Computation of the Optimal Normal Load of a Friction Damper Under Different Types of Excitation

2003 ◽  
Vol 125 (4) ◽  
pp. 1042-1049 ◽  
Author(s):  
D. Cha ◽  
A. Sinha
Keyword(s):  
White Noise ◽  
Normal Load ◽  
Harmonic Balance Method ◽  
Random Excitation ◽  
Linearization Method ◽  
Equivalent Linearization ◽  
Friction Damper ◽  
Different Types ◽  
Forced Responses ◽  
Sinusoidal Excitation

In this paper, forced responses of a frictionally damped turbine blade are investigated for three different types of excitation: white noise excitation, narrowband random excitation, and deterministic sinusoidal excitation. To determine the steady-state nonlinear response, the harmonic balance method is used for sinusoidal excitation, and the equivalent linearization method is used for white noise and narrowband random excitations. Using a new set of nondimensionalized variables, the optimal value of normal load of a friction damper is found to be almost independent of the nature of excitation. The effectiveness of the damper in reducing the vibration level is also examined for the aforementioned three different types of excitation.

scholarly journals Computation of the Optimal Normal Load of a Friction Damper Under Different Types of Excitation

1999 ◽  
Author(s):  
D. Cha ◽  
A. Sinha
Keyword(s):  
White Noise ◽  
Narrow Band ◽  
Normal Load ◽  
Harmonic Balance Method ◽  
Random Excitation ◽  
Linearization Method ◽  
Equivalent Linearization ◽  
Friction Damper ◽  
Different Types ◽  
Sinusoidal Excitation

In this paper, forced responses of a frictionally damped turbine blade are investigated for three different types of excitation: white noise excitation, narrow band random excitation and deterministic sinusoidal excitation. To determine the steady state nonlinear response, the harmonic balance method is used for sinusoidal excitation, and the equivalent linearization method is used for white noise and narrow band random excitations. Using a new set of nondimensionalized variables, the optimal value of normal load of a friction damper is found to be almost independent of the nature of excitation. The effectiveness of the damper in reducing the vibration level is also examined for the aforementioned three different types of excitation.

Computation of the Optimal Normal Load for a Mistuned and Frictionally Damped Bladed Disk Assembly Under Different Types of Excitation

2001 ◽  
Author(s):  
D. Cha ◽  
A. Sinha
Keyword(s):  
Harmonic Balance ◽  
Normal Load ◽  
Harmonic Balance Method ◽  
Random Excitation ◽  
Friction Dampers ◽  
Analytical Technique ◽  
Bladed Disk ◽  
Different Types ◽  
Bladed Disk Assembly ◽  
Sinusoidal Excitation

Using non-dimensional variables, the performances of friction dampers of a mistuned bladed disk assembly are examined for different types of excitation: white noise excitation, independent narrow band random excitation and sinusoidal excitation with unknown amplitudes. Based on the harmonic balance method, an analytical technique is developed to compute the statistics of response for sinusoidal excitation with unknown amplitudes. The performances of blade-to-blade and blade-to-ground dampers are compared under different types of excitation. It is found that non-dimensional optimal normal loads of friction dampers are almost independent of the nature of excitation. Therefore, optimal normal loads of friction dampers can be chosen without any knowledge of the nature of excitation.

Computation of the Optimal Normal Load for a Mistuned and Frictionally Damped Bladed Disk Assembly Under Different Types of Excitation

2010 ◽  
Vol 6 (2) ◽  
Author(s):  
Douksoon Cha ◽  
Alok Sinha
Keyword(s):  
Harmonic Balance ◽  
Normal Load ◽  
Harmonic Balance Method ◽  
Random Excitation ◽  
Friction Dampers ◽  
Analytical Technique ◽  
Bladed Disk ◽  
Different Types ◽  
Bladed Disk Assembly ◽  
Sinusoidal Excitation

Using nondimensional variables, the performances of friction dampers of a mistuned bladed disk assembly are examined for different types of excitation: white noise excitation, independent narrow band random excitation, and sinusoidal excitation with unknown amplitudes. Based on the harmonic balance method, an analytical technique is developed to compute the statistics of response for sinusoidal excitation with unknown amplitudes. The performances of blade-to-blade and blade-to-ground dampers are compared under different types of excitation. It is found that the nondimensional optimal normal loads of friction dampers are almost independent of the nature of excitation. Therefore, optimal normal loads of friction dampers can be chosen without any knowledge of the nature of excitation.

Equivalent Linearization of Bladed Disk Assemblies with Friction Nonlinearities Under Random Excitation

2020 ◽  
Author(s):  
Alwin Förster ◽  
Lars Panning-von Scheidt ◽  
Jörg Wallaschek
Keyword(s):  
Degrees Of Freedom ◽  
Turbine Blades ◽  
Random Excitation ◽  
Linearization Method ◽  
Equivalent Linearization ◽  
Friction Damper ◽  
Bladed Disk ◽  
Stationary Stochastic Processes ◽  
Bladed Disk Assembly ◽  
Equivalent Linearization Method

Abstract The present article addresses the vibrational behaviour of bladed disk assemblies with nonlinear shroud coupling under random excitation. In order to increase the service life and safety of turbine blades, intense calculations are carried out to predict the vibrational behaviour. The use of friction dampers for energy dissipation and suppression of large amplitudes makes the mechanical system nonlinear, which complicates the calculations. Depending on the stage, different types of excitation can occur in a turbine, from clearly defined deterministic to random excitation. So far, the latter problem has only been dealt with to a limited extent in the literature on turbomachinery. Nevertheless, there are in general different approaches and methods to address this problem most of which are strongly restricted with regard to the number of degrees of freedom. The focus of this paper is the application of an equivalent linearization method to calculate the stochastic response of an academic model of a bladed disk assembly under random excitation. The nonlinear contact is modelled both with an elastic Coulomb-slider and a Bouc-Wen formulation to reproduce the hysteretic character of a friction nonlinearity occurring in the presence of a friction damper. Both the excitation and the response are limited to mean-free, stationary stochastic processes, which means that the stochastic moments, do not change over time. Unlike previous papers on this topic, the calculations are performed on a full bladed disk assembly in which each segment is approximated with several degrees of freedom.

Statistics of Responses of a Mistuned and Frictionally Damped Bladed Disk Assembly Subjected to White Noise and Narrow Band Excitations

2000 ◽  
Author(s):  
D. Cha ◽  
A. Sinha
Keyword(s):  
White Noise ◽  
Narrow Band ◽  
Random Excitation ◽  
Linearization Method ◽  
Equivalent Linearization ◽  
Friction Dampers ◽  
Analytical Technique ◽  
Bladed Disk ◽  
Bladed Disk Assembly ◽  
Equivalent Linearization Method

In this paper, the effects of friction dampers on the vibration of a mistuned bladed disk assembly are examined for the following types of random excitation: white noise and narrow band. To compute the statistics of nonlinear response, an analytical technique is developed based on the equivalent linearization method. The validity of the analytical technique has been established by comparison with the results from numerical simulations. The relation between the vibration mode of the system and the performance of friction dampers is investigated.

On the Performance of Wavy Dry Friction and Piezoelectric Hybrid Flexible Dampers

2021 ◽  
Author(s):  
Yaguang Wu ◽  
Yu Fan ◽  
Lin Li ◽  
Zhimei Zhao
Keyword(s):  
Piezoelectric Material ◽  
Dry Friction ◽  
Normal Load ◽  
Harmonic Balance Method ◽  
Element Model ◽  
Total Output ◽  
Friction Damper ◽  
Damping Effect ◽  
Thin Walled Structures ◽  
Friction Plate

Abstract This paper proposes a flexible dry friction plate to mitigate the vibration of thin-walled structures for one resonance crossing. Based on a cantilever beam-friction damper finite element model, the geometry and material parameters of the friction plate are optimized numerically through steady-state response analyses by the widely-used Multi-Harmonic Balance Method (MHBM). In order to further improve the damping effect, piezoelectric material is distributed to the flexible damper, and two types of dry friction and piezoelectric hybrid dampers are explored, namely semi-active and passive, respectively. For semi-active hybrid dampers, piezoelectric material is used as an actuator to adjust the normal load applied to the friction interface in real time, so that the friction damping is improved. For passive ones, piezoelectric material is used as a transducer, which dissipates the strain energy stored in the wavy plate by the shunting circuit, additional shunted piezoelectric damping contributes to the total output damping accordingly. Better damping effect compared with the friction baseline is realized for the two types ideally. This damping module has a simple structure and avoids the problem of installation and maintenance of piezoelectric material which is generally bonded to the host structure. Technical challenges are: the semi-active type requires excessive voltage applied to the piezoelectric actuator, while the passive one needs to connect a programmable synthetic circuit.

On the Performance of Wave-Like Dry Friction and Piezoelectric Hybrid Flexible Dampers

2021 ◽  
Author(s):  
Y. G. Wu ◽  
Y. Fan ◽  
L. Li ◽  
Z. M. Zhao
Keyword(s):  
Piezoelectric Material ◽  
Dry Friction ◽  
Normal Load ◽  
Harmonic Balance Method ◽  
Element Model ◽  
Total Output ◽  
Friction Damper ◽  
Damping Effect ◽  
Thin Walled Structures ◽  
Friction Plate

Abstract This paper proposes a flexible dry friction plate to mitigate the vibration of thin-walled structures for one resonance crossing. Based on a cantilever beam-friction damper finite element model, the geometry and material parameters of the friction plate are optimized numerically through steady-state response analyses by the widely-used Multi-Harmonic Balance Method (MHB-M). In order to further improve the damping effect, piezoelectric material is distributed to the flexible damper, and two types of dry friction and piezoelectric hybrid dampers are explored, namely semi-active and passive, respectively. For semi-active hybrid dampers, piezoelectric material is used as an actuator to adjust the normal load applied to the friction interface in real time, so that the friction damping is improved. For passive ones, piezoelectric material is used as a transducer, which dissipates the strain energy stored in the wave-like plate by the shunting circuit, additional shunted piezoelectric damping contributes to the total output damping accordingly. Better damping effect compared with the friction baseline is realized for the two types ideally. This damping module has a simple structure and avoids the problem of installation and maintenance of piezoelectric material which is generally bonded to the host structure. Technical challenges are: the semi-active type requires excessive voltage applied to the piezoelectric actuator, while the passive one needs to connect a programmable synthetic circuit.

Extension of Nonlinear Stochastic Solution to Include Sinusoidal Excitation—Illustrated by Duffing Oscillator

2017 ◽  
Vol 12 (5) ◽  
Author(s):  
R. J. Chang
Keyword(s):  
White Noise ◽  
Correction Factor ◽  
Duffing Oscillator ◽  
Gaussian White Noise ◽  
Noise Spectrum ◽  
Linearization Method ◽  
Algebraic Equations ◽  
Stochastic Solution ◽  
Non Gaussian ◽  
Sinusoidal Excitation

A new non-Gaussian linearization method is developed for extending the analysis of Gaussian white-noise excited nonlinear oscillator to incorporate sinusoidal excitation. The non-Gaussian linearization method is developed through introducing a modulated correction factor on the linearization coefficient which is obtained by Gaussian linearization. The time average of cyclostationary response of variance and noise spectrum is analyzed through the correction factor. The validity of the present non-Gaussian approach in predicting the statistical response is supported by utilizing Monte Carlo simulations. The present non-Gaussian analysis, without imposing restrictive analytical conditions, can be obtained by solving nonlinear algebraic equations. The non-Gaussian solution effectively predicts accurate sinusoidal and noise response when the nonlinear system is subjected to both sinusoidal and white-noise excitations.

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