Experimental Evaluation of Dynamic Characteristics of Circular Arc Spring Dampers for Rotating Machinery

2021 ◽  
Author(s):  
Ryota Takeuchi ◽  
Hidetsugu Ishimaru ◽  
Hideaki Yamashita ◽  
Shota Yabui ◽  
Tsuyoshi Inoue
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Evaluation ◽  
Rotating Machinery ◽  
Circular Arc

Experimental Evaluation of Dynamic Characteristics of Circular Arc Spring Dampers for Rotating Machinery

2020 ◽  
Author(s):  
Ryota Takeuchi ◽  
Hidetsugu Ishimaru ◽  
Hideaki Yamashita ◽  
Shota Yabui ◽  
Tsuyoshi Inoue
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Evaluation ◽  
Mass Effect ◽  
Added Mass ◽  
Rotating Machinery ◽  
Squeeze Film ◽  
Outer Diameter ◽  
Circular Arc ◽  
Dynamic Coefficients ◽  
New Findings

Abstract This study presents an experimental evaluation of the dynamic characteristics of the circular arc spring damper (CASD), which attenuates the vibration of rotating machinery. A major advantage of CASDs over conventional Squeeze Film Dampers (SFDs) with squirrel-cage springs is their compactness and low weight. However, the basic characteristics of this type of damper, including the influence of the geometries, added mass coefficients, and cross-coupled terms of dynamic coefficients have not been investigated. To clarify these characteristics, a series of excitation tests was conducted on three types of CASDs to identify their dynamic coefficients. Tested dampers have the same outer diameter and damper width but different arc patterns and radial clearances. All dampers were tested in both open-end and end-sealed configuration. The influence of the end-seal clearances was also examined. The following results were obtained: (1) 4-arc type CASDs have greater damping than that of 2-arc types; (2) CASDs have a considerable amount of added mass coefficients, especially in the end-sealed condition; (3) Smaller end-seal clearances make the damping and added-mass coefficients significantly larger; (4) A large level of damping can be produced with dashpot configuration (large radial clearances and small end-seal clearances), though the added-mass effect becomes more prominent; (5) Cross-coupled terms are very small in centered / small amplitude motion. These new findings can be utilized for the design and application of CASDs to real rotating machineries.

Experimental Evaluation of Dynamic Characteristics of Circular Arc Spring Dampers for Rotating Machinery

2020 ◽  
Author(s):  
Ryota Takeuchi ◽  
Hidetsugu Ishimaru ◽  
Hideaki Yamashita ◽  
Shota Yabui ◽  
Tsuyoshi Inoue
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Evaluation ◽  
Mass Effect ◽  
Added Mass ◽  
Rotating Machinery ◽  
Squeeze Film ◽  
Outer Diameter ◽  
Circular Arc ◽  
Dynamic Coefficients ◽  
New Findings

Abstract This study presents an experimental evaluation of the dynamic characteristics of the circular arc spring damper (CASD), which attenuates the vibration of rotating machinery. The CASD is a novel type of fluid film damper that has two or more arc-shaped beams and dual slits (radial clearances) formed by wire electric discharge machining (WEDM). A major advantage of CASDs over conventional Squeeze Film Dampers (SFDs) with squirrel-cage springs is their compactness and low weight. The concept of CASDs was originally proposed by Kanki et al. in 2005. However, the basic characteristics of this type of damper, including the influence of the geometries, added mass coefficients, and cross-coupled terms of dynamic coefficients have not been investigated. To clarify these characteristics, a series of excitation tests was conducted on three types of CASDs to identify their dynamic coefficients. The features of the newly developed test rig and experimental results are presented in this study. Tested dampers have the same outer diameter (160 [mm]) and damper width (44 [mm]) but different arc patterns (2-arc or 4-arc) and radial clearances (about 0.3 or 1.2 [mm]). All dampers were tested in both open-end and end-sealed configuration. The influence of the end-seal clearances (about 0.1 to 0.4 [mm]) was also examined. The following results were obtained: (1) 4-arc type CASDs have greater damping than that of 2-arc types; (2) CASDs have a considerable amount of added mass coefficients, especially in the end-sealed condition; (3) Smaller end-seal clearances make the damping and added-mass coefficients significantly larger; (4) A large level of damping can be produced with dashpot configuration (large radial clearances and small end-seal clearances), though the added-mass effect becomes more prominent; (5) Cross-coupled terms are very small in centered / small amplitude motion. These new findings can be utilized for the design and application of CASDs to real rotating machineries.

A Review on Active Bearings and Perspectives of Using Them in Rotating Machinery

2014 ◽  
Vol 630 ◽  
pp. 181-187
Author(s):  
Denis Shutin ◽  
Leonid Savin ◽  
Alexander Babin
Keyword(s):  
Mathematical Modeling ◽  
Artificial Intelligence ◽  
Control System ◽  
Motion Control ◽  
Dynamic Characteristics ◽  
Rotating Machinery ◽  
Fluid Film ◽  
Motion Control System ◽  
Fluid Film Bearings ◽  
System Components

The paper examines the issues of improving the rotor units by means of using support units with actively changeable characteristics. An overview of the known solutions related to the use of active bearings in various types of turbomachinery is provided. A closer look is given at the design and features of active radial bearings, the main elements of which are fluid film bearings. The results of mathematical modeling of active hybrid bearings are presented. The prospects of the use of this type of supports to improve the dynamic characteristics of rotating machinery, including reducing vibrations caused by various factors, are analyzed. Promising directions of development of active bearings are considered, which primarily involves the modification of system components and rotor motion control system algorithms, including intelligent technologies and artificial intelligence methods.

Experimental evaluation of damage effect on dynamic characteristics of concrete encased composite column-beam connections

2018 ◽  
Vol 91 ◽  
pp. 129-150 ◽  
Author(s):  
Metin Hüsem ◽  
Mohammad Manzoor Nasery ◽  
Fatih Yesevi Okur ◽  
Ahmet Can Altunişik
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Evaluation ◽  
Damage Effect ◽  
Composite Column

Effect of Bearing Profile on the Stability of Statically Indeterminate Rotor Bearing Systems

2007 ◽  
Author(s):  
N. S. Feng ◽  
E. J. Hahn
Keyword(s):  
Dynamic Characteristics ◽  
Rotating Machinery ◽  
Fluid Film ◽  
System Stability ◽  
Fluid Film Bearings ◽  
Flexible Rotors ◽  
Rotor Bearing ◽  
The Stability

The stability of rotating machinery consisting of flexible rotors supported by fluid film bearings is significantly affected by the dynamic characteristics of the bearings and in particular, the bearing profiles as well as the bearing reaction loads, which, in statically indeterminate systems, are in turn strongly influenced by the relative transverse alignment of the bearings. Using a simple four bearing statically indeterminate model, it is shown that relatively simple variants of the circular bearings, viz. elliptic and 2-pad offset bearings display better system stability characteristics systems in aligned situations and are also more likely to be stable in misaligned situations.

scholarly journals Nonlinear Vibration Mechanism of the Marine Rotating Machinery with Airbag Isolation Device under Heaving Motion

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Xiaolei Du ◽  
Ming Li
Keyword(s):  
Nonlinear Vibration ◽  
Mechanical System ◽  
Dynamic Characteristics ◽  
Vibration Isolation ◽  
Rotating Machinery ◽  
Largest Lyapunov Exponent ◽  
Rotor Speed ◽  
Mass Unbalance ◽  
Vibration Mechanism ◽  
Isolation Device

In this paper, we put an investigation into the nonlinear vibration mechanism of the marine rotating machinery with an airbag isolation device under heaving motion. First, we consider the effects of mass unbalance and heaving motion and propose a mathematical model of the marine rotating mechanical system with airbag vibration isolation. Then, the multiple-scale method is conducted to analyze the nonlinear dynamic characteristics of the mechanical system; the frequency-response curves are mainly studied under different parameters, such as the heave excitation, rotor speed, and damping; and the numerical method is also introduced to analyze its dynamic behaviors, such as the steady-state response and its corresponding phase diagram, Poincaré section. The dynamic stability of the system is investigated based on the bifurcations and the largest Lyapunov exponent about rotor speed and heaving frequency. The obtained results indicate complex nonlinear characteristics of the system compared to the system without heaving excitation, which can help us fully understand the dynamic characteristics and parametric optimization as well as structural design of the marine mechanical isolation system.

The Physical Reason and the Analytical Condition for the Onset of Dry Whip in Rotor-to-Stator Contact Systems

2004 ◽  
Vol 127 (6) ◽  
pp. 594-603 ◽  
Author(s):  
Jun Jiang ◽  
Heinz Ulbrich
Keyword(s):  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Equations Of Motion ◽  
Multiple Scale ◽  
Rotating Machinery ◽  
Multiple Scale Method ◽  
Catastrophic Failure ◽  
Physical Reason ◽  
Scale Method ◽  
Onset Condition

Dry whip is an instability of rotor-to-stator contact systems and may lead to a catastrophic failure of rotating machinery. The physical reason for the onset of dry whip in rotor/stator systems with imbalance is not yet well understood. This paper explores the development of the rotor response into dry whip of a specific rotor-to-stator contact model and finds that the rotor in resonance at a negative (natural) frequency of the coupled nonlinear rotor/stator system is the physical reason for the onset of dry whip with imbalance. Based on this find, the equations of motion of the rotor/stator system are formulated in a different way that includes the dynamic characteristics in the vicinity of the onset point of dry whip. The onset condition of dry whip with imbalance is then derived by using the multiple scale method. As shown by examples, the analytical onset condition of dry whip agrees well with the numerically simulated one. In addition, the results are consistent with phenomena observed in tests.

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