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Journal articles on the topic 'Motion; Vibration damping'
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1
Iskakov, Zharilkassin. "SIMULATION OF NON-LINEAR CHARACTERISTICS INFLUENCE DYNAMIC ON VERTICAL RIGID GYRO ROTOR RESONANT OSCILLATIONS." CBU International Conference Proceedings 6 (September 25, 2018): 1094–100. http://dx.doi.org/10.12955/cbup.v6.1319.
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The influence of viscous linear and cubic nonlinear damping of an elastic support on the resonance oscillations of a vertical rigid gyroscopic unbalanced rotor is investigated. Simulation results show that linear and cubic non-linear damping can significantly dampen the main harmonic resonant peak. In non-resonant areas where the speed is higher than the critical speed, the cubic non-linear damping can slightly dampen rotor vibration amplitude in contrast to linear damping. If linear or cubic non-linear damping increase in resonant area significantly kills capacity for absolute motion, then they have little or no influence on the capacity for absolute motion in non-resonant areas. The simulation results can be successfully used to create passive vibration isolators used in rotor machines vibration damping, including gyroscopic ones.
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You, Ki Pyo, Young Moon Kim, Cheol Min Yang, and Dong Pyo Hong. "Increasing Damping Ratios in a Tuned Liquid Damper Using Damping Bars." Key Engineering Materials 353-358 (September 2007): 2652–55. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.2652.
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Wind-induced vibration of tall buildings have been of interest in engineering for a long time. Wind-induced vibration of a tall building can be most effectively controlled by using passive control devices. The tuned liquid damper(TLD) is kind of a passive mechanical damper, which relies on the sloshing liquid in a rigid tank. TLD has been successfully employed in practical mitigation of undesirable structural vibrations because it has several potential advantages: low costs, easy installation in existing structures, and effectiveness even against small-amplitude vibrations. Shaking table experiments were conducted to investigate the characteristics of the shallow water sloshing motion in a rectangular tank. To increase the damping ratio of the rectangular water tank, triangle sticks were installed at the bottom of water tank. This installation increased the damping ratio by amaximum of 40-70%.
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Sarangi, M., B. C. Majumdar, and A. S. Sekhar. "On the Dynamics of Elastohydrodynamic Mixed Lubricated Ball Bearings. Part II: Non-Linear Structural Vibration." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 219, no. 6 (June 1, 2005): 423–33. http://dx.doi.org/10.1243/135065005x34080.
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Equations of motion of a ball bearing are formulated in generalized coordinates, using Lagrange's equation considering the vibrational characteristics of the individual constituents such as inner race, outer race, cage, and balls, in order to investigate the structural vibration of the bearing. This article is the second part of the present study dealing with structural vibration, whereas in the first part, elastohydrodynamic mixed lubricated contact stiffness and damping coefficients are determined. Utilizing these stiffness and damping coefficients, a non-linear load-deflection contact model is developed. This is then used in the equations of motion. The equations of motion are solved using Runge-Kutta integration technique. This work differs from the previous studies in the sense that the model simulates the vibration, considering that both the lubricated contact stiffness and damping correspond to the conservative and dissipative energies, respectively. It is observed that under undamped conditions, all the elements of the bearing actively participate in energy sharing and oscillate periodically, containing more than one frequency. The system vibration, however, died down rapidly in the presence of damping.
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Yu, Jianda, Zhibo Duan, Xiangqi Zhang, and Jian Peng. "Wind-Induced Vibration Control of High-Rise Structures Using Compound Damping Cables." Shock and Vibration 2021 (April 22, 2021): 1–9. http://dx.doi.org/10.1155/2021/5537622.
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Based on the vibration reduction mechanism of compound damping cables, this study focuses on the wind-induced vibration control of high-rise structures with additional mass at the top. The differential equation of motion of the system under the action of the composite damping cable is established, and the analytical solution of the additional damping ratio of the structure is deduced, which is verified by model tests. The vibration response of the structure under the action of simple harmonic vortex excitation and randomly fluctuating wind loads is studied, and the effect of different viscous coefficients of the dampers in the composite damping cable and different installation heights of the damping cable on the vibration control is analyzed. The results show that a small vortex excitation force will cause large vibrations of low-dampened towering structures, and the structure will undergo buffeting under the action of wind load pulse force. The damping cable can greatly reduce the amplitude of structural vibration. The root means square of structural vibration displacement varies with damping. The viscosity coefficient of the device and the installation height of the main cable of the damping cable are greatly reduced.
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Inoue, Masanobu, Isao Yokomichi, and Koju Hiraki. "Particle Damping with Granular Materials for Multi Degree of Freedom System." Shock and Vibration 18, no. 1-2 (2011): 245–56. http://dx.doi.org/10.1155/2011/309682.
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A particle damper consists of a bed of granular materials moving in cavities within a multi degree-of-freedom (MDOF) structure. This paper deals with the damping effects on forced vibrations of a MDOF structure provided with the vertical particle dampers. In the analysis, the particle bed is assumed to be a single mass, and the collisions between the granules and the cavities are completely inelastic, i.e., all energy dissipation mechanisms are wrapped into zero coefficient of restitution. To predict the particle damping effect, equations of motion are developed in terms of equivalent single degree-of-freedom (SDOF) system and damper mass with use made of modal approach. In this report, the periodic vibration model comprising sustained contact on or separation of the damper mass from vibrating structure is developed. A digital model is also formulated to simulate the damped motion of the physical system, taking account of all vibration modes. Numerical and experimental studies are made of the damping performance of plural dampers located at selected positions throughout a 3MDOF system. The experimental results confirm numerical prediction that collision between granules and structures is completely inelastic as the contributing mechanism of damping in the vertical vibration. It is found that particle dampers with properly selected mass ratios and clearances effectively suppress the resonance peaks over a wide frequency range.
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Aoki, Shigeru, and Takeshi Watanabe. "An Investigation of an Impact Vibration Absorber With Hysteresis Damping." Journal of Pressure Vessel Technology 128, no. 4 (February 16, 2006): 508–15. http://dx.doi.org/10.1115/1.2349557.
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The dynamic vibration absorber is a device for reducing the vibration of many structures and mechanical equipment. It consists of a small mass which is attached to the primary vibrating system or main mass. The impact damper is one of such dynamic vibration absorbers in which motion of auxiliary mass is limited by motion-limiting stop or placed inside a container. In this paper, in order to consider energy loss for an impact represented by the coefficient of restitution and duration of collision, an analytical model with hysteresis damping is introduced. Using this model, dynamic response of the system under harmonic and that under random excitations are analyzed. Some numerical results are shown.
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Rezaei DA, Hojjat, Mahmoud Kadkhodaei, and Hassan Nahvi. "Analysis of nonlinear free vibration and damping of a clamped–clamped beam with embedded prestrained shape memory alloy wires." Journal of Intelligent Material Systems and Structures 23, no. 10 (May 6, 2012): 1107–17. http://dx.doi.org/10.1177/1045389x12441509.
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Nonlinear free vibration and damping of a clamped–clamped composite beam containing shape memory alloy wires with different prestrains embedded in the midsurface are investigated. The constitutive relations of shape memory alloy are considered in the large deflection response of the elastic Euler–Bernoulli beam, and Hamilton’s principle is used to derive differential equation of the beam motion with extensible midplane. Considering midplane stretching due to tension in the shape memory alloy wires provides an ability to model damping in a nonlinear analysis although there is no distinct damping expression in the governing equation of motion. The results show a gradual decrease in the free vibration amplitude of the beam until it reaches a fully elastic response while this cannot be seen in linear models. Free vibrations of the beam are investigated, and time response, phase diagram, state of stress and strain in the wires, and variations of loss factor are studied. The effect of prestrain in the shape memory alloy wires on the final stable vibration amplitude and loss factor in free vibrations of the beam is also investigated.
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Zolkiewski, Sławomir, and Leszek Dziczkowski. "Mathematical Model of the Damped Variable Cross Section Beam in Transportation." Advanced Materials Research 837 (November 2013): 517–22. http://dx.doi.org/10.4028/www.scientific.net/amr.837.517.
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The paper concerns the problem of vibrations of beamlike system with variable cross section. The beam is treated as the movable system in transportation. The considered problem focuses on modelling and dynamic analysis of geometrically nonlinear beam systems in rotational motion within the context of damping. The major scientific purpose of the paper is to elaborate the mathematical model of such a system. Additionally, the main motion impact on the local vibrations due to the mathematical sense is determined. Moreover, it is necessary to remember the interactions between damping forces of the above mentioned mechanisms and the transportation effect. The main motion of the system is treated as transportation, whereas the vibrations of the system are treated as relative motion. There are two types of systems considered: simple vibrating longitudinally and simple vibrating transversally in the plane transportation. The most interesting elements of the analysis determine the dynamic state of the system and present the mutual coupling of vibration amplitudes, natural frequency, and transportation velocity. Analysis of systems moving with low velocities or vibrating only locally treats the systems as already known models in literature. There are many scientific articles where the forms of vibrations of these systems have been described. Due to the obtained results it will be possible to confront mathematical models with the known stationary and non-stationary systems. As regards complex and simple systems running at high speed, the resonance phenomenon can be noticed, and depending on the amplitude and frequency of vibrations, we consider the following cases: when the amplitude reaches theoretical infinity leading in practice to permanent damage of the mechanism or when the amplitude of vibration reaches a certain speed which can cause the decrease of durability of the whole system. The adequate practical usage of the above mentioned researches is justified by its wide range of applications. In the majority of technical cases, further analysis of the systems is considered to be far too much simplified when we ignore the elements of flexibility, damping, or the nonlinear geometry of the beam. All the mentioned influences are presented in the derived mathematical model in form of equations of motion.
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Issa, J. S. "Ground motion isolation using a newly designed vibration absorber." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, no. 3 (October 12, 2011): 636–47. http://dx.doi.org/10.1177/0954406211417548.
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A new vibration absorber setup for vibration attenuation in single degree of freedom systems subjected to harmonic base motion is proposed. The absorber is placed so as to separate between the vibrating ground and the main undamped system. It consists of a mas spring damper directly connected to the vibrating ground. The main system is modelled as a mass spring attached to the absorber's mass. The optimal absorber parameters are determined with the aim of reducing the steady-state amplitude of the main mass. It is shown that the amplitude of the main mass passes through three fixed points, two of which are used in the determination of the optimal shape of the transfer function. One of the fixed points is independent of the damping ratio and the second is independent of both the damping and tuning ratios. For this setup, the solution is not unique since the ultimate design is reached by a complete isolation of the main mass from the moving ground and is attained by removing the absorber's damper and stiffness. Since this solution is not physically achievable, for a given mass ratio of the system, the smallest tuning ratio which ensures structural integrity of the system is selected. The optimal damping ratio which yields the optimal shape of the objective function is determined analytically in terms of the mass and tuning ratios. A design flowchart is presented to be used for the design of such absorbers.
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Fang, X., and J. Tang. "Granular Damping in Forced Vibration: Qualitative and Quantitative Analyses." Journal of Vibration and Acoustics 128, no. 4 (February 2, 2006): 489–500. http://dx.doi.org/10.1115/1.2203339.
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Granular damping is a passive vibration suppression technique which attenuates the response of a vibrating structure by the use of a granule-filled enclosure attached to or embedded in the structure. While promising in many applications especially under harsh conditions, the granular damping mechanism is very complicated and highly nonlinear. In this paper, we perform correlated analytical modeling and numerical studies to evaluate qualitatively and quantitatively the energy dissipation in granular damping. First, an improved analytical model based on the multiphase flow theory is developed for the description of granular motion inside the damper, which accounts for the complete effects of collisions/impacts and dynamic frictions among the granules and between the granules and the enclosure. This model can efficiently characterize the damping effect with high fidelity over a very wide range of parameters, and thus can be used to develop guidelines for parametric studies. With this as a basis, detailed numerical studies using the discrete element method are also carried out to analyze the underlying mechanisms and then provide mechanistic insight for granular damping. In this paper, we focus our attention on the granular damping effect on forced vibrations, which has potential application to a variety of systems.
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Ren, Yongsheng, and Yuhuan Zhang. "Free Vibration and Damping of Rotating Composite Shaft with a Constrained Layer Damping." Shock and Vibration 2016 (2016): 1–20. http://dx.doi.org/10.1155/2016/9045460.
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The free vibration and damping characteristics of rotating shaft with passive constrained layer damping (CLD) are studied. The shaft is made of fiber reinforced composite materials. A composite beam theory taking into account transverse shear deformation is employed to model the composite shaft and constraining layer. The equations of motion of composite rotating shaft with CLD are derived by using Hamilton’s principle. The general Galerkin method is applied to obtain the approximate solution of the rotating CLD composite shaft. Numerical results for the rotating CLD composite shaft with simply supported boundary condition are presented; the effects of thickness of constraining layer and viscoelastic damping layers, lamination angle, and rotating speed on the natural frequencies and modal dampings are discussed.
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SU, Dongxu, Kimihiko NAKANO, Rencheng ZHENG, and Matthew P. CARTMELL. "2A23 Stiffness tunable nonlinear vibrational energy harvester with damping control(The 12th International Conference on Motion and Vibration Control)." Proceedings of the Symposium on the Motion and Vibration Control 2014.12 (2014): _2A23–1_—_2A23–9_. http://dx.doi.org/10.1299/jsmemovic.2014.12._2a23-1_.
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Veselovska, Natalia, Oksana Zelinska, Yaroslav Ivanchuk, and Olena Gnatyuk. "MODELING OF OPERATING MODES OF VIBRATION AND VIBRATION DAMPING MACHINES." ENGINEERING, ENERGY, TRANSPORT AIC, no. 1(104) (June 27, 2019): 56–63. http://dx.doi.org/10.37128/2520-6168-2019-1-7.
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In previous studies, studies were conducted on the main modes of inertial load during the development of technological processes of forming blanks of powder materials by the method of vibro-impact pressing. The design of the model of the inertial vibropress hammer and the description of its parameters makes it possible to select different pressing modes, to evaluate the effectiveness of their application. Various mathematical models of the system were used in constructing exact solutions at the stages of movement between shocks and at the moments of spivudaryan. They were described by linear differential equations or finite ratios of stereomechanical theory of impact, which were introduced as boundary conditions of the process. It is advisable to build and analyze a single form of writing the equations of motion for the driving elements of machines on the entire time axis, which describe the complete set of realizable motions. This is achieved through the introduction of nonlinear relationships, reflecting the process of force interaction of the collision or their elements.
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Liu, Y. C., and S. M. Yang. "Three Simple and Efficient Methods for Vibration Control of Slewing Flexible Structures." Journal of Dynamic Systems, Measurement, and Control 115, no. 4 (December 1, 1993): 725–30. http://dx.doi.org/10.1115/1.2899205.
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Three simple and efficient methods are presented for the vibration control of slewing flexible structures. These methods are developed based on the constrained motion method in which the rotational maneuver is formulated as prescribed trajectory constraint. The constrained motion method in two stage, CMM-TS, accomplishes the first stage rigid-body slewing motion and minimizes the flexible body vibration at terminal state by an optimal control law. The constrained motion method with active damping, CMM-AD, employs piezoelectric actuator with velocity feedback for active damping control. The required slewing time and settling time is governed by the control torque and control voltage, respectively. The third method, CMM-CO, combines the active damping and optimal torque control for vibration suppression during and after the slewing motion. All methods are shown to be efficient in computation, concise in formulation, and effective in hardware realizable application.
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Bian, Yushu, Zhihui Gao, and Ming Fan. "A Vibration Control Method for the Flexible Arm Based on Energy Migration." Shock and Vibration 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/382145.
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A vibration control method based on energy migration is proposed to decrease vibration response of the flexible arm undergoing rigid motion. A type of vibration absorber is suggested and gives rise to the inertial coupling between the modes of the flexible arm and the absorber. By analyzing 1 : 2 internal resonance, it is proved that the internal resonance can be successfully created and the exchange of vibration energy is existent. Due to the inertial coupling, the damping enhancement effect is revealed. Via the inertial coupling, vibration energy of the flexible arm can be dissipated by not only the damping of the vibration absorber but also its own enhanced damping, thereby effectively decreasing vibration. Through numerical simulations and analyses, it is proven that this method is feasible in controlling nonlinear vibration of the flexible arm undergoing rigid motion.
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Akpan, U. O., and M. R. Kujath. "Stochastic Vibration of a Mobile Manipulator." Journal of Applied Mechanics 64, no. 3 (September 1, 1997): 670–75. http://dx.doi.org/10.1115/1.2788945.
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The stochastic vibration of a flexible, articulated, and mobile manipulator is studied. The manipulator is mounted on a vehicle which is supported by a suspension system. Stochastic excitation of the manipulator is induced by the uniform horizontal motion of the vehicle on a traction surface. The power spectral density representation and the state-space representation are used to derive expressions for the covariance matrices of the manipulator tip motions. Sensitivity of the variance of the tip motion to the manipulator configuration, length, vehicle velocity, surface roughness coefficient, and structural damping and stiffness are explored. Suggestions for mobile manipulator design to minimize the influence of the stochastic base vibration on the manipulator tip motion are proposed.
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Polukoshko, Svetlana, Vladimirs Gonca, and Jurujs Svabs. "Vibration Damping Using Laminated Elastomeric Structures." Solid State Phenomena 220-221 (January 2015): 81–90. http://dx.doi.org/10.4028/www.scientific.net/ssp.220-221.81.
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The work considers using a multilayer elastomeric package for the vibroisolation of engineering constructions under the action of periodic vibration. The multilayer elastomeric package is located between the protected object and a vibrating base; it consists of alternating thin metallic and elastomeric layers jointed by vulcanization or gluing. The paper discusses flat rubber-metal elements of circular shapes with reinforcing steel layers and describes kinematic excitation directed flatwise. The analytical expression of the characteristics of the compression stiffness of the plane multilayered elastomeric structure is derived on the basis of the variational principle, and metallic plates-layers are assumed to be perfectly rigid. An analytical solution was confirmed by experimental data. The fitted equation for “force-displacement” was derived and used in the equation of motion on of the protected object.
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Teo, Chek Sing, Chea Jack Ong, C. J. Ho, S. Huang, and K. K. Tan. "Precision Motion Control with Active Eddy Current Damper." Key Engineering Materials 447-448 (September 2010): 493–97. http://dx.doi.org/10.4028/www.scientific.net/kem.447-448.493.
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This paper describes the design and proof of concept for an active eddy current damper which is integrated into a single-axis linear motor. Although developments on active eddy current damper are well documented, none has been implemented in a linear motor. The advantage of such a system is two-fold. Firstly, the relative motion between the magnets and the conducting sheet produces eddy currents resulting in an electromagnetic force opposing the direction of motion; which can be utilized to suppress vibrations. Secondly, it is possible to enhance the damping effect of the system; Due to environmental noise, it is normally not possible to increase the D coefficient in a PID controller as much as desirable. The damper is thus able to supplement this damping effect to improve settling time. Here, we will present the damper design as well as the preliminary experiment results for both vibration suppression and motion damping.
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Barry, O., R. Long, and DCD Oguamanam. "Simplified Vibration Model and analysis of a single-conductor transmission line with dampers." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 22 (July 15, 2016): 4150–62. http://dx.doi.org/10.1177/0954406216660736.
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A novel model is developed for a vibrating single-conductor transmission line carrying Stockbridge dampers. Experiments are performed to determine the equivalent viscous damping of the damper. This damper is then reduced to an equivalent discrete mass-spring-mass and viscous damping system. The equations of motion of the model are derived using Hamilton’s principle and explicit expressions are determined for the frequency equation, and mode shapes. The proposed model is verified using experimental and finite element results from the literature. This proposed model excellently captures free vibration characteristics of the system and the vibration level of the conductor, but performs poorly in regard to the vibration of the counterweights.
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LITAK, GRZEGORZ, GRZEGORZ SPUZ-SZPOS, KAZIMIERZ SZABELSKI, and JERZY WARMIŃSKI. "VIBRATION OF EXTERNALLY-FORCED FROUDE PENDULUM." International Journal of Bifurcation and Chaos 09, no. 03 (March 1999): 561–70. http://dx.doi.org/10.1142/s0218127499000407.
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Motion of self-excited Froude pendulum under external forcing were analyzed. Differential equation of motion includes the nonlinear damping term of Rayleigh's type. Using multiple time scale method and Lyapunov theory, vibrations, synchronization and stability of the system were examined. Chaotic motion was analyzed here by means of Lyapunov exponent and Melnikov approach.
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Krenk, Steen. "Frequency Analysis of the Tuned Mass Damper." Journal of Applied Mechanics 72, no. 6 (May 15, 2005): 936–42. http://dx.doi.org/10.1115/1.2062867.
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The damping properties of the viscous tuned mass damper are characterized by dynamic amplification analysis as well as identification of the locus of the complex natural frequencies. Optimal damping is identified by a combined analysis of the dynamic amplification of the motion of the structural mass as well as the relative motion of the damper mass. The resulting optimal damper parameter is about 15% higher than the classic value, and results in improved properties for the motion of the damper mass. The free vibration properties are characterized by analyzing the locus of the natural frequencies in the complex plane. It is demonstrated that for optimal frequency tuning the damping ratio of both vibration modes are equal and approximately half the damping ratio of the applied damper, when the damping is below a critical value corresponding to a bifurcation point. This limiting value corresponds to maximum modal damping and serves as an upper limit for damping to be applied in practice.
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Mitsuya, Yasunaga, Hidekazu Sawai, Masaki Shimizu, and Yasushi Aono. "Damping in Vibration Transfer Through Deep-Groove Ball Bearings." Journal of Tribology 120, no. 3 (July 1, 1998): 413–20. http://dx.doi.org/10.1115/1.2834564.
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Damping characteristics in vibration transfer through deep-groove ball bearings were measured precisely using a single ball bearing (equivalent to the 6200 type) and the compliance transfer function resulting from the impulses applied to the bearing. To eliminate uncertainties caused by bearing assembly and preloading, a monolithic-type ball bearing was specially fabricated by unifying its inner ring with a shaft, and its outer ring with a rotor. This structure enables preloading without the need for any solid contact using an externally pressurized air bearing. Experimental damping ratios were found to range from two to four percent and damping coefficients 0.15-0.35 Ns/mm. Damping was found to decrease with an increasing preload, and to be larger for a larger clearance and for a larger ball number. The decreases in damping resulting from superimposing the tilting mode vibration upon the lateral mode and from an increasing clearance indicated more ball rolling motion rather than slipping motion to be the cause of decreased damping. Also, the bearing rotation effect is found to be small. Addition of grease hardly provided any additional damping during rotation.
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Griffin, J. H., and C. H. Menq. "Friction Damping of Circular Motion and Its Implications to Vibration Control." Journal of Vibration and Acoustics 113, no. 2 (April 1, 1991): 225–29. http://dx.doi.org/10.1115/1.2930173.
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When vibrating bodies are mutually constrained through friction contact they may move with respect to each other and dissipate energy at the interface. If the relative motion of the contacting surfaces follows a straight line the motion is said to be one-dimensional. This case has been examined extensively in the literature. More generally the point of contact can follow a path which is not a straight line. For the case of a periodic response the path will form a closed loop. In this paper we investigate the simplest, yet most extreme case of two dimensional motion—when the contacting point moves in a circular path. It is found that an exact solution can be derived for the problem of a frictionally constrained system when it is subjected to a circular excitation. The solution is used to determine the characteristics of the system’s response and they are compared with those for one-dimensional motion. In the case of one-dimensional motion if the contacting surfaces are compliant they will stick for at least a portion of each cycle. This is not the case for circular motion as it is found that the interface is either always stuck for small motions or always slipping if the excitation is above a certain level. This result suggests that the slip/stick transition which occurs during every cycle for the one-dimensional case may not be as important for the more general two-dimensional friction contact problem. Friction is often a major source of energy dissipation in vibrating machinery. As a result, the friction contact is sometimes used to reduce the peak response of the system by designing the contacting parts so as to have an optimum friction constraint. In order to investigate this effect expressions are derived for the peak amplitude as a function of the friction force, for the friction force that will minimize peak response, and for the amplitude of the peak response under optimum friction conditions. The results for circular motion are compared with those for straight line motion in order to assess the importance of two-dimensional effects.
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Wang, Hui Ping. "Calculation on Modal Damping Ratio of Stay Cable Using Nonlinear Friction Damper." Advanced Materials Research 538-541 (June 2012): 1800–1803. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.1800.
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Stay cables of long span cable-stayed bridges are easy to vibrate under wind or wind/rain loads owning to their very low inherent damping. To install cable dampers near to the anchorages of cable has become a common practice for cable vibration control of cable-stayed bridge structures. In this study, the behaviors of a nonlinear frictional type of damper were investigated. The equations of motion of a cable with a friction damper were derived by using a lumped mass model. Then by introducing modal transformation, the analytical solution for the motion equations was obtained. The results show that the friction damper evokes linearly decaying of free vibrations of the cable as long as the damper does not lock the cable. The modal damping ratio of cable with the friction damper is strongly amplitude dependent. Calculation of modal damping ratio can be simplified using control parameter and the maximum modal damping ratio can be obtained. A universal estimation curve is proposed that is similar to linear viscous damper. These studies could provide design basis for the vibration mitigation of stay cables using nonlinear friction.
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Gao, Pei-xin, Jing-yu Zhai, Fu-zheng Qu, and Qing-kai Han. "Vibration and damping analysis of aerospace pipeline conveying fluid with constrained layer damping treatment." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 232, no. 8 (February 19, 2017): 1529–41. http://dx.doi.org/10.1177/0954410017692367.
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The constrained layer damping materials are thoroughly used to control the vibration duo to their high capacity to dissipate vibration energy. Researchers have handled the vibration and damping behavior of the constrained layer damping structures accurately. However, for the constrained layer damping pipeline conveying fluid, there are few works on the investigation of the vibration characteristics. This paper is aimed to investigate the vibration and damping characteristics of the constrained layer damping pipeline conveying fluid under elastic boundary supports. Considering the fluid–structure interaction, the developed finite element method is employed to establish the motion equations of the constrained layer damping pipeline. The influence of the support stiffness, the fluid velocity and pressure, the thickness and the elasticity modulus of viscoelastic, and constraining layer parameters are all considered. The results indicate that an appropriate selection of the boundary support stiffness, the viscoelastic, and constraining layer parameters can obtain desirable modal properties, which can provide an efficient tool in the design and maintenance of aerospace pipeline for passive vibration control.
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Yuan, Ying Cai, Yan Li, and Yi Ming Wang. "Study on the Influence of the Damping to Nonlinear Vibration Caused by Pair Clearance." Advanced Materials Research 139-141 (October 2010): 2376–80. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.2376.
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Because the two components have relative motion, pair clearance is inevitable. With the machine’s speed increasing, nonlinear vibration phenomenon caused by clearance is much obviously. The state of damping in pair clearance will often make mechanism’s nonlinear vibration appear different status. For the study of damping in joint clearances impact to nonlinear vibration, four-bar mechanism with clearance is taken as research object. A nonlinear dynamic model has been established based on continuous contact model. Through analysis the nonlinear vibration in different damping and clearance, it can be found that in weak damping condition, nonlinear vibration in small pair clearance is more sensitive to the small changes of damping than that in large pair clearance. So, it’s very important to keep the pair clearance in proper lubrication conditions.
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Lin, B. C., and A. S. Papageorgiou. "Demonstration of Torsional Coupling Caused by Closely Spaced Periods—1984 Morgan Hill Earthquake Response of the Santa Clara County Building." Earthquake Spectra 5, no. 3 (August 1989): 539–56. http://dx.doi.org/10.1193/1.1585539.
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The parameters of the dominant modes of vibration of the steel-framed Santa Clara County Office Building in San Jose, California, are determined using “the modal minimization method” for structural identification. The optimal estimates of the model parameters are determined by minimizing a selected measure-of-fit between the responses of the structure and the model. Two types of models are used: (1) A planar linear model with classical damping and (2) A three dimensional linear model consisting of rigid floor decks, where each floor is allowed three degrees of freedom - two orthogonal translations plus a rotation. The Santa Clara County Office Building continued vibrating in a free vibration manner with very low damping, long after the intense part of ground motion had ended. The records of its torsional motion exhibit a strong beating effect which is explained by the strong coupling of torsional and translational modes of vibration. Such a strong coupling of modes of vibration is attributed to the proximity of the value of torsional stiffness to that of translational stiffnesses.
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Ashrafiuon, H. "Optimal Design of Vibration Absorber Systems Supported by Elastic Base." Journal of Vibration and Acoustics 114, no. 2 (April 1, 1992): 280–83. http://dx.doi.org/10.1115/1.2930258.
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This paper presents the effect of foundation flexibility on the optimum design of vibration absorbers. Flexibility of the base is incorporated into the absorber system equations of motion through an equivalent damping ratio and stiffness value in the direction of motion at the connection point. The optimum values of the uncoupled natural frequency and damping ratio of the absorber are determined over a range of excitation frequencies and the primary system damping ratio. Optimal design parameters are computed and compared for the rigid, and flexible models of the base as well as different levels of base flexibility.
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Popp, Karl, and Martin Rudolph. "Vibration Control to Avoid Stick-Slip Motion." Journal of Vibration and Control 10, no. 11 (November 2004): 1585–600. http://dx.doi.org/10.1177/1077546304042026.
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Friction-induced self-sustained oscillations result in a very robust limit cycle that characterizes stick-slip motion. This type of motion should be avoided under any circumstances because it creates noise, wear, and damage. In this paper we show, by simple models, how stick-slip motion can be avoided. Effective methods are: (i) appropriate increase of internal damping that compensates the negative damping induced by a friction characteristic, which decreases with increasing sliding speed; (ii) external excitation that breaks up the limit cycle (however, this often leads to chaotic motion); (iii) passive vibration control by fluctuating normal forces. The last mentioned mechanism is new and will be investigated in detail. The stick-slip oscillator is extended by an additional degree of freedom, which couples the slipping motion to the normal force. The dynamic behavior of the system has been worked out by analytical investigations and numerical integration. Scanning a broad range of values, parameters of the additional system, called the dynamic vibration absorber, have been found that prevent stick-slip and minimize the amplitude of the residual limit cycle. For this task the evaluation of the system behavior has been achieved by observing its energy content. The feasibility of the proposed dynamic vibration absorber is demonstrated by an experiment.
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Zhang, Chao, De Jiang Shang, and Qi Li. "Investigation on Vibro-Acoustic Characteristics from Submerged Cylindrical Shell with Double Damping Layers." Applied Mechanics and Materials 345 (August 2013): 94–98. http://dx.doi.org/10.4028/www.scientific.net/amm.345.94.
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The vibration and sound radiation from submerged cylindrical shell with double damping layers are presented. The cylindrical shell motion was described with classical thin shell theory. The double damping layers motion was described with the Navier viscoelasticity theory. For different Youngs modulus parameters of double damping layers, the sound radiated power and the radial quadratic velocity of cylindrical shell models were calculated and analyzed. The results show that the sound radiated power and radial quadratic velocity are reduced to varying degrees due to double damping layers in a large frequency domain except low frequency. The double damping layer with soft inner layer and hard outer layer can make the sound radiated peaks move to high frequency, can help to reduce the radial quadratic velocity on outer surface of damping layer, and can help to reduce the vibration of model at antiresonance frequency.
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Hou, Yong Jun. "Dynamics Analysis of Vibrating Screen Based on Double Compound Pendulum with Single Motor Driving." Applied Mechanics and Materials 459 (October 2013): 335–41. http://dx.doi.org/10.4028/www.scientific.net/amm.459.335.
Full textAbstract:
By Lagrange equation, the dynamic equation of vibrating screen based on double compound pendulum with single motor driving was established. With simulation method, dynamic simulating model was built, and influences of pendulum installing position, stiffness of torsion damping spring of pendulum rod, initial installing angle and length of pendulum rod on motion characteristics of vibrating screen was discussed. Research results showed that, by choosing suitable stiffness of torsion damping spring or length of pendulum rod, this kind of vibrating screen may achieve the approximate linear trajectory, or normal elliptic trajectory of deck; when the angle between the rotating joint of pendulum rod and screen surface equals to initial installing angle of pendulum rod, the vibration of deck is most close to translational motion..
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Okada, Yohji, Ken-Ichi Matsuda, and Junji Tani. "Active Vibration Control of a Thin Steel Sheet." Shock and Vibration 2, no. 1 (1995): 15–22. http://dx.doi.org/10.1155/1995/182535.
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The commercial rolling process used in the steel industry to manufacture thin steel sheets tends to cause plate vibrations that lower the quality of the surface finish. This article introduces a noncontact method of active vibration control for reducing the flexural vibrations of a thin steel sheet. The proposed electromagnetic method of control has been implemented in a simple experimental setup where the signal from a motion sensor regulates the attractive force of the magnets that produce a damping force on the steel sheet.
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Grover, D. "Damping in thin circular viscothermoelastic plate resonators." Canadian Journal of Physics 93, no. 12 (December 2015): 1597–605. http://dx.doi.org/10.1139/cjp-2014-0575.
Full textAbstract:
The governing equations of transverse motion and heat conduction of a homogenous, isotropic, thermally conducting, Kelvin–Voigt-type medium, based on Kirchhoff–Love plate theory, are established for out-of-plane vibrations of a generalized viscothermoelastic circular thin plate. The analytical expressions for thermoelastic damping of vibration and frequency shift are obtained for generalized and coupled viscothermoelastic plates. It is noticed that the damping of vibrations significantly depends on mechanical relaxation times and thermal relaxation time in addition to thermomechanical coupling in a circular plate under resonance conditions. The surface conditions also impose significant effects on the vibrations of such resonators. The numerical results may also be illustrated in the case of a circular plate and an axisymmetric circular plate for clamped and simply supported boundary conditions for fixed aspect ratio, fixed radius, and fixed thickness, respectively.
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Luo, H., and S. Hanagud. "On the Dynamics of Vibration Absorbers With Motion-Limiting Stops." Journal of Applied Mechanics 65, no. 1 (March 1, 1998): 223–33. http://dx.doi.org/10.1115/1.2789030.
Full textAbstract:
The dynamics of a class of vibration absorbers with elastic stops is discussed in this paper. The mechanical model proposed in previously published papers are modified to explain certain nonlinear effects, chaotic vibrations, and lower damping observed in our studies. Refined contact-noncontact criteria are presented. Exact steady-state solutions are obtained for a piecewise linear system by using the proposed contact-noncontact criteria. Numerical simulations are presented and compared with the results of the previous work. Significant differences that have been found include some chaotic responses of the system. Experiments are conducted to validate the theoretical results. Chaotic and period-2 responses are also detected experimentally.
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Khatri, K. N. "Vibration Control of Conical Shells Using Viscoelastic Materials." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 206, no. 3 (May 1992): 167–78. http://dx.doi.org/10.1243/pime_proc_1992_206_113_02.
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The vibration and damping analysis of multi-layered conical shells incorporating layers of viscoelastic materials in addition to elastic ones, the former causing dissipation of vibratory energy, is the subject matter of this paper. The analysis given herein uses Hamilton's variational principle for deriving equations of motion of a general multi-layered conical shell. In view of the correspondence principle of linear viscoelasticity which is valid for harmonic vibrations, the solution is obtained by replacing the moduli of viscoelastic layers by complex moduli. An approximate solution for axisymmetric vibrations of multi-layered conical shells with two end conditions—simply supported edges and clamped edges—is obtained by utilizing the Galerkin procedure. The damping effectiveness in terms of the system loss factor for all families of modes of vibrations for three-, five- and seven-layered shells is evaluated and its variation with geometrical parameters is investigated.
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Liu, Lin, and Huang Cheng Fang. "Parametric Selection of Dynamic Vibration Absorbers for Resonant Suppression of Structure-Absorber Systems." Applied Mechanics and Materials 723 (January 2015): 31–35. http://dx.doi.org/10.4028/www.scientific.net/amm.723.31.
Full textAbstract:
The selection of absorber parameters is of utmost significance for structural vibration control by dynamic vibration absorbers. Based on the classical frequency tuning approach by Den Hartog, optimal damping ratio is derived in close form by equating the dynamic magnification factors of the structural motion at three particular frequencies of interest. In addition, by maximizing the two identical modal damping ratios through root locus in the first quadrant of complex plane, the corresponding absorber damping ratio is derived and proposed as the upper bound of the absorber damping ratio for practical applications.
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Zhang, Yuanlin, Xuefeng Liu, Weichong Rong, Peixin Gao, Tao Yu, Huawei Han, and Langjun Xu. "Vibration and Damping Analysis of Pipeline System Based on Partially Piezoelectric Active Constrained Layer Damping Treatment." Materials 14, no. 5 (March 4, 2021): 1209. http://dx.doi.org/10.3390/ma14051209.
Full textAbstract:
Pipelines work in serious vibration environments caused by mechanical-based excitation, and it is thus challenging to put forward effective methods to reduce the vibration of pipelines. The common vibration control technique mainly uses the installation of dampers, constrained layer damping materials, and an optimized layout to control the vibration of pipelines. However, the passive damping treatment has little influence on the low frequency range of a pipeline system. Active control technology can obtain a remarkable damping effect. An active constrained layer damping (ACLD) system with piezoelectric materials is proposed in this paper. This paper aims to investigate the vibration and damping effect of ACLD pipeline under fixed support. The finite element method is employed to establish the motion equations of the ACLD pipeline. The effect of the thickness and elastic modulus of the viscoelastic layer, the laying position, and the coverage of ACLD patch, and the voltage of the piezoelectric material are all considered. The results show that the best damping performance can be obtained by selecting appropriate control parameters, and it can provide effective design guidance for active vibration control of a pipeline system.
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Cai, Wenhua, Bujun Yu, Fajong Wu, and Jianhua Shao. "Seismic Response and Vibration Reduction Analysis of Suspended Structure under Wave Passage Excitation." Advances in Civil Engineering 2020 (July 21, 2020): 1–13. http://dx.doi.org/10.1155/2020/6468181.
Full textAbstract:
In order to study the influence of traveling wave effect on the seismic response and damping effect of suspended structure, a series of shaking table tests of the 1 : 20 suspended structure have been carried out to compare and analyze the dynamic responses of suspended structures under two points and a consistent input. The vibration damping effect and vibration reduction law of suspended structure are discussed at different apparent wave velocity and in the different connection. The research shows that the damping suspended structure has a good damping effect, and the amplitude reduction of the top displacement peak response is up to 15%, which corresponds to smaller apparent velocities. Moreover, the upper bound of the maximum acceleration response at the structures’ top under nonuniform input motions equals that of the uniform motion. However, there is a hysteresis in the acceleration response under wave travelling excitations, and the smaller the apparent wave velocity, the more obvious the hysteresis.
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Lamrhari, M. "Vibration with non-linear damping. stochastic approach." MATEC Web of Conferences 286 (2019): 01005. http://dx.doi.org/10.1051/matecconf/201928601005.
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This paper describes a stochastic approach to the vibration behavior of a nonlinear damping structure. The deterministic approach is based on motion equations including the non-linearity of damping. For the stochastic calculation, the deviations were assigned to the input parameters of the mathematical model. The probabilistic distribution of these parameters must reflect real operational situations. Numerical simulations were performed with MATLAB using the Monte Carlo and perturbation method. The resulting curves for the parameters studied can find a practical application in the optimization of rotating machines (washing machine), where the parameters of mass, position of the center of gravity, etc. change during operation.
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Kim, Seon-Jae, and Youn-Sik Park. "Self-motion utilization for reducing vibration of a structurally flexible redundant robot manipulator system." Robotica 16, no. 6 (November 1998): 669–77. http://dx.doi.org/10.1017/s0263574798000770.
Full textAbstract:
This paper focuses on overcoming the problem of tracking control in structurally flexible redundant manipulators by utilizing their self-motion capabilities. In the proposed algorithm, the self-motion is evaluated in order to nullify the dominant modal force of flexural motion that is induced by a rigid body motion.The flexure motions of manipulators, which are induced by joint motion, cause undesired inaccuracy in end-effector tracking. In-plath planning states, joint trajectories are so designed as not to excite but to damp out the flexure motions. The self-motion, inherent in redundant manipulators, can alter joint motion, influencing the flexure motion (by exciting and damping the flexure modes), while not affecting end-effector motion at all. Therefore, the self-motion can be utilized to regulate flexibility and effectively reduce the end-effector tracking error.The effectiveness and applicability of the proposed algorithm have been demonstrated through numerical simulation with three-link planar robotic manipulators possessing flexible links.
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Vaswani, J., N. T. Asnani, and B. C. Nakra. "Vibration and Damping Analysis of Curved Multilayered Beams." Transactions of the Canadian Society for Mechanical Engineering 9, no. 2 (June 1985): 59–63. http://dx.doi.org/10.1139/tcsme-1985-0008.
Full textAbstract:
Governing equations of motion for a general curved multilayered beam with alternate elastic and viscoelastic layers, subjected to harmonic excitation are derived using an energy method. A solution for simply supported end conditions has been obtained, to determine the resonant frequencies and associated system loss factors of beams with 3, 5 and 7 layers. Both constant size and constant weight criteria have been used for comparison.
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Rahn, C. D., and C. D. Mote. "Axial Force Stabilization of Transverse Vibration in Pinned and Clamped Beams." Journal of Dynamic Systems, Measurement, and Control 118, no. 2 (June 1, 1996): 379–80. http://dx.doi.org/10.1115/1.2802333.
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An axial force stabilizes the transverse vibration of a beam with pinned and/or clamped boundary conditions. The nonlinearly coupled, longitudinal and transverse equations of motion of the beam with axial force control are simplified using a quasistatic assumption for longitudinal motion. It is shown that axial damping can ensure weak asymptotic stability of transverse vibration.
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Zapoměl, Jaroslav, Vladimír Dekýš, Petr Ferfecki, Alžbeta Sapietová, Milan Sága, and Milan Žmindák. "Identification of Material Damping of a Carbon Composite Bar and Study of Its Effect on Attenuation of Its Transient Lateral Vibrations." International Journal of Applied Mechanics 07, no. 06 (December 2015): 1550081. http://dx.doi.org/10.1142/s1758825115500817.
Full textAbstract:
Reduction of noise and vibrations is one of the major requirements put on operation of modern machines. It can be achieved by application of new materials. The ability to utilize them properly requires learning more about their mechanical properties. Vibration attenuation depends on material damping as an important factor. This paper presents the results of research in a carbon composite material focusing on its internal damping, on the measurement of the damping coefficients and on its implementation into mathematical models. The obtained results were used for investigation of suppressing lateral vibrations of a long homogeneous carbon composite bar oscillating in the resonance area. During the transient period and due to nonlinear effects, the harmonic time-varying loading excites the bar response consisting of a number of harmonic components. The specific damping capacity referred to several oscillation frequencies determined by measurement. The results were evaluated from the point of view of two simple damping theories — viscous and hysteretic. The experiments showed that internal damping of the investigated material could be considered as frequency independent. Therefore, in order to carry out simulations, the bar was represented in the computational model by an Euler beam constituted of Maxwell–Weichert theoretical material. A suitable setting of material constants enabled reaching a constant value of the damping parameters in the required frequency range. The investigated bar vibration is governed by the motion equation in which the internal damping forces depend not only on instantaneous magnitudes of the system’s kinematic parameters but also on their past history. Solution of the equations of motion was performed after its transformation into the state space in the time domain. Results of the computational simulations showed that material damping significantly reduced amplitude of the bar vibrations in the resonance area. The producers of composite materials usually provide material parameters allowing to solve various stationary problems (density, modulus of elasticity, yielding point, strength, etc.), but there is only little or almost no information concerning the data needed for carrying out dynamical or other time-dependent analyses such as internal damping coefficients, fatigue limit, etc. Therefore, determination of the hysteretic character of material damping of the investigated carbon composite material, measurement of its specific damping capacity and implementation of the frequency-independent damping into the computational model are the principal contributions of this article.
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Lee, Seung-Yop, and C. D. Mote. "Wave Characteristics and Vibration Control of Translating Beams by Optimal Boundary Damping." Journal of Vibration and Acoustics 121, no. 1 (January 1, 1999): 18–25. http://dx.doi.org/10.1115/1.2893942.
Full textAbstract:
The transverse motion of a translating tensioned Euler-Bernoulli beam is controlled by passive or active damping applied at a boundary. Even for an undamped beam with a symmetric boundary configuration, the interaction between the translating continuum and the stationary or moving boundary leads to energy variation in free motion. With the time-varying energy chosen as a Lyapunov functional, boundary control laws are designed based on Lyapunov’s second method. For various types of translating beams, energy dissipation by boundary damping is quantified using the method of traveling waves. The optimal value of damping, maximizing the energy dissipation, is also explicitly represented by system parameters. The analytical results are compared with numerical simulations using the finite difference scheme.
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Ünker, Faruk, and Olkan Çuvalcı. "Optimum Tuning of a Gyroscopic Vibration Absorber for Vibration Control of a Vertical Cantilever Beam with Tip Mass." June 2019 24, no. 2 (June 2019): 210–16. http://dx.doi.org/10.20855/ijav.2019.24.21158.
Full textAbstract:
In this paper, a symmetric gyro with coupling to the tip mass of a beam mounted on a vibrating base is considered. Taking advantage of the angular momentum of the rotating gyroscope, gyrostabilizer systems are expected to become more widely actualized as they provide an effective means of motion control with several significant advantages for various structures. This paper mainly focused on finding optimized stiffness and damping values that minimize the vibration responses with the derivation of the frequency equations of a special combined gyro-beam system. Correctness of the analytical results is verified by numerical simulations. The comparison with the results from the derivation of the corresponding frequency equations shows that the optimized stiffness and damping values are very accurate.
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Shen, I. Y., Weili Guo, and Y. C. Pao. "Torsional Vibration Control of a Shaft Through Active Constrained Layer Damping Treatments." Journal of Vibration and Acoustics 119, no. 4 (October 1, 1997): 504–11. http://dx.doi.org/10.1115/1.2889752.
Full textAbstract:
This paper proposes a hybrid damping design to control torsional vibration of a shaft with a circular cross section through use of actively constrained layer (ACL) damping treatments proposed by Baz (1993) and Shen (1993, 1994a). The ACL damping treatment consists of a piezoelectric constraining layer and a viscoelastic shear layer wrapping around the shaft in the form of a helix. In addition, the angular displacement of the shaft is fed back to regulate the helical motion of the piezoelectric constraining layer. The equation of motion of this design is derived, and its stability and controllability are discussed. Finally, numerical examples show that this ACL design can reduce torsional vibration of a shaft. A sensitivity analysis shows that ACL is most effective in suppressing those modes with significant torsional vibration response. Stability, in general, is not a critical factor in designing ACL systems, because the piezoelectric strain of the constraining layer at the threshold of instability is too large to occur.
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Ling, Zheng, Xie Ronglu, Wang Yi, and Adel El-Sabbagh. "Topology Optimization of Constrained Layer Damping on Plates Using Method of Moving Asymptote (MMA) Approach." Shock and Vibration 18, no. 1-2 (2011): 221–44. http://dx.doi.org/10.1155/2011/830793.
Full textAbstract:
Damping treatments have been extensively used as a powerful means to damp out structural resonant vibrations. Usually, damping materials are fully covered on the surface of plates. The drawbacks of this conventional treatment are also obvious due to an added mass and excess material consumption. Therefore, it is not always economical and effective from an optimization design view. In this paper, a topology optimization approach is presented to maximize the modal damping ratio of the plate with constrained layer damping treatment. The governing equation of motion of the plate is derived on the basis of energy approach. A finite element model to describe dynamic performances of the plate is developed and used along with an optimization algorithm in order to determine the optimal topologies of constrained layer damping layout on the plate. The damping of visco-elastic layer is modeled by the complex modulus formula. Considering the vibration and energy dissipation mode of the plate with constrained layer damping treatment, damping material density and volume factor are considered as design variable and constraint respectively. Meantime, the modal damping ratio of the plate is assigned as the objective function in the topology optimization approach. The sensitivity of modal damping ratio to design variable is further derived and Method of Moving Asymptote (MMA) is adopted to search the optimized topologies of constrained layer damping layout on the plate. Numerical examples are used to demonstrate the effectiveness of the proposed topology optimization approach. The results show that vibration energy dissipation of the plates can be enhanced by the optimal constrained layer damping layout. This optimal technology can be further extended to vibration attenuation of sandwich cylindrical shells which constitute the major building block of many critical structures such as cabins of aircrafts, hulls of submarines and bodies of rockets and missiles as an invaluable design tool.
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Ingard, K. Uno, and Adnan Akay. "On the Vibration Damping of a Plate by Means of a Viscous Fluid Layer." Journal of Vibration and Acoustics 109, no. 2 (April 1, 1987): 178–84. http://dx.doi.org/10.1115/1.3269411.
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Vibration damping of a plate by means of a fluid layer is investigated. First, the frequency-dependent flow resistance of a fluid layer is explained with a simple illustration of the damping mechanism. Then, the vibration response of a plate is examined when it is backed by a rigid plane or another flexible plate with a fluid layer constricted in-between. Effects of the plate motion and acoustic radiation on the damping mechanism are also considered. The numerical results are presented in terms of frequency response of the plates.
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Walker, Mario P., Masaaki Okuma, and Hiraku Sakamoto. "Attenuation of tall flexible structures using longitudinal moving mass: Moving finite element method." Noise & Vibration Worldwide 48, no. 9-10 (September 25, 2017): 119–31. http://dx.doi.org/10.1177/0957456517728619.
Full textAbstract:
For the foreseeable future, tall building structures will be built taller and more flexible, which means more vulnerable to excitations. As such, there is considerable interest in developing structural control methods to protect against harmful vibrations. However, challenges present themselves for conventional mass damper systems as these tend to primarily utilise lateral motion which becomes very limited as the height of structures increases. This article proposes a novel approach to reduce tall building’s long-period oscillations using mass damper motion in the much larger longitudinal direction. This motion induces Coriolis effect and if manoeuvred properly can be used to effectively reduce vibration of the primary structure. Numerical analysis was done using finite element method. The Shinjuku Mitsui Building was used as a benchmark for the primary structure, which was modelled as a vertical cantilever beam. The results showed the concept to be a viable approach for damping long-period vibrations of flexible structures. Enhancing this effect was also introduced and briefly discussed, using a multiple-degree-of-freedom damper and a constant positive velocity water-flow damper as examples. Further work continues for optimum design of the concept to make it a practical approach for tall buildings. Additionally, investigation into enhancing the damping effect is being done in more detail. This approach provides new possibilities for vibration control of any long-period structure.
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Xiao, Linjing, and Qiang Liu. "Analysis of the Deep Sea Mining Pipe Transverse Vibration Characteristics Based on Finite Element Method." Mathematical Problems in Engineering 2021 (July 5, 2021): 1–20. http://dx.doi.org/10.1155/2021/8216439.
Full textAbstract:
This paper analyzes the transverse vibration laws of 5000 m ladder-shaped mining pipe under different towing velocities and accelerations in the ocean, thinking of the pipe as the beam model, discretized based on the FEM. The algorithm is used to solve the problem to obtain the transverse vibration law. The research shows that the mining pipe overall transverse vibration trend decreases first and then increases, the minimum vibration value occurs at 3000 m, and the maximum occurs at the top. Increasing the towing velocity, acceleration, and ore bin weight will increase the transverse vibration value. The vibration intensity produced by the same acceleration in the constant acceleration and deceleration stages is different, and the damping effect after adding the same damping is also different. In the range of 0.01 m/s2–0.1 m/s2, the vibration reduction effect after adding damping in the constant deceleration stage is more significant, and in the range of 0.1 m/s2-0.2 m/s2, the vibration reduction effect after adding damping in the constant acceleration stage is more significant. In the stage of the constant acceleration or deceleration, when adding the same damping, the vibration intensity generated by the large acceleration is still far greater than the vibration intensity generated by the small acceleration, so the mining ship should keep the small acceleration for towing motion.