Vibration Reduction Mechanism Research Articles

Development of tuned particle impact damper for reduction of transient railway vibrations

Herein, a tuned particle impact damper to reduce rail rolling noise is proposed, and its vibration reduction capability is investigated experimentally. The proposed damper was designed for easy attachment to a rail and possessed the combined characteristics of a tuned dynamic absorber and an impact damper. The vibration behaviour of the damper-attached rail was investigated using an actual UIC60 rail specimen. The measured vibration reduction performance was verified by simulation of the collision behaviours. The proposed damper exhibited excellent vibration reduction capability at a specific frequency band with additional damping in the broadband frequency range owing to partially inelastic particle impacts. A modal analysis of the tuned particle impact damper illustrated the mechanism of vibration reduction via the modal response of the proposed damper on the rail specimen. The interaction of the rail transverse vibration with the attached damper was analysed. The vibration reduction performances were investigated based on the damping coefficient predicted from both the least-squares and Prony’s methods. The damping capability was identified to investigate the effects of excitation force, coefficient of restitution, mass ratio, clearance, and clamping force. Based on applying impact damping on railway tracks, the proposed tuned particle impact damper showed excellent damping capability in reducing transient vibrations, which is essential for minimising rolling noise from passing trains.

Flexural band gaps and response attenuation of periodic piping systems enhanced with localized and distributed resonators

Novel metamaterial concepts can be used to economically reduce flexural vibrations in coupled pipe-rack systems. Here, we model pipe on flexible supports as periodic systems and formulate dispersion relations using Floquet-Bloch theory which is verified by a finite element model. Owing to the flexibility of the coupled system, a narrow pass band is created in low frequency regime, in contrast to the case of pipe without any rack. Two types of vibration reduction mechanisms are investigated for pipe with different supports, i.e. simple and elastic support. In order to tune the band gap behaviour, lateral localized resonators are attached at the centre of each unit cell; conversely, the lateral distributed resonators are realized with a secondary pipe existing in the system. The results reveal that both Bragg and resonance type band gaps coexist in piping systems due to the presence of spatial periodicity and local resonance. Although, the response attenuation of a coupled pipe-rack system with distributed resonators is found to be little lower than the case with the localized one, the relatively low stiffness and damping values lead to cheaper solutions. Therefore, the proposed concept of distributed resonators represents a promising application in piping, power and process industries.

Application of Tuned Vibration Absorber Concept to Blisk Ring Dampers: A Nonlinear Study

AbstractIn this study, a novel design for ring dampers is proposed, where the concept of tuned vibration absorbers is leveraged to substantially increase damper effectiveness while minimizing potential stresses near the blade root. Tuned absorbers have been used in the past to reduce the forced response amplitudes of both mechanical and civil structures. The absorber natural frequency is tuned to the targeted frequency of the host structure where it is attached. The vibration reduction mechanism relies on energy transfer from the host structure to the absorber. The novel design technique proposed here uses a vibration absorber approach to achieve energy transfer from the blisk to the damper, which leads to larger damper motion. This enables energy dissipation due to friction, reducing vibrations even in blade-dominated modes. An academic finite element model of a blisk with a ring damper is used to demonstrate the novel tuned damper concept and design technique. The geometric mistuning of the damper due to the presence of a gap in the ring structure is also taken into account. The results demonstrate the validity of the proposed tuned damper concept, showing a substantial vibration amplitude reduction compared to the linear baseline results, in which the damper is not tuned or absent.

Research of mechanical model of particle damper with friction effect and its experimental verification

Particle damping (PD) technology has a remarkable effect in reducing vibration and noise for high frequency vibration such as mechanical analysis and aviation, and has been widely applied in some engineering practices. However, in the field of low frequency and low amplitude vibration control for building structures, the research and application of particle damper technology is still in the preliminary stage. The deficiencies and problems mainly include the mechanical model of PD is not perfect enough and the mechanism of vibration reduction is not clear enough. In the light of the shortcomings of the existing theoretical model of the PD, a mechanical model of the PD with friction effect between the particle and the structure is proposed, and the analytical solution of the displacement response for the mechanical model subjected to harmonic excitation is obtained. The model can fully represent the collision and non-collision process of PD, and the phase trajectories can embody the complex nonlinear characteristics of PD. The theoretical and motion characteristics of the PD are verified by the electromagnetic shaking table test of a single-story steel frame with PD, which proves the rationality of the theoretical model and the correctness of the analytical results, as well as the necessity of considering the friction effect. The parameters of mass ratio, excitation amplitude, excitation frequency and motion gap are further analyzed, so the mechanism of vibration reduction is clearer. Finally, compared with the traditional model of impact damper, it is obvious that the mechanical model of PD with friction effect can more reasonably evaluate the damping performance in practical engineering.

Dynamic model and analysis of a dielectric elastomer vibration isolator

Dielectric elastomers are a kind of electroactive polymer and have a great potential for application to soft actuators. Dielectric elastomer materials also feature nonlinear response owing to the electromechanical coupling. In this work, a theoretical dynamic model was developed to characterize the nonlinear performance of a dielectric elastomer actuator used as a vibration isolator. The vibration reduction mechanism of dielectric elastomer structures is theoretically described. An experiment was also performed to validate the model. The experimental results tend to match well with the numerical calculation.

Vibration suppression of a viscoelastic isolation system by nonlinear integral resonant controller

The nonlinear integral resonant controller (NIRC) is implemented and analyzed to control the vibration of a viscoelastic isolation system under harmonic excitation. The NIRC consists of a first-order resonant integrator, which provides additional damping in the closed-loop system to reduce the high-amplitude vibration near the resonance frequency. The method of multiple scales is applied to analytically find the relationship of the amplitude–frequency response of the viscoelastic isolation system. Besides, the equation of the backbone curve satisfied is derived. Meanwhile, the suppression performance is verified based on time-domain analysis. It is found that the NIRC can effectively suppress vibration and improve stability of the viscoelastic isolation system. Furthermore, the influence of the detuning parameters, the real-power exponent, the viscoelastic damping, and the external excitation amplitude on the stability regions is investigated. Overall, the vibration reduction mechanism of the NIRC on the viscoelastic isolation system is revealed.

Study on damping characteristic of honeycomb paperboard and vibration reduction mechanism of packaging system

Honeycomb paperboard has been widely used in transportation and packaging of electronic instruments and furniture owing to the advantages of light weight, good compression resistance, environmental friendliness, and easy degradation. As a common cushioning material in transportation, it is worth studying the damping characteristic and vibration reduction mechanism of honeycomb paperboard. Based on the basic principles of vibration mechanics, the damping of honeycomb paperboard was proposed. Then the influences of cell length, paperboard thickness, grammage of core paper, and the honeycomb structures with face sheet or without face sheet on the damping characteristic of honeycomb paperboard were analyzed. Finally, the vibration reduction mechanism of packaging system with honeycomb paperboard and block was discussed briefly. The results show that the damping value of honeycomb paperboard decreases with the increase of cell length and paperboard thickness. The honeycomb paperboard with large grammage of core paper has high damping value, and yet paper honeycomb core structure without face sheet has poor damping capacity. What's more, the vibration reduction capacity of packaging system is influenced by the deformation and damping characteristic of honeycomb paperboard, among which material damping and structural damping contribute more, honeycomb deformation and air damping contribute less. The weight of block does not affect the damping characteristic of honeycomb paperboard, but affects the vibration reduction capacity of the whole system.

Vibration Reduction Using Wave Barrier: Model Test and Theoretical Analysis

In this study, Boit wave theory and Snell’s law were used to deduce the transmission coefficients of waves in saturated sandy soil passing through elastic barriers. The theoretical equations were verified using previously published results and experimental data. At the same time, a series of indoor model tests was used to investigate the vibration reduction of an in-filled barrier under vertical excitation. The vibration reduction effect of the barrier is evaluated by measuring vibration amplitude at a measuring point, in either the presence or absence of a barrier. The effects of barrier geometry and material properties on the vibration reduction effect were systematically studied. Our experimental results show that a barrier can reduce the vibration amplitude of the protected area. Concrete barriers and foam barriers have different vibration reduction mechanisms, and enlargement will occur at the rear of the concrete barrier. Additionally, a new type of tooth-shaped vibration reduction barrier is proposed. The experimental results show that this barrier can effectively reduce vibration.

Analysis of the stick-slip vibration of a new brake pad with double-layer structure in automobile brake system

Abstract This study establishes a dynamic model of a new brake system with two-layer structure to explore the mechanism of vibration and noise reduction of a brake pad with new structure. The model is used to analyze the effects of parameters of the double-layer pad on the stability and stick-slip vibration characteristics of the brake system. The stability of the brake system is optimized by brake parameters with respect to the stability diagram of brake pressure under a relatively wide range. System vibration modes can be changed from period-doubling bifurcation to chaos based on the variation of brake pressure and the parameters of double-layer pad via numerical analysis. The chaotic vibration region is optimized in this study using the correlation coefficient, which consists of friction-layer pad mass mb2 and connection stiffness k2. Results show that the range of chaotic vibration region can be reduced when the friction-layer pad mass and connection stiffness are large.

Vibration suppressions using a dynamic absorber embedded with acoustic black hole features

By capitalizing on the acoustic black hole (ABH) phenomena, an ABH-featured vibration absorber is proposed for the broadband vibration suppressions of a primary structure. As an add-on device to be attached to the primary structure, the proposed absorber embraces the principles of both dynamic vibration absorbers and waveguide absorbers. Its design and implementation avoids the tedious parameter tuning, thus showing robustness to accommodate structural variations in the primary structure. Using a beam as a benchmark example, both numerical simulations and experiments show that multiple resonances of the primary structure can be significantly reduced, and the same absorber can be used for different primary systems. Analyses reveal the existence of three types of vibration reduction mechanisms, manifested differently and dominated by different physical process, i.e.,structural interaction, damping enhancement, and their combination. Comparisons with a conventional uniform beam absorber shows that the superiority of the proposed absorber is attributed to its ABH-specific features exemplified by the enriched system dynamics and the enhanced broadband damping.

A resonant beam damper tailored with Acoustic Black Hole features for broadband vibration reduction

By capitalizing on the Acoustic Black Hole (ABH) phenomenon, a so-called ABH-featured Resonant Beam Damper (ABH-RBD) is proposed for the broadband vibration suppressions of a primary structure. As an add-on device to be attached to the primary structure, the proposed ABH-RBD embraces the principles of both dynamic vibration absorbers and waveguide absorbers. Its design and implementation do not need a tedious parameter tuning, thus showing robustness to accommodate structural variations in the primary structure. Using a beam as a benchmark, both numerical simulations and experiments show that multiple resonances of the primary structure can be significantly reduced by the proposed ABH-RBD, and the same ABH-RBD is effective on different primary systems. Typical control effects and the underlying mechanisms are investigated. Analyses reveal the existence of three types of vibration reduction mechanisms, manifested differently and dominated by different physical process, i.e. structural interaction, damping enhancement and their combination. Comparisons with a conventional uniform beam absorber show that the superiority of the proposed ABH-RBD is attributed to its ABH-specific features exemplified by the enriched system dynamics and the enhanced broadband damping.

弾性トーラスによる鉄道車両の車体弾性振動低減効果（実車を用いた制振効果の確認と制振メカニズムの数値的検討）

弾性トーラスによる鉄道車両の車体弾性振動低減効果（実車を用いた制振効果の確認と制振メカニズムの数値的検討）

Mechanism of Optimal Targeted Energy Transfer

A novel nonlinear vibration reduction mechanism based on targeted energy transfer (TET) is proposed. Targeted energy transfer is a physical phenomenon that describes a one-way irreversible energy flow from a linear oscillator (LO) to a nonlinearizable (essentially) nonlinear auxiliary substructure, noted as nonlinear energy sink (NES). The optimal targeted energy transfer where NES is set on the optimal state is investigated in this study. Complexification-averaging methodology is used to derive the optimal TET of the undamped system for different initial conditions. It is revealed that the optimal TET is dependent on the energy, indicating that passive control of NES cannot be optimally set for arbitrary initial conditions. In addition, it is found that for the undamped system, the optimal phrase difference between the linear primary oscillator and the nonlinear attachment is π/2. From the perspective of active control, the NES can be taken as an actuator to keep the system vibrating on the optimal TET. An available modification form of the optimal equations is proposed for the impulse excitation with relatively small damping. The comparisons of the effectiveness of the optimal TET is validated by using numerical simulations with the excitations including impulse, harmonic, to input with sufficient bandwidth, and random signal. The design procedure would pave the way for practical implications of TET in active vibration control.

Railway vibration and noise reduction using particle impact dampers

Rolling noise is becoming a increasing concern for residential areas near railways. Rail vibration caused by moving loads of a train and corrugations generates noise. This study presented a particle impact dampers and its application to reduction of the rolling noise. The particle impact dampers to efficiently reduce the vibration were designed and verified using simplified models of a railway. To verify the particle impact damper performance, the vibration of a simplified railway attached with particle impact dampers was measured. The effects of different clearances and mass ratio of the damper to the railway was investigated. The numerical predictions of finite element model of impacting dampers were proposed and verified to the measured results to find the vibration reduction mechanism.

Research on Vibration Reduction Mechanism for Robot Joints by Imitating the Owl Surface Characteristics

On the base of bionics and mechanics of vibration, the mechanism of the structure and function of robot joint vibration reduction was researched for more and more prominent vibration problems in the design of the robot. Drawing the model by Solid works and making finite element analysis (FEA) by Abaqus, vibration frequency was analyzed on different condition, exploring the influence of vibration of robot joint with and without package coatings as well as with and without holes in the package coatings. The experiment and simulation result showed that vibration reduction effect was obvious in robot joint covering package coatings with high punching rate.

Evaluation of styrene-butadiene latex as a vibration damping admixture for concrete: a micromechanical analysis

The styrene-butadiene latex as an admixture for Portland cement concrete is evaluated in this study using a numerical simulation approach aided by a series of laboratory experiments conducted for material parameter determination and numerical model validation. Using the discrete element method (DEM), a three-dimensional (3D) beam of concrete was built with due consideration of the concrete microstructural features. The beam was employed to simulate the cyclic three-point flexural test at three loading frequencies: 0.2, 1 and 5 Hz and a representative in-service temperature: 25 °C. The effects of admixture usage and loading frequency on the overall damping properties of concrete were evaluated to explore the vibration-reduction mechanisms of the latex-admixtured concrete. Results show that a 20 percent usage of styrene-butadiene latex (by weight of cement) was found to significantly enhance the storage and loss moduli and the loss tangent of concrete. The developed 3D DEM model realistically accounts for the micro-structural features of concrete matrix and can potentially be used for evaluating and designing high performance concretes against detrimental dynamic loads.

Vibration Reduction of Pipe Systems Using Phononic Crystals

The vibration of pipe systems not only worsens their working environment, but also may result in the loosening of mechanical connections between pipelines, as well as the structural fatigue damages. This paper presents a new method for vibration control of pipe systems, by specially designing some pipe structures based on two vibration reduction mechanisms of phononic crystals, for the vibration frequency in the actual tests. Some numerical analyses are then performed about the effects of the parameters of vibrator, for instance, the ratio of material components, and the numbers of period. The simulation results demonstrate that the proposed phononic crystals structures can reduce the vibration of pipe systems effectively.

Study on vibration reduction mechanism of variable pitch end mill and cutting performance in milling titanium alloy

The vibration reduction mechanism of variable pitch end mills was analyzed by the theory of energy balance of the frequency spectrum line. The variable pitch mill can reduce the forced vibration in the cutting process due to the uniform distribution of frequency spectrum line energy and lower peak energy of the cutting force. Aimed at the vibration phenomenon which restricted the efficiency in cutting aero material titanium alloy, high-speed cutting experiments of titanium alloy Ti6Al4V were set with variable and equal pitch mills under dry and down-milling environment. The influences of cutting speeds on cutting forces and tool vibration were analyzed at time domain and frequency domain, respectively, by which the vibration reduction mechanism of variable pitch mill was verified. Due to the misalignment of end mill no. 3, high-level cutting forces and tool vibration were caused by the unequal cutting load on each edge. It is found that severe tool vibration was produced under the cutting speed of 150 m/min because of low-frequency resonance in the cutting process.

Study on the Mechanism of Vibration Reduction by Variable Speed Cutting

Chatter occurring in cutting process is an unstable vibration phenomenon, which affects the machining accuracy and the production efficiency, studied by many researchers for dozens of years. By analyzing the relationship with energy feedback and energy consumption on the machine structure system, this paper revealed that the mechanism of vibration reduction by variable speed cutting, qualitatively analyzed the obvious effect in suppressing cutting chatter by the continuous change of spindle speed. According to the principle of vibration, it established mathematical model of vibration reduction by variable speed cutting. Calculate the spindle phase difference angle within a week and each vibration after a week, thus get variable amplitude values after the start of each cycle. And further example analyzed the advantage of variable speed in suppressing cutting chatter.

Experimental Study of Particle Collision Damper for Vibration Attenuation

In cantilever beam system, through the experimental method to study vibration reduction mechanism of particle collision damper. The filling rate of particle damping agent in damper is 40%, added the damper with different diameter impacters and different kinds of particle damping agent in combinations ways, the cantilever beam system obtained the varying vibration reduction, according to the quality of vibration reduction, analyzed the joined impacters and particle damping agent influence of vibration attenuation rule. Experimental results show that damper added impacters and particle damping agent can dramatically reduce the maximum amplitude of cantilever beam system in resonant frequency, and can effectively restrain vibration of cantilever beam system.