Vibration Reduction Method Research Articles

Dynamic Response Analysis and Vibration Reduction of Steel Truss Corridor Pedestrian Bridge Under Pedestrian Load

With the advancement in civil engineering, the applications of lightweight and high-strength materials, and large-span, low-damping structural systems, are increasing. One important structural system for such applications is the corridor pedestrian bridge structure. The vibration frequency of the corridor pedestrian bridge structure is often in the same range as the step frequency of pedestrians, and it is easy to cause the appearance of the corridor structure. The vibration frequency of the corridor pedestrian bridge structure is often in the same range as the step frequency of pedestrians, and it is easy to cause the appearance of the corridor structure. Vibration comfort issues even affect the safe use of the corridor. Vibration comfort issues even affect the safe use of the corridor. Regarding the vertical vibration caused by pedestrians on the steel structure corridor footbridge, using a tuned mass damper (TMD) system can reduce the vibration effect. After the TMD vibration reduction test of the steel structure corridor footbridge, it can be found that the vibration reduction rate of the footbridge has reached 62.56%. The results show that vibration reduction by TMD system is a safe and effective method for pedestrian bridge vibration reduction, improving the structural performance and pedestrian comfort of the structural corridor pedestrian bridge.

Tidal Turbine Apparatus Vibration and Its Effect on Power Production Measurement

The effect of vibration and oscillation of an instrumented testing apparatus on horizontal axis tidal turbine rotor energy generation performance was examined and analyzed. Enforcement struts and an accelerometer were installed to measure and record vibration during the test with and without struts. Three rotors with a solidity (i.e., expanded area ratio, EAR) of 0.25, 0.4, and 0.51 were tested to obtain the rotor energy generation performance data. The analysis of the results is focused on the rotor open-water performance, in terms of the drag and power coefficient, respectively. The results show the reduced overall oscillation/vibration achieved an improvement in the measured power coefficient of about 6% and the drag measurement improved by about 3%. The allowable inflow velocity was also extended from 2 to 4 m/s. These results indicate that the enhanced vibration reduction method is effective and necessary for tidal turbine apparatus and its instrumentation.

Adaptive torsional vibration active control for hybrid electric powertrains during start-up based on model prediction

Torsional vibration occurs when the hybrid vehicle transmission system is influenced by the multiple excitations and the dynamic loads caused by mode switching. Torsional vibrations of transmission system directly affect the stability, reliability, and safety of vehicles. In order to suppress the torsional vibration, this paper studied the active vibration control algorithm for the hybrid powertrains under rapid acceleration. Primarily, the architecture and the dynamic modeling of the drive system of the hybrid vehicle was built. Moreover, the hybrid control system including engine controller, motor controller and transmission controller was proposed. Furthermore, an adaptive active control controller was constructed to solve the torsional vibration problem. And model prediction control (MPC) and Butterworth filter control were combined into the controller. Finally, the efficacy of this active method for vibration reduction under start-up conditions was simulated. The simulation results showed that the torsional vibration of the transmission system was reduced by 96%–99% with external interference and the system stabilization time was advanced by 93% without external interference. The adaptive control algorithm suggested in this paper effectively suppressed the torsional vibration of hybrid electric vehicles (HEV) when accelerating in pure electric mode, without affecting vehicles’ dynamic performance.

Torsional vibrations in heavy-truck powertrains with flywheel attached centrifugal pendulum vibration absorbers

A nonlinear centrifugal pendulum vibration absorber (CPVA) with normal-force dependant friction loss is investigated in a torsional model of a downspeeded powertrain of a heavy-truck. The engine model includes gas-pressure excitation and the existing pendulum model is extended to include a continuous formulation of end-stops at the end of the pendulum-path. Furthermore, the friction loss of the pendulum is experimentally determined. A pendulum-path parameter-study in the complete powertrain model is conducted to consider the effects of the system dynamics on the CPVA. It is shown that the performance of the CPVA is affected by the powertrain system-dynamics and thus important to consider in the design of the CPVA. Downspeeding of the engine by appropriate gearing of the driveline is a measure to decrease the CO2 emissions. However, downspeeding increases the torsional vibration and noise of the powertrain with conventional torsional vibration reduction methods. The CPVA can be used to reduce the torsional vibration and thus facilitate to reach environmental goals.

Analysis and design of electromagnetic vibration and noise reduction method of permanent magnet motor

Vibration and noise parameters have a significant influence on the performance of permanent magnet motor (PMM). A new method of reducing vibration and noise of PMM was proposed in this study by optimizing the stator teeth profile. The optimal offset distance was determined by finite element method, and the results indicate that the vibration and noise amplitude become larger when the frequency is an even multiple of the fundamental frequency. The maximum and average vibration acceleration of the optimized PMM is reduced by 22.27% and 11.11%, respectively, and the total sound pressure level (SPL) is decreased by 3.67%. Finally, the correctness of the theoretical parameters was verified by the vibration and noise measuring experiment. The experimental data suggest that the average acceleration error is 7.07%, and the average SPL error is 2.28%. The research methods and conclusions of this study may be extended to the vibration and noise optimization of other PMM.

A semi-analytical method for the vibration of cylindrical shells with embedded acoustic black holes

Embedding acoustic black holes (ABHs) on beams and plates has revealed as an appealing passive method for noise and vibration reduction. However, most ABH designs to date only concern straight beams and flat plates, while cylindrical structures are commonly found in the aeronautical and naval sectors. In this work, we suggest a semi-analytical method to compute the vibration field of a cylinder with an ABH indentation. We also show the ABH efficiency in terms of shell vibration reduction. It is proposed to resort to Gaussian basis functions in the framework of the Rayleigh-Ritz method, to reproduce the ABH cylinder vibration field. The ABH shell displacements in the three directions are decomposed in terms of Gaussian functions, which can be dilated and translated analogously to what is done with wavelet transforms. The functions are also forced to satisfy the continuity periodic conditions in the shell circumferential direction. The Gaussian expansion method (GEM) results in high precision at a low computational cost. The suggested semi-analytical method is validated against a detailed finite element (FEM) model. Modal frequencies and modal shapes are recovered very accurately. Besides, the mean square velocity of the annular ABH shell under point external excitation is compared to that of a uniform shell, in the 50-1000 Hz frequency range. Noticeable vibration reduction is achieved.

Progress and applications of acoustic black holes

<p indent=0mm>The problem of vibration and noise has always been one of the difficulties in the development of society. Therefore, the innovation of vibration and noise reduction methods has never stopped. In recent years, the introduction of acoustic black holes to manipulate flexural waves has become a hot topic in the field of vibration and noise. In this review, the acoustic black hole is defined as a kind of structure which can converge the flexural wave by changing the geometric parameters or material properties. In the absolute ideal case, the flexural wave velocity gradually decreases to zero in the acoustic black hole region. Acoustic black hole structures, as a new kind of flexural wave manipulation technique, can effectively reduce the propagation speed of flexural waves in the structure, thus reducing the reflection at the end of the boundary and forming a region with high energy density. Therefore, it has a broad application prospect in vibration reduction, noise reduction, fluctuation control and energy recovery. Different from the composite structure of vibration reduction and noise reduction in the past, the acoustic black hole has some certain advantages in practical application because of its simple structure, material and preparation process. Up to now, a great deal of theoretical modeling and experimental research has been carried out on the structural form of acoustic black holes, and some certain research results have been obtained. This review first introduces the origin, basic definition and principle of acoustic black holes, then introduces the theoretical calculation and experimental research methods, including frequency domain methods (semi-analytical method, Gauss expansion method, geometric acoustics method, transfer matrix method, finite element method, unit decomposition finite element method, spectral element method, and finite difference method) and wave-number domain method. Additionally, the laser ultrasonic scanning technology is emphasized in the experimental research. Next, the four main functions of acoustic black holes are classified and described, which are vibration reduction, noise reduction, fluctuation control and energy recovery, and the research status and existing problems of each application direction are summarized. The application of acoustic black holes in vibration reduction and noise reduction is becoming more and more comprehensive, and its applications in wave regulation and energy recovery are emerging in recent years. As a new research direction, the basic theory and practical application of acoustic black holes still need to be widely studied further. The breakthrough points include: (1) The acoustic vibration coupling mechanism of acoustic black holes and the matching with functional materials need to be further clarified; (2) the nonlinear wave behavior in acoustic black holes needs to be further improved; (3) according to different engineering scenarios, the bearing integrated design method of acoustic black hole composite structures is developed; (4) theoretical modeling and application development of imperfect acoustic black hole structures. The development of acoustic black holes is also a supplement and broadening to the related research of vibration and noise reduction. From the perspective of social development needs, the related research of acoustic black holes has potential applications in the independent research and development of functional structures and materials.

Modal Research of Underground Arch Structure With Elastic Support

Elastic support is a commonly used method of vibration isolation and vibration reduction. The research on the mode of underground arch structure with elastic support can improve the battlefield survival ability of personnel and equipment in underground protection engineering. In this paper, the ANSYS/LS-DYNA nonlinear explicit dynamic finite element analysis program is used to numerically simulate the mode of the elastically supported underground arch structure, and the natural vibration circle frequency variation curve and mode diagram of the structure are obtained. The results show that the elastic support reduces the natural frequency of the structure, prolongs the natural vibration period of the structure, and has a good vibration isolation and vibration reduction effect; the critical stiffness coefficient causes the first and second modes of the structure to be easily excited at the same time, which should be avoided in structural design.

Low frequency vibration reduction method for floating slab tracks based on tuned viscous mass damper

Low frequency vibration reduction method for floating slab tracks based on tuned viscous mass damper

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.

In-Wheel Motor Vibration Control for Distributed-Driven Electric Vehicles: A Review

Efficient, safe, and comfortable electric vehicles (EVs) are essential for the creation of a sustainable transport system. Distributed-driven EVs, which often use in-wheel motors (IWMs), have many benefits with respect to size (compactness), controllability, and efficiency. However, the vibration of IWMs is a particularly important factor for both passengers and drivers, and it is, therefore, crucial for the successful commercialization of distributed-driven EVs. This article provides a comprehensive literature review and state-of-the-art vibration-source analysis and mitigation methods in IWMs. First, selection criteria are given for IWMs, and a multidimensional comparison for several motor types is provided. The IWM vibration sources are then divided into internally and externally induced vibration sources and discussed in detail. Next, vibration reduction methods, which include motor-structure optimization, motor controller, and additional control components, are reviewed. Emerging research trends and an outlook for future improvement aims are summarized at the end of this article. This article can provide useful information for researchers who are interested in the application and vibration mitigation of IWMs or similar topics.

Vibration reduction methods of large-scale wind turbines based on system-TMD coupled algorithm

To relieve response of OWTs, this paper investigates the application of fore–aft tuned mass damper (TMD) in nacelle/tower for passive control. Considering flexibility of key components, system-TMD coupled algorithm is proposed based on the multi-body dynamics theory for a monopile offshore wind turbine. Hereby the improved artificial fish swarm algorithm is applied to optimize parameters and installation location of a TMD in terms of dynamic response and modal analysis. The results show that when TMD inherent frequency approximates the first-order inherent frequency of the tower front/back bending moment, vibration reduces to the maximum extent, so does the nacelle acceleration in the frequency domain; optimal installation location is within 0~1 m away from the center of the tower top-nacelle connection toward the front end of the nacelle; and the TMD after parameter optimization may function to reduce the tower top displacement by 68.30% under the shutdown condition.

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 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.

&lt;b&gt;Parameter Determination Method of Three-dimensional Analytical Models for Elastic Vibration of Railway Vehicle Carbodies&lt;/b&gt;

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.

Residual vibration reduction in back-and-forth moving systems driven by slider-crank mechanisms working through a dead point configuration

This study proposes an algorithm to construct back-and-forth motion profiles to reduce residual vibrations of 1-dof linear oscillatory systems, driven through a transmission chain made up of a 1-dof linkage mechanism. This set can be advantageous for high transmission ratios, when multistage drive trains are discouraged to prevent a build-up of backlash nonlinearities. We assume that the mechanism: i) is moved by a conventional electric actuator and, ii) is working through a dead point configuration. The solution focuses on the continuity degree Cn of the motion profile to guarantee its feasibility by means of the mentioned actuators. We aim to provide an algorithm to design these profiles. The development meshes several conclusions from other studies: the classical strategies of residual vibration reduction together with an analytical solution, with regard to Cn, of the inverse kinematic problem at a dead point configuration. The development includes an analytical approach to some methods of residual vibration reduction, in addition to numerical simulations. Finally, we present experimental results on a slider-crank mechanism test bed, with a pendulum acting as the oscillatory system.

APPROACHES TO CLASSIFICATION OF REDUCTION METHODS OF LOW FREQUENCY NOISE AND VIBRATION OF POWER PLANTS

The importance of the problem of low-frequency noise and vibration reduction now may be considered as urgent. Increased influence of low-frequency noise and vibration may cause both human health problems and equipment damage. Power plants (internal combustion engines, compressors, heat-exchanges etc.) are one of the main low-frequency noise and vibration sources. The principles of classification of methods of power plants low-frequency noise and vibration reduction are suggested. Author is proposing energetic approach, according of which all the methods and arrangements of reduction may be classified as passive (adaptive and non-adaptive), active and hybrid passive-active. The classification is illustrated by the different examples, including constructions of mufflers and dampers, some of which are developed by author.

Impacts of PU Foam Stand-Off Layer on the Vibration Damping Performance of Stand-Off Free Layer Damping Cantilever Beams

Stand-off free layer damping is a vibration reduction method based on the traditional free layer damping. In this paper, a stand-off free layer damping cantilever beam is prepared with the steel plate as the base layer, rigid polyurethane (PU) foam as the stand-off layer, and rubber as the damping layer, and the motion equation of the cantilever beam is derived. The dynamic mechanical properties of damping rubber and PU foam are tested and analyzed. Through hammering tests, we have studied the effect of the density and thickness of the PU foam layer on the amplitude-frequency curves, modal frequencies, and loss factors of the cantilever beams. The results show that the rubber damping material is a major font of energy dissipation of the cantilever beam, and PU foam acts mainly to expand the deformation of the damping layer and plays a role in energy consumption. By increasing the density and thickness of PU foam within a certain range, the vibration peaks of the first five modes of the cantilever beam decreases gradually, the loss factors rise, and the damping performance is improved. Meanwhile, increased density and thickness enhances the overall stiffness of the beam, making the modal frequencies get higher.

Experimental study of vibration characteristics of 110 kV oil-immersed transformer

As the voltage level and capacity of power transformer continue to rise, this results in its increasingly prominent vibration and noise problems. In this article, we study the vibration characteristics of the 110-kV oil-immersed transformer by means of experiments. Under different no-load voltages and short-circuit currents, the vibration signals in different positions and directions of the transformer are monitored respectively, and the vibration laws are analyzed. First, the vibration law of transformers is closely related to the operating conditions of transformers, which directly affects the frequency components of transformer vibration and the amplitude corresponding to different frequencies; second, it is found that the vibration law of transformers facing different directions will change under different operating conditions; and third, it summarizes the vibration of transformers in different positions under different operating conditions. These results can not only be used as the experimental basis for the theoretical research on large-scale transformer noise but also provides experimental support for the research on vibration reduction and noise reduction methods of large-scale transformer in engineering.