Journal articles: 'Dynamic damping'

1

Gudmestad, Ove T. "Transient motions of an oscillating system caused by forcing terms proportional to the velocity of the structural motion." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 369, no. 1947 (July 28, 2011): 2881–91. http://dx.doi.org/10.1098/rsta.2011.0107.

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Damping limits the motions of an oscillator, which is a dynamic system. The selection of formulations for damping is discussed. If the forcing of the dynamic system contains terms that are proportional to the velocity of motion of the oscillator (drag-type forcing functions), these effects will additionally contribute to dampening the oscillations. Should the total damping under certain conditions become apparently negative, the oscillations will grow until the damping has again become positive. Investigations into damping effects that apparently are negative, and discussions where apparent negative damping might appear in practical applications are of great interest.

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Chernyshev, V., and O. Fominova. "Dynamic Damping Process Control." Procedia Engineering 206 (2017): 272–78. http://dx.doi.org/10.1016/j.proeng.2017.10.473.

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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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Feireisl, Eduard. "Dynamic von Kármán equations involving nonlinear damping: Time-periodic solutions." Applications of Mathematics 34, no. 1 (1989): 46–56. http://dx.doi.org/10.21136/am.1989.104333.

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Liang, Huiqi, Wenbo Xie, Peizi Wei, Dehao Ai, and Zhiqiang Zhang. "Identification of Dynamic Parameters of Pedestrian Walking Model Based on a Coupled Pedestrian–Structure System." Applied Sciences 11, no. 14 (July 12, 2021): 6407. http://dx.doi.org/10.3390/app11146407.

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As human occupancy has an enormous effect on the dynamics of light, flexible, large-span, low-damping structures, which are sensitive to human-induced vibrations, it is essential to investigate the effects of pedestrian–structure interaction. The single-degree-of-freedom (SDOF) mass–spring–damping (MSD) model, the simplest dynamical model that considers how pedestrian mass, stiffness and damping impact the dynamic properties of structures, is widely used in civil engineering. With field testing methods and the SDOF MSD model, this study obtained pedestrian dynamics parameters from measured data of the properties of both empty structures and structures with pedestrian occupancy. The parameters identification procedure involved individuals at four walking frequencies. Body frequency is positively correlated to the walking frequency, while a negative correlation is observed between the body damping ratio and the walking frequency. The test results further show a negative correlation between the pedestrian’s frequency and his/her weight, but no significant correlation exists between one’s damping ratio and weight. The findings provide a reference for structural vibration serviceability assessments that would consider pedestrian–structure interaction effects.

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Rasmussen, F., J. T. Petersen, and H. A. Madsen. "Dynamic Stall and Aerodynamic Damping." Journal of Solar Energy Engineering 121, no. 3 (August 1, 1999): 150–55. http://dx.doi.org/10.1115/1.2888426.

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Riso̸ has developed a dynamic stall model that is used to analyze and reproduce open air blade section measurements as well as wind tunnel measurements. The dynamic stall model takes variations in both angle of attack and flow velocity into account. The paper gives a brief description of the dynamic stall model and presents results from analyses of dynamic stall measurements for a variety of experiments with different airfoils in wind tunnel and on operating rotors. The wind tunnel experiments comprises pitching as well as plunging motion of the airfoils. The dynamic stall model is applied for derivation of aerodynamic damping characteristics for cyclic motion of the airfoils in flapwise and edgewise direction combined with pitching. The investigation reveals that the airfoil dynamic stall characteristics depend on the airfoil shape, and the type of motion (pitch, plunge). The aerodynamic damping characteristics, and thus the sensitivity to stall induced vibrations, depend highly on the relative motion of the airfoil in flapwise and edgewise direction, and on a possibly coupled pitch variation, which is determined by the structural characteristics of the blade.

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7

Yttervoll, Per O., and Karl J. Eidsvik. "Dynamic estimation of hydrodynamic damping." Ocean Engineering 14, no. 5 (January 1987): 377–88. http://dx.doi.org/10.1016/0029-8018(87)90051-5.

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8

Silva, Demian G., and Paulo S. Varoto. "Effects of Variations in Nonlinear Damping Coefficients on the Parametric Vibration of a Cantilever Beam with a Lumped Mass." Mathematical Problems in Engineering 2008 (2008): 1–19. http://dx.doi.org/10.1155/2008/185351.

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Uncertainties in damping estimates can significantly affect the dynamic response of a given flexible structure. A common practice in linear structural dynamics is to consider a linear viscous damping model as the major energy dissipation mechanism. However, it is well known that different forms of energy dissipation can affect the structure's dynamic response. The major goal of this paper is to address the effects of the turbulent frictional damping force, also known as drag force on the dynamic behavior of a typical flexible structure composed of a slender cantilever beam carrying a lumped-mass on the tip. First, the system's analytical equation is obtained and solved by employing a perturbation technique. The solution process considers variations of the drag force coefficient and its effects on the system's response. Then, experimental results are presented to demonstrate the effects of the nonlinear quadratic damping due to the turbulent frictional force on the system's dynamic response. In particular, the effects of the quadratic damping on the frequency-response and amplitude-response curves are investigated. Numerically simulated as well as experimental results indicate that variations on the drag force coefficient significantly alter the dynamics of the structure under investigation.

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Wang, Ji Cheng, Hong Mei Liu, and Gao Yan. "Effect of Damping Ditch in Dynamic Compaction." Applied Mechanics and Materials 353-356 (August 2013): 284–88. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.284.

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Damping ditch was dug beside the underground pipeline so as to prevent housing from damage and reduce displacement of underground pipelines caused by dynamic vibration. Different damping ditches were simulated and field measurement was tested. Research shows that vibration and squeezing effect cannot be neglected, and damping ditch can decrease the vibration and squeezing effect. The deeper and nearer to the housing the damping ditch is, the better the damping effect is. The underground pipelines displacement is slight, when the damping ditch is between underground pipelines and tamping points and much closer to the former. Otherwise, if the damping ditch is considerably closer to the tamping points, the displacement is comparatively large.

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10

Cui, Ling Zhi, Gao Min Li, Yi Ting He, Qin Liao, and Fei Luo. "Status Analysis of the Frozen Soil’s Dynamics Parameter Study." Advanced Materials Research 941-944 (June 2014): 2626–30. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.2626.

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In this paper, the author points out several key problems needed to be solved about the dynamics of frozen soil by reviewing related literatures about hysteretic curve of frozen soil ,dynamic constitutive relation and dynamical parameter. The problems are the insufficient understanding on morphological characteristics of hysteretic curve and how to transform qualitative understanding into quantitative understanding about morphological characteristics of hysteretic curve. The problem is the rationality of selecting the dynamic constitutive model, namely how to establish the engineering applicable model which conforms to the actual soil mechanics performance.The problem is the rationality of the calculation method about dynamic elastic modulus and damping ratio, namely how to define dynamic modulus of elasticity of frozen soil correctly and the limitation of using the classical method to calculate the damping.

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11

Keskinen, R. P. "Dynamic Stability of Pipes Under Jet Forces From a Circumferential Through-Crack." Journal of Pressure Vessel Technology 109, no. 3 (August 1, 1987): 329–35. http://dx.doi.org/10.1115/1.3264873.

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An investigation is made into the dynamic stability of a pipe with a postulated circumferential through-crack. The dynamic deformation of the pipe is found to control the ensuing jet force in such a manner that positive or negative damping results, depending on the local mode shape geometry. The leak is governed by quasi-steady fluid dynamics, which permits a simple closed-form evaluation of the damping energy for a crack geometry idealized from existing LEFM solutions. Energy losses develop via structural damping and plastic dissipation at the crack tip; the latter is estimated using the Irwin’s plastic zone correction approach. Application to a PWR plant primary circuit piping suggests that structural damping in practice rules out the instability.

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Chen, Xiao Ming, Jin Duan, Hu Qi, and Yun Gui Li. "Rayleigh Damping in Abaqus/Explicit Dynamic Analysis." Applied Mechanics and Materials 627 (September 2014): 288–94. http://dx.doi.org/10.4028/www.scientific.net/amm.627.288.

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In the nonlinear time-history analysis for high-rise building, different damping models may lead to results with great difference. Limited by the stable time increment, the stiffness proportional damping is usually neglected in Abaqus/Explicit, and only a simplified mass proportional damping is used, which can be derived from the fundamental frequency and the critical damping factor. In this paper, the influence on the results of this method has been researched by numerical examples, the numerical results also show that the stiffness proportional damping cannot be neglected. Based on these comparisons, a more reasonable damping model is presented for improving the results of high frequencies.

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13

Viet, LD. "A single mass dynamic vibration absorber producing linear damping, Coriolis damping and gyro-damping." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 4 (November 24, 2015): 506–13. http://dx.doi.org/10.1177/0954406215618227.

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To reduce the vibration of a planar pendulum, this paper proposes a single mass dynamic vibration absorber (DVA), which can simultaneously produce linear damping, Coriolis damping and gyro-damping. The proposed DVA contains a rotor inside a gimbal. The rotor has a constant angular speed and its axis is direct to the fulcrum. At the same time, the gimbal can move in the normal and tangential directions of the pendulum orbit. The translations in tangential and normal directions and the gimbal rotation result in the linear damping, Coriolis damping and gyro-damping, respectively. Because each type of damping has advantages and disadvantages, the combined DVA has the improved performance. A numerical demonstration is carried out to show the effectiveness of the proposed DVA.

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14

Niu, Lei, Quan Jie Song, Shuang Xu, and Xiao Ming Guo. "Dynamic Experimental Study on Highly Weathered Granite." Applied Mechanics and Materials 518 (February 2014): 132–37. http://dx.doi.org/10.4028/www.scientific.net/amm.518.132.

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The shear modulus and damping ratio are two important index in equivalent nonlinear model which is widely used in seismic response analysis. GDS resonant-column is used to study the shear modulus and damping ratio of highly weathered granite by controlling the consolidation confining pressure and pore water pressure. Variation of resonant frequency, shear modulus and damping ratio can be observed when different effective stress which is changed with confining pressure and pore water pressure applied on the sample. Hadin-Drnevich fitting curves are given on the basis of experimental data, and damping mechanism of highly weathered granite is discussed by making use of frictional theory. We can conclude from the results that there is a positive correlation between resonance frequency and shear strain, while there is a negative correlation between samples damping ratio and shear strain. The effective stress impact both samples shear modulus and damping ratio. However, pore water pressure can only act on damping ratio.

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15

Xue, Ruan, Li, Bai, and Xiao. "Nonlinear Dynamic Modelling of Two-Point and Symmetrically Supported Pipeline Brackets with Elastic-Porous Metal Rubber Damper." Symmetry 11, no. 12 (December 4, 2019): 1479. http://dx.doi.org/10.3390/sym11121479.

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This paper aims to investigate the nonlinear dynamic properties of a two-point and symmetrically supported pipeline bracket system coated with the damping element using an elastic-porous metal rubber. The dynamic model of the studied two-point and symmetric pipeline system was established based on impulse response matrix for accurate and reliable description on its nonlinear behaviours, e.g., energy dissipation and loss factor. The experimental verification of the developed model was performed by means of dynamic test as well as the analyses of nonlinear damping characteristics. The experimental results show a good agreement with the prediction results obtained from the proposed dynamic model. This work provides an alternative method to investigate the dynamics of pipeline vibration system equipped with a damping structure.

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Sahto, Muhammad Punhal, Wei Wang, Ali Nawaz Sanjrani, Chengxu Hao, and Sadiq Ali Shah. "Dynamic Performance of Partially Orifice Porous Aerostatic Thrust Bearing." Micromachines 12, no. 8 (August 20, 2021): 989. http://dx.doi.org/10.3390/mi12080989.

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The aerostatic thrust bearing’s performance under vibration brings certain changes in stiffness and stability, especially in the range of 100 to 10,000 Hz, and it is accompanied by significant increase in fluctuations due to the changes in frequency, and the size of the gas film damping. In this research work, an analysis is carried out to evaluate the impact of throttling characteristics of small size orifice on stiffness and stability optimization of aerostatic thrust bearings. There are two types of thrust bearing orifices such as: partial porous multiple orifice and porous thrust bearings and their effects on variations in damping and dynamic stiffness are evaluated. A simulation based analysis is carried out with the help of the perturbation analysis model of an aerostatic thrust bearing simulation by using FLUENT software (CFD). Therefore, two models of aerostatic thrust bearings—one with the porous and other with partial porous orifice are developed—are simulated to evaluate the effects of perturbation frequencies on the damping and dynamic stiffness. The results reveal a decrease in the amplitude of dynamics capacity with an increase in its frequency, as well as a decrease in the damping of partial porous aerostatic thrust bearings with an increase in the number of orifices. It also reveals an increase in the radius of an orifice with an increment of damping of bearing at the same perturbation frequency and, with an increase in orifice height, a corresponding decrease in the damping characteristics of bearings and in the dynamic stiffness and coefficient of damping of bearing film in the frequency range less than 100 Hz.

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Chaterjee, S., and G. Pohit. "Dynamics of nonlinearly damped microcantilevers under electrostatic excitation." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 227, no. 3 (October 23, 2012): 630–46. http://dx.doi.org/10.1177/0954406212465371.

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Nonlinear dynamic behaviour of a cantilever microbeam actuated by a combination of DC and AC loading are investigated in presence of squeeze-film damping. A reduced order model formulated accounting for the nonlinearities of the system arising out of electrostatic forces and squeeze-film damping is numerically simulated to observe the large amplitude dynamic characteristics near primary and superharmonic resonances. The emphasis is on the significance of nonlinear damping in capturing the true dynamic characteristics of microsystems formulated as distributed parameter model. The damping nonlinearity is found to considerably affect the dynamics with a profound stabilising effect on the microsystem. Under the effect of large DC bias voltage, frequency–response curves obtained for different amplitudes of AC excitation exhibit local and global bifurcations. Response sensitivity to initial conditions is investigated near bifurcation points. Findings in the superharmonic resonance domain are emphasised.

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18

QI, Shemiao. "Dynamic stiffness and dynamic damping coefficients of aerodynamic bearings." Chinese Journal of Mechanical Engineering 43, no. 05 (2007): 91. http://dx.doi.org/10.3901/jme.2007.05.091.

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Gauthier, Michel, and Masaru Tsukada. "Damping Mechanism in Dynamic Force Microscopy." Physical Review Letters 85, no. 25 (December 18, 2000): 5348–51. http://dx.doi.org/10.1103/physrevlett.85.5348.

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20

Khomyakov, V. S. "Damping in dynamic machine-tool calculations." Russian Engineering Research 30, no. 9 (September 2010): 934–38. http://dx.doi.org/10.3103/s1068798x10090170.

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21

Jones, D. I. G. "High Temperature Damping of Dynamic Systems." Shock and Vibration Digest 17, no. 10 (October 1, 1985): 3–5. http://dx.doi.org/10.1177/058310248501701003.

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Molina, Francisco J., Georges Magonette, Pierre Pegon, and Beatriz Zapico. "Monitoring Damping in Pseudo-Dynamic Tests." Journal of Earthquake Engineering 15, no. 6 (June 29, 2011): 877–900. http://dx.doi.org/10.1080/13632469.2010.544373.

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23

Nakra, B. C. "Structural dynamic modification using additive damping." Sadhana 25, no. 3 (June 2000): 277–89. http://dx.doi.org/10.1007/bf02703545.

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Li, Jian-feng, and Xing-long Gong. "Dynamic damping property of magnetorheological elastomer." Journal of Central South University of Technology 15, S1 (September 2008): 261–65. http://dx.doi.org/10.1007/s11771-008-0359-2.

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Yi, Sung, M. Fouad Ahmad, and H. H. Hilton. "Dynamic Responses of Plates With Viscoelastic Free Layer Damping Treatment." Journal of Vibration and Acoustics 118, no. 3 (July 1, 1996): 362–67. http://dx.doi.org/10.1115/1.2888191.

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Dynamic transient responses of plates with viscoelastic free damping layers are studied in order to evaluate free layer damping treatment performances. The effects of forcing frequencies and temperatures on free-layer viscoelastic damping treatment of plates are investigated analytically. Young’s modulus ratio of structures to viscoelastic damping materials and the damping layer thickness effects on the damping ability are also explored.

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Li, Junlan, Shaoze Yan, Feng Guo, and Pengfei Guo. "Effects of damping, friction, gravity, and flexibility on the dynamic performance of a deployable mechanism with clearance." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 227, no. 8 (December 4, 2012): 1791–803. http://dx.doi.org/10.1177/0954406212469563.

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Space deployable mechanisms have been widely employed in modern spacecraft, and the dynamic performance of such mechanisms has become increasingly important in the aerospace industry. This article focuses on the dynamic performance of a deployment mechanism with clearance considering damping, friction, gravity, and flexibility. The modeling methods of revolute joint with clearance, close cable loop, and lock mechanism of a typical deployable mechanism are provided in this article. Based on these proposed methods, the dynamics model of a space deployable mechanism with clearance is established using the multi-body program ADAMS. The effects of clearance, damping, friction, gravity, and flexibility on the dynamic performance of a deployable mechanism in the deploying and locking processes are studied using simulations. The results reveal that the deployable mechanism exhibits evidently nonlinear dynamic characteristics, thus validating the significance of clearance, damping, friction, gravity, and flexibility in system dynamic performance.

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ROY, SAJAL, and SUBRATA CHAKRABORTY. "IDENTIFICATION OF DAMPING PARAMETERS OF LINEAR DYNAMIC SYSTEM." International Journal of Structural Stability and Dynamics 09, no. 03 (September 2009): 473–87. http://dx.doi.org/10.1142/s0219455409003132.

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The identification of damping in a structural system is extremely important for reliable prediction of response of dynamic systems. The present study focuses on the damping parameters identification of linear multi-degree of freedom (MDOF) systems defined by Rayleigh damping model. A system identification (SI) algorithm based on the free vibration response of structures is proposed to identify the damping parameters. In doing so, the equation error based SI approach is readily developed for identification of damping properties at element level. The formulation is elucidated using numerically simulated modal data obtained through finite element analysis. The robustness of the algorithm is also studied by Monte Carlo simulation based error sensitivity analysis. The identified damping values are found to be in consistent with those of pre-assigned values used to simulate modal data.

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Zhang, Wen-Ming, Guang Meng, and Ke-Xiang Wei. "Dynamics of Nonlinear Coupled Electrostatic Micromechanical Resonators under Two-Frequency Parametric and External Excitations." Shock and Vibration 17, no. 6 (2010): 759–70. http://dx.doi.org/10.1155/2010/107404.

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In this paper, nonlinear dynamics and chaos of electrostatically actuated MEMS resonators under two-frequency parametric and external excitations are investigated analytically and numerically. A nonlinear mass-spring-damping model is used to accounting for squeeze film damping and the parallel plate electrostatic force. The micro-structure is excited by a dc bias electrostatic force and a harmonic force with a frequency tuned closely to their fundamental natural frequencies (combination oscillation). The quality factor is calculated for the microcantilever beam of the resonator considering squeeze film damping. The effect of nonlinear squeeze film damping on the frequency response, quality factor, resonant frequency and nonlinear dynamic characteristics of the dynamic system are provided with numerical simulations using the bifurcation diagram, Poicare maps, largest Lyapunov exponent and phase portrait. The results show that the dynamic system goes through a complex nonlinear vibration as the system parameters change. It is indicated that the effect of nonlinear squeeze film damping should be considered due to its decreasing the quality factor and changing the nonlinear phenomena of the MEMS resonators.

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Barabash, Mariia, Bogdan Pisarevskyi, and Yaroslav Bashynskyi. "Material Damping in Dynamic Analysis of Structures (With LIRA-SAPR Program)." Civil and Environmental Engineering 16, no. 1 (June 1, 2020): 63–70. http://dx.doi.org/10.2478/cee-2020-0007.

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AbstractThe purpose of this paper is to justify that it is necessary to take account of physical and mechanical properties of soil and different materials of erected structure for damping vibrations in dynamic loads; to suggest tools for modelling the damping effect (natural or engineering induced) between foundation and soil. Certain technique is suggested for modelling behaviour of structure in time history analysis with account of material damping. In the software, the damping effect is modelled in two variants: Rayleigh damping (for structure) and finite element of viscous damping. When solving this problem, the following results were obtained: physical meaning of material damping is described; Rayleigh damping coefficients were computed through modal damping coefficients. Numerical analysis is carried out for the structure together with soil in earthquake load using developed FE of viscous damping. Time history analysis was carried out for the problem. Peak values of displacement, speed and acceleration at the floor levels were compared. Analysis results are compared (with and without account of material damping). Significant influence of damping on the stress-strain state of the structure is confirmed. Scientific novelty of the paper is in the following: the damping effect is proved to happen regardless of the presence of installed structural damping equipment; technique for account of damping with Rayleigh damping coefficients is developed; new damping element is developed – FE of viscous damping (FE 62), its behaviour is described as linear mathematical model. Practical implications of the paper: developed technique and new FE enables the user to carry out numerical analysis properly and work out a set of measures on seismic safety for buildings and structures.

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Qin, Bai, Bo Zhang, Quan Fu Wang, Ya Juan Ji, Yan Jiang Zhao, Xiao Dong Yu, and Yu Qiu Ma. "Research on Simulation and Design of Dynamical Vibration Absorption Lathe Tool with Large Length to Diameter Ratio." Applied Mechanics and Materials 274 (January 2013): 99–102. http://dx.doi.org/10.4028/www.scientific.net/amm.274.99.

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The dynamic simulation analysis method is adopted to investigate the dynamic damping characteristics of lathe tool with large length to diameter (L/D) ratio. The multi flexible body dynamical simulation model of dynamical damping lathe tool with large length to diameter ratio is built up according to the actual experiment lathe by using the software ADAMS and ANSYS. Simulation analysis of the multi flexible body dynamical model which has been optimized shows that the system damping performance is improved greatly. On this basis the relationship of rubber bush, mass body and vibration absorption cavity is discussed. And the result of the discussion indicates that the shape of rubber bush should be confirmed by repeatedly simulating the model.

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Mallipudi, Prasanth Kumar, Padala Jyothi, N. Ramanaiah, and V. V. S. Bhaskara Raju. "Damping Performance of Polychloroprene Rubber for Unconstrained Damping Applications." Advances in Science and Technology 106 (May 2021): 131–36. http://dx.doi.org/10.4028/www.scientific.net/ast.106.131.

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Damping properties are crucial in determining the dynamic structural response. In this paper, the experimental results for Neoprene rubber of 40, 50 and 60 shore A hardness are reported in view of improving structural damping to control noise and vibrations. Additionally, the system loss factors of the unconstrained layer damped structures of same material were predicted by Ross-Kerwin-Ungar equation to validate the obtained experimental results. The results showed that Neoprene rubber (also known as Polychloroprene) of 60 shore A showed better static and dynamic characteristics than those of the 40 and 50 shore A hardness. The system loss factor results reached the saturation when the applied viscoelastic layer thickness was increased from 40 mm to 50 mm in unconstrained damping. As such, the proposed method can help to build a database of the properties of various materials which are applicable in the design of noise and vibration control.

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Chen, Dong, Cong Zhou, Xian Feng Li, Yi Jie Zhang, and Nai Heng Ma. "Effect of TiB₂ on Damping Capacity and Dynamic Young's Modulus of 2219 Alloy." Applied Mechanics and Materials 470 (December 2013): 27–30. http://dx.doi.org/10.4028/www.scientific.net/amm.470.27.

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2219 aluminum alloy reinforced with 10wt. % TiB2 particulate was fabricated through mixed-salts method. The damping capacity and dynamic Yongs modulus was investigated. The damping capacity and dynamic Yongs modulus of 10wt. % TiB2/2219 is higher than that of the matrix alloy.The improved damping capacity is due to dislocation damping at low temperature, and grain boundary damping and interface damping at high temperature.

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Eliseev, S. V., A. S. Mironov, and Quang Truc Vuong. "Dynamic damping under introduction of additional couplings and external actions." Vestnik of Don State Technical University 19, no. 1 (April 1, 2019): 38–44. http://dx.doi.org/10.23947/1992-5980-2019-19-1-38-44.

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Introduction.The dynamic interaction features in mechanical oscillating systems, whose structure includes additional couplings, are considered. In practice, such cases occur when using various optional mechanisms and motion translation devices under the formation of technical objects. The study objective is to develop a method for constructing mathematical models in the problems of dynamics of the mechanical oscillating systems with optional devices and features in the system of external disturbing factors.Materials and Methods. The techniques used to study properties of the systems and the dynamic effects are based on the ideas of structural mathematical modeling. It is believed that the mechanical oscillating system, considered as a design model of a technical object, can be compared to the dynamically equivalent automatic control system. The mathematical apparatus of the automatic control theory is used.Research Results.A method for constructing mathematical models is developed. The essential analytical relations for plotting oscillating systems are obtained, which enable to form a methodological basis for the integral estimation and comparative analysis of the initial system properties in various dynamic states. Dynamic properties of the two-degree-offreedom systems within the framework of the computer simulation are investigated. The implementability of dynamic oscillation damping mode simultaneously in two coordinates with the joint action of two in-phase kinematic perturbations in the mechanical oscillating systems is shown.Discussion and Conclusions.The possibilities of new dynamic effects, which are associated with the change in the system structure under certain forms of dynamic interactions, are noted. The study is of interest to experts in machine dynamics, robotics, mechatronics, nano and mesomechanics.

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Li, Miaomiao, Jian Chen, Rupeng Zhu, Cheng Duan, Shuai Wang, and Xiong Lu. "Dynamic Stiffness and Damping Characteristics of a Shaft Damping Ring: A Combined Hyperelastic and Viscoelastic Constitutive Model." Shock and Vibration 2020 (October 5, 2020): 1–13. http://dx.doi.org/10.1155/2020/8822760.

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At higher velocities, the helicopter tail transmission system encounters notable difficulties due to excessive bending vibrations. The shaft damping ring installed on the shaft system was shown to effectively suppress the shaft system vibrations. In this paper, the dynamic stiffness and damping characteristics of polyurethane shaft damping rings were studied using hyperelastic and viscoelastic constitutive models. The constitutive model and the damping ring material parameters were determined using uniaxial tensile and double-shear frequency scanning tests. Based on the test results, the dynamic damping ring characteristics were simulated and verified by dynamic stiffness tests; the influence of structural parameters and operating conditions on the dynamic stiffness and damping characteristics of the damping ring were obtained. The results provide a theoretical basis for the design of shaft systems with reduced sensitivity to vibrations.

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Lin, Yu Sen, Li Hua Xin, and Min Xiang. "Parameters Analysis of Train Running Performance on High-Speed Bridge during Earthquake." Advanced Materials Research 163-167 (December 2010): 4457–63. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.4457.

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A model of coupled vehicle-bridge system excited by earthquake and irregular track is established for studying train running performance on high-speed bridge during earthquake, by the methods of bridge structure dynamics and vehicle dynamics. The results indicate that under Qian’an earthquake waves vehicle dynamical responses hardly vary with the increasing-height pier, but vehicle dynamical responses increase evidently while the height of pier is 18m, which the natural vibration frequency is approaching to dominant frequency of earthquake waves. Dynamic responses are linearly increasing with earthquake wave strength. Dynamic response of vehicles including lateral car body accelerations and every safety evaluation index all increase with train speed, so the influences of train speed must be taken into account in evaluating running safety of vehicles on bridge during earthquakes, but lateral displacement of bridge is varying irregularly. Dynamic responses and lateral displacement of bridge reduce under the higher dominant frequency of earthquake wave. Derailment coefficient, later wheel-rail force and lateral vehicle acceleration become small with increasing damping ratio. Vertical vehicle acceleration and reduction rate of wheel load are hardly varying with damping ratio.

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Han, Miao, Jinwei Jiang, Hongkai Du, and Sijia Feng. "Research on Damping Engagement Methodology in Dynamic Analysis of Isolated Structure." Shock and Vibration 2021 (September 21, 2021): 1–17. http://dx.doi.org/10.1155/2021/6613952.

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Damping has a significant influence on the calculation of structural seismic response. In this paper, we compare the commonly used viscous damping (Rayleigh damping (RD) and Caughey damping (CD)) in combination with the isolated structure test. To avoid the arbitrariness of choosing two reference vibration frequencies in constructing RD, all the combinations of the first several vibration frequencies were calculated. Because the material characteristics of the isolation layer and the superstructure are significantly different and the deformation of the isolation layer is large, we construct nonproportional damping according to these two kinds of damping and make a comparative analysis. Analyzing experimental data, we can obtain the optimal frequency combination of RD and nonproportional damping during dynamic analysis of the isolated structure, the priority order of choosing damping models. For the calculation of RD, the 1st modal frequency of the structure should be included, and the 2nd and 3rd modal frequencies of the nonisolated structure are proposed to calculate the nonproportional damping based on Rayleigh damping (NP-RD) for the three-story frame structure in this paper. RD and nonproportional damping based on Caughey damping (NP-CD) are firstly recommended to be used in the calculation of the isolated structure, followed by NP-RD and then CD.

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Cherkasov, V. D., Yuriy V. Yurkin, and V. V. Avdonin. "Theoretical and Experimental Investigation of Vibration Damping Sheet Dynamic Behavior." Solid State Phenomena 265 (September 2017): 439–44. http://dx.doi.org/10.4028/www.scientific.net/ssp.265.439.

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A great deal of attention is presently being drawn to the question of noise and vibration damping. One of the basic means of the effective damping of unfavorable noises and vibrations is the usage of special sheets with high vibration and noise damping properties in thin-slab structures. In this article the results of a study of the dynamic behavior (of the loss factor) of multilayer vibration damping sheets are being described. The aim of this article is to show the design optimization of multilayer vibration damping sheets, carrying a high loss factor. The theoretical prerequisites for the structure optimization of vibration damping sheets, having a high loss factor, have been determined. The experimental studies on the influence of the thickness of the vibration damping layer, thickness and Young’s modulus of experimental with theoretical data have also been carried out. More effective designs of multilayer vibration damping sheets have been scientifically substantiated.

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Wang, Daoyong, Wencan Zhang, Mu Chai, and Xiaguang Zeng. "Research on the dynamic characteristic of semi-active hydraulic damping strut." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, no. 6 (October 18, 2019): 1779–91. http://dx.doi.org/10.1177/0954407019881514.

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To reduce the vibration and shock of powertrain in the process of engine key on/off and vehicle in situ shift, a novel semi-active hydraulic damping strut is developed. The purpose of this paper is to study and discuss the dynamic stiffness model of the semi-active hydraulic damping strut. In this study, the dynamic characteristics of semi-active hydraulic damping strut were analyzed based on MTS 831 test rig first. Then, the dynamic stiffness model of semi-active hydraulic damping strut was established based on 2 degrees of freedom vibration system. In this research, a linear, fractional derivative and friction model was used to represent the nonlinear rubber bushing characteristic; the Maxwell model was used to describe the semi-active hydraulic damping strut body model; and the parameters of rubber bushing and semi-active hydraulic damping strut body were identified. The dynamic stiffness values were calculated with solenoid valve energized and not energized at amplitudes of 1 mm and 4 mm, which were consistent with experimental results in low-frequency range. Furthermore, the simplified dynamic stiffness model of the semi-active hydraulic damping strut was discussed, which showed that bushing can be ignored in low-frequency range. Then, the influence of equivalent spring stiffness, damping constant, and rubber bushing stiffness on the stiffness and damping capacity of the semi-active hydraulic damping strut were analyzed. Finally, the prototype of the semi-active hydraulic damping strut was developed and designed based on the vehicle in situ shift and engine key on/off situations, and experiments of the vehicle with and without semi-active hydraulic damping strut were carried out to verify its function.

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Karlsson, Martin, Håkan Nilsson, and Jan-Olov Aidanpää. "Numerical Estimation of Torsional Dynamic Coefficients of a Hydraulic Turbine." International Journal of Rotating Machinery 2009 (2009): 1–7. http://dx.doi.org/10.1155/2009/349397.

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The rotordynamic behavior of a hydraulic turbine is influenced by fluid-rotor interactions at the turbine runner. In this paper computational fluid dynamics (CFDs) are used to numerically predict the torsional dynamic coefficients due to added polar inertia, damping, and stiffness of a Kaplan turbine runner. The simulations are carried out for three operating conditions, one at about 35% load, one at about 60% load (near best efficiency), and one at about 70% load. The runner rotational speed is perturbed with a sinusoidal function with different frequencies in order to estimate the coefficients of added polar inertia and damping. It is shown that the added coefficients are dependent of the load and the oscillation frequency of the runner. This affect the system's eigenfrequencies and damping. The eigenfrequency is reduced with up to 65% compared to the eigenfrequency of the mechanical system without the fluid interaction. The contribution to the damping ratio varies between 30–80% depending on the load. Hence, it is important to consider these added coefficients while carrying out dynamic analysis of the mechanical system.

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Wang, Y. R., and C. Y. Lo. "Design of Hybrid Dynamic Balancer and Vibration Absorber." Shock and Vibration 2014 (2014): 1–18. http://dx.doi.org/10.1155/2014/397584.

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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.

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Behera, A. K., and B. K. Nanda. "Dynamic Characteristics of Structures Bonded with Viscoelastic Unconstrained Layers." Transactions of the Canadian Society for Mechanical Engineering 10, no. 3 (September 1986): 175–82. http://dx.doi.org/10.1139/tcsme-1986-0020.

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In order to control the intensity of troublesome vibration in the modern day structures, viscoelastic materials are sometimes bonded to one or both sides of those structures. This type of unconstrained damping layer treatment is quite effective for abating structural vibration. In this paper both theoretical and experimental investigation has been made on the dynamic characteristics of such beam-like structures in order to get sufficient design data. Theoretical analysis based on the energy principle is presented in a generalised form for predicting damped and undamped natural frequencies as well as logarithmic decrement of such beams. Expressions for the loss-factor and static stiffness are also found out in order to evaluate dimensional inter-relationship between base metal and damping layer for maximizing damping capacity of the structure without losing its stiffness. Experimental measurements for natural frequency and log-decrement bear out the fact that theoretical predictions are indeed accurate. It is found that there is an optimum value of thickness ratio between base metal and damping layer for maximizing damping in a structure with a single unconstrained damping layer. Results for beams having single damping layer as well as for symmetric damping layers on both sides are also presented for comparison.

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Hammami, Lotfi, Bacem Zghal, Tahar Fakhfakh, and Mohamed Haddar. "Characterization of Modal Damping of Sandwich Plates." Journal of Vibration and Acoustics 127, no. 5 (February 9, 2005): 431–40. http://dx.doi.org/10.1115/1.2013294.

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The homogenization of the energy functional of a sandwich plate, its minimization and its discretization by finite element methods and modeling the viscoelastic core behavior by an hysteretic structural damping lead to the homogenized dynamic equation of a sandwich plate. The vibratory analysis permits the determination of the elastic eigenmodes and the characterization of the modal damping which will serve to the establishment of dynamical responses if we used the modal dynamic recombination method. The numerical results obtained show that the eigenmodes are not orthogonal to the damping matrix but are only weakly coupled. Besides, the modal damping matrix coefficients vary according to the ratio of the core thickness and the total thickness of sandwich plate and follow a second-order polynomial function of this ratio.

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Wang, Yuan Feng, and Xiao Ran Li. "Analysis of Influence of Material Damping on the Dynamic Response of Concrete-Filled Square Steel Tubular Columns." Applied Mechanics and Materials 226-228 (November 2012): 905–9. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.905.

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The damping characteristic and dynamic responses of the concrete-filled square steel tubular (CFST) columns were numerically investigated in this paper. Finite element iteration method in the hysteretic damping system for CFST materials was presented, and an improved method considering viscous damping dynamic equilibrium equation with hysteretic damping model was also proposed. Based on the proposed methods, the loss factor and dynamic response of CFST columns subjected to the earthquake and harmonic loadings were effectively calculated. The results indicate that the stress-dependent damping method induces a larger dynamic response, and the loss factor of the CFST columns increases with the increase of the stress amplitude and lower steel ratio.

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Vellios, L., V. Kostopoulos, and S. A. Paipetis. "Fatigue Effect on the Dynamic Properties of Cfrp Composites." Advanced Composites Letters 3, no. 4 (July 1994): 096369359400300. http://dx.doi.org/10.1177/096369359400300405.

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Damage developing during fatigue of composite laminates affects both dynamic modulus of elasticity and damping coefficient of the material. It has been shown that the effect of fatigue on the damping coefficient is of particular importance. The damping variation could be used to characterise the damage state of the material, produced by fatigue. A model relating damage with damping was developed to correlate damage development to mechanical response. The damping coefficients of the composite of the fatigue test were measured at various stages, using the flexural free vibration of the test coupon hi cantilever configuration. The method was applied both in multidirectional and unidirectional laminates.

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Zhang, Limin, Michael C. McVay, and Charles WW Ng. "A possible physical meaning of Case damping in pile dynamics." Canadian Geotechnical Journal 38, no. 1 (February 1, 2001): 83–94. http://dx.doi.org/10.1139/t00-073.

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This paper presents some possible interpretations of the physical meaning of the lumped, toe, and skin Case damping factors, jcL, jct, and jcs, respectively, which are extensively utilized in the dynamic analysis of pile driveability and capacity. A single degree of freedom model is employed to relate the Case damping to the hysteretic damping ratios of soil and pile materials. This relation and the damping ratios of soils and piles show that the Case damping factors for piles in sandy and clayey soils may overlap at all strain magnitudes. Coupling of pile toe and skin resistance is analyzed, and the jcL factor is found to be a function of the skin and toe resistance ratio of the pile. Consequently, the jcL factor is an important indicator with which the skin friction and toe resistance of piles can be separated. A database of 133 cases of dynamic pile tests in Florida has been used to substantiate the analyses and interpretations. The effects of the assumptions made in this paper are also discussed.Key words: pile dynamics, wave equation, Case damping, hysteretic damping, bearing capacity, skin friction.

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Shen, Yujie, Mengqi Jia, Kai Yang, Zhong Chen, and Long Chen. "Optimal Design and Dynamic Performance Analysis Based on the Asymmetric-Damping Vehicle ISD Suspension." Shock and Vibration 2021 (August 11, 2021): 1–11. http://dx.doi.org/10.1155/2021/9996563.

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This paper concerns the optimal problem of the vehicle ISD (inerter-spring-damper) suspension based on the asymmetric-damping effect. In order to explore the benefits of the asymmetric damping, a quarter car model of the four-element ISD suspension is built by considering the symmetric and asymmetric reciprocating damping factors. The parameters of the proposed vehicle ISD suspension with symmetric-damping and asymmetric-damping features are optimized by means of the genetic algorithm in single-objective scenario and multiobjective scenario, respectively. The dynamic performances are analyzed through simulations in time and frequency domains, and the impacts of the compression and tensile damping on the body acceleration, the suspension working space, and the dynamic tire load are discussed. Results indicate that, compared with the conventional passive suspension, the proposed ISD suspensions manifest excellent vibration isolation performance, and the asymmetric reciprocating damping ISD suspension even showcases extra improving space of the dynamic performances except for the dynamic tire load in the impulse input condition. It seems that the dynamic performance of the vehicle ISD suspension will be much superior when considering the asymmetric reciprocating damping factors.

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Saravanos, D. A., and J. M. Pereira. "Dynamic Characteristics of Specialty Composite Structures with Embedded Damping Layers." Journal of Vibration and Acoustics 117, no. 1 (January 1, 1995): 62–69. http://dx.doi.org/10.1115/1.2873868.

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Damping mechanics for predicting the damped dynamic characteristics in specialty composite structures with compliant interlaminar damping layers are presented. Finite-element based mechanics incorporating a discrete layer (or layer-wise) laminate damping theory are utilized to represent general laminate configurations in terms of lay-up and fiber orientation angles, cross-sectional thickness, shape and boundary conditions. Evaluations of the method with exact solutions and experimental data illustrate its accuracy. Additional parametric studies demonstrate the unique capability of angle-ply composite laminates with cocured interlaminar damping layers to significantly enhance structural damping.

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Rezaiee-Pajand, M., and S. R. Sarafrazi. "Nonlinear dynamic structural analysis using dynamic relaxation with zero damping." Computers & Structures 89, no. 13-14 (July 2011): 1274–85. http://dx.doi.org/10.1016/j.compstruc.2011.04.005.

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Mi, Bai-gang, and Hao Zhan. "Numerical Simulation of the Static and Dynamic Aerodynamics of a UAV under Wake Flows." Journal of Advanced Transportation 2019 (April 1, 2019): 1–12. http://dx.doi.org/10.1155/2019/6326794.

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Frequent flight conflicts will be observed as the number of aircrafts increases, and such conflicts will cause unprecedented challenges in flight safety; thus, the flight characteristics of small aircrafts under the wake flow of a large airliner should be thoroughly analyzed. Combined with the sliding mesh technique, a computational fluid dynamics (CFD) method is proposed in this paper to simulate three wake flow patterns, i.e., wingtip vortex, jet flow, and propeller slipstream, and then, the static and dynamic derivatives that represent the stability of the fly wing under the wake flow are identified by using the least squares method. The results demonstrate that both the steady and unsteady aerodynamics of the fly wing are affected by wake flows: wingtip vortices increase the lift-to-drag ratio and considerably change the dynamic damping; jet flow reduces both the static and dynamic damping; and propeller slipstream leads to slow variations in the dynamic damping and decreases in the lift-to-drag ratio.

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Zhang, Bin, Yan Yun Luo, and Zhi Nan Shi. "Dynamic Property Analysis of Damping Rubber in Rail Fastenings under Different Deformation Condition." Applied Mechanics and Materials 494-495 (February 2014): 706–10. http://dx.doi.org/10.4028/www.scientific.net/amm.494-495.706.

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This paper studies the experimental research on dynamic characteristics of the damping rubber in high elastic fastening by the electro-hydraulic servo movement tester. Based on a hypothesis superposition theory of nonlinear elastic restoring force and nonlinear damping force, a non-linear dynamic mechanical model is proposed. The dynamic stiffness and damping parameters of the rubber are obtained in different deformation conditions based on the dynamic mechanical model. The dynamic stiffness is analyzed, and the results show that dynamic stiffness is closely related to excitation frequency and amplitude. Furthermore the dynamic stiffness is analyzed under different free surface of rubber components by using FEM. That also reveals the changeable characteristics and affected factors of the damping rubber of the high elastic fastenings in large distortion condition.

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Journal articles on the topic 'Dynamic damping'

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