scholarly journals Design and Experimentation of New Balancing Technique Based on the Jeffcott Rotor Model

2020 ◽  
pp. 186-194
Keyword(s):  
Influence Coefficient ◽  
Rotating Speed ◽  
Vibration Data ◽  
Jeffcott Rotor ◽  
Common Causes ◽  
Influence Coefficient Method ◽  
Phase Angles ◽  
The Mathematical Model ◽  
Rotor Model

Unbalance is one of the most common causes of machinery vibrations, present in rotating machines. The influence coefficient method of balancing used for in-situ balancing requires vibration data (Phase angles and vibration values) of many trial runs which may result in a lengthy balancing process. The vibration data can be measured with the help state-of-the-art four channel Adash 4400 VA4 Pro FFT analyzer platform along with data acquisition system and electronic instrumentation. It has been identified in the literature that it is possible to balance the rotor without the use of trial weight. This paper presents a new systematic approach of balancing method based on the Jeffcott rotor dynamic model. The mathematical model on Jeffcott rotor model is presented here. The proposed method requires vibration data of two test runs at different speeds without trial weight. For experimental verification of proposed method, a test rig has been developed. Systematic experiments done on the Jeffcott rotor model at different rotating speed are described in this paper. The experimental results shows the success of proposed balancing method. The importance of identifying type of rotor unbalance (static, couple, quasi-static, or dynamic) and the method to detect type of unbalance present in the rotor is presented.

Experimental Evaluation of Multiplane-Multispeed Rotor Balancing Through Multiple Critical Speeds

1976 ◽  
Vol 98 (3) ◽  
pp. 988-998 ◽  
Author(s):  
J. M. Tessarzik ◽  
R. H. Badgley ◽  
D. P. Fleming
Keyword(s):  
Experimental Tests ◽  
Influence Coefficient ◽  
Critical Speeds ◽  
Vibration Data ◽  
Vibration Sensors ◽  
Flexible Rotors ◽  
Speed Range ◽  
Full Speed ◽  
Influence Coefficient Method ◽  
Rotor Balancing

Experimental tests have been conducted to further demonstrate the ability of the Influence Coefficient Method to achieve precise balance of flexible rotors of virtually any design for operation through virtually any speed range. Four distinct practical aspects of flexible-rotor balancing were investigated in the present work: (1) Balancing for operation through multiple bending critical speeds; (2) balancing of rotors mounted in both rigid and flexible bearing supports, the latter having significantly different stiffnesses in the horizontal and vertical directions so as to cause severe ellipticity in the vibration orbits; (3) balancing of rotors with various amounts of measured vibration response information (e.g., numbers of vibration data sets, and numbers and types of vibration sensors), and with different number of correction planes; (4) balancing of rotors with different (though arbitrary) initial unbalance configurations. Tests were made on a laboratory quality machine having a 122-cm (48-in.) long rotor weighing 50 kg (110 lb) and covering a speed range up to 18,000 rpm. The balancing method was found in every instance to be effective, practical, and economical, permitting safe rotor operation over the full speed range covering four rotor bending critical speeds.

A Method to Select Weights in Online Dynamic Balance Technology Based on Rotor-Active Magnetic Bearing System

2017 ◽  
Author(s):  
Yan Xunshi ◽  
Zhao Jingjing ◽  
Sun Zhe ◽  
Shi Zhengang
Keyword(s):  
Dynamic Balance ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Influence Coefficient ◽  
Rotating Speed ◽  
Balance Weight ◽  
Influence Coefficient Method ◽  
Short Time ◽  
Coefficient Method ◽  
Bearing System

Online dynamic balance technology is the key to rotor-active magnetic bearing system, which helps the rotating speed of the system surpass the critical speed. Usually, balance weight and angle are calculated by influence coefficient method. However, how to decompose the weight and angle into sub-weights fixed in the balance holes is troublesome, and determined manually by trial and error, which is always time-consuming. In this paper, a new hierarchical and automatic method is proposed to find the optimized solution to select proper sub-weights in a short time, which limits to a pre-defined error. The algorithm focuses on reducing the move of sub-weights and addition of new sub-weights. Experiments show our algorithm perform effective and efficient.

Unsteady Aerodynamic Analysis of Subsonic Oscillating Cascade

1994 ◽  
Vol 116 (3) ◽  
pp. 501-512
Author(s):  
S. H. Chen ◽  
A. H. Eastland ◽  
E. D. Jackson
Keyword(s):  
Minimum Cost ◽  
Flow Speed ◽  
Flow Coefficient ◽  
Aerodynamic Load ◽  
Influence Coefficient ◽  
Unsteady Aerodynamic ◽  
Grid Deformation ◽  
Influence Coefficient Method ◽  
Phase Angles ◽  
Interblade Phase Angle

This paper describes the development of the source-doublet-based potential paneling method for oscillating cascade unsteady aerodynamic load predictions. By using the integral influence coefficient method and by using the interblade phase angles, the unsteady loads on an oscillating cascade can be accurately predicted at a minimum cost. As the grids are placed only on the blade surfaces, the blades are allowed to vibrate without grid deformation problems. Four notable subsonic oscillating cascade test cases that cover most important parameters, e.g., blade geometry, interblade phase angle, flow coefficient, flow speed, frequency, etc., are studied in this paper. The agreement between the present solutions and other numerical/experimental results demonstrates the robustness of the present model. Applicability of the method for realistic compressible flow cascades is also discussed.

Analytical and Experimental Study on Balancing Using Influence Coefficient Method

2013 ◽  
Vol 393 ◽  
pp. 694-702
Author(s):  
Wan Sulaiman Wan Mohamad ◽  
A.A. Mat Isa ◽  
M.A. Ismail
Keyword(s):  
Experimental Study ◽  
Experimental Verification ◽  
Mass Concentration ◽  
Vibration Reduction ◽  
Influence Coefficient ◽  
Centrifugal Forces ◽  
Experimental Procedure ◽  
Influence Coefficient Method ◽  
Phase Angles ◽  
Coefficient Method

Unbalance effect on rotating element happens as a result of an off centered mass concentration which will generate centrifugal forces with increasing running speeds. This unwanted situation requires correction to avoid failure due to excessive vibration. In this study, unbalance problem are studied by using theoretical influence coefficient method followed by the experimental verification. Experimental procedure is performed by using trial mass to calculate the influence coefficient and the corrected mass values as well as the phase angles. Finally, the vibration reduction of the rotor is compared theoretically and experimentally. Based on the results, the improved vibration reduction could be obtained reasonably for both single and two-plane balancing by using influence coefficient method.

scholarly journals Vibration analysis based on the spectrum kurtosis for adjustment and monitoring of ball bearing radial clearance

2018 ◽  
Vol 211 ◽  
pp. 06006 ◽  
Author(s):  
Anthimos Georgiadis ◽  
Xiaoyun Gong ◽  
Nicolas Meier
Keyword(s):  
Signal Analysis ◽  
Vibration Signal ◽  
Radial Clearance ◽  
Spectral Kurtosis ◽  
Vibration Data ◽  
Bearing Clearance ◽  
Bearing Condition Monitoring ◽  
Bearing Vibration ◽  
Vibration Signal Analysis

Vibration signal analysis is a common tool to detect bearing condition. Effective methods of vibration signal analysis should extract useful information for bearing condition monitoring and fault diagnosis. Spectral kurtosis (SK) represents one valuable tool for these purposes. The aim of this paper is to study the relationship between bearing clearance and bearing vibration frequencies based on SK method. It also reveals the effect of the bearing clearance on the bearing vibration characteristic frequencies This enables adjustment of bearing clearance in situ, which could significantly affect the performance of the bearings. Furthermore, the application of the proposed method using SK on the measured data offers useful information for predicting bearing clearance change. Bearing vibration data recorded at various clearance settings on a floating and a fixed bearing mounted on a shaft are the basis of this study

Stability-Optimized Clearance Configuration of Fluid-Film Bearings

2006 ◽  
Vol 129 (1) ◽  
pp. 106-111 ◽  
Author(s):  
Koichi Matsuda ◽  
Shinya Kijimoto ◽  
Yoichi Kanemitsu
Keyword(s):  
Fourier Series ◽  
Load Capacity ◽  
Fluid Film ◽  
Eccentricity Ratio ◽  
Rotating Speed ◽  
Fluid Film Bearings ◽  
Wide Range ◽  
Jeffcott Rotor ◽  
The Stability ◽  
Frequency Ratios

The whirl instability occurs at higher rotating speeds for a full circular fluid-film journal bearing, and many types of clearance configuration have been proposed to solve this instability problem. A clearance configuration of fluid-film journal bearings is optimized in a sense of enhancing the stability of the full circular bearing at high rotational speeds. A performance index is chosen as the sum of the squared whirl-frequency ratios over a wide range of eccentricity ratios, and a Fourier series is used to represent an arbitrary clearance configuration of fluid-film bearings. An optimization problem is then formulated to find the Fourier coefficients to minimize the index. The designed bearing has a clearance configuration similar to that of an offset two-lobe bearing for smaller length-to-diameter ratios. It is shown that the designed bearing cannot destabilize the Jeffcott rotor at any high rotating speed for a wide range of eccentricity ratio. The load capacity of the designed bearings is nearly in the same magnitude as that of the full circular bearing for smaller length-to-diameter ratios. The whirl-frequency ratios of the designed bearing are very sensitive to truncating higher terms of the Fourier series for some eccentricity ratio. The designed bearings successfully enhance the stability of a full circular bearing and are free from the whirl instability.

scholarly journals An Optimum Balance Weight Search Algorithm

1993 ◽  
Author(s):  
James C. Austrow
Keyword(s):  
Search Algorithm ◽  
Least Square ◽  
Test Case ◽  
Influence Coefficient ◽  
Residual Vibration ◽  
Single Plane ◽  
Vibration Data ◽  
Influence Coefficients ◽  
Balance Weight ◽  
Optimum Balance

A mathematical description for an optimum balance weight search algorithm for single plane multipoint balance is presented. The algorithm uses influence coefficients, either measured or known beforehand, and measured complex vibration data to determine an optimum balance correction weight. The solution minimizes the maximum residual vibration. The algorithm allows user defined balance weights to be analyzed and evaluated. A test case is presented showing actual results and comparison with a least square solution algorithm. An efficient multiplane influence coefficient calculation scheme is also presented.

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