallel circuits can effectively suppress this nonlinear resonance. As a result, it was confirmed that the parallel type electromagnetic shunt damper is more effective in reducing the amplitude of the subharmonic resonance than the series type, even under the condition of a larger excitation amplitude.

Low-frequency spillover phenomenon in NC-piezoelectric shunt damping

Low-frequency spillover phenomenon in NC-piezoelectric shunt damping

Design of wave-like dry friction and piezoelectric hybrid dampers for thin-walled structures

This paper proposes a wave-like hybrid damper containing both dry friction and piezoelectric damping mechanisms for thin-walled structures. The idea is to distribute piezoelectric material on the wave-like friction plate, so that the elastic deformation of the plate can be further utilized to generate additional shunted piezoelectric damping. The proposed damper has the following advantages: simple structure, easy installation and maintenance, convenient to adjust the normal preload, and feasible to mount piezoelectric materials. Combined with damped nonlinear normal modes (dNNMs), the nonlinear modal electromechanical coupling factor (nonlinear MEMCF) is proposed, and its relationship with piezoelectric damping is established for electromechanically coupled systems with contact nonlinearities. Based on the extended periodic motion concept (E-PMC) of dNNMs for non-conservative systems, the preliminary design guidelines of wave-like hybrid dampers are given through nonlinear modal analyses. The modal damping ratio and the nonlinear MEMCF are used to evaluate the damping generated by friction and piezoelectric mechanisms, respectively. The damping effect is also verified by steady-state response analyses through the Multi-Harmonic Balance Method (MHBM). By using a cantilever beam finite element (FE) model, the spatial distribution of piezoelectric material is optimized for a single wave-like hybrid damper. Four optimized hybrid dampers are then implemented to an industrial thin-walled structure. Taking the normal preload as an example, the influence of parameter distribution patterns at different interfaces on the damping effect is also discussed. Compared with the underlying friction damper, the wave-like hybrid damper not only provides greater damping, but is also less sensitive to the variation of excitation amplitude and the normal preload. Whether friction or piezoelectric damping is inactive, the proposed damper can still generate considerable damping.

Tunable electromagnetic shunt damper with opposing magnets configuration

Electromagnetic damper (EMD) has been widely studied in the control of vibrating structures. It has higher tunability when compared with a viscous damper and lower cost when compared with a magnetorheological damper. However, its use is limited mainly due to the high ratios of system mass/volume to the damping force produced. In this paper, an electromagnetic shunt damper (EMSD) with opposing magnets configuration to provide a tunable damping force is proposed for vibration damping applications. The proposed EMSD configuration allows a significant reduction in size in comparison with other similar designs of EMSD found in the literature. Both simulations and experiments are conducted to verify the improvements of this proposed design over existing ones. In particular, an ESMD comprising six opposing magnets is designed and tested on a single-degree-of-freedom (SDOF) vibration system. The damping coefficient of the proposed EMSD offers a large tunable range with maximum damping coefficient about nine times or 900% of the minimum damping coefficient. As a result, the force and displacement transmissibilities can be minimized in a wide frequency band by varying the damping ratio in the SDOF system at different vibrating frequencies.