Vibration Reduction Method Research Articles

Approach for a General Pose-dependent Model of the Dynamic Behavior of Large Lightweight Machine Tools for Vibration Reduction

Large-scale machine tools for the manufacturing of large work pieces, e.g. blades, casings or gears for wind turbines, feature pose-dependent dynamic behavior. Small structural damping coefficients lead to long decay times for structural vibrations that have negative impacts on the production process. Typically, these vibrations are handled by increasing the stiffness of the structure by adding mass. That is counterproductive to the needs of sustainable manufacturing as it leads to higher resource consumption both in material and in energy. Recent research activities have led to higher resource efficiency by radical mass reduction that rely on control-integrated active vibration avoidance and damping methods. These control methods depend on information describing the dynamic behavior of the controlled machine tools in order to tune the avoidance or reduction method parameters according to the current state of the machine.The paper describes the approach for a general pose-dependent model of the dynamic behavior of large lightweight machine tools that provides the necessary input to the aforementioned vibration avoidance and reduction methods to properly tackle machine vibrations. The paper starts with an overview of the state of the art of the pose-dependent dynamic behavior of machine tools followed by the most common methods for vibration avoidance and reduction. Based on the results of an experimental modal analysis of a lightweight machine tool structure, the relevant pose-dependency is shown and the relevant parameters to derive the dynamic behavior are deduced. Then, a general model structure to model the machine tool's dynamic behavior is introduced. After updating the model parameters to different discrete machine poses the dynamical behavior of the model and the real machine tool structure are compared. Finally, it is explained how the model contributes to the actual vibration reduction of lightweight machine tools.

Development and Approbation of Methods and Technical Solutions of Reduction of Vibration of Power Plants and Joining Mechanical Systems

Power plants of different kinds are widely used in modern machinery, energetic, chemical industry, other branches, in transport and domestic conditions. Vibration and related with it mechanical noise of power plants and joining mechanical systems are the factors negatively impacted to the durability, reliability, productivity and other parameters of power plants. Methodological basics of methods of power plants vibration and mechanical noise complex reduction developed by author are described. According to the energetic criteria it is suggested to classify methods of vibration reduction as passive, active and hybrid (active-passive). Technical solutions for vibration reduction developed by author and results of it approbation are described. Results of approbation are confirming sufficiently high efficiency of technical solutions.

Vibration Reduction Method Using Transfer Function Characteristics of Operational TPA

Vibration Reduction Method Using Transfer Function Characteristics of Operational TPA

Residual vibration reduction of a flexible beam deploying from a translating hub

Abstract This paper presents a method for reducing the residual vibration of a flexible beam deployed from a translating hub. Whereas previous studies have discussed reducing vibration in translating constant-length beams, this study investigates a vibration reduction method for translating beams of variable length. The partial differential equation of motion for a translating beam is derived and transformed into a variational equation. Based on the discretized equations from the variational equation, the dynamic responses of the flexible beam under translation are analyzed. A vibration reduction method is proposed that is effective for both constant- and variable-length deploying translating beams.

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.

Vibration reduction of flexible solar array during orbital maneuver

Purpose – Orbital maneuver of the spacecraft can cause large-amplitude vibration of its flexible solar array, which leads to large dynamic stress and a risk of structural failure and fatigue failure. This paper aims to provide a method to reduce such vibration. Design/methodology/approach – Through controlling the rotation at the root of the solar array, a method of vibration reduction is proposed using zero-placement input shaping technique. Experimental research on a beam scale model of the solar array is performed to verify the effectiveness of the method. Simulation of a detailed example is carried out to investigate whether the method can be applied in engineering. Findings – The experimental results demonstrate the effectiveness of such method. The simulation results indicate that, by adopting the presented method, the vibration induced by orbital maneuver can be diminished remarkably. Research limitations/implications – Studies on the robustness of the method are left for further work. Additionally...

Electrical Elements in Reduction of Mechanical Vibrations

This work presents methods of reduction of the vibration of mechanical systems by means of active elements as well as examples of implementation of active reduction of vibration by means of electrical elements [. This work also describes a structural and parametric synthesis, which can be defined as the design of systems meeting specific requirements. These requirements refer to the frequency values of the systems vibration. The presented approach i.e. a non-classical synthetic method applied in designing mechanical systems, one (as early as at the design and construction stage) may verify future systems [1-. This work presents the description of vibration reduction methods. The most popular methods are passive, active and semi-active. An important aspect of this work is the presentation of several possibilities of the physical implementation of active subsystems. In examples active subsystems consisted of the following electric elements is coil with a movable core. In this work is presents influence of electrical subsystem to basic mechanical system. Designer should analyse the resultant systems and investigate the interaction between the subsystems and the basic system [4-.

단거리 이동을 반복하는 위치결정장치를 위한 효율적인 진동저감 방법

Article history: The current vibration reduction methods for positioning systems lead to either complicated motion or the need for additional hardware when the positioning systems carry out frequent short-distance movements. This paper proposes a simple yet efficient vibration reduction method for positioning systems subjected to frequent short-distance movements. The essence of the proposed method is the trapezoidal or triangular velocity profiles,whose acceleration/deceleration rates are designed to be related to the natural frequency of concern. The combined use of the proposed method and the input shaping method is also proposed for the possible application to multimode systems. Experiments are performed to validate the proposed method. The simulation and experiments prove that the proposed method is of great use for residual vibration reduction in positioning systems subjected to frequent short-distance movement.

Mechanical Subsystem as Implementation of Active Reduction of Vibration

The main objective of this work is to present a reverse task of the dynamics of discrete vibratory mechanical systems. This task is reverse to analysis and is called structural and parametric synthesis. As a result of performing the synthesis one obtains a structure and values of individual parameters of the system of required properties. Such properties refer to the determination of individual frequencies of the system vibration. Synthesis is divided into two stages. The first stage consists in definition of the structure as well as the values of parameters of a passive system without vibration reduction. In the second phase, one selects a method of vibration reduction as well as system structure and parameters with vibration-reducing elements. In case of already-existing systems, the first stage consists in the identification of the system and its analysis. There are no changes in the second stage (Figure 1) [. Another objective of this work is to use mechanical elements in the form of kinematic excitations as the implementation of active reduction of vibration as well as to check the influence of this subsystem on the basic system. The application of the synthesis presented in this work enables the correction of the already-existing machines and devices as well as the modification of newly-created systems with the view of their future functioning.

Directional Blasting Demolition Technology of 150m-High Reinforced Concrete Chimney and 75m Cooling Tower

This paper describes the successful experience of the directional control blasting demolition of 150m-high reinforced concrete chimney and 75m cooling tower of Shizuishan Power Plant in Ningxia. It emphatically describes the pretreatment measures, blasting cut shape and size, blasting parameters, detonating network and blasting safety technology of the directional window, oriented window and load reducing slot. This paper provides the method for opening the overlarge arch oriented window, opening the special-shape load reducing slot and dense mesh safety net cross-multilayer coverage as well as comprehensive protection method for anti-flyrock splash and vibration reduction. Especially, the blast holes for opening the special-shape load reducing slot and the herringbone column are centralized at the bottom and top, which not only reduces the drilling workload, but also reduces the maximum detonating explosive amount of single section, and also reduces the safety protection workload.

456 曲率を有する導波路における負の群速度を利用した振動低減手法

The dispersion curve of a curved beam has negative slope at a frequency region. A wave packet which is synthesized by more than two waves at the region of negative slope has negative group velocity. This paper addresses an issue of engineering application of the negative group velocity. Firstly, a dimensionless frequency of dispersion curve was introduced to achieve negative group velocity, in order to establish a design method of vibration reduction in mechanical structures. Then, backward movement of wave energy with negative group velocity was realized by using the design method, and was verified using transient response analysis of a FE-model of a curved beam. Validation was carried out from the standpoint of both negative group velocity of a wave packet and backward movement of vibration intensity. The results show that the wave energy in a curved beam does not propagate in the positive direction along the axial direction of a waveguide.

Vibration Reduction Analysis of Reticulated Shell

Reticulated shell is one type of the common spatial structure form. This paper proposes a vibration reduction method by supplementing viscous dampers in the reticulated shell. It analyzes the seismic performance on the optimum partial double-layer reticulated shell with dampers by ANSYS soft, gains the stress in the members and the nodal displacements, and compares the dynamic responses between the normal and vibration reduction structure. By means of different parameters, the rules of vibration reduction effect in the reticulated shell with viscous dampers are acquired. It is shown through the calculation that the method developed in this paper is efficient for the dynamic analysis of the reticulated shells.

319 AMDを用いた鉄道車両の車体弾性振動の多モード振動制御(車両サスペンションおよび振動制御,OS-16 運動と振動の制御,総合テーマ「伝統を,未来へ!」)

The vertical elastic vibrations of railway vehicle carbodies are needed to reduce from the viewpoint of riding quality. The first bending mode and diagonal distortion mode are commonly observed almost all railway vehicle carbodies. The natural frequencies of the two modes exist around 10Hz which is known to be a sensitive frequency for human. In this paper, a vibration reduction method about the two modes by using active mass dampers is suggested. A stationary excitation test for an actual railway vehicle is conducted to confirm the feasibility of this method. As a result of the excitation test, two modes of above mentioned elastic vibration of the carbody are reduced successfully.

アクティブマスダンパによる露光装置の性能改善(機械力学,計測,自動制御)

In the field of ultra precise positioning, such as semiconductor lithograph machine, an active isolation system is generally installed. In a present lithograph manufacturing machine, the scanning type is a main current, furthermore the main structure supported projection lens is separated from wafer stage which can be freely moved in the stage stroke, and the stage is supported by independent isolation system on the base. When wafer stage move, its reaction force is caught by mechanical supported structure (reaction frame) to avoid exciting the surface plate of the wafer stage. At this time, reaction frame is vibrating due to its natural frequency, and this remaining vibration transfer to surface plate directly or through floor. Still more the accuracy of the machine get worse. In this paper, when wafer stage moved and its reaction force excite the reaction frame, it is introduced that the improvement of vibration reduction method by using active mass damper. Eventually it is able to improve the enough performance for vibration disturbance.

530 リンク機構を有する鍛圧機械の運動と振動の制御

This paper proposes a control method for the crank-slider mechanism as the active mass damper (AMD). Vibration isolation systems with spring support cause an increase in oscillating displacement at a natural frequency. A system of elastic supported machine frame with crank-slider mechanism can be expressed as time-varying system depends on crank angle. A state equation which contained variable parameters in coefficient matrices is derived from non-linear equations of motion. A controller is adapted the gain-scheduled control method for frame vibration reduction, and the linear velocity control method for crank motion control. State feedback gains are calculated by the linear quadratic regulator (LQR). The proposed method is confirmed by numerical analysis. As results, the system is reduced disturbance vibration by using the slider as active mass.

Vibration Reduction Control Using Active Mass Damper with Crank-Slider Mechanism

This paper proposes a control method for the crank-slider mechanism as the active mass damper (AMD). Vibration isolation systems with spring support cause an increase in oscillating displacement at a natural frequency. Crank-slider mechanisms have been used for many kinds of industrial machines. A system of elastic supported machine frame with crank-slider mechanism can be expressed as time-varying system depends on crank angle.A state equation which contained variable parameters in coefficient matrices is derived from non-linear equations of motion. A controller is adapted the gain-scheduled control method for frame vibration reduction, and the linear velocity control method for crank motion control. State feedback gains are calculated by the linear quadratic regulator (LQR). The proposed method is confirmed by analysis and experiment. As results, the system is reduced disturbance vibration by using the slider as active mass. Furthermore, the system can consist of low costs since the existing mechanisms are used.

Reduction of Vibrations in Maglev Vehicles Using Active Primary and Secondary Suspension Control

In the superconducting magnetically levitated transport (Maglev) system, the vehicles travel at high speeds of over 500 km/h and have car bodies that are light in weight, resulting in vibrations that affect the ride comfort. Vibration reduction methods discussed in this report include prior examinations of superconducting magnets resiliently mounted on to the bogie frame to reduce vibrations in the primary suspension, and semi-active vibration control of the secondary suspension. The authors performed simulations applying electromagnetic forces from a linear generator device to control the primary suspension between the bogies and guideway, and controlling actuators in the secondary suspension between the car body and bogies. The results verified the basic effectiveness of combining control methods of the primary and secondary suspension to reduce vehicle vibrations.

Improved Active Vibration Isolation Systems

The control force, feedback gain, and actuator stroke of several active vibration isolation systems were analyzed based on a single-layer active vibration isolation system. The analysis shows that the feedback gain and actuator stroke cannot be selected independently and the active isolation system design must make a compromise between the feedback gain and actuator stroke. The performance of active isolation systems can be improved by the joint vibration reduction using an active vibration isolation system with an adaptive dynamic vibration absorber. The results show that the joint vibration reduction method can successfully avoid the compromise between the feedback gain and actuator stroke. The control force and the object vibration amplitude are also greatly reduced.

On the way to active systems: AVR Rotor – active vibration reduction for a textile bobbin

The application of machines is often limited by vibrations. In the course of the AVR Rotor project methods and tools for the control of vibration resonances of a rotor were developed. For that purpose, the applicability of sensors, control systems and actuators in combination with smart materials such as piezo-ceramic or materials with modifiable stiffness and magnetic bearing had to be considered. The different tools for active vibration reduction were compared and evaluated regarding their effectiveness and applicability. After completion of this technically oriented process different active vibration reduction methods for a demonstrator were tested. Within one analysis run both structural model and control system had to be simulated. On that basis three piezo-based active vibration methods for the bobbin were developed and realised.

A Portable device to illustrate two methods for vibration reduction namely tuned dynamic absorber and isolation mounting

Mechanical vibrations can be harmful to structures as well as to humans. It is important to understand the principles of design that are used in developing various methods for reducing vibration. There are several tools at our disposal to reduce the vibrations transmitted from a vibration machine to the building structure. Two commonly available methods of vibration control are using passive vibration isolation mountings and tuned mass absorbers. This paper presents the design and working of a portable device to illustrate both methods of vibration reduction. We can examine the performance of both mounting and absorber using this physical device. The analytical and experimental work shows that such a device can effectively illustrate the principles involved in the design of mountings and absorbers. Also, the device can be used to show the influence of various physical parameters on performance. The presentation will also include the discussion on the role of such devices in enhancing the understanding of design principles in acoustics, noise, and vibration.