Articoli di riviste: "Damping (Mechanics)"

1

Barone, P. M. V. B., e A. O. Caldeira. "Quantum mechanics of radiation damping". Physical Review A 43, n. 1 (1 gennaio 1991): 57–63. http://dx.doi.org/10.1103/physreva.43.57.

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2

Saravanos, D. A. "Integrated Damping Mechanics for Thick Composite Laminates and Plates". Journal of Applied Mechanics 61, n. 2 (1 giugno 1994): 375–83. http://dx.doi.org/10.1115/1.2901454.

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Abstract (sommario):

A method for predicting the damped dynamic characteristics of thick composite laminates and plates is presented. Unified damping mechanics relate the damping of composite plates to constituent properties, fiber volume ratio, fiber orientation, laminate configuration, plate geometry, temperature, and moisture. Discrete layer damping mechanics for thick laminates, entailing piecewise continuous displacement fields and including the effects of interlaminar shear damping, are described. A semi-analytical method for predicting the modal damping and natural frequencies of thick simply-supported specialty composite plates is included. Applications demonstrate the validity, merit, and ranges of applicability of the new theory. The applications further illustrate the significance of interlaminar shear damping, and investigate the effects of lamination, thickness aspect ratio, fiber content, and temperature.

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Shen, I. Y. "Hybrid Damping Through Intelligent Constrained Layer Treatments". Journal of Vibration and Acoustics 116, n. 3 (1 luglio 1994): 341–49. http://dx.doi.org/10.1115/1.2930434.

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This paper is to propose a viable hybrid damping design that integrates active and passive dampings through intelligent constrained layer (ICL) treatments. This design consists of a viscoelastic shear layer sandwiched between a piezoelectric constraining cover sheet and the structure to be damped. According to measured vibration response of the structure, a feedback controller regulates axial deformation of the piezoelectric layer to perform active vibration control. In the meantime, the viscoelastic shear layer provides additional passive damping. The active damping component of this design will produce adjustable and significant damping. The passive damping component of this design will increase gain and phase margins, eliminate spillover, reduce power consumption, improve robustness and reliability of the system, and reduce vibration response at high frequency ranges where active damping is difficult to implement. To model the dynamics of ICL, an eighth-order matrix differential equation governing bending and axial vibrations of an elastic beam with the ICL treatment is derived. The observability, controllability, and stability of ICL are discussed qualitatively for several beam structures. ICL may render the system uncontrollable or unobservable or both depending on the boundary conditions of the system. Finally, two examples are illustrated in this paper. The first example illustrates how an ICL damping treatment, which consists of an idealized, distributed sensor and a proportional-plus-derivative feedback controller, can reduce bending vibration of a semi-infinite elastic beam subjected to harmonic excitations. The second example is to apply an ICL damping treatment to a cantilever beam subjected to combined axial and bending vibrations. Numerical results show that ICL will produce significant damping.

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4

Qin, Yan, Shi Wei Zhao, Bi Fang Dai, Qi Lin Mei e Zhi Xiong Huang. "Studies on Properties of Epoxy Resin Base Piezoelectricity Damping Carbon Fiber Composite Materials". Key Engineering Materials 508 (marzo 2012): 271–75. http://dx.doi.org/10.4028/www.scientific.net/kem.508.271.

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Damping Materials Have Been Wildly Used in Aerospace, Traffic, Construction Fields and so on. The Piezo-Damping Materials Have Received much Attention due to the Novel Energy Loss Mechanism. In this Paper, Piezo-Damping Composite Materials Were Prepared from the Epoxy Resin (EP) as the Resin Matrix, Nano Lead Titanate (Nano-PT) Ceramics as Piezoelectric Material and Chopped Carbon Fibers (CF) as Conductive Materials. The Mechanical and Damping Properties of the Composites Were Analyzed by Mechanics Test, DMA and Vibration Beam Method. The Results Showed that when the Nano-PT Content Was 60% of EP and CF Content Was 0.25% of EP, the Composite Got the Better Mechanical Properties. Form DMA, the Loss Factor (tanδ) Peak Reached 0.58. Damping Temperature Range △T (tanδ>0.3) Was about 36.3°C. In Comparison, Damping Loss Factor Measured by Vibration Beam Method Was 0.82.

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van KAMPEN, N. G. "DAMPING AND NOISE IN QUANTUM MECHANICS". Fluctuation and Noise Letters 01, n. 02 (giugno 2001): C7—C13. http://dx.doi.org/10.1142/s0219477501000299.

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In a quantum system damping and noise enter through the coupling with an external large bath. The usual treatments computes the density matrix of the system by expanding in the coupling strength to the bath and averaging over the bath. The result, however, is known to be unacceptable as it leads to negative probabilities. It is here proposed to study correlation functions rather than the density matrix itself. Equations for them are derived and compared with the result obtained by the usual method.

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6

Buchmüller, W., e A. Jakovác. "Classical statistical mechanics and Landau damping". Physics Letters B 407, n. 1 (agosto 1997): 39–44. http://dx.doi.org/10.1016/s0370-2693(97)00746-6.

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7

Kausel, Eduardo. "Damping Matrices Revisited". Journal of Engineering Mechanics 140, n. 8 (agosto 2014): 04014055. http://dx.doi.org/10.1061/(asce)em.1943-7889.0000770.

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8

Heo, B., H. Bittner, M. L. Shumway e I. Y. Shen. "Identifying Damping of a Gyroscopic System Through the Half-Power Method and Its Applications to Rotating Disk/Spindle Systems". Journal of Vibration and Acoustics 121, n. 1 (1 gennaio 1999): 70–77. http://dx.doi.org/10.1115/1.2893950.

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This paper applies the half-power method to identify damping of a gyroscopic system. At first, the underlying principle of the half-power method for damped, gyroscopic systems is explained. Then the method is demonstrated on a rotating disk/spindle system often used in computer hard disk drives. The disk/spindle system consists of multiple elastic disks mounted on a rigid spindle supported by ball bearings. The flexibility of the bearings allows the spindle to undergo rigid-body translation and rocking. Calibrated experiments were conducted in vacuum to obtain frequency response functions at different rotational speed. Application of the half-power method shows that the disk and bearing dampings are independent of rotational speed and can be modeled adequately as viscous damping. Moreover, the damping of the ball bearings is two orders of magnitude smaller than that of a fluid-film bearing of similar size.

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9

Saravanos, D. A., e J. M. Pereira. "Dynamic Characteristics of Specialty Composite Structures with Embedded Damping Layers". Journal of Vibration and Acoustics 117, n. 1 (1 gennaio 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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10

ADHIKARI, S., e J. WOODHOUSE. "IDENTIFICATION OF DAMPING: PART 1, VISCOUS DAMPING". Journal of Sound and Vibration 243, n. 1 (maggio 2001): 43–61. http://dx.doi.org/10.1006/jsvi.2000.3391.

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11

Cao, You Qiang, Zhao Xiang Deng e Pan Wang. "A Mechanics Model and Active Control for Smart Constrained Layer Damping Structure". Applied Mechanics and Materials 184-185 (giugno 2012): 767–73. http://dx.doi.org/10.4028/www.scientific.net/amm.184-185.767.

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The active vibration control of beam is researched by using piezoelectric constrained damping structure. The energy characteristic of each layer for the piezoelectric smart constrained damping beam is completely expressed based on the finite element method and the damping layer shearing movement relationship is described by ADF model. Then the structure mechanics model for dynamic parameters is established. Applying displacement error signal, an adaptive filter controller is designed. Under the different outside disturbance, structure vibration responses with active control are analyzed. It shows that the piezoelectric smart constrained damping structure can have good control performance for the active and it has a good engineering prospects.

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12

Wu, Ziying, Hongzhao Liu, Lilan Liu e Daning Yuan. "New Methods for Nonlinear Damping Identification of Damping Alloy". Journal of Vibration and Acoustics 129, n. 5 (10 febbraio 2007): 678–84. http://dx.doi.org/10.1115/1.2748460.

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This paper presents two methods for the identification of nonlinear internal damping of alloy. One is the moving autoregressive model (MARM) method, and the other is the time-varying autoregressive model (TVARM) method. These procedures have been successfully implemented on two numerical examples. Comparison between simulation results demonstrates that the computation accuracy of the TVARM method is higher than that of the MARM method. In the experiments, the internal damping properties of the alloy Al-33Zn-6Si are researched, employing the rectangle beam with a nonuniform stress field and the trapezoid beam with a quasi-uniform stress field, respectively. Experimental results show that the internal damping of the alloy increases with the increasing strain and appears a nonlinear behavior. Moreover, the damping values of the trapezoid beam are relatively higher than those of the rectangle beam. Compared to the MARM method, the TVARM method can give a better description of nonlinear damping because the relation curve of loss factor versus strain obtained by the TVARM method is smoother than that obtained by the MARM method.

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13

Liang, Z., e G. C. Lee. "Representation of Damping Matrix". Journal of Engineering Mechanics 117, n. 5 (maggio 1991): 1005–19. http://dx.doi.org/10.1061/(asce)0733-9399(1991)117:5(1005).

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14

Glenne, B., J. E. Jorgensen e J. D. Chalupnik. "SKI VIBRATIONS AND DAMPING". Experimental Techniques 18, n. 6 (novembre 1994): 19–22. http://dx.doi.org/10.1111/j.1747-1567.1994.tb00315.x.

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15

Jeon, Jin-Young. "Passive vibration damping enhancement of piezoelectric shunt damping system using optimization approach". Journal of Mechanical Science and Technology 23, n. 5 (maggio 2009): 1435–45. http://dx.doi.org/10.1007/s12206-009-0402-8.

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16

Li, Ming, Zeng He, Huiming Zheng e Ning Zhang. "Dependence of Damping Characteristics of a Beam with Damping Rubber Magnetic Powder on Rubber Property". Acta Mechanica Solida Sinica 21, n. 3 (giugno 2008): 247–56. http://dx.doi.org/10.1007/s10338-008-0828-z.

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17

Si, Heyong, Lihua Cao e Pan Li. "Dynamic Characteristics and Stability Prediction of Steam Turbine Rotor Based on Mesh Deformation". Strojniški vestnik – Journal of Mechanical Engineering 66, n. 3 (15 marzo 2020): 164–74. http://dx.doi.org/10.5545/sv-jme.2019.6283.

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In order to study the steam flow excited vibration caused by the eccentricity of a rotor, three-dimensional rotor whirl motion is simulated based on mesh deformation. The mechanism of steam flow excited vibration and its influence on the dynamic characteristics of the rotor are investigated. The results show that the exciting forces change with the displacement of the rotor’s centre. Rotor dynamic coefficients are nonlinear when the rotor whirls pass the mesh deformation. The rotor dynamic coefficients and effective damping increase with the increase of whirl frequency. When the whirl frequency is 24.41 Hz, the rotor dynamic coefficients are strongly affected by rotational velocity. The maximum fluctuations of average direct stiffness, cross-coupling stiffness, direct damping and cross-coupling damping are 8.1 %, 113.2 %, 45.8 %, and 121.0 %, respectively. Effective damping fluctuates greatly when both whirl and rotational frequency are 24.41 Hz. The direct stiffness, direct damping, and effective damping increase with the increase of pressure ratio, which can improve rotor stability. The pressure fluctuation on the rotor’s surface is a primary reason for steam flow excited vibration. The stability margin of the rotor can be estimated precisely via effective damping.

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18

Jadhav, Abhijitkumar, Sanjay Zope, Ravindra Malagi e Deepali Suryawanshi. "Design and development of a novel tunable electrorheological fluid (ERF) damper-foundation to attenuate residual vibrations in machine tools". FME Transactions 51, n. 1 (2023): 1–13. http://dx.doi.org/10.5937/fme2301001j.

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Residual vibrations in machine tools hamper accuracy and productivity. The attenuation of residual vibrations has been an industrial concern for decades. Meanwhile, the residual vibrations' vibration pattern reveals that the support foundation's damping capabilities predominantly influence them. Therefore, inserting dampers in any other location on a machine tool (such as a machine column) is ineffective. Hence, the scope of inserting the damper into the machine foundation needs to be verified. However, conventional machine mounting systems (concrete foundation and rubber mounts) equally respond to all variable inputs. Both these flocks resulted in inadequate dampening and perhaps poor accuracy. This paper provides a first-generation model of a semiactive-viscous damper (ERF damper-foundation) with tunable damping facilitating machine installation. Controlled experimentation by exposing the developed damper foundation to excitations of medium duty lathe machine confirms its effectiveness and obtains over 48% attenuation compared to a conventional concrete foundation.

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19

ADHIKARI, S., e J. WOODHOUSE. "IDENTIFICATION OF DAMPING: PART 2, NON-VISCOUS DAMPING". Journal of Sound and Vibration 243, n. 1 (maggio 2001): 63–88. http://dx.doi.org/10.1006/jsvi.2000.3392.

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20

Kawabe, Hisashi, e Kazunobu Yoshida. "An approach to higher damping capacity: a comparison of material damping with computer-controlled damping". Journal of Alloys and Compounds 211-212 (settembre 1994): 589–91. http://dx.doi.org/10.1016/0925-8388(94)90573-8.

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21

Agbenyega, Jonathan. "SMAs for mechanical damping". Materials Today 12, n. 6 (giugno 2009): 10. http://dx.doi.org/10.1016/s1369-7021(09)70172-5.

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22

Szyszkowski, W., e K. Fielden. "Effects of Flexibility and Damping on Momentum Transfer During Locking of Two Moving Links, Part I: Numerical Simulation". Journal of Applied Mechanics 65, n. 2 (1 giugno 1998): 479–84. http://dx.doi.org/10.1115/1.2789079.

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The system consisting of two links and two joints is examined. The joints are idealy frictionless when unlocked. Due to flexibility of the links, the locking generates some damped vibrations. It is demonstrated that the presence of these vibrations, even of very small and seemingly neglegible amplitudes, have dramatic effects on the after-locking motion of the links. Depending on the level of flexibility and damping involved, the locking triggers a large-scale “slow” motion that may have either oscillatory or circular (clockwise or counterclockwise) characters. The links will stop at some resting configuration only at certain “critical” values of damping. The set of “critical dampings” seems to be infinite, though only two degrees-of-freedom are used to model the system. Governing equations for these phenomena are derived and discussed in Part II of this paper.

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23

Mulder, Gerben. "On strain-rate independent damping in continuum mechanics". Journal of Sound and Vibration 407 (ottobre 2017): 240–52. http://dx.doi.org/10.1016/j.jsv.2017.06.028.

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24

Ding, Zhi Hua, Zheng Bao Lei e Mu Xi Lei. "Research on Damping Characteristics of New Recycling Vibrational Energy Hydraulic Damping System". Advanced Materials Research 308-310 (agosto 2011): 610–13. http://dx.doi.org/10.4028/www.scientific.net/amr.308-310.610.

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A vibrational energy-recycling vibration damper is introduced which can recycle some vibrational energy by exporting pressurized oil from rebound cavity to energy accumulator. Pressurized oil can be used for HPS, hydraulic power braking and so on which saves energy. Nonlinear parameterized model of damping characteristics is constructed by fluid mechanics theory, and simulation is made under MATLAB. The results show that damping characteristics of the vibration damper is better than conventional dampers.

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25

Wang, Chang, Jun Liu e Zhiwei Luo. "Suppression of Self-Excited Vibrations in Rotating Machinery Utilizing Leaf Springs". Strojniški vestnik – Journal of Mechanical Engineering, n. 10 (15 ottobre 2019): 599–608. http://dx.doi.org/10.5545/sv-jme.2019.6112.

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When rotating machinery is operated above the major critical speed, self-excited vibrations appear due to internal friction of the shaft. Internal frictions are classified into hysteretic damping due to the friction in the shaft material and structural damping due to the dry friction between the shaft and the mounted elements. In this paper, a method to suppress the self-excited vibration using leaf springs are proposed. The structural damping is considered as the internal damping. The characteristics of a rotor with leaf springs are investigated systematically by using simulative and theoretical analyses. The validity of the proposed method is also proved by experiments.

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26

Johnson, Erik A., Greg A. Baker, B. F. Spencer e Yozo Fujino. "Semiactive Damping of Stay Cables". Journal of Engineering Mechanics 133, n. 1 (gennaio 2007): 1–11. http://dx.doi.org/10.1061/(asce)0733-9399(2007)133:1(1).

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27

Udwadia, Firdaus E. "A Note on Nonproportional Damping". Journal of Engineering Mechanics 135, n. 11 (novembre 2009): 1248–56. http://dx.doi.org/10.1061/(asce)0733-9399(2009)135:11(1248).

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28

Johnson, C. D. "Design of Passive Damping Systems". Journal of Vibration and Acoustics 117, B (1 giugno 1995): 171–76. http://dx.doi.org/10.1115/1.2838659.

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This paper presents a brief review of techniques for designed-in passive damping for vibration control. Designed-in passive damping for structures is usually based on one of four damping technologies: viscoelastic materials, viscous fluids, magnetics, or passive piezoelectrics. These methods are discussed and compared. The technology of using viscoelastic materials for passive damping is discussed in more detail than the other methods since it is presently the most widely used type of damping technology. Testing and characterization of viscoelastic materials and design methods for passive damping are discussed. An example showing the benefits of a passive damping treatment applied to a stiffened panel under an acoustic load is presented.

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29

Kim, Kyoung-Whan, e Hyun-Woo Lee. "Chiral damping". Nature Materials 15, n. 3 (24 febbraio 2016): 253–54. http://dx.doi.org/10.1038/nmat4565.

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30

Oyelade, A. O., e O. M. Sadiq. "ENHANCED DAMPING CHARACTERISTICS OF TIMOSHENKO BEAM ON ELASTIC AND METAMATERIAL FOUNDATIONS". Journal of the Serbian Society for Computational Mechanics 14, n. 1 (30 giugno 2020): 52–62. http://dx.doi.org/10.24874/jsscm.2020.14.01.05.

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An analytical model is developed for the flexural wave propagation of a continuous Timoshenko beam resting on elastic and metamaterial foundations. The metamaterial foundation consists of positive and negative springs with a damper. This added negative stiffness component is constructed in such a way to provide the same static stiffness and the same damping component with the equivalent reference beam on elastic foundation. Numerical examples are used to investigate the effect of the shear on wavenumber and damping for beam with elastic and metamaterial foundations. The effects of engineering safety, damping coefficient and resonating mass on the dissipative property of the beam is investigated analytically. The simulation results provide indication of an enhanced damping characteristics for the damping ratio of the flexural waves propagating within the beam.

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31

Gröhlich, Martin, Andrej Lang, Marc Böswald e Jens Meier. "Viscoelastic damping design – Thermal impact on a constrained layer damping treatment". Materials & Design 207 (settembre 2021): 109885. http://dx.doi.org/10.1016/j.matdes.2021.109885.

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32

Langote, Pankaj K., e P. Seshu. "Experimental Studies on Active Vibration Control of a Beam Using Hybrid Active∕Passive Constrained Layer Damping Treatments". Journal of Vibration and Acoustics 127, n. 5 (12 marzo 2005): 515–18. http://dx.doi.org/10.1115/1.2013292.

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Hybrid damping designs with active piezoelectric materials and passive viscoelastic materials (VEMs) combine the advantages of both active and passive constrained layer damping treatments. In this study, experiments have been conducted on nine systems viz., bare beam, active damping (AD), passive constrained layer damping (PCLD—three variants) and hybrid active∕passive constrained layer damping (Hybrid AD∕PCLD—four variants). Based on the time domain analysis of these systems, it is shown that the “best” performance is obtained using a hybrid damping configuration wherein the VEM and the piezoelectric layers are acting separately.

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Chudakov, I. B., N. L. Fedotova e I. V. Saikov. "Special Features of Formation of the High Damping State in Bimetallic Structural Materials Obtained by Explosion Welding". Key Engineering Materials 887 (maggio 2021): 28–33. http://dx.doi.org/10.4028/www.scientific.net/kem.887.28.

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Special features of the high-damping state formation in bimetallic materials produced by explosion welding have been studied. High-damping Mn-Cu alloy was used for the damping base of the bimetallic composite and high–strength steel (grade: 30HGSA) was used to form the coating layer. The effect of planar tensile stresses (observed in the damping component of the bimetal and caused by valuable difference between coefficients of thermal expansion of components of the bimetal) is discussed. Damping properties of bimetallic materials were found to be comparable with damping characteristics of monolithic high damping alloys. High-strength steel provides high-strength characteristics of the surface layer of the bimetal, where the strength level reaches 1100MPa and the hardness is equal to 50 HRC. Obtained combination of high damping and high strength in developed bimetallic materials provides real chance for practical application of these materials in industry.

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Abdelhafid, Rahmane. "Modal damping ratio of symmetric laminate composite under the effect of attached mass using experimental design". FME Transactions 49, n. 3 (2021): 740–48. http://dx.doi.org/10.5937/fme2103740a.

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Nowadays, the use of composite materials has taken a large place in civilian industries as well as in military and aerospace industries. Therefore, significant investigations about their mechanical and physical properties are needed. The present study addresses the effect of attached mass on damping ratio of symmetric angle ply laminate composite. Furthermore, factor influencing the effect of attached mass on damping ratio of laminate composite are studied using Taguchi method. The considered factors parameters are: attached mass locations from the clamped edge, stacking sequences and boundary conditions. The results of this study indicate that the damping ratio of the laminate composite plates is sensitive to the attached mass, where the damping ratio is found to be proportional to the locations of the attached mass. The findings of this study indicate that the attached mass decreases frequency parameter and increase the damping ratio of the composite plate, if it is inserted at a point other than a nodal line. In addition, the paper presents a good correlation between the numerical results of the fundamental frequency obtained by the ANSYS software and those obtained experimentally.

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Paimushin, V. N., V. A. Firsov e V. M. Shishkin. "Modeling a Dynamic Response at Resonant Vibrations of an Elongated Plate with an Integral Damping Coating". PNRPU Mechanics Bulletin, n. 1 (15 dicembre 2020): 74–86. http://dx.doi.org/10.15593/perm.mech/2020.1.06.

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Classical methods of surface damping using free and constraining damping layers are discussed. The structure of a perspective integrated version of a damping coating is presented. This integral damping coating consists of two layers of a material with pronounced viscoelastic properties, between which there is a thin reinforcing layer of a high modulus material. A generalization of the Thompson-Kelvin-Voigt model is given for the description of viscoelastic properties of the material under tension-compression in the case of a complex stress state. A finite-element method was developed to determine the dynamic response of an elongated plate with the integral damping coating. This method is based on a four-layer finite element with 14 degrees of freedom: the main material is within the Kirchhoff-Love's model, the damping layers are in a flat stress state, the reinforcing layer perceives tension and compression. This model allows us to take into account the effect of transverse compression of the damping layers of the plate, which significantly increases its damping properties at high vibration frequencies. The stiffness matrices, the damping matrices, and the mass matrices of the constituent layers aim at obtaining similar complete matrices of a finite element. A system of resolving equations was obtained on the basis of the Lagrange equations of the second kind with respect to the vector of nodal displacements of the finite element model of the plate with an arbitrary dynamic load. In the case of a harmonic load with a frequency that coincides with one of the frequencies of free vibrations of the plate, a transition to a modal equation with respect to the normal coordinate corresponding to the given frequency is possible. Numerical experiments were carried out to test the developed finite element method using the example of a hingedly supported elongated plate with an integral damping coating. The numerical experiments showed a qualitative change in the composition of stresses in the damping layers of the plate at high vibration frequencies, which significantly affects its damping properties.

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Hein, Rafał, e Cezary Orlikowski. "Hybrid Reduced Model of Rotor". Archive of Mechanical Engineering 60, n. 3 (1 settembre 2013): 319–33. http://dx.doi.org/10.2478/meceng-2013-0021.

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Abstract In the paper, the authors describe the method of reduction of a model of rotor system. The proposed approach makes it possible to obtain a low order model including e.g. non-proportional damping or the gyroscopic effect. This method is illustrated using an example of a rotor system. First, a model of the system is built without gyroscopic and damping effects by using the rigid finite element method. Next, this model is reduced. Finally, two identical, low order, reduced models in two perpendicular planes are coupled together by means of gyroscopic and damping interaction to form one model of the system. Thus a hybrid model is obtained. The advantage of the presented method is that the number of gyroscopic and damping interactions does not affect the model range

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37

Frolov, K. V., e T. S. Krasnopol'skaya. "Sommerfeld effect in systems without internal damping". Soviet Applied Mechanics 23, n. 12 (dicembre 1987): 1122–26. http://dx.doi.org/10.1007/bf00884888.

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Lu, Jing, Yu Xiang, Yuying Huang, Xiaoni Li e Qiao Ni. "Transfer matrix method for analyzing vibration and damping characteristics of rotational shell with passive constrained layer damping treatment". Acta Mechanica Solida Sinica 23, n. 4 (agosto 2010): 297–311. http://dx.doi.org/10.1016/s0894-9166(10)60032-8.

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Bogoryad, I. B. "Damping factors for damping due to the presence of fluid with a free surface in a moving vessel". Soviet Applied Mechanics 26, n. 4 (aprile 1990): 397–402. http://dx.doi.org/10.1007/bf00887135.

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40

Shen, I. Y. "Response of a Stationary, Damped, Circular Plate Under a Rotating Slider Bearing System". Journal of Vibration and Acoustics 115, n. 1 (1 gennaio 1993): 65–69. http://dx.doi.org/10.1115/1.2930316.

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This paper is to demonstrate that axisymmetric plate damping will suppress unbounded response of a stationary, elastic, circular plate excited by a rotating slider. Use of the method of multiple scales shows that the axisymmetric plate damping will suppress parametric resonances excited by slider stiffness and slider inertia at supercritical speed. In addition, the plate damping will increase the onset speed above which slider damping destabilizes the elastic circular plate. Moreover, numerical examples show that the plate damping could stabilize the plate/slider system at discrete rotation speeds above the onset speed.

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Yu, Y. Jun, Xiao-Geng Tian e Jie Liu. "Size-dependent damping of a nanobeam using nonlocal thermoelasticity: extension of Zener, Lifshitz, and Roukes’ damping model". Acta Mechanica 228, n. 4 (5 dicembre 2016): 1287–302. http://dx.doi.org/10.1007/s00707-016-1769-0.

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Chen, Lin, e Xing-long Gong. "Damping of magnetorheological elastomers". Journal of Central South University of Technology 15, S1 (settembre 2008): 271–74. http://dx.doi.org/10.1007/s11771-008-0361-8.

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Marsh, E. R., e L. C. Hale. "Damping of Flexural Waves With Imbedded Viscoelastic Materials". Journal of Vibration and Acoustics 120, n. 1 (1 gennaio 1998): 188–93. http://dx.doi.org/10.1115/1.2893803.

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Abstract (sommario):

This paper considers a passive damping method that can be applied to beam-like structures such as machine tool bases and columns. The method uses viscoelastic materials to dissipate energy in the manner of classic constrained-layer damping; however, the layers are embedded within the structure as opposed to being applied externally. This provides a robust means of incorporating damping without encountering several of the common disadvantages associated with external damping treatments. An analytical solution to the amount of damping that can be achieved using embedded layers is available, but is known to be inaccurate when the viscoelastic stiffness approaches that of the structural components. Therefore, a new prediction of the maximum damping level that can be expected in a structure is developed and presented here. This prediction gives good results in a wide variety of applications, and offers insight into the relationship between key design parameters. Finite element and experimental verification of the maximum damping predictor are also presented.

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Krenk, Steen. "Frequency Analysis of the Tuned Mass Damper". Journal of Applied Mechanics 72, n. 6 (15 maggio 2005): 936–42. http://dx.doi.org/10.1115/1.2062867.

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Abstract (sommario):

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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Al-Jamal, Rehab, e Mara S. Ludwig. "Changes in proteoglycans and lung tissue mechanics during excessive mechanical ventilation in rats". American Journal of Physiology-Lung Cellular and Molecular Physiology 281, n. 5 (1 novembre 2001): L1078—L1087. http://dx.doi.org/10.1152/ajplung.2001.281.5.l1078.

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Excessive mechanical ventilation results in changes in lung tissue mechanics. We hypothesized that changes in tissue properties might be related to changes in the extracellular matrix component proteoglycans (PGs). The effect of different ventilation regimens on lung tissue mechanics and PGs was examined in an in vivo rat model. Animals were anesthetized, tracheostomized, and ventilated at a tidal volume of 8 (Vt 8), 20, or 30 (Vt 30) ml/kg, positive end-expiratory pressure of 0 (PEEP0) or 1.5 (PEEP1.5) cmH2O, and frequency of 1.5 Hz for 2 h. The constant-phase model was used to derive airway resistance, tissue elastance, and tissue damping. After physiological measurements, one lung was frozen for immunohistochemistry and the other was reserved for PG extraction and Western blotting. After 2 h of mechanical ventilation, tissue elastance and damping were significantly increased in rats ventilated at Vt 30PEEP0 compared with control rats (ventilated at Vt 8PEEP1.5). Versican, basement membrane heparan sulfate PG, and biglycan were all increased in rat lungs ventilated at Vt 30PEEP0 compared with control rats. At Vt 30PEEP0, heparan sulfate PG and versican staining became prominent in the alveolar wall and airspace; biglycan was mostly localized in the airway wall. These data demonstrate that alterations in lung tissue mechanics with excessive mechanical ventilation are accompanied by changes in all classes of extracellular matrix PG.

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Young, M. I. "Spot damping anomalies". Journal of Sound and Vibration 131, n. 1 (maggio 1989): 160–63. http://dx.doi.org/10.1016/0022-460x(89)90831-6.

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FRIEND, R. D., e V. K. KINRA. "PARTICLE IMPACT DAMPING". Journal of Sound and Vibration 233, n. 1 (maggio 2000): 93–118. http://dx.doi.org/10.1006/jsvi.1999.2795.

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Yin, Fuxing, Kotobu Nagai, Kenji Watanabe e Kohji Kawahara. "The Damping Behavior of Ni Added Mn-Cu Damping Alloys". MATERIALS TRANSACTIONS 44, n. 9 (2003): 1671–74. http://dx.doi.org/10.2320/matertrans.44.1671.

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49

SARRAZIN, JEROME, JEROME CLARACQ e JEAN-PIERRE MONTFORT. "PHYSICAL MODELING OF DAMPING CHARACTERISTICS OF MR FLUIDS". International Journal of Modern Physics B 16, n. 17n18 (20 luglio 2002): 2704–10. http://dx.doi.org/10.1142/s0217979202012876.

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Abstract (sommario):

The behavior of MR fluids involved in industrial devices is often modeled by analogical models which do no link the parameters with the physical properties of the fluid. From the equations of fluid mechanics, we give a physical meaning to parameters such as friction, elastic and mass coefficients used in the mentioned models. The predictions are checked with experimental data which mimic the behavior of devices such as antiseismic systems. The viscoelastic behavior of MR fluids is characterized by mechanical spectroscopy. The complex shear modulus G *(ω) contains all the information about the restoring and viscous forces. For example, the relation between elastic modulus, yield stress and magnetic force is discussed in terms of strain amplitude.

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Shen, I. Y. "A Variational Formulation, a Work-Energy Relation and Damping Mechanisms of Active Constrained Layer Treatments". Journal of Vibration and Acoustics 119, n. 2 (1 aprile 1997): 192–99. http://dx.doi.org/10.1115/1.2889702.

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The purposes of this paper are to formulate active constrained layer (ACL) damping treatments through a variational approach, to study the work-energy relation of ACL, and to identify damping mechanisms of ACL treatments. Application of the extended Hamilton principle to ACL results in the equations of motion of ACL and the charge equation of electrostatics for the piezoelectric constraining layer. The work-energy equation together with the charge equation shows that the power dissipated through the active damping is the product of the electric field and the axial velocity of the piezoelectric constraining layer at the boundaries. This unique feature suggests that a self-sensing and actuating piezoelectric constraining layer may be an appropriate design in dissipating vibration energy without causing instability. To identify the damping mechanisms, a sensitivity analysis shows that the effectiveness of ACL damping primarily depends on the active and passive damping forces transmitted to the vibrating structure through the viscoelastic layer. The active damping force transmitted depends on the controller transfer function as well as a system parameter, termed active damping sensitivity factor, which depends entirely on the configuration of the passive constrained layer and the sensor. Finally, numerical results on ACL beams are obtained to illustrate the theoretical predictions above.

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