Frictional Damping of Flutter: Microslip Versus Macroslip

2016 ◽  
Author(s):  
Robert B. Hudson ◽  
Alok Sinha
Keyword(s):  
Harmonic Balance ◽  
Function Method ◽  
Friction Model ◽  
Describing Function ◽  
Friction Dampers ◽  
Method Of Harmonic Balance ◽  
Frictional Damping ◽  
Negative Damping ◽  
Describing Function Method ◽  
Microslip Friction

Friction dampers are utilized in turbomachinery to reduce blade vibrations resulting from aeroelastic interactions. In this paper, the microslip friction model is applied to a blade with blade to ground damper and subjected to negative damping. Analysis using the describing function method, also known as the method of harmonic balance, is used to identify the behavior of the system and the maximum negative damping that can be stabilized by such a damper. These results are compared to those for the macroslip friction model.

Frictional Damping of Flutter: Microslip Versus Macroslip

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Robert Hudson ◽  
Alok Sinha
Keyword(s):  
Harmonic Balance ◽  
Function Method ◽  
Friction Model ◽  
Describing Function ◽  
Friction Dampers ◽  
Method Of Harmonic Balance ◽  
Frictional Damping ◽  
Negative Damping ◽  
Describing Function Method ◽  
Microslip Friction

Friction dampers are utilized in turbomachinery to reduce blade vibrations resulting from aeroelastic interactions. In this paper, the microslip friction model is applied to a blade with blade to ground damper and subjected to negative damping. Analysis using the describing function method, also known as the method of harmonic balance, is used to identify the behavior of the system and the maximum negative damping that can be stabilized by such a damper. These results are compared to those for the macroslip friction model.

Harmonic Loss Calculation of Three-Phase Transformer Based on J-A Model

2013 ◽  
Vol 325-326 ◽  
pp. 519-524
Author(s):  
Lian Liu ◽  
Qiong Lin Li ◽  
Hui Jin Liu ◽  
Xue Cui ◽  
Lei Zou
Keyword(s):  
Maxwell Equations ◽  
Function Method ◽  
Domain Model ◽  
Iron Core ◽  
Describing Function ◽  
Good Convergence ◽  
Proposed Model ◽  
Three Phase ◽  
Describing Function Method ◽  
Transformer Model

Beginning with characterizing the nonlinearities of transformer, this paper uses the J-A model to represent the hysteresis of iron core, and fits the model in calculating exciting current. Compared with the other methods, such as polynomial and describing function method, J-A model is more capable in representing nonlinearity, so the calculated current would be more accurate. Then, after analyzing Maxwell equations that meet certain boundary conditions, the paper considers comprehensively the effects of skin and proximity, and then obtains the computing way of ac resistance under harmonics. At last, based on the mentioned results, paper proposes a set of three-phase transformer model which could calculate harmonic losses. The proposed model is a kind of combined time-and frequency-domain model that possesses good convergence. The introduced example has verified the correctness and effectiveness of the model which absolutely suits the engineering applications.

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