Готові списки джерел за темами / Non-classical linear damping

Добірка наукової літератури з теми "Non-classical linear damping"

Автор: Grafiati

Опубліковано: 14 березня 2023

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Статті в журналах з теми "Non-classical linear damping"

Fang, W., J. G. Tseng, and J. A. Wickert. "Asymptotic Treatment of Non-Classically Damped Linear Systems." Applied Mechanics Reviews 48, no. 11S (November 1, 1995): S111—S117. http://dx.doi.org/10.1115/1.3005058.

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Анотація:

The presence of non-classical dissipation in a general discrete dynamic system is investigated through a perturbation method for the eigenvalues and vectors. Results accurate to second-order are obtained, with corrections to the base solution being expressed in terms of readily-calculated quadratic forms. Exact solutions, and the derived asymptotic ones, are compared with the predictions of the so-called method of approximate decoupling, in which certain non-classical dissipative terms are omitted from calculations in the eigenvalue problem. The perturbation method is discussed through its application in several examples, indicating circumstances in which a non-classically damped system can be well-approximated by an “equivalent” classically damped one. Somewhat surprisingly, the addition of non-classical damping does not necessarily increase the stability of all vibration modes, and the perturbation method is shown to be useful in identifying those critical modes.

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Liu,, Z. S., D. T. Song, and, C. Huang, D. J. Wang, and S. H. Chen. "Vibration Analysis of Non-Classically Damped Linear Systems." Journal of Vibration and Acoustics 126, no. 3 (July 1, 2004): 456–58. http://dx.doi.org/10.1115/1.1760563.

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This Technical Brief presents a new method for vibration analysis of a non-classically damped system. The basic idea is to introduce a transformation, which bears clear physical meaning, so that the original non-classical damped system is transformed into a new 2nd-order system that does not have the damping term. The transformed system not only provides an alternative of calculating response, but also reveals more clearly vibration behaviors of the original system.

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Staszewski, W. J. "Analysis of non-linear systems using wavelets." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 214, no. 11 (November 1, 2000): 1339–53. http://dx.doi.org/10.1243/0954406001523317.

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Analysis of non-linear systems is an essential part of engineering structural dynamics. A number of methods have been developed in recent years. Classical Fourier-based methods have been extended to the use of phase plane, combined time-frequency, time-scale approaches and multidimensional spectra. This paper is an attempt to collate in one place some of the recent advances in wavelet analysis for the study of non-linear systems. This includes methods related to system identification based on wavelet ridges and skeletons, damping estimation procedures, wavelet-based frequency response functions, cross-wavelet analysis, self-similar signals, coherent structures and chaos.

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Adhikari, Sondipon. "Qualitative dynamic characteristics of a non-viscously damped oscillator." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 461, no. 2059 (June 16, 2005): 2269–88. http://dx.doi.org/10.1098/rspa.2005.1485.

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This paper considers the linear dynamics of a single-degree-of-freedom non-viscously damped oscillator. It is assumed that the non-viscous damping force depends on the history of velocity via a convolution integral over an exponentially decaying kernel function. Classical qualitative dynamic properties known for viscously damped oscillators have been generalized to such non-viscously damped oscillators. The following questions of fundamental interest have been addressed: (i) under what conditions can a non-viscously damped oscillator sustain oscillatory motions? (ii) how does the natural frequency of a non-viscously damped oscillator compare with that of an equivalent undamped oscillator? and (iii) how does the decay rate compare with that of an equivalent viscously damped oscillator? Introducing two non-dimensional factors, namely, the viscous damping factor and the non-viscous damping factor, we provide answers to these questions. Wherever possible, attempts are made to relate the new results with equivalent classical results for a viscously damped oscillator.

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Zhang, Zhiying, Ying Li, Yihe Yin, and Zhiyu Han. "Study on Identification Method of Motion States at Interface for Soil-Structure Interaction Damping System." Applied Sciences 12, no. 3 (February 8, 2022): 1729. http://dx.doi.org/10.3390/app12031729.

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The damping system characterizes the spatial distribution of structural energy dissipation. Identifying a damping system is the premise for determining the dynamic analysis method. Concepts of nonlinear processes and non-classical damping systems are often confused without theoretical primary and experimental verification. This paper proposes an identification method of damping systems based on motion states at the interface by analyzing the correlation between the damping system and dynamic characteristics. The relationship between the change of damping system type and relative motion states at the interface is studied by investigating multiple material properties through shaking table model tests of a large-scale soil-structure interaction (SSI) system. The results show that a nonlinear system can demonstrate the characteristics of the classical damping system as soon as there is no mutation of motion states at the interface of the system. The identification method of damping system based on motion states at the interface can reflect the change of dynamical characteristics of the system under linear and nonlinear processes.

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Ahmadi Taleshian, Hamed, Alireza Mirzagoltabar Roshan, and Javad Vaseghi Amiri. "Use of viscoelastic links for seismic pounding mitigation under random input." International Journal of Structural Integrity 11, no. 3 (November 19, 2019): 471–96. http://dx.doi.org/10.1108/ijsi-06-2019-0055.

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Purpose The purpose of this paper is to study the effects of viscoelastic links between two adjacent buildings for pounding mitigation under white-noise seismic input. Design/methodology/approach A formulation is first extracted for the effective modal damping ratios of the system. Then, two single DOF linear buildings connected by viscoelastic links are considered with both classical and non-classical damping schemes. The inelastic behavior is also taken into account by using equivalent natural frequencies and damping ratios of the buildings. The effect of ground dominant frequency and damping on the displacement response is also investigated by using Kanai‒Tajimi filtered white noise as the random input. Findings The difference between classical and non-classical damping is shown to be less than 20 percent, implying the permission in using the simpler classical damping scheme. Finally, the problem is extended to two-storey buildings, where using viscoelastic links only at the top story level of the buildings is shown to be sufficient for controlling individual, as well as relative, motions of the structures. Originality/value Results demonstrate that the use of link with a moderate stiffness may reduce the stiffer building displacement up to approximately 20 percent in comparison to the free displacement, while the seismic pounding of the adjacent buildings is effectively controlled. Further, an upper limit of link stiffness is obtained for preventing the increase in the stiffer building displacement, which may be exceeded by the minimum link stiffness necessary for pounding prevention if small gap size exists.

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Li, Gui Ling. "Nonlinear Measurement Data Processing Based on Improved Damping Least Squares." Applied Mechanics and Materials 105-107 (September 2011): 2034–38. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.2034.

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Datum are the key of “Digital Earth”.In measurement, dealing with nonlinear models of observation datum, we may take their approximate values at observation values by Taylor series expansion, say, taking first-order item as a linear function of classical adjustment. But requirements of observation data, processing and accuracy assessment are higher and higher with today's fast-growing of high-tech mapping and surveying. So study on nonlinear least squares adjustment has been paid more and more attention. Damping least squares, as a modified algorithm of Gauss-Newton’s algorithm, is necessary to add a damping factor to improve the nature of a coefficient matrix. But it is difficult to choose a suitable damping factor, and needs to solve a group of linear equations repeatedly. In this paper, an improved damping least square was utilized for the non-linear processing of measurement datum in order to reduce a lot of computational workload.

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Žmindák, Milan. "Dynamic and Sensitivity Analysis General Non-Conservative Asymmetric Mechanical Systems." Strojnícky casopis – Journal of Mechanical Engineering 68, no. 2 (November 1, 2018): 105–24. http://dx.doi.org/10.2478/scjme-2018-0021.

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AbstractIn this paper the concept of generalized form of proportional damping is proposed. Classical modal analysis of non-conservative continua is extended to multi DOF linear dynamic systems with asymmetric matrices. Mode orthogonality relationships have been generalized to non-conservative systems. Several discretization methods of continua are presented. Finally, an expression for derivatives of eigenvalues and eigenvectors of non-conservative system is presented. Examples are provided to illustrate the proposed methods.

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Yazici, Hakan, and Mert Sever. "Active control of a non-linear landing gear system having oleo pneumatic shock absorber using robust linear quadratic regulator approach." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 232, no. 13 (June 14, 2017): 2397–411. http://dx.doi.org/10.1177/0954410017713773.

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This paper deals with the active control of a non-linear active landing gear system equipped with oleo pneumatic shock absorber. Runway induced vibration can cause reduction of pilot’s capability of control the aircraft and results the safety problem before take-off and after landing. Moreover, passenger–crew comfort is adversely affected by vertical vibrations of the fuselage. The active landing gears equipped with oleo pneumatic shock absorber are highly non-linear systems. In this study, uncertain polytopic state space representation is developed by modelling the pneumatic shock absorber dynamics as a mechanical system with non-linear stiffness and damping properties. Then, linear matrix inequalities-based robust linear quadratic regulator controller having pole location constraints is designed, since the classical linear quadratic regulator control design is dealing with linearized state space models without considering the non-linearities and uncertainties. Thereafter, numerical simulation studies are carried out to analyse aircraft response during taxiing. Bump- and random-type runway irregularities are used with various runway class and wide range of longitudinal speed. Simulation results revealed that neglecting the non-linear dynamics associated with oleo pneumatic shock absorber results significant performance degradation. Consequently, it is demonstrated that proposed robust linear quadratic regulator controller has a superior performance in terms of passenger–crew comfort and operational safety when compared to classical linear quadratic regulator.

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Rasa, Ahmad Yamin, and Mehmet Hamit Özyazıcıoğlu. "Determination of the exact mode frequencies of multi-storey structures by state-space method and a comparison with mode superposition method." Challenge Journal of Structural Mechanics 7, no. 1 (March 12, 2021): 1. http://dx.doi.org/10.20528/cjsmec.2021.01.001.

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Анотація:

A comparative research has been carried out for obtaining the time-consuming exact solution (state-space) and approximate solution (mode superposition) of transient and steady-state vibrations of linearly damped linear frame buildings. In the mode superposition method, the proportional damping matrix has been constructed by different approaches such as modal combination of mass and stiffness matrixes (Rayleigh) and disregarding the off-diagonal elements of the non-classical damping matrix, while in the state-space method the non-proportional damping matrix is constructed in exact situation. These observations are individually investigated, which the most suitable parameter to render the approximate results as close as possible to the exact results. Harmonic forces are applied on the different storeys of three and five storey frame buildings, and the responses are displayed in comparative tables and figures. The maximum responses are calculated by square root of sum of the squares (SRSS) method. A MATLAB code is generated and the equations of exact and approximate methods are solved.

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Більше джерел

Частини книг з теми "Non-classical linear damping"

Cheung, S., and S. Bansal. "A stochastic simulation algorithm for Bayesian model updating of linear structural dynamic system with non-classical damping." In Safety, Reliability, Risk and Life-Cycle Performance of Structures and Infrastructures, 1907–12. CRC Press, 2014. http://dx.doi.org/10.1201/b16387-278.

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Тези доповідей конференцій з теми "Non-classical linear damping"

Lombard, Jean-Pierre, Pierrick Jean, and Pascal Lubrina. "Calibrated Non Linear Dissipative Model of Fan Bladed Disk." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22046.

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The results of non linear modeling of mechanical damped behavior of fan bladed disk are presented in the paper. A combined test/modeling strategy dedicated to the prediction of behavior of bladed disk in all operating flight range is proposed. The proposed methodology is applied on 2 configurations: firstly, on a well known fan stage (wide chord titanium blade with curvilinear attachment) and secondly, on a new one based on woven composite technology. This strategy needs to perform efficient and precise modal tests able to measure as well as possible the damping parameters. The test procedure is set up after trying of different test configurations: the robustness/repeatability of measure is verified and the scatter is quantified. A non linear tool (Snecma in-house code) is used to predict the behavior of the test configuration and allows the identification of damping parameters. These damping parameters are then used to assess the dissipative behavior in operating conditions. This tool is based on DLFT method derived from classical harmonic balance method and allows fast calculations of NL responses. The results presented illustrate the quality of tests measurement and the validity of the non linear model used to predict the characterized physics. The calibration is based on the damping parameters updated on a wide test configurations.

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Lu, Xia, and S. Hanagud. "Modified Extended Thermodynamic Model for Material Damping." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0569.

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Abstract During the process of damping of a structure, the mechanical energy is converted to thermal energy. Yet, the most commonly used model for material damping is the linear viscous damping. There are many attempts to develop thermodynamic models for damping. To adequately describe damping, we need more variables than the classical state variables. A simple thermodynamic model that is based on the framework of extended non-equilibrium thermodynamics is presented. Heat flux, non-equilibrium stress field and the associated non-equilibrium internal energy are used as additional variables. Longitudinal vibrations of a uniform rod are studied to present the flexibility of thermodynamic modeling for material damping.

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de Lemos, Marcelo J. S., and Marcelo Assato. "Heat Transfer in a Suddenly Expanded Turbulent Flow Past a Porous Insert Using Linear and Non-Linear Eddy-Viscosity Models." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-39402.

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This work presents numerical results for heat transfer in turbulent flow past a backward-facing-step channel with a porous insert using linear and non-linear eddy viscosity macroscopic models. The non-linear turbulence models are known to perform better than classical eddy-diffusivity models due to their ability to simulate important characteristics of the flow. Parameters such as porosity, permeability and thickness of the porous insert are varied in order to analyze their effects on the flow pattern, particularly on the damping of the recirculating bubble after the porous insertion. The numerical technique employed for discretizing the governing equations is the control-volume method. The SIMPLE algorithm is used to correct the pressure field. Wall functions for velocity and temperature are used in order to bypass fine computational close to the wall. Comparisons of results simulated with both linear and non-linear turbulence models are presented.

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Assato, Marcelo, and Marcelo J. S. de Lemos. "Turbulent Flow and Heat Transfer in a Porous Chamber." In ASME 2003 Heat Transfer Summer Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ht2003-47253.

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This work presents a numerical investigation of turbulent flow past a porous structure in a channel using linear and non-linear eddy viscosity macroscopic models. Parameters such as porosity and permeability of the porous material are varied in order to analyze their effects on the flow pattern, particularly on the damping of the recirculating bubble after the entrance and exit regions. The numerical technique employed for discretizing the governing equations is the control-volume method. The SIMPLE algorithm is used to correct the pressure field. The classical wall function is utilized in order to handle flow calculation near the wall. A discussion on the use of this technique for simulating the flow in question is presented. Comparisons of results simulated with both linear and non-linear turbulence models are shown.

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Franco, Guillermo, Jun Yu, and Raimondo Betti. "Uniqueness of Solutions for the Identification of Linear Reduced Order Structural Systems." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-61193.

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Анотація:

The problem of identification of structural systems is an inverse problem that uses input (say force excitation) and output information (accelerations, for instance) to obtain an optimal model to describe the system’s behavior. Since a full instrumentation setup is expensive, situations usually arise where only partial measurements are available. Uniqueness of the solution in these circumstances might not be guaranteed. This paper analyzes the minimum number of measurements required to ensure that only one solution exists for the identification problem of mass, damping and stiffness distributions of shear-type N degrees of freedom linear structures. Three typical configurations of measurements are studied with two distinct theoretical approaches, one based on classical polynomial theory, the other based on reduced order model theory. Both these approaches lead to the conclusion that only one input and one or two output measurements are sufficient to guarantee uniqueness of identification, depending on the selected location of the input measurement. Additionally, the identification of a 3DOF system is carried out analytically with the usage of Sylvester’s Dyalitic Elimination to show that fewer measurements than the ones proposed lead to non-unique identification. This fact is also illustrated with the usage of a recently developed optimization technique, with which convergence to the different solutions is observed depending on the initial estimate used.

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Markeng, Kevin, Torgeir Vada, and Zhi Yuan Pan. "Investigation of Free Surface Damping Models With Applications to Gap Resonance Problems." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61288.

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In this paper two methods for modelling the damping in a narrow gap are investigated. The first method is called the Pressure Damping Model. This method has been used in studies of wave energy devices. An attractive feature of this model is that the modified input is directly related to the energy dissipation in the gap, which means that if this dissipation is estimated the input to the model can be obtained directly. The idea of the method is to add a pressure input in the gap to suppress the resonant motion. A challenge with the method is that it contains a non-linear term. The second method is the Newtonian Cooling damping model. The method is based on introducing a dissipation term in the free surface boundary condition. This dissipation term contains a coefficient which is not directly related to the energy dissipation. Hence this method is not so easy to relate directly to the estimated energy dissipation. An advantage with this method is that it is linear and hence can be expected to be more robust. In the first part of the paper a 2-dimensional problem is investigated using both methods. In addition to the numerical performance and robustness, much focus is put on investigation of the energy balance in the solution, and we attempt to relate both models to the energy dissipation in the gap. In the second part the Newtonian cooling method is implemented in a 3-dimensional potential flow solver and it is shown that the method provides a robust way to handle the resonance problem. The method will give rise to a modified set of equations which are described. Two different problems are investigated with the 3D solver. First we look at a side-by-side problem, where the 3D results are also compared with 2D results. Finally, the moonpool problem is investigated by two different 3D solvers, a classical Green’s function based method and a Rankine solver. It is also shown how this damping model can be combined with a similar model on the internal waterplane to remove irregular frequencies.

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Bass, D., and K. Haddara. "Roll Damping For Small Fishing Vessels." In SNAME 22nd American Towing Tank Conference. SNAME, 1989. http://dx.doi.org/10.5957/attc-1989-050.

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The successes of Naval Architects in predicting ship motions in waves, have been mainly confined to motions other than roll. For roll motions it has long been recognized that roll damping for wave encounter frequencies near the natural roll frequency is not only an extremely significant parameter but also very difficult to predict accurately. Because of the need to consider viscous flow (or even 'slightly viscous flow') to correctly model roll damping phenomena, there is still some way to go before an adequate numerical model of the hydrodynamics of roll is forthcoming. For this reason empirical and semi-empirical methods have played and will continue to play an important role in the prediction of roll motions. For small fishing vessels with deep skegs, hard chines and nonstandard hull shapes, the prediction of roll damping is particularly difficult due to lack of available data bases, semi- empirical formulae, and of course adequate theoretical models. It was for this reason that the present study was undertaken. In all, six small fishing vessels will be studied, each of which lies in the 'less-than 25 meter' class. They are all of similar dimensions but have varying hull forms ranging from the angular (e.g. model '363') to the rounded hull form of '366' (see figure 1). Apart from providing a data base for the estimation of damping for different hull forms, the study will be used in the analysis of mathematical and/or numerical methods for the prediction of roll damping that the authors hope to develop (or hope will be developed) in the future. The present paper describes preliminary investigations of roll damping characteristics for just 3 of the boats. The methodology employed was that of the classical roll decay test with an innovative feature-namely the use of a newly developed method of analysis which enabled the authors to obtain the non- dimensional damping coefficient from the complete roll decay curve taken over just one full cycle. This method of analysis is based on an energy approach and is explained in [l]. Using this approach, the roll damping moment dependence on the initial roll angle is easy to obtain. The emphasis in this paper is a 'frequency domain' analysis of the results with equivalent linear damping as the primary target. The advantage of the simple decay test is that it allows for analysis in both the frequency and time domains. A study of the results in the time domain will be presented in a later paper. The simplicity of the roll decay experiment also means that many experiments can be perfomed and regression analysis carried out on the results. Over one thousand such tests were performed for the three models in this study. The body plans for the three models are shown in figures 1 (a), (b), (c), and their particulars are given in Table l. In the experiments the models were attached to a dynamometer with just 2 degrees of freedom; the model was free to roll and heave, but restrained in all other modes.

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de Lemos, Marcelo J. S., and Wagner C. Galuppo. "Effect of Porous Insert on Heat Transfer in a Backward-Facing Step Flow." In ASME 2016 Heat Transfer Summer Conference collocated with the ASME 2016 Fluids Engineering Division Summer Meeting and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/ht2016-7328.

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Анотація:

We present numerical results for turbulent heat transfer past a backward-facing-step channel with a porous insert. A non-linear eddy viscosity model was applied to handle turbulence. For a constant Darcy number, the thickness of the porous insert was varied in order to analyze its effects on the flow pattern, particularly the damping of the recirculating bubble past the insert. Further, the reduction of the Nusselt number along the bottom heated surface, when using porous materials inside the channel, was investigated. The numerical technique employed for discretizing the governing equations was the control-volume method. The SIMPLE algorithm was used to correct the pressure field and the classical wall function approach was utilized in order to handle flow calculations near the wall. Comparisons of results simulated with different porous materials were presented.

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Silkowski, Peter D., Chae M. Rhie, George S. Copeland, James A. Eley, and James M. Bleeg. "CFD Investigation of Aeromechanics." In ASME Turbo Expo 2001: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-gt-0267.

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A Computational Fluid Dynamics (CFD) tool was developed and applied to a variety of aeromechanics problems, including both forced response and flutter. This 3-D non-linear, viscous, time accurate code, in conjunction with a large parallel network, is used to demonstrate the mature capability of CFD based tools for aeromechanical analysis. An example of multistage blade row interaction analysis is presented and compared against detailed experimental data highlighting the fidelity of current CFD tools. Flutter analyses of isolated blade rows are also compared to data and used to demonstrate several classical aeromechanical concepts such as influence coefficients, the destabilizing effect of neighboring blades in cascade flutter, the depiction of an aerodynamic damping map, and the flutter benefit of frequency mistuning. These two capabilities, multistage and flutter, are then combined to examine the effect of multistage interaction on the flutter problem. Finally the reasons for extending the above modeling to include full-aeroelastic capability are discussed and an example is presented.

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Spanos, Pol D., Federica M. Strati, Giovanni Malara, and Felice Arena. "Stochastic Dynamic Analysis of U-OWC Wave Energy Converters." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61522.

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Анотація:

The paper presents a random vibration analysis of a U-Oscillating Water Column wave energy harvester (U-OWC). The U-OWC comprises a vertical duct on the wave beaten side, in addition to the elements of conventional OWCs. From a mathematical perspective, the U-OWC dynamic response is governed by a set of coupled non-linear differential equations with asymmetric matrices of mass, damping, and stiffness. In this work, an approximate analytical solution of the U-OWC equations of motion is sought by using the technique of statistical linearization. This technique allows pursuing rapid random vibration analyses via classical linear input-output relationships. The analysis is conducted by considering the case of the full-scale prototype in the port of Civitavecchia (Rome, Italy). The reliability of the proposed approach is assessed versus relevant Monte Carlo data. For this, realizations of sea states compatible with typical power spectral density functions of sea waves are employed. The performed analyses prove that the statistical linearization technique based approach is an efficient and reliable tool which may both circumvent the use of time-consuming Monte Carlo simulations, and be used for a variety of design optimization related parameter studies.

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