Vibration Reduction Effect Research Articles

Experimental Research on the Vibration Absorption Performance of Medium Damping Fasteners in Metro Shield Tunnel

Medium damping fasteners have the advantages of low cost, easy maintenance, and convenient in gauge adjustment, etc., which are gradually and widely used in metro construction. In order to study the performance of medium damping fasteners in a driving environment, we performed measurement on site about the vertical and lateral displacement of the rail, as well as the vertical acceleration of the rail and the tunnel wall on a straight and curved metro cross-section with medium damping fasteners. By comparing with the results of ordinary fasteners, it can be seen that: (1) The medium damping fastener has a vibration reduction effect on the vertical acceleration level of the tunnel wall in the frequency range of 6.3∼31.5Hz and 50∼80Hz; moreover, it has a vibration reduction effect on the lateral acceleration of the tunnel wall in the frequency range of 5∼31.5 Hz and 50∼80 Hz. (2) The vertical and lateral displacement of the rail and the gauge change with the medium damping fasteners are larger than those of the ordinary fasteners. (3) The maximum Z vibration level measured from the tunnel wall is most suitable for evaluating the source strength of the metro, wherein the source strength of this metro line is 88.42 dB.

Performance evaluation of dynamic pulley damper system for installation angle

Dynamic pulley damper system (DPDS) as an innovative methodology for a response control system using a block and tackle mechanism to provide enhanced vibration reduction in high-rise buildings, has been proposed. The key aspect of this system is to exponentially increase the damper movement using an amplification mechanism comprising movable pulleys and a wire. This paper presents the relation between the arrangement of the wire’s angles, particularly in the amplification part, and the vibration reduction effect. The DPDS is introduced into a center-core high-rise building. Two small building varieties with different core heights are designed; then, a wire is stretched between the frame and the core structures. The capability of the DPDS to control vibration is confirmed via the shaking table test. Additionally, the accuracy of the simulation models is verified by a comparison with the experimental results. Moreover, this paper includes a parametric analysis test to determine the wire-stretching angle for establishing the most efficient design. The results of the above analysis show that the wire-stretching angle influences the seismic performance of the DPDS.

Effect of modal analysis on vibration reduction of hollow aluminum alloy profiles

Through the classification of the noise types in the train, this paper discusses the influence of the car body profile structure on the vibration reduction and noise reduction in the train compartment, introduces the principle and advantages of modal analysis in the natural frequency analysis of the object, attempts to use the modal analysis function of ANSYS software to analyze the natural frequency and mode of the complex hollow aluminum alloy profile structure, and finds out the relevant parameter changes. The influence of chemical on the overall vibration reduction and noise reduction effect of profiles.

Dynamic response analysis of shrouded blades under impact-friction considering the influence of passive blade vibration

A new dynamic model of shrouded blades with elastic support and variable cross-section is derived based on the Timoshenko beam theory, in which factors to be considered include centrifugal stiffening, spin softening, Coriolis force, blade stagger angle, and twist angle. The proposed model (PM) is verified by comparing the dynamic frequency results of the finite element model (FEM) and the PM. An impact-friction model of shrouded blades is established which can take into account the inertia effects of two passive blades. By comparing the vibration response of the two models (PM and FEM), the established impact-friction model is verified. Finally, the influences of normal contact stiffness, blade root support stiffness, and shroud position on the vibration response of the system are analyzed. Meanwhile, bifurcation diagrams, time-domain waveforms, phase diagrams, Poincaré maps, and frequency spectrum are utilized to analyze the nonlinear vibration characteristics of shrouded blades. The results show that the impact and friction between adjacent shrouds will cause the complex nonlinear vibration of the blades. Under small initial gaps, hard nonlinear phenomena can be observed in the vibration response of the shrouded blade. While under small initial preloads, it shows an obvious soft nonlinear phenomenon. Furthermore, with the increase of normal contact stiffness and blade root support stiffness, the resonance peak of the blade-tip flexural displacement decreases. When the shroud is closer to the blade-tip of the blade, the vibration reduction effect of the shrouded blade is better. The active blade experiences the chaos, period-one motion due to the nonlinear behavior of the impact-friction coupling at the adjacent shroud contact interfaces.

A new magnetorheological elastomer torsional vibration absorber: structural design and performance test

Abstract. The semi-active torsional vibration absorber can effectively reduce the torsional vibration of the power-train system. In this paper, a new type of variable stiffness torsional vibration absorber with a magnetorheological elastomer (MRE) as an intelligent controlling element is designed, and the modal analysis, frequency-tracking scheme, and damping effects have been studied. A transient dynamic simulation is utilized to validate the rationality of the mechanical structure, the magnetic field parameters of the absorber are matched, and the magnetic circuit simulation analysis and the magnetic field supply analysis are carried out to verify the closed magnetic circuit. The principle prototype of the innovative vibration absorber is manufactured, the magnetic field strength of the absorber is tested by a Gauss meter, and the results show the efficacy of magnetizing the vibration absorber with a conductive slip ring by solving the magnetizing problem of the rotating parts of the vibration absorber. A special-purpose test rig with a torsional vibration exciter as a power source has been implemented. A comparative experiment has been carried out to test the frequency shift characteristics and authenticate the vibration-reduction effect of the new MRE torsional vibration absorber.

Modeling and Experimental Verification of a Semi-rotary Fluid Damper Based on an Improved Kelvin Model

The semi-rotary fluid damper is a shock-absorbing device that is widely used for the protections of various mechanical structures. In this research, a new small semi-rotary fluid damper for vibration reduction of helicopter control system is introduced. The damping medium used in the damper is hydraulic oil with a high shear thinning rate, which has a high degree of nonlinear hysteresis and viscoelastic properties. The accuracy of the mechanical model of the damper is of great significance to the design of control strategies for effective vibration reduction. Based on the adaptive genetic algorithm, the parameter identification of the semi-rotary fluid damper is studied with the objective function of minimizing the square of the difference between the analytical force and the experimental force. The Kelvin and generalized Kelvin with friction models lack parameters to properly describe the frequency and amplitude dependence. Therefore, an improved Kelvin model which is based on generalized Kelvin is proposed to capture the nonlinear dynamic characteristics of the damper. Through error analysis, it is concluded that the improved Kelvin model can more accurately describe the nonlinear damping characteristics of the semi-rotary fluid damper subjected to different amplitudes and frequencies.

Dynamic characteristic difference of steel-spring floating slab track between single-carriage and multi-carriage models

The steel-spring floating slab track (SSFST) is a low-stiffness structure, sensitive to the vehicle loads. Due to the coupling effect of the superposition of adjacent bogies, it is difficult for conventional single-carriage models to meet the simulation requirements. To find a balance between computation efficiency and authenticity of analytical model results, the influence of carriage number on SSFST should be studied. Based on the finite element method and multi-body dynamics, a refined three-dimensional coupled model of multi-carriage-SSFST-tunnel was established. The difference in the dynamic response of the SSFST between single-carriage and multi-carriage models was analyzed and compared with the measured data. The field test results show that structural displacements and accelerations under the two-carriage model are much closer to the measured data. The dynamic model analysis results show that the maximum displacement of the rail and SSFST in the midspan of the slab increase by 0.48 mm and 0.34 mm under the multi-carriage model, and the vibration reduction effectiveness increases by 1.4–2.0 dB. Dynamic responses of the rail and SSFST show minor differences under the two-carriage and three-carriage models. The article is expected to provide a reference for the theoretical research, design, and layout optimization of subway SSFST.

Test Evaluation on Vibration Reduction Effect of Compacted Stone Mastic Asphalt Mixture

AbstractThe vibration reduction effect of compacted stone mastic asphalt (SMA) mixture with rubber particles or rubber powder has been widely explored, but the vibration reduction effect of common ...

Event-triggered [formula omitted] control for networked spar-type floating production platforms with active tuned heave plate mechanisms and deception attacks

The service life of floating production platforms can be substantially shortened due to undesirable excessive vibrations caused by dynamic loads. It is thus necessary to develop effective vibration reduction methods for floating production platforms. This article proposes a network-based active control approach for a spar-type floating production platform (SP) against wave exciting loads and deception attacks. First, a novel active tuned heave plate (ATHP) mechanism based on the concept of the active tuned mass damper is developed for the SP. Second, in the context of networked control of the SP-ATHP system, an event-triggering transmission mechanism is introduced to significantly improve communication efficiency. Meanwhile, a Bernoulli distribution and a nonlinear function are employed to character possible deception attacks in shared communication channels. Then, by modelling the network-based closed-loop SP-ATHP system as a time-delay stochastic system, its stability and H∞ performance analysis is derived. Besides, some criteria are obtained to co-design the triggering mechanism and the H∞ controller. Finally, simulation studies demonstrate that compared with some existing heave plate mechanisms, the designed event-triggered H∞ controllers under this ATHP mechanism are more effective to suppress heave motions of the platform and save network resources and control expenditure. Furthermore, even though there are deception attacks, the proposed scheme can still guarantee satisfactory system performance.

A Prediction Method with Altering Equivalent Stiffness for Damping Evaluation of Shrouded Bladed Disk Dynamic Systems

In turbomachinery bladed disks are typical cyclic symmetric structures where high-cycle fatigue of the blades can easily occur. Increasing the shroud structure is an effective blade vibration reduction method using the dry friction of the shroud contact surface to dissipate vibration energy. During one vibration cycle of the blade, the contact surface of the shroud may have one or several states of stick, slip, and separation due to the different amplitude of blade, which affects not only the damping, but also the stiffness of the system. This paper proposes a method to analyze the damping characteristics of blades with shroud considering the change of equivalent contact stiffness of the shroud by using the finite element method. With a 2D contact model, this method calculates the equivalent damping and obtains the damping characteristic curve to evaluate the damping of shroud. During the design phase, the objective is that when resonance occurs, the shroud can provide the optimal damping ratio under the allowable vibration stress of the blade. The parameter sensitivity of the damping characteristic for one bladed disk with parallel shroud is investigated. It is shown that vibration phase angle, contact stiffness, contact force, friction coefficient significantly influence the damping characteristics.

Vibration suppression of an elastic beam with boundary inerter-enhanced nonlinear energy sinks

Nonlinear vibration absorbers have been widely used for vibration suppression of elastic structures, but they were usually placed within the structures. However, designing such a vibration damping device within an engineering structure is possibly difficult. In this paper, an inertial nonlinear energy sinks (NES) is mounted on the boundaries of the elastic beam to suppress its vibration. Although this vibration suppression approach is more in line with engineering requirements, it introduces nonlinear oscillators at boundaries. This brings certain difficulties to the structural vibration analysis and the optimal absorber design. An approximate analytical approach for the steady-state response is developed in this work and verified by numerical solutions. The comparison with the uncontrolled system demonstrates the high-efficiency vibration suppression of the inertial NES installed on the boundary. Besides, the optimization of the NES parameters is performed. Resonance amplitude of the elastic structure can be reduced by 98% with the optimized NES. In summary, this paper proposes a novel approach to suppress the bending vibration of elastic structures through boundary NESs. The vibration reduction effect is very significant, and it is more feasible to implement. Therefore, this work is helpful to study the vibration of elastic structures with nonlinear boundaries and to promote the application of nonlinear vibration absorbers. A boundary damping strategy is proposed to solve the problem of the difficulty of installing the vibration absorber in engineering. Introduce an inertial nonlinear energy sinks (NES) to reduce the weight of the shock absorber. The nonlinear boundary is separated and merged into the elastic beam vibration control equation to realize the decoupling of the continuum model. Resonance peak of the elastic structure can be reduced by 98% with the optimized NES. This work is helpful to study the vibration of elastic structures with nonlinear boundaries and to promote the application of nonlinear vibration absorbers.

Phase difference and stability of a shaft mounted a dry friction damper: Effects of viscous internal damping and gyroscopic moment

This study investigates the stability and phase difference of a shaft mounted a dry friction damper with effects of viscous internal damping and gyroscopic moment. The equations of the system with the vibration reduction effect of the dry friction damper on the shaft are derived in the form of the rectangular coordinate and polar coordinate in the vicinity of critical speed. The phase difference characteristics in the rub-impact process and its physical mechanism are analyzed by mathematical derivation. The characteristic equation is studied to investigate the stability of the periodic solution. Effects of different parameters of the system, especially viscous internal damping of the composite shaft and gyroscopic moment on the phase difference and stability regions are presented in detail by analytical and numerical simulation based on a helicopter tailrotor driveline. The experimental investigation is conducted in a test rig to validate theoretical formulas and simulation analysis. The analysis results show that rub impact delays the change of phase difference, viscous internal damping improves the stability of synchronous full annual rub solution, and gyroscopic moment affects the increase of the phase difference.

Wave-resistance sleeper with locally resonant phononic crystals: Bandgap property and vibration reduction mechanism

As an artificially engineered metamaterial, locally resonant phononic crystals (LRPCs) exhibit great potential for the vibration reduction of urban rail transit due to their capability to prohibit the propagation of elastic waves with long wavelengths. This study proposes a wave-resistance sleeper with negative dynamic mass density by periodically embedding LRPCs into the concrete sleeper and provides new approaches to improve its bandgap property. Furthermore, the vibration reduction effect of the wave-resistance sleeper applied in a slab track was evaluated with a three-dimensional half-track model. The results show that the wave-resistance sleeper has two bandgaps below the frequency of 2000 Hz and can effectively prohibit the vibration within the bandwidth from transmitting to the track bed. Setting intervals in the rubber coating and increasing the void fraction can significantly reduce boundary frequencies of the first bandgap, whereas the second bandgap attenuates completely as the vibration can no longer be localized in the discontinuous rubber coating. A larger metal core is beneficial for obtaining a wider bandgap in the low-frequency range, whereas a thicker rubber coating can be used to obtain a wider bandgap in the medium-frequency range. To obtain wider bandgaps, the steel tube used should be as thin as possible and the use of an oval metal core should be avoided. It is hoped that the research results can provide a useful reference for the vibration reduction of track in rail transit.

Topological optimization design on constrained layer damping treatment for vibration suppression of aircraft panel via improved Evolutionary Structural Optimization

Light-weight panel structures are commonly used in inlets of the Auxiliary Power Unit (APU) of aircraft. In this paper, a study on topological optimization design of constrained layer damping (CLD) treatment for vibration suppression of aircraft panel based on improved Evolutionary Structural Optimization (ESO) is presented. In the analysis, the volume fraction of CLD material is selected as the constraint condition, and the maximization of modal loss factor is considered as the objective function to enhance damping in the topology optimization model of the structure with CLD treatment, Modal Strain Energy (MSE) method is adopted to deduce the sensitivity of the objective function to design variables, using mesh-independent filter method to solve the checkerboard pattern and the mesh-dependent problem, the ESO with improved evolutionary rate is proposed to search the optimal layout of CLD material, and the correctness and effectiveness of the optimization results are demonstrated through the numerical examples. Compared with conventional ESO, the improved ESO can not only increase the calculation efficiency but also obtain a more reasonable optimized topology geometry. The vibration suppression of the optimized panel is compared with those of the original panel, stiffened panel, and full cover CLD material damping panel and verified by experiments. The results show that the optimized damping panel has a better vibration reduction effect.

A Method Based on Spectrum Superposition for Minimizing the Hazards of Blasting Vibration

The selection of delay time will directly affect the effect of vibration reduction in millisecond delay blasting. The commonly used frequency spectrum control methods have some problems such as the difficulty of seed wave selection and the complexity of nonlinear superposition model. Based on the principle of waveform linear superposition, this study proposes a new spectrum superposition method for minimizing the vibration hazards in an open deep-hole bench blasting. This method, with no need to select the seed waves, mainly uses the ratio of the Fourier spectrum of the combined vibration waveform and the single hole vibration waveform to quantify the suppressed vibration. By defining the suppression ratio K, the suppression ratio with frequency range of 10 – 60 Hz under different delay times was calculated, and the theoretical optimal vibration reduction delay time value of 10 – 15 ms was given. A high precision digital electronic detonator was used to verify the proposed spectrum superposition method. The test results show that the best delay time of field vibration reduction is 5 – 10 ms, which is lower than the theoretical best delay time of 10 – 15 ms. It is the authors’ belief that this phenomenon is mainly caused by the joints and cracks in the rock mass, which will prolong the actual superposition time of blasting seismic waves between adjacent holes. In addition, it is found that there is a negative correlation between the delay time and the main vibration frequency, which is mainly caused by the low-pass filtering characteristic of rock medium. In order to minimize the probability of resonance failure, an optimal delay of 5 ms based on the main vibration frequency was given.

Vibration reduction by stiffness modulation – A theoretical study

Semi-active vibration reduction techniques are defined as techniques in which controlled actions do not operate directly on the system’s degrees of freedom (as in the case of active vibration control) but on the system’s parameters, i.e., mass, damping, or stiffness.Cyclic variations in the stiffness of a structural system have been addressed in several previous studies as an effective semi-active vibration reduction method. The proposed applications of this idea, denoted here as stiffness modulation, range from stepwise stiffness variations on a simple spring-mass system to continuous stiffness changes on rotor blades under aerodynamic loads.Semi-active systems are generally claimed to be energetically passive. However, changes in stiffness directly affect the elastic potential energy of the system and require external work under given conditions. In most cases, such injection or extraction of energy (performed by the device in charge of the stiffness variation and denoted as the pseudo-active effect) usually coexists with the semi-active effect, which operates by redistributing the potential energy within the system in such a way that it can be dissipated more efficiently.This work focuses on the discrimination between these two effects, which is absent in previous literature. A first study on their dependence on the process parameters of stiffness modulation is presented here, with emphasis on the spatial distribution of the stiffness changes. It is shown that localized changes tend to result in a larger semi-active share of vibration attenuation, whereas a spatially homogeneous stiffness modulation only generates a pseudo-active effect.

Band Gap and Vibration Reduction Properties of Damped Rail with Two-Dimensional Honeycomb Phononic Crystals

The prevention of environmental vibration pollution induced by train operation is one of the inevitable problems in the construction of urban rail transit. With the advantage of flexible adjustment, phononic crystals (PCs) have a broad application prospect in suppressing elastic wave propagation of rail transit. In this paper, a damped rail with two-dimensional honeycomb PCs was proposed, and its band structure was analysed with FEM. Then, a parametric study was used to investigate the influences of design parameters of the honeycomb PCs on its band gap property. Furthermore, with a 3D half-track model, the vibration reduction property of the damped rail with honeycomb PCs was discussed. The results show that the damped rail with honeycomb PCs has an absolute band gap in the frequency range of 877.3–1501.7 Hz, which includes the pinned-pinned resonance frequency of the rail internally. Reducing the filling fraction and elastic modulus of the matrix can obtain an absolute band gap in a lower frequency range but also bring a narrower bandwidth. The decrease of scatterer density leads to higher boundary frequencies of the absolute band gap and descends the bandwidth. In order to obtain an absolute band gap which can suppress the pinned-pinned resonance of the rail and keep a wider bandwidth, the filling fraction is suitable to be about 0.5, and the elastic modulus of the matrix is proposed to be not more than 0.6 MPa. Metals with heavy density can be used as the scatterer to obtain a better vibration reduction effect. It is hoped that the research results can provide a reference for the application of PCs in track vibration reduction.

The vibration reduction performance of Tuned Liquid Damper on high-rise buildings with three-dimensional numerical simulation

The vibration reduction effect of high-position fire-fighting water tanks on the roof of office buildings in State Grid Corporation of China is discussed in this article. A three-dimensional tuned liquid damper(TLD for short)-structure model was established based on Coupled Euler-Lagrange algorithm to compare the calculated results under unidirectional and bidirectional seismic waves. Meanwhile, a 10-storey frame structure with asymmetric plane was selected to study the controlling performance of TLD on torsional response. Top displacement and aseismic ratio are taken as the key parameters to verify the availability, and the results show that the displacement response of TLD-structure has the character of linear-superposition geometrically, and the response gets the maximum when the seismic characteristic period tends to its natural period. The position with smaller structural stiffness should be taken as the primary controlling part, and reduction effect is better in the direction with strong displacement-response. TLDs have positive effects on controlling the structural torsional response and the aseismic ratio could reach 30% or more.

<b>Parameter Determination Method of Three-dimensional Analytical Models for Elastic Vibration of Railway Vehicle Carbodies</b>

Reducing elastic vibration of railway vehicle carbodies is required to improve ride comfort. A high-accuracy numerical analysis model is required to study effective vibration reduction methods. This paper describes a new numerical analysis model, and a method for determining parameters for the proposed model by using particle swarm optimization. After the application of the proposed method to a Shinkansen-type test vehicle, the authors created an analytical model with a maximum natural frequency difference between measured and calculated results of the targeted six elastic vibration modes within 0.86%, which indicates the effectiveness of the proposed model and parameter determination method.

Optimal design of inerter‐based nonpacked particle damper considering particle rolling

AbstractThis paper presents an optimal design method for a nonpacked particle damper (NPPD) based on a simplified mechanical model and corresponding damping mechanism analysis. First, an equivalent inertial single‐particle mechanics model (EISM) and the corresponding equivalent principle were proposed to consider the influence of particle rolling on the vibration reduction. The experimental verification of the EISM under seismic ground motion was subsequently carried out. Based on a reasonable verification of the proposed model, an analytical solution of the EISM single‐degree‐of‐freedom structure system for the symmetric two‐impacts‐per‐cycle motion was obtained. The influence analyses of collision distance on the damping effect and the damping mechanism under resonance and nonresonance harmonic excitation were performed. The theoretical calculation formula for the optimal collision distance for energy consumption was obtained based on the damping mechanism analysis. Finally, numerical simulations under harmonic excitation and seismic ground motion were carried out to verify the rationality and generalization of the proposed optimal collision distance. Accordingly, an optimal design method for the NPPD was proposed. Based on the proposed optimization method, the vibration reduction effect of NPPD under far‐field records, near‐fault pulse‐like records, and near‐fault nonpulse records are discussed. The analysis results show that the vibration reduction effect of the NPPD is affected by the response frequency of the uncontrolled structure. The proposed optimization method can be used as the basis for the optimization of NPPD under earthquakes.