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Study of Magnetic Vibration Absorber with Permanent Magnets along Vibrating Beam Structure  [PDF]
F. B. Sayyad,N. D. Gadhave
Journal of Structures , 2013, DOI: 10.1155/2013/658053
Abstract: The vibration absorbers are frequently used to control and minimize excess vibration in structural system. Dynamic vibration absorbers are used to reduce the undesirable vibration in many applications such as pumps, gas turbines, engine, bridge, and electrical generator. To reduce the vibration of the system, the frequency of absorber should be equal to the excitation frequency. The aim of this study is to investigate the effect of magnetic vibration absorber along vibrating cantilever beam. This study will aim to develop a position of magnetic vibration absorber along the cantilever beam to adopt the change in vibratory system. The absorber system is mounted on a cantilever beam acting as the primary system. The objective is to suppress the vibration of the primary system subjected to a harmonic excitation whose frequencies are varying. It can be achieved by varying the position of magnetic vibration absorber along the length of beam. The advantage of magnetic vibration absorber is that it can be easily tuned to the excitation frequency, so it can be used to reduce the vibration of system subjected to variable excitation frequency. 1. Introduction Dynamic vibration absorbers are used to reduce undesirable vibrations in many applications such as electrical transmission lines, helicopters gas turbines, engines, and bridges. Traditional treatment methods of vibration control that involve structural modifications are often time consuming and expensive. Some of them can be used as tunable vibration absorbers to control vibrations. Tunable dynamic vibration absorber which is simple to construct can be easily tuned to excitation frequency to minimize the vibrations and can be effectively used to minimize vibrations of structure. Absorber with variable frequencies can be used to minimize vibrations of structures having variable frequency drive. Dynamic vibration absorbers (DVAs) were first invented in 1909 by Hermann Frahm, and since then it has been successfully used to suppress wind-induced vibration and seismic response in buildings. In recent studies, interest has also been focused on the use of feedback and feedforward control systems and the synthesis of DVAs for multiple-degree-of-freedom systems. Igarasi et al. [1] have developed a magnetic dynamic vibration absorber with adjustable natural frequency, in these three permanent magnets arranged with opposite pole to each other. Repelling force between two magnets was used as spring constant. In 1993 they developed a dynamic vibration absorber using permanent magnets to suppress the vibrations of beam
Design of Hybrid Dynamic Balancer and Vibration Absorber  [PDF]
Y. R. Wang,C. Y. Lo
Shock and Vibration , 2014, DOI: 10.1155/2014/397584
Abstract: This study proposed a novel hybrid dynamic balancer and vibration absorber that is cheaper than active dampers and more effective than passive dampers. The proposed damping system does not need to be altered structurally to deal with different damping targets. Rather, the proposed vibration absorber is capable of self-adjustment to the optimal damping location in order to achieve balance and, thereby, optimize damping effects. The proposed device includes a groove under the damping target with inertial mass hung from a coil spring beneath. This allows the device to bounce vertically or rotate in order to reduce vibrations in the main body. The coil spring vibration absorber can also slide along the groove in order to adjust its location continuously until the vibrations in the system are minimized and the main body is balanced. Experiments verify the efficacy of the proposed device in improving damping performance beyond what has been achieved using conventional devices. We also provide an explanation of the theoretical underpinnings of the design as well as the implications of these findings with regard to future developments. 1. Introduction Vibration can affect the stability of a structure, and constant vibration can lead to fatigue and structural damage. Babitsky and Veprik [1] studied vibration suppression from the perspective of balance using an elastic beam with a sliding washer damping system. Their results proved that this type of self-damping system is capable of eliminating resonance and decreasing beam vibration. Another approach to maintaining balance is the ball-type automatic balancer system (ABS), comprising several balls moving along a fixed circular orbit. Under proper conditions, the balls move to specific positions of equilibrium, thereby suppressing unbalanced vibrations. The application of this approach in optical disk drives was outlined by Chao et al. [2, 3]. Lu and Hung [4] proposed the balancing of components using two or three balls. Their approach proved to be three times more effective than using a single-ball balancer system. Based on these achievements, this study sought to extend the application of free-moving components in vibrating rigid bodies for the elimination of vibration. Vibration damping methods can roughly be divided into two types: active and passive. Generally speaking, active damping is the most effective approach to vibration damping; however, most conventional machine tools vibrate in the vertical direction, which is best dealt with using a tuned-mass damper (TMD) comprising a mass and one or more springs.
The Nonlinear Tuned Vibration Absorber  [cached]
Viguié R.,Kerschen G.
MATEC Web of Conferences , 2012, DOI: 10.1051/matecconf/20120105007
Abstract: The objective of this paper is to introduce a new nonlinear dynamical absorber, the nonlinear tuned vibration absorber, through a rigorous nonlinear extension of the tuning rule for the linear tuned vibration absorber. This nonlinear tuning methodology combined with the increased suppression bandwidth brought by the intentional use of nonlinearity leads to the development of an absorber that is effective in wide ranges of frequencies and motion amplitudes. The results are illustrated using a one-degree-of-freedom primary system.
Influence of Non-Structural Localized Inertia on Free Vibration Response of Thin-Walled Structures by Variable Kinematic Beam Formulations  [PDF]
Alfonso Pagani,Francesco Zangallo,Erasmo Carrera
Shock and Vibration , 2014, DOI: 10.1155/2014/141982
Abstract: Variable kinematic beam theories are used in this paper to carry out vibration analysis of isotropic thin-walled structures subjected to non-structural localized inertia. Arbitrarily enriched displacement fields for beams are hierarchically obtained by using the Carrera Unified Formulation (CUF). According to CUF, kinematic fields can be formulated either as truncated Taylor-like expansion series of the generalized unknowns or by using only pure translational variables by locally discretizing the beam cross-section through Lagrange polynomials. The resulting theories were, respectively, referred to as TE (Taylor Expansion) and LE (Lagrange Expansion) in recent works. If the finite element method is used, as in the case of the present work, stiffness and mass elemental matrices for both TE and LE beam models can be written in terms of the same fundamental nuclei. The fundamental nucleus of the mass matrix is opportunely modified in this paper in order to account for non-structural localized masses. Several beams are analysed and the results are compared to those from classical beam theories, 2D plate/shell, and 3D solid models from a commercial FEM code. The analyses demonstrate the ineffectiveness of classical theories in dealing with torsional, coupling, and local effects that may occur when localized inertia is considered. Thus the adoption of higher-order beam models is mandatory. The results highlight the efficiency of the proposed models and, in particular, the enhanced capabilities of LE modelling approach, which is able to reproduce solid-like analysis with very low computational costs. 1. Introduction to Refined Beam Theories In engineering practice, problems involving non-structural masses are of special interest [1]. An important example is that of aerospace engineering. In aerospace design, in fact, non-structural masses are commonly used in finite element (FE) models to incorporate the weight of the engines, fuel, and payload, see, for example, [2–5]. In this paper, the effects due to localized inertia on free vibration of thin-walled beams are investigated through one-dimensional (1D) higher-order models. A brief overview about the evolution of refined beam theories is given below. A number of refined beam theories have been proposed over the years to overcome the limitation of classical beam models such as those by Euler [6] (hereinafter referred to as EBBM) and Timoshenko [7, 8] (hereinafter referred to as TBM). If the rectangular cartesian coordinate system shown in Figure 1 is adopted and we consider bending on the -plane, the kinematic
Vehicle wheels vibration suppression by dynamic vibration absorber
Zinovij STOTSKO
Transport Problems : an International Scientific Journal , 2007,
Abstract: The article deals with the methods of calculation and optimization ofdynamic processes in vibroexcitated constructions with dynamic absorbers. The improved constructions of such absorbers for vehicle wheels vibration suppression are discussed.
自适应主动共振吸振器的设计和减振性能研究
On the Design of Adaptive Active Resonant Vibration Absorber and its Vibration Damping Effect
 [PDF]

闫立勋,周鸿,彭超,龚兴龙
- , 2015, DOI: 10.7520/1001-4888-15-125
Abstract: 为了扩大吸振器的工作频带,减小吸振器的阻尼,最终提高吸振器的减振效果,本文设计了一种自适应主动共振吸振器。文中对几种不同种类吸振器的减振原理、动力学特性等进行了理论分析和比较,集成自调谐吸振器和主动吸振器的优点,完成了一种自适应主动共振吸振器的设计,并提出了一种变步长、双寻优的控制算法。在振动台上测试了吸振器的动力学特性并理论分析了吸振器的移频特性和阻尼特性。在两端固支梁上对吸振器的减振效果进行了实验评估。实验结果显示,相比自调谐吸振器,加入主动力控制后,自适应主动共振吸振器的阻尼比从0.04减小至0.02,减振效果得到了显著的提高。
In order to expand vibration absorber frequency bandwidth and reduce its damping, and finally to improve its vibration damping effect, the design of a novel adaptive active resonant vibration absorber is presented in this paper. Based on theoretical analysis and comparison of vibration reduction principle and dynamic characteristics of several different kinds of absorbers, and taking advantage the merits of adaptive tuned vibration absorber (ATVA) and active vibration absorber (AVA), a design of adaptive active resonant vibration absorber (AARA) was completed, and a double variable step length optimization algorithm was also put forward. Dynamic properties of proposed AARA were experimentally studied on platform vibrator and its frequency shift range and damping characteristics were theoretically analyzed. An experimental evaluation of AARA vibration damping effect was carried out on a both ends clamped beam. Experimental results demonstrate that comparing with adaptive tuned vibration absorber, the damping ratio of AARA decreases from 0.04 roughly to 0.02 due to adding active force control. Consequently, AARA vibration damping effect is significantly improved
电涡流耗能动力吸振器设计与试验研究
Eddy Current Vibration Absorber Design and Experiments
 [PDF]

李斌,牛文超,徐兆懿
- , 2016,
Abstract: 针对飞机垂尾抖振抑制的需要,提出一种空间布局紧凑、基于非接触式电涡流耗能机理、阻尼可设计的动力吸振器设计方案。电涡流耗能机制的引入保证该动力吸振器具有良好的环境适应性、耐久性和可靠性。基于电磁场理论,建立了电涡流阻尼力的计算模型,获得电磁阻尼的设计规律,通过与试验结果对比,验证了电涡流阻尼模型的准确性。并以等效悬臂梁结构为对象,应用最优参数设计原理确定动力吸振器参数,设计制造了动力吸振器样机。试验结果表明,该电涡流动力吸振器具有良好的吸振性能,最大减幅比可达98%。
Aiming at the need of vertical tail buffet suppression, a design scheme of dynamic vibration absorber with compact layout and adjustable damping is proposed; this is based on the mechanism of eddy current energy dissipation. Eddy current energy dissipation can ensure that the dynamic vibration absorber has good environmental adaptability, durability and reliability. Based on the electromagnetic theory, the calculation model of eddy current damping force is established and the design rule of eddy damping force is concluded. Through the comparison between the calculations and the experiments, the validation and accuracy of eddy current damping force model are verified. Taking an equivalent cantilever beam system as the object of vibration control, and on the basis of the theory of dynamic vibration absorber optimal design, we determined the optimal parameters of dynamic vibration absorber and completed the design and manufacture of eddy current dynamic vibration absorber prototype. Experimental results show that the maximum amplitude of cantilever beam can be decreased at most by 98%, and the proposed eddy current dynamic vibration absorber has obvious vibration-absorption effect
基于新型材料的吸振器设计及电流控制方法
Design of Broadband Vibration Absorber and Current Control Method
 [PDF]

宋伟志,姚永玉,赵海军,赵红霞,岳遂录,陈智勇
- , 2018, DOI: 10.16450/j.cnki.issn.1004-6801.2018.05.021
Abstract: 被动式吸振器(passive dynamic vibration absorber,简称PDVA)结构参数不可调,减振频带单一,不适用于宽频减振。为解决上述问题,首先,以磁流变弹性体(magnetorh eological elastomer,简称MRE)为刚度元件,设计一种刚度可调的自适应吸振器(adaptive dynamic vibration absorber,简称ADVA);其次,对弹性体原料组成及磁流变效应进行介绍和分析;然后,对受控系统增加吸振器,引起系统新的共振问题提出了吸振器工作过程中的电流控制方法以消除新增的共振现象;最后,进行了仿真及实验研究。结果表明,本设计可将减振频带拓宽至11.37 Hz,并且利用提出的电流控制方法可有效消除系统新增的共振峰。
Passive dynamic vibration absorber (PDVA), whose structural parameters can not be adjusted and vibration frequency band is single, is not suitable for broadband vibration. To solve the above problem, first, the magnetorheological elastomer (MRE) is used as the stiffness element to design an adaptive dynamic vibration absorber (ADVA). Second, the composition and MR effect of MRE are introduced and analyzed. Then, the current control method in the process of dynamic vibration absorber is proposed to eliminate the new resonance phenomenon which is caused by the addition of a vibration absorber to the controlled system. Finally, the simulation and experiment results show that the design can broaden the vibration frequency band to 11.37Hz. At the same time, the new resonant peak of the controlled system is eliminated effectively by the proposed control method.
Confinement of Vibrations in Variable-Geometry Nonlinear Flexible Beam  [PDF]
W. Gafsi,F. Najar,S. Choura,S. El-Borgi
Shock and Vibration , 2014, DOI: 10.1155/2014/687340
Abstract: In this paper, we propose a novel strategy for controlling a flexible nonlinear beam with the confinement of vibrations. We focus principally on design issues related to the passive control of the beam by proper selection of its geometrical and physical parameters. Due to large deflections within the regions where the vibrations are to be confined, we admit a nonlinear model that describes with precision the beam dynamics. In order to design a set of physical and geometrical parameters of the beam, we first formulate an inverse eigenvalue problem. To this end, we linearize the beam model and determine the linearly assumed modes that guarantee vibration confinement in selected spatial zones and satisfy the boundary conditions of the beam to be controlled. The approximation of the physical and geometrical parameters is based on the orthogonality of the assumed linear mode shapes. To validate the strategy, we input the resulting parameters into the nonlinear integral-partial differential equation that describes the beam dynamics. The nonlinear frequency response curves of the beam are approximated using the differential quadrature method and the finite difference method. We confirm that using the linear model, the strategy of vibration confinement remains valid for the nonlinear beam. 1. Introduction Vibration is one of the major problems that influence the performance of flexible structures. Vibration is a natural phenomenon that is unavoidable whatever its size may be, including conventional systems, such as aircraft wings, robot manipulators, blades in turning engines, crank mechanisms, and nonconventional systems that include large space structures, arm-type positioning mechanisms of magnetic disk drives, and microbeams in microelectromechanical systems. In certain cases, vibration excites unwanted resonances characterized by intolerable amplitudes. Because of the need for controlling structural vibrations and satisfying the increasing demand on security, accuracy, and long-life of these structures, researches focused on synthesizing control strategies, which are classified into three types: active [1, 2], passive [3, 4], and hybrid [5, 6]. Allaei [7] showed that vibration confinement is a superior control issue over the conventional control in isolating the sensitive parts of a structure. It has the potential to confine the vibrational energy, to reduce the control effort, and to optimize the required sensors and actuators. Choura et al. [8] proposed a design methodology for vibration confinement in nonhomogeneous rods. They established conditions for
Testing Results of the Prototype Beam Absorber for the PXIE MEBT  [PDF]
Curtis Baffes,Alexander Shemyakin
Physics , 2015,
Abstract: One of the goals of the PXIE program at Fermilab is to demonstrate the capability to form an arbitrary bunch pattern from an initially CW 162.5 MHz H^{-} bunch train coming out of an RFQ. The bunch-by-bunch selection will take place in the 2.1 MeV Medium Energy Beam Transport (MEBT) by directing the undesired bunches onto an absorber that needs to withstand a beam power of up to 21 kW, focused onto a spot with a ~2 mm rms radius. A prototype of the absorber was manufactured from molybdenum alloy TZM, and tested with an electron beam up to the peak surface power density required for PXIE, 17W/mm2. Temperatures and flow parameters were measured and compared to analysis. This paper describes the absorber prototype and key testing results.
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