Interaction Between Coriolis Forces and Mistuning on a Cyclic Symmetric Structure with Geometrical Nonlinearity

2020 ◽  
Author(s):  
Anthony Tacher ◽  
Fabrice Thouverez ◽  
Jason Armand
Keyword(s):  
Standing Wave ◽  
Geometrical Nonlinearity ◽  
Numerical Approach ◽  
Travelling Wave ◽  
Lumped Parameter Model ◽  
Coriolis Forces ◽  
High Speeds ◽  
Symmetric Structure ◽  
Lumped Parameter ◽  
Cyclic Symmetric

Abstract An investigation of the interaction between Coriolis forces and mistuning on a cyclic symmetric structure is presented in this paper. The sensitivity of the eigenvalues and eigenvectors to mistuning is first studied with the perturbation method. A lumped parameter model is used to perform a modal analysis using a numerical approach after which geometrical nonlinearity is added to compare behavior with the linear case. Two different modes are thoroughly investigated for different rotational speeds, the first with an eigenvalue isolated from the others and the second presenting a frequency veering zone. The evolution from a standing wave domination at low speeds to a travelling wave domination at high speeds is observed for the isolated mode, whereas a standing wave domination remains around the veering zone for the second mode studied. It is also shown that the geometrical nonlinearity reinforces the mistuning effect versus the Coriolis forces.

Interaction Between Coriolis Forces and Mistuning on a Cyclic Symmetric Structure With Geometrical Nonlinearity

2020 ◽  
Author(s):  
Anthony Tacher ◽  
Fabrice Thouverez ◽  
Jason Armand
Keyword(s):  
Standing Wave ◽  
Geometrical Nonlinearity ◽  
Numerical Approach ◽  
Travelling Wave ◽  
Lumped Parameter Model ◽  
Coriolis Forces ◽  
High Speeds ◽  
Symmetric Structure ◽  
Lumped Parameter ◽  
Cyclic Symmetric

Abstract An investigation of the interaction between Coriolis forces and mistuning on a cyclic symmetric structure is presented in this paper. The sensitivity of the eigenvalues and eigenvectors to mistuning is first studied with the perturbation method. A lumped parameter model is used to perform a modal analysis using a numerical approach after which geometrical nonlinearity is added to compare behavior with the linear case. Two different modes are thoroughly investigated for different rotational speeds, the first with an eigenvalue isolated from the others and the second presenting a frequency veering zone. The evolution from a standing wave domination at low speeds to a travelling wave domination at high speeds is observed for the isolated mode, whereas a standing wave domination remains around the veering zone for the second mode studied. It is also shown that the geometrical nonlinearity reinforces the mistuning effect versus the Coriolis forces.

On the Acceleration of a Superconducting Macroparticle in a Magnetic Travelling Wave Accelerator

1971 ◽  
Vol 26 (9) ◽  
pp. 1415-1424 ◽  
Author(s):  
D. Anderson ◽  
S. Claflin ◽  
F. Winterberg
Keyword(s):  
Transmission Line ◽  
Travelling Wave ◽  
Lumped Parameter Model ◽  
Rotational Stability ◽  
Transmission Line Model ◽  
Persistent Currents ◽  
Line Model ◽  
Lumped Parameter ◽  
Limiting Case ◽  
The Magnetic Field

Abstract Two models for describing the operation of a magnetic travelling wave accelerator, the transmission line model and the lumped parameter model, are analyzed. For both cases the current distribution and the magnetic field are calculated. It is shown that the transmission line model can be obtained as the limiting case of the lumped parameter model. It is then assumed that a superconducting solenoid with large persistent currents is used as a projectile with a constant magnetic dipole moment. The motion of this projectile is studied in the case of ignorable flux interaction. The conditions for phase and rotational stability are obtained. It is shown that the projectile has a transverse translational instability. A derivation of the flux interaction current wave is included in the Appendix.

Current Monitoring of Field Controlled DC Spindle Drives

1986 ◽  
Vol 108 (4) ◽  
pp. 289-295 ◽  
Author(s):  
J. L. Stein ◽  
Kyung-Chul Shin
Keyword(s):  
Signal To Noise Ratio ◽  
Operating Conditions ◽  
Lumped Parameter Model ◽  
Cnc Machine ◽  
Spindle System ◽  
High Speeds ◽  
Lumped Parameter ◽  
Cnc Lathe ◽  
Speed Range ◽  
Current Monitoring

Unmanned machine tools as part of an automated factory require reliable inexpensive sensors to provide machine and process information. The electric current in the DC motor of a CNC machine tool can be inexpensively measured and used to calculate loads on the drive system. To characterize the bandwidth, sensitivity and accuracy of current monitoring on a DC field controlled spindle drive of a CNC lathe, a dynamic lumped parameter model of this sensor system is developed. The model is used to identify the system components that have a dominant effect on the behavior of the sensor when the spindle system is operated above the base speed. Tests were conducted to determine the model’s parameters and to verify the model. The bandwidth and sensitivity of this sensor are shown to be spindle speed dependent. High speeds improve sensitivity and reduce bandwidth. Sensitivity and bandwidth vary by factors of 4.3 and 18.5, respectively, over the speed range. The signal to noise ratio is limited by external load induced variations in the spindle system friction. Recommendations concerning machine designs and process operating conditions to improve current monitoring on spindle drives are presented.

scholarly journals A Distributed Lumped Parameter Model of Blood Flow

2020 ◽  
Vol 48 (12) ◽  
pp. 2870-2886
Author(s):  
Mehran Mirramezani ◽  
Shawn C. Shadden
Keyword(s):  
Blood Flow ◽  
Lumped Parameter Model ◽  
Lumped Parameter

scholarly journals Design of External Rotor Ferrite-Assisted Synchronous Reluctance Motor for High Power Density

2021 ◽  
Vol 11 (7) ◽  
pp. 3102
Author(s):  
Md. Zakirul Islam ◽  
Seungdeog Choi ◽  
Malik E. Elbuluk ◽  
Sai Sudheer Reddy Bonthu ◽  
Akm Arafat ◽  
...  
Keyword(s):  
Rare Earth ◽  
Permanent Magnets ◽  
Design Procedure ◽  
Lumped Parameter Model ◽  
High Power Density ◽  
Analytical Design ◽  
Synchronous Reluctance Motor ◽  
Lumped Parameter ◽  
Reluctance Motor ◽  
External Rotor

The rare-earth (RE) permanent magnets (PM) have been increasingly adopted in traction motor application. However, the RE PM is expensive, less abundant, and has cost uncertainties due to limited market suppliers. This paper presents a new design of a RE-free five-phase ferrite permanent magnet-assisted synchronous reluctance motor (Fe-PMaSynRM) with the external rotor architecture with a high saliency ratio. In such architecture, the low magnetic coercivity and demagnetization risk of the ferrite PM is the challenge. This limits the number of flux barriers, saliency ratio, and reluctance torque. A precise analytical design procedure of rotor and stator configuration is presented with differential evolution numerical optimizations by utilizing a lumped parameter model. A 3.7 kW prototype is fabricated to validate the proposed idea.

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