Vibration Reduction Efficiency Research Articles

Failure mechanism and vibration control for tower tube of wind generator under extreme climate

The wind power tower is sensitive to wind loads with high aspect ratio. The failure characteristics and failure mechanism of the wind turbine tower structure are analyzed under the extreme climate conditions. Based on the principle of tuned mass damper theory, the suspension damper application in wind turbine tower structure is designed. The appropriate typhoon wind speed spectrum is selected. With the finite element software, the 3D model for tower structure is established and the control effect of the damper structure is analyzed. The maximum displacement and acceleration of the structure under extreme climatic conditions are greatly reduced after the suspension tuned mass damper being given. The efficiency of vibration reduction is 80.26% and 54% respectively. The results show that the response of displacement and acceleration for the damper are obviously decreased, which is beneficial to the safety of the tower structure under the extreme climate condition.

Research on Abnormal Vibration and Vibration Reduction Measures of a Natural Gas Compressor Station: A Case Study of the JYG Compressor Station

As an important medium transmission element, the pipeline has a very important application in the chemical industry, electric power industry, and petroleum industry. However, the pipeline vibration problem has seriously restricted the large-scale development of equipment, reduced the reliability of equipment operation, and even caused serious accidents. Therefore, it is very important to analyze the dynamic characteristics of these vibrations and to reduce the impact of vibrations within pipelines. We focus on the problem of abnormal vibrations within the JYG compressor station pipeline and use a 3D calculation model of the launcher pipeline of west–east gas pipeline III to perform simulation analysis using Fluent to find the cause of the abnormal vibrations. Our results show that the fluid pressure fluctuation in the pipeline is the main factor for the abnormal vibration of the launcher pipeline in the JYG compressor station. The main causes of the vibrations are excessive fluid flow and high flow velocity. Also, by comparing and analyzing the natural frequency of the pipeline system and the pressure fluctuation frequency of the vortex core in the pipeline, we found that the pressure fluctuation frequency is close to the low-order natural frequency of the pipeline system, which is prone to resonance. In this paper, three vibration reduction schemes of the JYG compressor station are suggested and verified. The efficiency of vibration reduction is 68–94%, which can be effectively applied to the outgoing pipeline of the west–east gas pipeline III to solve the abnormal vibration problem of the pipeline.

Global dynamics and performance of vibration reduction for a new vibro-impact bistable nonlinear energy sink

A new vibro-impact bistable nonlinear energy sink (VI-BNES) with relatively light weight attached to a damped linear oscillator (LO) is proposed to form a two-degree-of-freedom nonlinear mechanical system with bilateral rigid constraints. The state of the system after instantaneous impact is described by the simplified shock theory and the momentum conservation. When the LO subjected to impulse excitations with different levels is considered as the driver of the VI-BNES, a two-dimensional non-smooth reduced impact system with a harmonic perturbation and an irrational nonlinear restoring force is obtained to study the threshold for the homoclinic bifurcations and chaotic responses of the VI-BNES. Bistability of this mechanical model makes the reduced unperturbed system have a pair of symmetric homoclinic orbits as the pseudo-separatrix for in-well and cross-well oscillations. The Melnikov method developed by us for non-smooth planar systems with bilateral rigid constraints is firstly employed to detect the threshold of the amplitude of excitations of the LO for the onset of chaotic oscillations. Furthermore, cubic polynomial approximation of the restoring force on the premise of maintaining the equilibria of the system is carried out such that the analytical Melnikov analysis for the global dynamics becomes possible. The performance of the VI-BNES is also studied and compared with other NESs in detail through numerical analysis and experiments to show the high efficiency of vibration reduction of the VI-BNES due to the dual beneficial role of the bistability and the impacts with the bilateral rigid constraints.

A Novel Coaxial Balance Mechanism for Reciprocating Piston Engines

Vibration is an important issue faced by reciprocating piston engines, and is caused by reciprocating inertia forces of the piston set. To reduce the vibration without changing the main structure and size of the original engine, we proposed a novel coaxial balance mechanism design based on a compact unit body. By introducing a second-order balance mass, this mechanism can significantly increase the efficiency of vibration reduction. The proposed mechanism can effectively balance the first-order and second-order inertia forces with the potential of balancing high-order inertia forces. To accurately determine the second-order balance mass, a closed-form method was developed. Simulation results with a single-cylinder piston DK32 engine demonstrate the effectiveness and advantage of the proposed mechanism. At a crankshaft speed of 2350 r/min, compared with the first-order balance device, the average root mean square velocity of the test points on the engine’s cylinder was reduced by 97.31%, and the support reaction force was reduced by 96.54%.

Assessing and controlling of boulder deep-hole blasting-induced vibrations to minimize impacts to a neighboring metro shaft

When a metro is constructed by the shield method in the strata containing boulder group, it is prone to some engineering problems such as serious cutter wear, deformation of the cutter holder head, damage of the cutter spindle, which seriously affects the construction efficiency and bring enormous problems to the shield construction. This paper proposes the vibration reduction measures for the boulder deep-hole blasting to meet the construction safety. To achieve this purpose, the field test was applied to investigate the vibration response of adjacent building under five blasting areas. Then, three-dimensional numerical model was employed to discuss the vibration characteristics of the boulder and adjacent buildings under vibration reduction measures. The results show that increasing the damping hole and the isolation hole and changing the charging layout of the blasting areas can blast the boulder under the condition of ensuring effective and safe construction. Damping hole and isolation hole have a positive role in the control and attenuation of blasting stress wave. All of them have good vibration reduction effect, and the vibration reduction efficiency is more than 90%. The double row damping holes with 12.7 cm diameter and 20 cm spacing have good vibration reduction effect and economic benefit. When double row damping holes are used, the maximum particle velocity of the shaft structure under the influence of blasting stress wave is 1.47 cm/s, which is within the reasonable safety range.

Dynamic vibration absorption design and parameter analysis of oil tank wall of transformer

Taking a 10kV test transformer as the research object, based on the analysis of transformer vibration and noise vibration sources, the oil tank model of the test transformer is established firstly, and the vibration mode analysis of the oil tank is carried out, and the typical vibration modes of transformer oil tanks with different thicknesses are obtained Then, according to the characteristics of vibration and vibration source of distribution transformer tank wall, the design method and parameter optimization analysis of transformer tank wall vibration absorption are carried out. The analysis shows that the principle of dynamic vibration absorption is clear, and the vibration of the box wall can be effectively controlled with 76% vibration reduction efficiency under the condition of reasonable arrangement of vibration absorption devices and parameter selection. The vibration control effect of vibration absorber increases with the increase of mass ratio between vibration absorber and transformer tank wall. When the mass ratio is determined, the closer the stiffness of vibration absorber is to the optimal stiffness, the better the vibration reduction effect will be.

Active hybrid bearings as mean for improving stability and diagnostics of heavy rotors of power generating machinery

The article describes a theoretical study of basic features of active hybrid bearings used as supports for heavy energy-generating machines equipment, primarily turbine generators and their turbines. Due to the adjustable oil supply pressure and using a controller of a rotor position AHB reduces its vibration level. Vibration velocity can be reduced from several times for smaller rotors to tens of percent for heavier ones. The eccentricity of the rotor position in the bearing also affects the efficiency of vibration reduction. In this case also some nonlinear effects are observed. In addition, AHB can possibly be used as a diagnostic tool for monitoring the health of a heavy power generating machinery due to its ability to generate power test impulses for rotor excitation and further analysis of its response.

Damping Cutters with Varying Stiffness

Purpose of research. Improving surfaces' forming by a blade tool is an up-to-date task. Labour intensity of turning processing is a dominant part of all working. Vibrations during turning work are the result of premature tool wear and increased surface roughness of the parts. New cutter designs are of practical and scientific interest. They can reduce vibrations occurring during cutting, increase their persistence and improve processing quality. The aim and objectives of this proposed structural line of damping cutters with adjustable (controlled) rigidity are improvement of cutting tool structures, which allow to increase its resistance due to vibration damping; creation of efficient technological processes of cutting materials, which improve quality of treatment; improved operational characteristics of cutters.Methods. Existing structures of vibration damping cutters with elastic damping pieces of constant rigidity, in which holder or mandrel with cutting plate is installed, do not have necessary requirements for efficiency of vibration reduction due to impossibility of tool stiffness variation. Besides, there is high labour intensity of cutters preparation for operation and dismantling. Innovative cutter designs with adjustable (controlled) rigidity are presented.Results. The developed line of vibration-quenching cutters with rigidity variation and taking into account disadvantages of existing structures makes it possible to control vibration frequencies of perturbating force and components of a tool system which excludes uncontrolled growth of vibration amplitude and significantly prolongs efficiency of cutters with high quality of processing. It depends on processed material and cutting process modes. Existing and new designs of damping cutters make it possible to classify them. So it is possible to carry out research on their improvement.Conclusion. Proposed damping cutters with varying rigidity meet goals and objectives. According to theoretical research and industrial tests, simplicity of structures and technologies of new damping cutters manufacturing it is possible to implement them into production.

Energy Consumption of an Active Vehicle Suspension with an Optimal Controller in the Presence of Sinusoidal Excitations

Control of vibration is a significant problem in the design and construction of vehicle suspensions. The usage of controlled suspensions is important due to ride comfort, driving safety, and vehicle road holding. The control law for such systems is usually determined as a solution of an optimisation problem with a quality indicator. The effectiveness of vibration reduction is possible to be improved in the entire useful frequency range of a system operation, but usually increasing external energy consumption is observed. An additional problem in the case of vehicle suspensions includes the necessity for increased vibration reduction at selected frequencies. This is related to the natural frequencies of the driver’s internal organs or to other reasons. The goal of this work is to find a compromise between efficiency of the suspension in terms of the aforementioned indicators and energy consumption in the presence of sinusoidal excitations. This paper presents a synthesis of a weighted multitone optimal controller (WMOC) for an active vibration reduction system. Energy limitation is taken into account by selection coefficients of the weighting matrix associated with the control signal vector. The control signal in this case is determined on the basis of the parameter estimation of the sinusoidal disturbances vector (PESDV). The vibration transmissibility function and the energetic indicators for the active suspension were determined while taking note of nonlinearities occurring in the actual vehicle. The analysis of energy indicators is presented, depending on the level of vibration reduction efficiency. The results were compared with referencing to LQR control strategy.

Study on optimization algorithm of tuned mass damper parameters to reduce vehicle-bridge coupled vibration

A vehicle-bridge tuned mass damper (TMD) coupled dynamic analysis and vibration-control model was established to optimize TMD damping effects on a steel-box girder bridge bearing vehicle loads. It was also used to investigate optimization efficiency of different algorithms in TMD design parameters. This model simulated bridges and vehicles with the use of a 7 degrees of freedom curved-beam element model and a 7 degrees of freedom vehicle model, respectively. The TMD system was simulated with the use of multiple rigid-body systems linked with springs and dampers. Road surface condition, as a vibration source, was simulated with the use of a frequency equivalent method based on a power spectrum. A variably-accelerated pattern search algorithm was proposed in line with the initial TMD parameters calculated by Den Hartog formula. Visual software was compiled by Fortran and used for an optimization study of vibration reduction. A three-span, curved, continuous steel-box girder bridge was used as the numerical example. Optimized effects and computational efficiency of vibration reduction under different methods were compared. The comparison included a single variable optimization based on Den Hartog formula, an ergodic search method, an integer programming method, a traditional genetic algorithm, a traditional pattern search algorithm, and a variably-accelerated pattern search algorithm. The results indicate that variably-accelerated pattern search algorithm is more efficient at improving TMD optimal parameter design. Final TMD parameter optimization values obtained by different methods are quite close to each other and tends verify the reliability of the optimization results.

Research on Vibration Reduction Design of Foundation with Entangled Metallic Wire Material under High Temperature

When the submarine is sailing at full speed, the power cabin has an abnormally high temperature. However, in the previous research on the vibration reduction design of the foundation, the influence of high temperature on the vibration characteristics of the foundation is not taken into account. In this paper, a new composite foundation with entangled metallic wire material (EMWM) is presented to reduce the vibration of the foundation. The energy transfer path of the foundation was obtained by the power flow method, and then the layout of EMWM was determined. The optimization of the constraining layer was carried out by modal analysis. The damping performance of the composite foundation with EMWM was validated by the thermal‐vibration joint test. The results show that, at room temperature, the composite foundation has remarkable vibration reduction efficiency in the middle and high‐frequency bands. The maximum insertion loss can reach 15.37 dB. The insertion loss varies with the location of the excitation point. As the temperature rises to 300°C, the insertion loss in the low‐frequency band was improved, and the insertion loss is not influenced by the excitation position.

Replacement models in the analysis of intelligent systems

In recent years, the methods of active vibration damping are often used in the construction of the machines. Most vibrations occurring in technical devices have a negative impact on their technical condition. Many methods of vibration reduction are widely known, generally they can be divided into passive methods and active methods. Traditional passive methods consisting in the modification of parameters and structure of existing systems have a number of limitations, among others they do not change in time and have a low efficiency of vibration reduction in the low frequency range. The active vibration dampers that are properly controlled can supply or absorb energy in a specific way behave in a completely different way. This article describe modelling piezoelectric by replacement models represented by appropriately connected elements, eg in mechanical systems in the form of susceptibility or stiffness, are mainly used to simplify a more complicated system or mapping of its actual parameters. In modeling the piezoelectric phenomenon, substitute models with the same input properties as the original systems are used. This publication presents the layout of a piezoelectric plate in the form of an analogous electric circuit composed of electrical components. These elements have the appropriate impedance values marked Zij. In order to use the known graph method, the analyzed system was reduced to a substitute system by means of an electric triangle star exchange and methods of structural numbers.

Hybrid Filtered‐x Adaptive Vibration Control with Internal Feedback and Online Identification

Active control is an effective way to suppress low‐frequency mechanical vibration. However, with applications to submarine equipment, there are still some shortcomings due to vibration coupling and multifrequency complex excitation. In this paper, a novel hybrid improved adaptive control strategy, feedback and online identification filtered‐x LMS, namely, FOFxlms, is proposed, which introduces the residual errors to correct variable step‐size, uses the estimated primary path to improve online identification, and applies internal feedback to compensate for the feedforward control. Then the FOFxlms algorithm is applied to a double‐layer vibration isolation system of submarine rotating equipment, and the simulation results show that the normalized variable step‐size with residual error can effectively improve convergence speed, the internal feedback can efficaciously compensate for steady‐state control accuracy, and the online identification can dynamically identify the time‐varying characteristics of the secondary path. The vibration reduction efficiency of Fxlms, FFxlms, and FOFxlms increases for the fundamental frequency vibration; the control effect and convergence speed are also enhanced in turn.

A study of the reduction of ground vibrations by an active generator

This paper presents the concept of using an additional generator to prevent ground vibrations. A linear, transversally isotropic three dimensional half-space with the hysteretic damping model, acted upon by a harmonic vertical excitation is assumed. Equations of motion for the transversally isotropic ground model with the absorbing boundary conditions are presented and numerically integrated using FlexPDE software, based on the finite element method. The efficiency of the solution is analysed in terms of reducing the vertical and horizontal components of ground surface vibrations. Results in the form of a dimensionless amplitude reduction factor are presented for four different locations of a generator. The influence of the soil parameters and layers locations on the additional generator's efficiency is investigated. The vibration reduction efficiency in a four-story building is also presented.

Reduction of Railway-induced Vibration using In-filled Trenches with Pipes

Reduction in railway-induced vibrations in urban areas is a very challenging task in railway transportation. Many mitigation measures can be considered and applied. Among these, a little attention has been paid to trenches. In this study, a numerical investigation on the effectiveness of in-filled trenches with pipes in reducing railway vibrations due to passing trains is presented. Particularly, a series of two-dimensional dynamic analysis was performed to model the behavior of ballasted railway track under harmonic load with ABAQUS software as a Finite Element method. In so doing, two types of in-filled trenches with pipes with steel and concrete materials have been investigated in this paper. In addition, effectiveness of pipes made of steel and concrete, filled with loose sand and clay in railway-induced vibration reduction has been assessed. The results point out that using in-filled trench with pipes does not effective a lot on railway-induced vibration reduction in comparison to other railway-induced vibration reduction methods. However, in-filled trenches with steel pipes are much more effective than in-filled trenches with concrete pipes. Moreover, filling pipes with loose sand and clay does not have any effect on vibration reduction efficiency of these in-filled trenches.

Optimal Control of Slow-Active Vehicle Suspension — Results of Experimental Data

Laboratory investigations of an active vehicle suspension of an in-series structure of the slow-active type are presented in this paper. The multidimensional model is reduced to a case representing quarter car suspension. Control laws for active vibration reduction systems are usually determined based upon linear models of objects. Active suspensions are characterised by nonlinearity, connected most often with actuating systems and their energetic restrictions. This causes divergences between theoretical quality factors and those determined experimentally. The second essential problem is finding a compromise between opposed quality factors (for example, minimum power requirement and high efficiency of vibration reduction). Thanks to the use of the proper control law in the active vibration reduction system of vehicle suspension, the goal of ensuring a high level of ride comfort, good vehicle handling and incessant contact of the wheels with the road surface with a minimum power requirement may be attained. The authors, in seeking a compromise, determined classical LQR controllers for the proposed quality indicators realising the aims mentioned above. These controllers are determined for a linearised suspension model obtained from identification. Experimental characteristics are determined for all of the suspension control systems.

주행 차량의 로드 노이즈 예측을 위한 각 입력원의 기여도 평가

The reduction of the vehicle interior noise has been the main interest of noise and vibration harshness(NVH) engineers. A passenger vehicle has various and complicated transmission paths of sound and vibration. In order to identify the mechanism of transfer path, estimation of excitation force and exact modeling of transfer path are required. This paper presents method for estimating the noise source contribution on the road noise of the vehicle in a multiple input system where the input sources may be coherent with each other. And vector synthesis technique is employed to identify the characteristics of road noise and its transmission to vehicle compartment through noise and vibration analysis. Vibration reduction efficiency of each transfer path is evaluated by comparing individual vector components obtained virtual simulation.

Vibration control and shock absorption techniques for Hi‐Tech manufacturing plants

SUMMARYThe Hi‐Tech industrial plant that houses manufacturing processes of high precision requires much more vibration‐proof and earthquake‐proof structures than conventional plants. Taiwan is densely populated in limited space so that the Hi‐Tech industry does not have too much leeway for locating the manufacturing plant at locations that are away from sources of vibration. Hence, strengthening the capacity of Hi‐Tech plant structures to resist vibration is of primary importance to Hi‐Tech industries. In this research, the TFT‐LCD plant structure is selected for improving its shock absorption capability by replacing the braces at soft floor of the structure with Viscous Damper (VD) and Velocity and Displacement Hydraulic Damper (VDHD). The reinforced structure is then subject to vibrations of various accelerations for analysing the dynamics and efficiency of vibration reduction. The results show that: (1) When subject to micro vibration, VD and VDHD that have similar capabilities in controlling displacement and responding to acceleration are more effective than Buckling Resistant Bracing, BRB; (2) When subject to medium vibration, VD, BRB and VDHD show tremendous improvements in controlling the momentum of story drift or slab acceleration. However, BRB shows buckling that may lead to permanent structural deformation whereas the overflow occurs in the Relief valve of VDHD causing the energy‐dissipating viscosity of VDHD from a VD‐like to BRB‐like behavior; (3) Under strong vibration, when the maximum force of a VD exceeds its design value, the VD has inferior capacity than BRB and VDHD in reducing acceleration. The VDHD always has smaller acceleration response than BRB because the former has damping effect under strong vibration. The results obtained in this research will obtain the suitability of VDHD in reducing vibration and confirm its superior vibration reduction capability. Copyright © 2010 John Wiley & Sons, Ltd.

벡터합성법을 이용한 차량 실내소음의 입력원 영향도 평가

A passenger vehicle has various and complicated transmission paths of sound and vibration. In order to identify the mechanism of transfer path, estimation of excitation force and exact modeling of transfer path are required. In this paper vector synthesis technique is employed to identify the characteristics of road noise and its transmission to vehicle compartment through noise and vibration analysis. Vibration reduction efficiency of each transfer path is evaluated by comparing individual vector components obtained virtual simulation. The degree of effect is used to estimate the contribution of vibration input components to total output. And in this paper presents a new technique based on simulation studies using vector synthesis diagram and design of experiments, by which the effects of magnitude and phase change of input paths can be predicted.

Distributed TLDs in RC floors and their vibration reduction efficiency

A novel distributed tuned liquid damper (DTLD) for reducing vibration in structures is proposed in this paper. The basic working principle of the DTLDs is to fill the empty space inside the pipes or boxes of cast-in-situ hollow reinforced concrete (RC) floor slabs with water or other liquid. The pipes or boxes then work as a series of small TLDs inside the structure, to increase the damping ratio of the entire structural system. Numerical simulation that accounts for the fluidstructure coupling effect is carried out to evaluate the vibration-reduction efficiency of the DTLDs. The results show that the DTLDs are able to considerably increase the damping of the structure and thus reduce its vibration. An additional benefit is that the DTLDs do not require architectural space to be added to the structure.