Resonance Damping Research Articles

Passive damping of several resonances using multi-branch resonant piezoelectric shunts

Vibration damping using resonant piezoelectric shunts is a method to reduce the amplitude of mechanical resonances by coupling an electrical circuit to a structure through a piezoelectric transducer. The shunt consists of an inductor which creates a resonator tuned to the frequency of the mode to be controlled. In order to damp several resonances simultaneously, multi-branch shunts can be used. Multiple electrical lines are then connected to a single piezoelectric patch. In this work, focused on purely passive control, a circuit involving resistors in series with the inductors is considered. Indeed, each wire wound inductor is usually associated with a non-negligible series resistance due to copper losses. Several multi-branch shunt architectures have been proposed in the literature. From a selection based on their feasibility in passive control, two solutions are retained: the Hollkamp shunt and the current blocking shunt. After numerical implementation, the two architectures are compared, notably by evaluating the effect of the inductance variations with respect to their nominal values and highlighting the influence of additional resistors.

Thermoelastic damping in asymmetric vibrations of nonlocal circular plate resonators with Moore-Gibson-Thompson heat conduction

Precise estimation of the amount of thermoelastic damping (TED) in small-sized resonators is one of the crucial issues in their optimal design. According to several experimental, numerical and theoretical findings, the behavior of structures with such small dimensions in structural and thermal domains does not follow classical elasticity theory and the Fourier law of heat conduction. The objective of this work is to develop a nonclassical formulation for computing TED in asymmetric vibrations of circular nanoplates according to nonlocal theory (NT) and Moore-Gibson-Thompson (MGT) heat transfer model. To do so, first, the coupled equations of motion and heat are derived in the purview of NT and MGT model. Then, the real and imaginary parts of the system frequency are extracted from the frequency equation affected by thermoelastic coupling. Finally, by means of the existing definition for TED, a mathematical expression including nonlocal parameter of NT and nonclassical constants of MGT model is obtained to make an estimate of TED value. In the numerical examples section, to ensure the credibility of the provided formulation, the results obtained through this model are compared with those reported in the literature in the context of simpler models. Then, by presenting various graphical data, the type and extent of the role of different factors in TED changes are appraised. The obtained results indicate that employing NT and MGT model can substantially impact the amount of TED compared to the estimations of the classical formulation. Furthermore, the comparison of results reveals that the magnitude of TED in asymmetric vibration modes surpasses that in symmetric ones, and consequently incorporating asymmetric vibration modes is crucial for thorough analysis of TED in circular nanoplates. Thus, the formulation presented in this article can aid in achieving an optimal design for such plates, particularly in terms of minimizing energy loss.

Propagating kink waves in an open coronal magnetic flux tube with gravitational stratification: Magnetohydrodynamic simulation and forward modelling

Context. In coronal open-field regions, such as coronal holes, there are many transverse waves propagating along magnetic flux tubes, which are generally interpreted as kink waves. Previous studies have highlighted their potential role in coronal heating, solar wind acceleration, and seismological diagnostics of various physical parameters. Aims. This study aims to investigate propagating kink waves, considering both vertical and horizontal density inhomogeneity, using 3D magnetohydrodynamic (MHD) simulations. Methods. We established a 3D MHD model of a gravitationally stratified open flux tube, incorporating a velocity driver at the lower boundary to excite propagating kink waves. Forward modelling was conducted to synthesise observational signatures of the Fe IX 17.1 nm line. Results. Resonant absorption and density stratification both affect the wave amplitude. When diagnosing the relative density profile with velocity amplitude, resonant damping needs to be properly considered to avoid a possible underestimation. In addition, unlike standing modes, propagating waves are believed to be Kelvin-Helmholtz stable. In the presence of vertical stratification, however, the phase mixing of transverse motions around the tube boundary can still induce small-scale structures, partially dissipating wave energy and leading to a temperature increase, especially at higher altitudes. Moreover, we conducted forward modeling to synthesise observational signatures, which revealed the promising potential of future coronal imaging spectrometers such as MUSE in resolving these wave-induced signatures. Also, the synthesised intensity signals exhibit apparent periodic variations, offering a potential method for indirectly observing propagating kink waves with current extreme ultraviolet imagers.

Study on the global and nano-scale characterization of heat-induced changes in ordinary Portland cement paste

Cement-based composite materials can be damaged by distributed micro-cracking and degradation of hydration products when exposed to sustained high temperatures. In this study, a nano-scale characterization tool (dynamic nanoindentation) and global mechanical methods (vibration resonance frequency and damping) are employed to better understand the degradation of ordinary Portland cement paste subjected to high temperature exposures. A connection between the methods is demonstrated.

Interband and Intraband Hot Carrier-Driven Photocatalysis on Plasmonic Bimetallic Nanoparticles: A Case Study of Au-Cu Alloy Nanoparticles.

Photoexcited nonthermal electrons and holes in metallic nanoparticles, known as hot carriers, can be judiciously harnessed to drive interesting photocatalytic molecule-transforming processes on nanoparticle surfaces. Interband hot carriers are generated upon direct photoexcitation of electronic transitions between different electronic bands, whereas intraband hot carriers are derived from nonradiative decay of plasmonic electron oscillations. Due to their fundamentally distinct photogeneration mechanisms, these two types of hot carriers differ strikingly from each other in terms of energy distribution profiles, lifetimes, diffusion lengths, and relaxation dynamics, thereby exhibiting remarkably different photocatalytic behaviors. The spectral overlap between plasmon resonances and interband transitions has been identified as a key factor that modulates the interband damping of plasmon resonances, which regulates the relative populations, energy distributions, and photocatalytic efficacies of intraband and interband hot carriers in light-illuminated metallic nanoparticles. As exemplified by the Au-Cu alloy nanoparticles investigated in this work, both the resonant frequencies of plasmons and the energy threshold for the d-to-sp interband transitions can be systematically tuned in bimetallic alloy nanoparticles by varying the compositional stoichiometries and particle sizes. Choosing photocatalytic degradation of Rhodamine B as a model reaction, we elaborate on how the variation of the particle sizes and compositional stoichiometries profoundly influences the photocatalytic efficacies of interband and intraband hot carriers in Au-Cu alloy nanoparticles under different photoexcitation conditions.

Active Resonant Damper With Control Strategy Based on Inverter Output Conductance Optimization Under Weak Grid Conditions

Active Resonant Damper With Control Strategy Based on Inverter Output Conductance Optimization Under Weak Grid Conditions

Design and Performance Evaluation of a Hybrid Active Power Filter Controller

This paper introduces a novel hybrid filter topology that combines passive and active components to enhance harmonic filtering and resonance damping in electrical power systems. The design integrates a three-phase two-level voltage-source converter with a double-tuned passive filter in parallel, significantly reducing the power rating and operational costs while maintaining good harmonic filtering performance and reactive current compensation. Double-tuned passive filters, compared to single-tuned ones, offer improved harmonic attenuation at multiple frequencies, enhancing overall system efficiency. Moreover, when used with the proposed hybrid filter topology, the double-tuned version allows for even lower dimensions of the active part, thereby further reducing system cost. A state-feedback controller is designed to enhance the performance of the hybrid filter, proving particularly effective in environments with complex impedance conditions. This paper also examines the impact of variations in passive component parameters, demonstrating the design’s robustness against potential deviations expected over the operational lifespan. The results indicate that the hybrid filter effectively mitigates harmonics and maintains operational stability under various transient conditions, as confirmed by analytical and simulation studies on a real industrial network model. These findings underline the hybrid filter’s potential to significantly improve power quality in modern electrical networks.

Thermoelastic damping of micromechanical resonators based on Quintanilla theory

Thermoelastic damping of micromechanical resonators based on Quintanilla theory

Low/Middle-Frequency Positive External- Damping Design Under Self-Stability Constraint for Inner Control Loop of Grid-Forming Converters

The inner voltage control loop and inductor current active damping loop of grid-forming (GFM) converters perform the output voltage control and filter resonance damping, and their stability design has been widely developed in the literature. However, the equivalent external-damping characteristics have not been fully explored. In this paper, the analysis shows that inappropriate design focusing only on self-stability would lead to negative external-damping in a wide low/middle-frequency band when LC resonant frequency is greater than one-sixth sampling frequency and less than one-third sampling frequency, which may cause system instability when interacting with loads or grids. Therefore, a low/middle-frequency positive external-damping design method under self-stability constraint is proposed for inner control loop of GFM converters. Detailed design process is presented with simple implementation. The key feature is the use of negative proportional gain of voltage controller. Through the proposed design method, the GFM converters can improve system damping capability, which is beneficial to promoting large-scale integration of distributed generation systems based on power electronics. Simulation and experimental results are finally provided to verify the feasibility and effectiveness of the design method.

Damping analysis of a transversely isotropic piezothermoelastic nanobeam resonator based on the MGT thermoelasticity

The present work investigates the vibration of a piezothermoelastic nanobeam in the frame of Moore–Gibson–Thompson (MGT) thermoelasticity theory. Closed form analytical expressions for the thermoelastic damping in terms of quality factor and frequency shift for a homogeneous transversely isotropic piezothermoelastic (PTE) beam is derived by using Euler–Bernoulli beam theory and complex frequency approach. Detailed analysis of damping of vibration owing to thermal fluctuations and electric potential in the present context under three sets of boundary conditions is attempted to investigate the influence of modes of vibration, electric potential, and beam length on energy dissipation caused by thermoelastic damping in PTE beam resonators. Analytical results are illustrated with the help of graphical plots on numerical findings in the case of the nanobeam resonator of Lead Zirconate Titanate (PZT-5A) material. The investigation brings out some significant key findings and observations in view of MGT heat conduction model.

Experimental-numerical analyses on energy harvesting characteristics of non-conventional T-shaped beams with varied piezoelectric patch location and anchor position

Recently, researchers have studied innovative beam structures in a quest to maximize the energy conversion capability of piezoelectric (PZT) transducers coupled with the shims. A T-shaped beam is one of the structural elements used for harvester design owing to its exceptional geometrical advantage. While a number of research papers have reported its performance characteristics, its potential for harnessing the vibration energy at much lower resonance frequency and damping has not been explored. This paper presents non-conventional T-shaped beam harvesters, namely, the Uniform Tapered T-shaped Beam (UTB) and the Reversed Tapered T-shaped Beam (RTB), with the purpose of enhancing the T-shaped beam functionality. A performance analysis between the UTB, RTB and a conventional T-shaped beam (CTB) harvester of equal mass was conducted, where experimental results show that the RTB harvester has a lower fundamental resonance frequency of 12.3% and 28.3% when compared to the CTB and UTB, respectively. Also, a maximum terminal voltage of 82.8 V and an output peak power of 4.6 mW were produced by the RTB harvester when the PZT patch was placed near its clamped end. In addition, we investigated the effect of the anchor position of the beams on their energy harvesting performance using a finite element analysis (FEA) tool. The numerical results show that the position of the anchor has a considerable effect on the overall characteristics of the configurations.

Relative Intensity Noise in a Two‐Section Distributed Bragg Reflector Tapered Laser

The relative intensity noise (RIN) in a two‐section distributed Bragg reflector (DBR) tapered laser emitting around 1060 nm is being studied experimentally. By analyzing the RIN spectra, a resonance frequency and damping is obtained. Herein, the dependence of the resonance frequency and the maximum RIN at the resonance frequency is studied as functions of the ridge waveguide (RW) and tapered section currents independently. The low frequency RIN is approximately −162 dB Hz−1, and the RIN peak at currents providing high output power is as low as −154 dB Hz−1. The observed nonlinearity of the squared resonance frequency with the RW section current is attributed to carrier saturation. The measured high values of the resonance frequency, exceeding 2.5 GHz for RW currents higher than 100 mA at a tapered current of 3 A, indicate gain lever enhancement.

Tunable Ultralow-Frequency Bandgaps Based on Locally Resonant Plate with Quasi-Zero-Stiffness Resonators

In order to suppress the transverse vibration of a plate, a quasi-zero-stiffness (QZS) resonator with tunable ultralow frequency bandgaps was introduced and analyzed. The resonator was designed by introducing the quasi-zero-stiffness systems into mass-in-mass resonators. The plane wave expansion method was employed to derive the bandgap characteristics of the locally resonant (LR) plate with QZS resonators, and corresponding simulations were carried out by finite element method (FEM). The results show that an LR plate with a QZS resonator can provide two bandgaps, and the ranges of the bandgaps agree well with the vibration attenuation bands calculated by FEM. Owing to the introduction of the QZS system, the bandgaps can be easily transferred to a lower frequency or even an ultralow frequency. The damping of the QZS resonators can effectively broaden the vibration attenuation bands. In addition, the differentiated design of the bandgap frequencies can be realized to obtain broadband low-frequency transverse wave suppression performance. Finally, a mechanical structure design scheme was proposed in order to achieve flexible adjustment of the bandgap frequency, which significantly increases the engineering applicability of QZS resonators.

High resolution acoustic sensing based on microcavity optomechanical oscillator.

In this paper, a simple sensing method based on a silicon oxide microcavity optomechanical oscillator (OMO) is proposed and demonstrated for the detection of acoustic signals. Firstly, the resonance damping was reduced by improving the optical quality factor (Qo) and increasing the sphere-to-neck ratio. After optimizing the process, a microsphere OMO was fabricated, which has an ultra-high mechanical quality factor (6.8 × 106) and greater sphere-to-neck ratio (∼11:1), based on which ultra-narrow linewidth phonon laser (∼1 Hz) is constructed. Secondly, by changing the refractive index of the coupling interval, the low-frequency acoustic pressure signal is efficiently coupled into the microcavity OMO to construct a high-resolution acoustic sensor. This sensing mechanism can not only measure the acoustic pressure, but also use the sideband signal in the modulation mechanism to measure the frequency of acoustic signals (15 Hz∼16 kHz), the sensitivity is 10.3 kHz/Pa, the minimum detectable pressure is 1.1 mPa, and noise-limited minimum detectable pressure is 28.8 µPa/Hz1/2. It is the highest detection resolution compared with the same type of low-frequency acoustic signal detection currently reported. This OMO-based acoustic sensing detection method opens up a new path for future miniaturized, ultra-high-precision, and cost-effective acoustic sensing.

Non-Fourier thermoelastic damping in small-sized ring resonators with circular cross section according to Moore–Gibson–Thompson generalized thermoelasticity theory

Non-Fourier thermoelastic damping in small-sized ring resonators with circular cross section according to Moore–Gibson–Thompson generalized thermoelasticity theory

On the frequency and damping of resonances in electrical networks: a discrete state-space approach using bounce Diagrams

The paper presents a novel method to compute resonances in a power system network using a discrete state-space approach based on bounce diagrams. The approach models the distributed parameter line as a lattice diagram, considering the refection/transmission of traveling waves. This model is then represented as a discrete-time linear time-invariant system, enabling the computation of resonances in the network. Two applications are demonstrated: fault location and load placement to improve damping in black start scenario. The method is particularly useful to understand and control resonances in electric grids. Theoretical analysis and numerical examples illustrate the behavior of resonances as resistive loads are connected along the transmission line, providing insights for fault location and load allocation strategies.

A Novel Proportional Multi-Resonant Current Controller Strategy for Reduced DC Voltage fed D-STATCOM with Internal LCL Resonance Damping

Abstract This work focuses on a new topology-control-based D-STATCOM solution with reduced DC bus voltage requirement and with an excellent grid side performance. The proposed solution consists of a main inverter and auxiliary inverter along with a transformer and LCL filter network to achieve the required DC bus reduction. A new controller structure with two proportional-multi resonant controller for the converters with only one of the inductors current as a controlled variable ensures the active damping of the LCL resonance. The power circuit configuration assists the controller to generate a difference in the modulation signal due to non-equal gains in two controllers and helps to achieve the resonance damping without capacitor current sensor. Hence, the corresponding capacitor current sensor can be eliminated. The converter operates for any point of common coupling (PCC) loading conditions and the performance of the controller is immune to the grid impedance variation. A detailed stability study is carried out for the proposed controller. The proposed controller can achieve a very fast dynamic response with an excellent stability margin. The proposed solution is verified through simulation studies and through a scaled-down experimental prototype.

Double-order coupling bandgap design of metamaterial beams and broadband vibration reduction properties

<sec>Local-resonance bandgap and Bragg bandgap can coexist in a metamaterial beam, and their coupling effect can be used to realize ultra-wide bandgap, which has great potential applications in the field of wide-band vibration reduction. Previous studies usually considered the single-order coupling between the local-resonance bandgap and Bragg bandgap in metamaterial beams with a single array of local resonators, which can only achieve the single-order ultra-wide coupling bandgap and cannot meet the wide-band vibration reduction requirements of double/multiple target frequency bands. In this paper, metamaterial beams with double arrays of local resonators are considered, and the regulation design and analysis of double-order coupling of local-resonance and Bragg bandgaps are carried out based on an analytical model of bending wave dispersion relation. Moreover, the vibration reduction characteristics of the double-frequency-resonator metamaterial beams with double-order coupling bandgaps are studied by using spectral element method and the finite element method. The main conclusions are as follows.</sec><sec>1) A design method is proposed for realizing double-order coupling wide bandgap in a metamaterial beam with double arrays of local resonators. By using this method, the resonance frequencies of the local resonators can be quickly designed on conditions that host beam parameters, lattice constant and added mass ratio of the local resonators are given.</sec><sec>2) The double-order coupling bandgaps in a metamaterial beam carrying double arrays of local resonators are compared with the single-order coupling bandgaps in metamaterial beams with a single array of local resonators. It is found that through proper design, the total normalized width of the double-order coupling bandgap can be much broader than that of the single-order coupling bandgap, so the double-order coupling bandgap is more beneficial to wide-band vibration reduction.</sec><sec>3) It is found that for a given total added mass ratio of the double arrays of local resonators, it is necessary to optimize the mass distribution ratio of the double resonators to maximize the total normalized width of double-order coupling bandgap. An approximate formula for designing the optimal mass distribution ratio of the double resonators is further established.</sec><sec>4) The spectral element method is used to study the vibration reduction characteristics of the metamaterial beams carrying double arrays of local resonators designed based on double-order bandgap coupling. The accuracy of the spectral element method is verified by comparing with the finite element method. The results show that significant vibration reduction can be achieved in two wide frequency bands corresponding to the double-order coupling bandgaps. The influences of number of unit cells and resonator damping on the vibration reduction characteristics of the metamaterial beam are further analyzed. It is shown that the increase of number of unit cells can enhance the vibration reduction performance in the bandgap, and the increase of resonator damping can effectively broaden the vibration reduction frequency band.</sec>

AC Current Sensor Based on Magnetoelectric Composites Transducers: Resonance Damping, Current Dynamic and Electric Field Disturbances

AC Current Sensor Based on Magnetoelectric Composites Transducers: Resonance Damping, Current Dynamic and Electric Field Disturbances

Improving Active Resonance Damping and Unbalanced Voltage Mitigation Based on Combined DDSRF and Washout Filter in Islanded Microgrids

Improving Active Resonance Damping and Unbalanced Voltage Mitigation Based on Combined DDSRF and Washout Filter in Islanded Microgrids