Vibration Suppression of Rotating Machinery Utilizing Discontinuous Spring Characteristics

2005 ◽  
Author(s):  
Yukio Ishida ◽  
Jun Liu
Keyword(s):  
Periodic Motion ◽  
Large Amplitude ◽  
Critical Speed ◽  
Vibration Suppression ◽  
Rotating Machinery ◽  
Almost Periodic ◽  
Suppression Method ◽  
Rotor Stiffness ◽  
Parameter Values ◽  
Almost Periodic Motion

In rotating machinery, resonance phenomena occur with large amplitude in the vicinities of the major critical speeds. In this paper, a new vibration suppression method utilizing a discontinuous spring characteristic is proposed. This spring characteristic is made by additional springs with preload. This method has the following advantages: In designing these additional springs, we need not adjust their parameter values to the rotor stiffness and the system damping. The amplitude of vibration can be suppressed to any desired level. Although this method has a disadvantage that an almost periodic motion occurs above the major critical speed, two countermeasures are proposed to diminish it. We clarified these phenomena theoretically and experimentally.

Vibration Suppression of Rotating Machinery Utilizing Discontinuous Spring Characteristics (Stationary and Nonstationary Vibrations)

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Yukio Ishida ◽  
Jun Liu
Keyword(s):  
Critical Speed ◽  
Vibration Suppression ◽  
Rotating Machinery ◽  
Almost Periodic ◽  
Nonstationary Vibrations ◽  
Nonstationary Vibration ◽  
Level 3 ◽  
Suppression Method ◽  
Rotor Stiffness ◽  
Parameter Values

In rotating machinery, resonance phenomena occur with large amplitude in the vicinities of the major critical speeds. In this paper, a new vibration suppression method utilizing a discontinuous spring characteristic is proposed. This spring characteristic is achieved using additional springs with preload. This method has the following advantages. (1) In designing these additional springs, we need not adjust their parameter values to the optimal ones, which are determined by rotor stiffness and the system damping. (2) The amplitude of vibration can be suppressed to any desired small level. (3) This method is also effective for nonstationary vibration. Although the method has a disadvantage that an almost periodic motion occurs above the major critical speed, two countermeasures are proposed to diminish it. The characteristics of the vibration suppression are demonstrated theoretically and experimentally.

Vibration Suppression of Rotating Machinery Utilizing an Automatic Ball Balancer and Discontinuous Spring Characteristics

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Jun Liu ◽  
Yukio Ishida
Keyword(s):  
Rotational Speed ◽  
Large Amplitude ◽  
Small Amplitude ◽  
Critical Speed ◽  
Vibration Suppression ◽  
Rotating Machinery ◽  
Almost Periodic ◽  
Periodic Motions ◽  
Speed Range ◽  
Suppression Method

Automatic ball balancer is a balancing device where two balls inside a hollow rotor move to optimal rest positions automatically to eliminate unbalance. As a result, vibrations are suppressed to the zero amplitude in the rotational speed range higher than the major critical speed. However, it has the following defects. The amplitude of vibration increases in the rotational speed range lower than the major critical speed. In addition, almost periodic motions with large amplitude occur in the vicinity of the major critical speed due to the rolling of balls inside the rotor. Because of these defects, an automatic ball balancer has not been used widely. This paper proposes the vibration suppression method utilizing the discontinuous spring characteristics together with an automatic ball balancer to overcome these defects and to suppress vibration. The validity of the proposed method is confirmed theoretically, numerically, and experimentally. The results show that amplitude of vibration can be suppressed to a small amplitude in the vicinity of the major critical speed and the zero amplitude in the range higher than the major critical speed.

Vibration Suppression of Rotating Machinery Utilizing an Automatic Ball Balancer and Discontinuous Spring Characteristics

2007 ◽  
Author(s):  
Jun Liu ◽  
Yukio Ishida
Keyword(s):  
Rotational Speed ◽  
Large Amplitude ◽  
Small Amplitude ◽  
Critical Speed ◽  
Vibration Suppression ◽  
Rotating Machinery ◽  
Almost Periodic ◽  
Periodic Motions ◽  
Speed Range ◽  
Suppression Method

Automatic ball balancer is a balancing device where two balls inside a hollow rotor move to optimal rest positions automatically to eliminate unbalance. As the result, vibrations are suppressed to a small amplitude or a zero amplitude in the rotational speed range higher than the major critical speed. However, it has the following defects. The amplitude of vibration increases in the rotational speed range lower than the major critical speed. In addition, almost periodic motions with large amplitude occur due to the rolling of balls inside the rotor in the vicinity of the major critical speed. Due to those defects, the automatic ball balancer has not been used widely. This paper proposes the vibration suppression method utilizing the discontinuous spring characteristics together with an automatic ball balancer to suppress vibration and to overcome these defects of the automatic ball balancer. The validity of proposed method is confirmed theoretically, numerically and experimentally. The results show that amplitude of vibration can be suppressed to a small amplitude in the vicinity of the major critical speed and the zero amplitude in the range higher than the major critical speed.

scholarly journals StablePand distal dynamical systems

1984 ◽  
Vol 7 (1) ◽  
pp. 181-185
Author(s):  
S. S. Prasad ◽  
Anant Kumar
Keyword(s):  
Dynamical Systems ◽  
Periodic Motion ◽  
Uniform Space ◽  
Almost Periodic ◽  
Almost Periodic Motion

In this paper we study the behavior of dynamical systems in uniform space which are Poisson stable and distal. The main results are that the trajectories of such motions are closed and every almost periodic motion is stablePand distal. In complete uniform space, this motion is periodic, Lagrange stable and recurrent.

scholarly journals Almost periodic motion in complete space

1986 ◽  
Vol 9 (3) ◽  
pp. 621-622
Author(s):  
Anant Kumar
Keyword(s):  
Limit Point ◽  
Periodic Motion ◽  
Almost Periodic ◽  
Complete Space ◽  
Null Set ◽  
Almost Periodic Motion

It is interesting that in a complete space an almost periodic motion is periodic if the null setϕis closed and ifϕis not closed then every point of its trajectory is a limit point.

Analysis of Actively Controlled Coulomb Damping for Rotating Machinery

1999 ◽  
Author(s):  
John M. Vance ◽  
Luis A. San Andrés
Keyword(s):  
Coulomb Friction ◽  
Critical Speed ◽  
Vibration Suppression ◽  
Friction Model ◽  
Rotating Machinery ◽  
Friction Damper ◽  
Control Laws ◽  
Coulomb Damping ◽  
Coulomb Type ◽  
Coulomb Friction Model

Attempts have been made in the past to use Coulomb damping for vibration suppression in rotating machinery. Typically, a dry friction damper is designed to operate on a flexible bearing support. These designs have usually been unsuccessful in practice, partly because the Coulomb coefficient changes with temperature, with ingress of dirt or lubricant, and with the surface wear conditions. It is known that purely Coulomb damping forces cannot restrain the peak rotor whirl amplitudes at a critical speed. The invention of a disk type of electroviscous damper, utilizing a fluid with electrorheological (ER) properties, has recently revived the interest in Coulomb type dampers. Several investigations have suggested that a Coulomb friction model was the best representation for an ER damper with voltage applied. This model was used to study the feasibility of developing actively controlled bearing dampers for aircraft engines. This paper analyzes the imbalance response of two different rotordynamic models with Coulomb friction damping and shows the benefit of adding active control. Control laws are derived to achieve minimum rotor vibration amplitudes while avoiding large bearing forces over a speed range that includes a critical speed. The control laws are derived for purely Coulomb type of damping and assuming a combination of Coulomb and viscous damping effects. It is shown that the most important feature of Coulomb damping for minimal rotordynamic amplitude response is the control of rotor support stiffness, i.e. leading to the relocation of critical speeds, rather than control of a damping coefficient.

Almost periodic motion of loose material inside vibrating cylinder

1985 ◽  
Vol 21 (8) ◽  
pp. 805-809
Author(s):  
V. F. Zadorozhnyi ◽  
G. A. Chechko
Keyword(s):  
Periodic Motion ◽  
Loose Material ◽  
Almost Periodic ◽  
Almost Periodic Motion

Suppression of the Forward Rub in Rotating Machinery by an Asymmetrically Supported Guide

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Tsuyoshi Inoue ◽  
Yukio Ishida ◽  
Gao Fei ◽  
Hossain Md Zahid
Keyword(s):  
Theoretical Analysis ◽  
Contact Surface ◽  
Rotational Speed ◽  
Critical Speed ◽  
Rotating Machinery ◽  
Suppression Method ◽  
Lubricated Contact ◽  
Impact Vibration ◽  
Directional Difference ◽  
Rubbing Condition

In rotating machinery, rubbing occurs between the rotor and the stator, at the seal, between the rotor and the guide and between the rotor and the backup bearing. The backward rub or the partial impact vibration can be avoided by lubricating the contact surface sufficiently in order to decrease the friction. However, forward rub may still occur in such a case with a lubricated contact surface. Once such a forward rub occurs, it remains even if the rotational speed increases to much larger than the first bending critical speed and it is difficult to escape from this forward rubbing condition automatically. This paper proposes the suppression method of this forward rub by introducing the directional difference in the support stiffness of the guide or the backup bearing. The nonlinear theoretical analysis clarifies and explains the usefulness of the proposed method and it is also validated experimentally.

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