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 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 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.

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.

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.

Vibration suppression method of humanoid flexible arm based on model-free predictive control

2021 ◽  
pp. 1-9
Author(s):  
Qinjun Du ◽  
Chuanming Song ◽  
Wei Ding ◽  
Long Zhao ◽  
Yonggang Luo
Keyword(s):  
Predictive Control ◽  
Vibration Suppression ◽  
Model Free ◽  
Flexible Arm ◽  
Suppression Method

An Active Vibration Suppression Method for Macro-Mini Manipulator

2021 ◽  
Author(s):  
Junjie Dai ◽  
Chin-Yin Chen ◽  
Renfeng Zhu ◽  
Guilin Yang ◽  
Chongchong Wang ◽  
...  
Keyword(s):  
Vibration Suppression ◽  
Active Vibration Suppression ◽  
Active Vibration ◽  
Suppression Method

scholarly journals MR Damper-Based Vibration Suppression Method for Control Moment Gyroscope

2018 ◽  
Vol 36 (5) ◽  
pp. 884-889
Author(s):  
Wendong Wang ◽  
Xing Ming ◽  
Yang Chu ◽  
Minghui Liu ◽  
Yikai Shi
Keyword(s):  
Active Control ◽  
Control Algorithm ◽  
Vibration Suppression ◽  
Control Method ◽  
Magnetorheological Damper ◽  
Magnetic Flux Density ◽  
Damping Force ◽  
Control Moment Gyroscope ◽  
Control Moment ◽  
Suppression Method

To restrain the interference of micro-vibration caused by Control Moment Gyroscope, a new control method based on Magnetorheological damper was proposed in this paper. A mechanical model based on the structure of the presented design was built, and the semi-active control algorithm of damping force was proposed for the designed Magnetorheological damper. The magnetic flux density and other magnetic field parameters were considered and analyzed in Maxwell, and also the related hardware circuit which implements the control algorithm was prepared to test the presented design and algorithm. The results of simulation and experiments show that the presented Magnetorheological damper model and semi-active control algorithm can complete the requirements, and the vibration suppression method is efficient for Control Moment Gyroscope.

Simulation and Parameter Optimization for Vibration Control System of MLRS Launcher

2014 ◽  
Vol 668-669 ◽  
pp. 526-531
Author(s):  
Xian Zhao ◽  
De Qing Luo
Keyword(s):  
Control System ◽  
Control Mechanism ◽  
Vibration Suppression ◽  
Structural Parameters ◽  
Pulse Frequency ◽  
Structure Parameter ◽  
Pulse Control ◽  
Lateral Direction ◽  
Parameter Values ◽  
Rocket System

Vibration suppression of the launcher is an important way to improve the firing accuracy of Multiple Launch Rocket System (MLRS). In order to get a better control result from the course that pulse control mechanism generates pulses to restrain the vibration of MLRS launcher, this paper analyzed the process that pulse thruster control the vibration of launcher under the modulation of pulse width and pulse frequency (PWPF) modulator. And the simulation model of the control system is established through the SIMULINK software in MATLAB. Under repeated modifications of the structural parameters of PWPF modulator, the influence laws of these parameters are found out, and the best structure parameter values are obtained. The final simulation result shows that the vibration in the pitch and lateral direction is greatly reduced. It is a big help to improve the firing accuracy of MLRS.

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