Vibration Reduction Mechanism Research Articles

Influence of the Side Branch Structure Pattern of the Imitation Cat's Claw Function on the Vibration and Noise of Tires

To study the method of reducing the low-frequency vibration noise of the tire, a passenger car tire(205/55R16) is taken as the research object. The dynamic grounding characteristics and vibration reduction mechanism of the cat's paw pad are analyzed. The research showed that the swing deformation characteristics of paw pads during the walking process of cats is one of the main ways to reduce the impact from the ground and achieve vibration reduction and silencing. To analyze the influence of tire grounding on noise, the tire grounding is divided into five areas, and the characteristics of ten tire grounding areas are analyzed through tests. Pearson correlation analysis is used to obtain the characteristics of the eight most relevant grounding areas with tire noise, and multiple linear regression is conducted between the characteristics of the eight grounding areas. The product of the correlation coefficient and the average value of the characteristics of the ground contact area shows that the central area of the tire tread contributes the most to the tire noise. The swing deformation characteristics of the bionic cat paw pad are realized by setting the staggered side branch pipe groove in the center of the tire, and the vibration reduction characteristics of the bionic tire are analyzed by using the finite element method. The results showed that when the tire rolls, the amplitude and fluctuation range of the ground radial excitation force acting on the bionic tire are reduced compared with the original tire, and the vibration and noise characteristics of the tire are improved.

Experimental study of vibration attenuation at rail joints by using Ethylene propylene Diene Monomer (EPDM) rubber

In railways the damage of rails at the joints due to heavy load transport has been a common issue for the last few years. To overcome this problem to some extent in this project, the projects will try to reduce dynamic vibration at rail joints. In this project, we will compare the frequencies of conventional rail pad in railways with the EPDM (Ethylene Propylene Diene Monomer) material-based pads with different layers at rail joints in railway track. EPDM rubber exhibits very good mechanical properties which last for long period. All the frequencies will be recorded with the help of vibration meter which consists of the sensor. The behavior of the track is also finding with the analysis tool (ANSYS – harmonic analysis).The main motto of this project is to Analysis of Vibration Attenuation at Rail Joints with Dynamic Vibration Absorber by Using EPDM Rubber. The Attenuation of dynamic vibration will be found through the collection of data from the rail with vibration meter and those values are utilized for harmonic analysis. The final output will be giving us how effectively EPDM rubber pads will optimize and sustain under the dynamic vibration in rails. This project is helpful in the future scope of railways, vibration reduction mechanisms and other sectors.

Research on seismic performance of new bridge pier seismic reduction isolation system based on shaking table test

In view of the current poor seismic performance of bridges, this paper started with the vibration isolation and reduction mechanism of the bearing, and deduced the coordination relationship between the stress and the deformation of the bearing under the vibration isolation and vibration reduction working conditions. Combined with the shaking table test, the defect that the traditional rubber bearing has poor seismic isolation effect was analyzed. Based on this, a base-bearing double reduction system was proposed and its vibration reduction and isolation effect was compared with the traditional bearing. The shaking table test results showed that, compared with the traditional bearing, the proposed vibration reduction system had better energy dissipation effect and could weaken the apparent cracking damage of the pier under the action of earthquake. Under the 125 m/s2-750 m/s2 peak acceleration excitation of the EI-Centro wave, the proposed vibration reduction system could greatly reduce the displacement variation of the upper main beam by 20 %-47 %. Moreover, the results of dynamic amplification factor measured at the corresponding height of the two types of piers also verified that the proposed base-bearing double vibration reduction system had greater competitiveness when the peak acceleration of seismic waves was less than 500 m/s2.

Modulated Vibration Reduction Design for Integral-Slot Interior Permanent Magnet Synchronous Machines

In this article, a targeted step skewing of rotor segments scheme is proposed to reveal the modulated vibration reduction mechanism in integral-slot interior permanent magnet synchronous machines (IPMSMs). First, the vibration characteristics of a 72-slot/12-pole integral-slot IPMSM are investigated. The dominant vibration at specific frequency band is introduced. Then, in order to analyze the main source of vibration, the magnetic field modulation effect and radial force modulation effect are investigated in detail. The results show that the high-order radial force can excite large vibration by radial force modulation effect. This kind of vibration is defined as modulated vibration. Afterwards, the optimal shift angle and number of rotor segments are determined by comparison. Finally, the conventional and proposed 72-slot/12-pole integral-slot IPMSMs are manufactured to validate the theoretical analysis. The experimental results verify that the proposed method can effectively reduce the modulated vibration of the 72-slot/12-pole integral-slot IPMSM.

The effect of constituent units on the vibration reduction of bamboo engineering materials: The synergistic vibration reduction mechanism of bamboo stiffness and wood damping

Determination of the influence and mechanism of constituent units on the vibration reduction performance of bamboo engineering materials is required to optimize application of these materials in the fields of construction and transportation. Testing was performed of typical bamboo engineering materials of Bamboo scrimber (BS), bamboo-wood composites (BWC), and Bamboo Glued laminated timber (GLT), all with different constituent units. Vibration reduction performance and parameters of vibration models were determined and compared using point-by-point multi-point tests and modal parameter identification methods. On this basis, equivalent stiffness was approximated based on inherent frequency. The results show that, BWC had the best vibration reduction performance, followed by BS, and GLT. The first three-order damping ratios of BWC were the largest, 2.14 %, 2.52 %, and 2.43 %, and those of GLT were the smallest, 1.40 %, 1.58 % and 1.60 %. Overall, the equivalent stiffness of the tested materials was in the order of: BS>BWC>GLT. The first three-order modal shape resembled the typical first-order quadrilateral torsional bump, the second-order middle-position bending bump, and the third-order bending-torsional bump. The resonance bands were mostly distributed at the middle position for GLT and BS, and at both ends of BWC. Vibration reduction of GLT was mainly attributed to the vibration reduction of solid bamboo, that of BS was mainly due to the high stiffness vibration reduction of bamboo fibers after recombination, and that of BWC resulted from the synergistic effect of the rigid surface layers and the even lamination of the low density and high porosity damping core layer after bamboo veneers. These results provide scientific reference for the vibration reduction design and optimization of bamboo engineering materials for applications in the fields of construction and transportation.

A novel triple-magnet magnetic suspension dynamic vibration absorber

The existing Nonlinear Dynamic Vibration Absorbers (NLDVA) have the disadvantages of complex structure, high cost, high installation space requirements, and difficulty in miniaturization. And most of the NLDVAs have not been applied to reality. To address the above issues, a novel Triple-magnet Magnetic Suspension Dynamic Vibration Absorber (TMSDVA), only composed of triple cylindrical permanent magnets and an acrylic tube, is proposed in this paper. Firstly, the equivalent dynamics model of a TMSDVA cantilever system is established. A comparison of the simulation and experimental results serves to indicate that the suspended magnet will be "locked" when the instantaneous total energy of the system is less than a certain threshold. According to that, we modify the dynamics model. Next, the vibration reduction mechanism of the TMSDVA is revealed from the perspective of transient dynamics and energy. The TMSDVA can resonate with primary structures with different natural frequencies, so that the vibration energy can be targeted transferred to the TMSDVA and dissipated by the damping. Whether the acrylic tube has holes affects the damping of the TMSDVA, then the energy transfer between the primary structure and the TMSDVA and the energy dissipation rate of the TMSDVA, and ultimately the vibration reduction effect of the TMSDVA. By comparing the vibration reduction effects of the TMSDVA with holes and the TMSDVA without holes, we find increasing the damping coefficient appropriately can improve the vibration reduction effect of the TMSDVA, reduce the sensitivity of the vibration reduction effect to the excitation amplitude, and further enhance the robustness of the TMSDVA. Taken together, the TMSDVA has potential application value in the gravity direction vibration reduction of engineering structures.

Research on new integral squeeze film damper vibration control of micro turbojet engine at high speed

Abstract In view of the problem that the vibration of the centrifugal impeller of the compressor exceeds the standard when a micro turbojet engine crosses the first-order critical speed, this research proposes a vibration control technology for the engine rotor system based on the new integral squeeze film damper (NISFD) according to the unique structure and assembly characteristics of the rotor bearing seat of the micro turbojet engine. Through numerical analysis and experimental research, the dynamic characteristics of NISFD are analyzed, and the vibration reduction mechanism of NISFD is revealed. The engine test verification based on NISFD is carried out. The results show that NISFD has good damping characteristics, which can improve the bending stress and strain energy distribution of the rotor. The engine test proves that NISFD can well solve the problem of excessive vibration of the engine when passing through the first-order critical speed, greatly reduce the vibration level within the working speed range, and significantly improve the reliability of the engine during operation. It provides a solid theoretical basis for the design of aeroengine, and provides a reference for the practical engineering application of NISFD in aeroengine.

Vibration Reduction Mechanism of a Novel Enhanced Particle Inerter Device

This work proposes an enhanced particle inerter device (EPID) capable of significantly enhancing the vibration control effect (VCE) of a conventional particle tuned mass damper (PTMD). EPID, an inerter is coupled to the PTMD device, that is, the inerter is attached to the damper cavity on one end and to the ground on the other, mainly using its mass amplification effect. To accomplish the goal, the EPID’s mechanical model is established first. Then, the system’s governing equation is derived based on the single degree of freedom (SDOF) system, and the EPID’s effectiveness is verified via inputting seismic excitation. Finally, the parameter analysis and multi-objective optimization design are carried out for EPID, and the superiority of the proposed multi-objective optimization design method compared with the traditional design method is verified. The results indicate that EPID can effectively minimize the main structure’s displacement and acceleration response. In particular, under the El Centro wave’s excitation, the vibration reduction rate of the dynamic responses (peak response and root mean square response) is close to 50%, which is over 35% increasing compared to PTMD, and its VCE is better for excitation band changes. At the same time, it is found that the lower the damper’s auxiliary mass ratio, the more obvious the enhancement of the inerter system’s VCE is, which brings about the lightweight design of the high-control effect of PTMD.

Investigation of the effect of vibration-reducing tracks on the vibration and noise from a large-span steel bridge

The vibration and noise problem of large-span steel bridge in urban rail transit have received increasing attention in recent years. As a common vibration control measure, the vibration-reducing track has been widely used on concrete bridges. However, systematic research on the vibration and noise reduction characteristics of large-span steel bridge by using vibration-reduction track remains insufficient. At the present paper, the vibration and noise reduction mechanism and characteristics of three typical vibration-reducing tracks, which are applied on large-span steel bridge, are studied. Firstly, based on the vehicle, track, and bridge coupling theory, a theoretical analysis model in the frequency domain was established. The dynamic receptance, wheel-rail force, force transmissibility ratio, and force transmitted to the bridge can be obtained, which are used to analyze the vibration-reduction mechanism of each vibration-reducing track. Then, the vibration and noise prediction model of a large-span steel-truss cable-stayed bridge is established by plate-beam combined finite element method and statistical energy method, and verified though the measured results. Finally, the vibration and noise reduction characteristics and effects of large-span steel bridge under the three vibration-reducing tracks are analyzed.

Numerical-based studies on hydraulic vibration of pipe flow in hydropower systems

Hydraulic vibrations of pipe flow in hydropower stations cause stability and reliability issues, or can result in local damage and operating accidents in hydraulic, structural, mechanical, electrical and associated power systems. Based on a comprehensive analysis focusing on hydraulic vibration in water conveyance system and relevant instability issues, key advances in numerical-based hydraulic vibration analysis for water conveyance systems are presented, including improved evaluation of hydraulic vibration characteristics, and new analytical models for pipe flow and analytical simulation of self-excited vibration; furthermore, the vibration reduction mechanism of the surge tank is concisely analysed. In addition, reliability-based hydraulic vibration analysis is preliminarily discussed. This detailed exploration helps to reveal the hydraulic vibration characteristics of the water conveyance system and then solve the possible hydraulic vibration problems, and shows that it is important to include hydraulic vibration analysis in engineering design.

Analysis of vibration reduction mechanism for variable pitch end mills

Analysis of vibration reduction mechanism for variable pitch end mills

Torsion and vibration reduction mechanism of roller PDC hybrid bit

In directional drilling, torque fluctuation generates a big shock when using polycrystalline diamond compact (PDC) bits, causing problems such as instability in vibration tools. This study presents a new type of composite bit with a roller on the blade. The mechanism of torsion reduction and vibration of the roller PDC hybrid bit is studied through a rock breaking experiment on the roller unit and a comprehensive drilling experiment on the composite bit. Six roller contour shapes, different pressures into the depth of the roller, six roller radial positions and the relative height of roller teeth, and PDC cutters that affect the novel hybrid torsion on bit (TOB) and weight on bit (WOB) are investigated. The equivalent friction coefficient of the roller and axial force per unit depth is used to evaluate the torsional and vibration reduction ability of the Roller. The results show that the equivalent friction coefficient of different contour Rollers is lower than that of PDC cutters, and the torsion reduction ability of the Rollers is higher than that of PDC cutters. The vibration reduction in the roller teeth in different radial positions was 1.59–9.17 times higher than that of PDC cutters, The torque of the roller PDC hybrid bit is 71.72%–98.33% of the conventional PDC bit. The roller shares 1.59%–23.06% of the WOB of the whole bit. As the cutter teeth and the PDC cutter's relative height decreases, the compound drilling torque decreases, the roller bit's weight proportion gradually increases, the torsional capacity decreases, and the damping capacity increases.

Experimental and Numerical Analysis of a High‐Rise Structure with a Dual FPS Isolation System

Given the issues existing in the isolation technology of high‐rise structures, this study displays a thorough examination ponder of three control strategies incorporating numerical and experimental investigation on high‐rise structures, which include friction pendulum system (FPS) base isolation, the FPS inter‐storey isolation, and the FPS dual isolation. Depending on the third‐generation benchmark structure, a scaled 9‐storey finite element model is designed, and the matching model of FPS is outlined and fabricated, as required by the geometric similarity criteria. Four typical ground motions and four types of peak ground acceleration (PGA) are considered to investigate the dynamic response of three control strategies. The findings demonstrate that the FPS dual isolation technology can viably smother that acceleration of the top layer of the high‐rise structure, and the vibration reduction effect of the substructure will be additionally self‐evident. For high‐rise structures, the FPS dual isolation technology has a significant vibration decrease impact, not just during minor earthquakes but also even during vast earthquakes. The vibration reduction mechanism of FPS dual isolation technology combines tuned mass damper (TMD) and base isolation technology. Those inertial force drives of the superstructure suppress response from claiming substructure, and same time, substructure is the form of base isolation, which extends that structural period segregates the seismic vitality. The structural deformation can be spread between the lower isolation storey and the upper isolation storey, which effectively limits the floor displacement of the structure. The FPS dual isolation does not mainly reduce that essential mode response of the system and suppresses the response of the high‐order mode, which will be the primary reason behind the tremendous vibration decreased impact of the long‐period structure. Eventually, it is demonstrated that the finite element model can simulate the dynamic response of the FPS dual isolation system with acceptable accuracy and is suitable for further parametric analysis and comparison by comparing the numerical analysis with the experimental findings.

Planar Swirl-shaped Acoustic Black Hole Absorbers for Multi-directional Vibration Suppression

A planar swirl-shaped Acoustic Black Hole (ABH) absorber is proposed and investigated in this paper. In addition to the well-known bending wave retarding phenomena, the speed of torsional waves in the curved ABH with a rectangular cross section is also shown to decrease with the thickness thinning. Alongside the enhanced bending-twisting coupling brought about by the planar and curvilinear configuration, the curved ABH absorber exhibits reduced orientation-dependent properties to cope with multi-directional rotational moment excitations, and meanwhile generates enriched dynamics and enhanced energy trapping and dissipation. As a result, the absorber enables broadband multi-directional vibration suppression when added on a primary thin structure. Experimental studies demonstrate that deploying multiple distributed ABH absorbers can entail effective, robust and broadband vibration reduction for an arbitrarily selected polygon plate. Analyses also confirm the dual vibration reduction mechanisms in terms of structural interaction and damping enhancement, both being fully played out through the proposed curvilinear ABH design.

Optimization of the frequency tracking scheme for an adaptively tuned vibration absorber

Vibration absorbers can absorb vibration energy and reduce the vibration amplitude of the primary system. With adaptive tuning, an adaptively tuned vibration absorber (ATVA) can track the dominant frequency of the external excitation, and reduce the vibration response amplitude of the primary system under variable-frequency external excitation. To realize the optimal vibration reduction performance, the 100% frequency tracking scheme of the adaptively tuned absorber must be optimized. In this regard, a dynamic model of an undamped primary system and a vibration absorber is established based on vibration absorption theory, and alternative tuning schemes for these absorbers are investigated in this paper. Using ATVA with the 100% frequency tracking scheme as a reference, a frequency tracking scheme is optimized by the segmented intercept optimization method. This optimization method continuously tunes the ratio of the absorber natural frequency and external excitation frequency to minimize the response in the variable-frequency vibration regions. Hilbert-Huang transform (HHT) time-frequency analysis is performed on the vibration response to reveal the vibration reduction mechanism of the improved vibration absorber. The vibration reduction effects are verified by comprehensive analysis results and experimental results.

Vibration reduction performance of an innovative vehicle seat with a vibration absorber and variable damping cushion

Road driving conditions are complicated, and road unevenness and speed bumps are main sources of vibration that cause the discomfort of passengers in vehicles. The vehicle seat can effectively reduce the system damage and human discomfort caused by this vibration. In this paper, an innovative damping seat that combines a vibration absorber and variable damping cushion is proposed for better vibration reduction performance under different external road excitations. A practical vertical human-seat-vehicle model is established, and uneven road excitation considering trapezoidal speed bumps and rectangular speed bumps is applied to the vertical model. The vibration reduction mechanisms of four different seats (without the absorber and variable damping cushion, with the absorber, with the variable damping cushion and with the new damping seat) are studied by comprehensive time-frequency analysis of the vibration responses. A comparison verifies the improved vibration damping performance of the newly proposed scheme, providing good theoretical guidance for the development of damping seats.

Research on Vibration Reduction Method of Nonpneumatic Tire Spoke Based on the Mechanical Properties of Domestic cat's Paw Pads.

Although there is no risk of puncture, the vibration problem caused by discontinuous structures limits nonpneumatic tire development (NPT). The vibration reduction of nonpneumatic tires is a solvable urgent problem. This current study analyzed the dynamic grounding characteristics and the vibration reduction mechanism of the cat's paw pads and then applied the mechanical properties to the bionic design of nonpneumatic tire spokes to solve the vibration problem. Domestic cats' paw pads' dynamic grounding characteristics were determined using the pressure-sensitive walkway, high-speed camera, and VIC-2D. The results indicated that the mechanical characteristics of swing deformation of paw pads during the grounding process attenuated the grounding stress and buffered the energy storage to achieve the vibration reduction effect. According to the similarity transformation, a finite element model of NPT that could accurately reconstruct the structure and realistically reflect the load deformation was employed. The structure design of asymmetric arcs on the spokes' side edges was proposed, and it can effectively reduce the radial excitation force of NPT. The three parameters, the asymmetric arc, the thickness, and the curvature of spokes, were used as design variables to maximize the vibration reduction. The orthogonal experimental, the Kriging approximate model, and the genetic algorithm were carefully selected for optimal solutions. Compared with the original tire, the results showed that peak amplitude 1, peak amplitude 2, and the root square of the optimized tire's amplitudes were reduced by 76.07%, 52.88%, and 51.65%, respectively. These research results offer great potential guidance in the design of low-vibration NPT.

Wind-Induced Vibration Control of High-Rise Structures Using Compound Damping Cables

Based on the vibration reduction mechanism of compound damping cables, this study focuses on the wind-induced vibration control of high-rise structures with additional mass at the top. The differential equation of motion of the system under the action of the composite damping cable is established, and the analytical solution of the additional damping ratio of the structure is deduced, which is verified by model tests. The vibration response of the structure under the action of simple harmonic vortex excitation and randomly fluctuating wind loads is studied, and the effect of different viscous coefficients of the dampers in the composite damping cable and different installation heights of the damping cable on the vibration control is analyzed. The results show that a small vortex excitation force will cause large vibrations of low-dampened towering structures, and the structure will undergo buffeting under the action of wind load pulse force. The damping cable can greatly reduce the amplitude of structural vibration. The root means square of structural vibration displacement varies with damping. The viscosity coefficient of the device and the installation height of the main cable of the damping cable are greatly reduced.

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.

Equivalent model of a multi‐particle damper considering particle rolling and its analytical solution

Multi-particle dampers (M-PD) can be potentially applied in civil engineering because of their good damping effect and wide frequency band. However, because of their complex nonlinear mechanical properties and the lack of a reasonable mechanical model, their development and application in practical engineering are limited. Therefore, without considering the accumulation of particles, an equivalent inertia single-particle mechanical model (EISM) is proposed by introducing an inerter to consider the effect of particle rolling on the damping mechanism and performance. Dynamic analyses of the EISM single degree of freedom system in the non-collision stage and the periodic motion after collision are performed based on the analytical solution. The influence of inertance on the frequency response curve of dynamic amplification factors in the no-collision stage and the analytical solution for the symmetric two-impacts-per-cycle motion are discussed in detail. Numerical simulations and experimental verification are conducted to verify the rationality of the above theoretical analysis. The results show that EISM can further clarify the nonlinear characteristics of M-PD. The inertance has a significant influence on the frequency response curve of the dynamic amplification factors as well as the boundary conditions and stability of the analytical solution of the symmetric two-impacts-per-cycle motion. The proposed EISM and the corresponding theoretical analysis in this study can theoretically support further analysis of the vibration reduction mechanism and design of M-PDs.