Influence Coefficients Obtained by Hammer Beat Permit Significant Time Savings When Balancing Simple Flexible Rotors

1999 ◽  
Author(s):  
D. Wiese ◽  
M. Breitwieser
Keyword(s):  
Influence Coefficient ◽  
Significant Time ◽  
Flexible Rotors ◽  
Influence Coefficients ◽  
Flexible Roll ◽  
Influence Coefficient Method ◽  
Time Savings ◽  
Positive Results ◽  
Coefficient Method

Abstract The following paper presents a method for balancing simple flexible rotors with the help of influence coefficients obtained by hammer beat. The method permits time savings of approx. 50% compared to the conventional influence coefficient method. Initial positive results obtained on a flexible roll are also presented.

Two-Plane Balancing of a Rotor System Without Phase Response Measurements

1987 ◽  
Vol 109 (2) ◽  
pp. 162-167 ◽  
Author(s):  
Louis J. Everett
Keyword(s):  
Phase Measurement ◽  
Influence Coefficient ◽  
Single Plane ◽  
Flexible Rotors ◽  
Influence Coefficients ◽  
Wide Range ◽  
Influence Coefficient Method ◽  
Require Response ◽  
Rigid Rotors ◽  
Coefficient Method

This paper presents, and experimentally verifies, a two-plane balancing technique for rigid rotors and possibly flexible rotors operating at a constant speed. The technique, based upon influence coefficients, extends the single-plane four-run balancing procedure to two planes. Like the four-run method, this technique is most easily performed graphically and does not require response phase measurement. Despite the additional runs required to obtain data, its simplicity and applicability to a wide range of equipment renders it more useful, in some cases, than the standard two-plane influence coefficient method.

Analysis of III-Conditioned Characteristics about Weight Location of Rotor Dynamic Balancing

2014 ◽  
Vol 602-605 ◽  
pp. 670-673
Author(s):  
Ke Wang ◽  
Zhixu Dong ◽  
Long Tao Cong ◽  
Xing Wei Sun ◽  
Meng Nan Sun
Keyword(s):  
Mechanical Vibration ◽  
Great Influence ◽  
Solution Process ◽  
Influence Coefficient ◽  
Influence Coefficients ◽  
Location Parameters ◽  
Influence Coefficient Method ◽  
The Relationship ◽  
Coefficient Method ◽  
Mechanical Nature

Balancing with the influence coefficient method can eliminate rotor unbalance effectively and briefly which usually causes mechanical vibration. But the accuracy of this method is susceptible to operating condition and the structure of mechanical equipments will leads to unstable equilibrium outcomes. The theoretical study of the influence coefficient balancing method can find that the solution process of balancing weight does not involve the mechanical nature of unbalance vibration, and therefore it will be subject to greater interference of equation’s ill-conditioned characteristics. By introducing the modal superposition, vibration mode function can be linked with the influence coefficients to establish the relationship between counter weight location parameters and ill-conditioned equations. The simulation results of multiple-blade rotor shows that positions of balancing weight will exert great influence on ill-conditioned characteristics. So the position parameters should be chosen in front of balancing service reasonably.

The Influence Coefficient Method and its Linear Increment Calculation Research of the Creep Effect for an Un-Cracked Concrete Beams Reinforced with FRP

2011 ◽  
Vol 250-253 ◽  
pp. 2129-2134
Author(s):  
Guo Dong Zheng
Keyword(s):  
Concrete Beams ◽  
Influence Coefficient ◽  
Cracked Concrete ◽  
Influence Coefficients ◽  
Influence Coefficient Method ◽  
Stress Prediction ◽  
Modulus Method ◽  
Coefficient Method ◽  
Linear Increment

On the basis of the time-adjusted effective modulus method (AEMM method) and the steel influence coefficients, the combined influence coefficients of the concrete beams strengthened with FRP is proposed. It will have a higher numerical accuracy if the initial stress is substituted with the average stress of concrete and the stress is assumed to remain linear with time during the period in the step by step calculation process. The linear incremental calculation method based on the idea of the creep combined influence coefficient method of concrete beams reinforced with FRP is proposed, which provides a theoretical basis for the creep calculation and long-term stress prediction for an un-cracked concrete beams reinforced with FRP.

Flexible Rotor Balancing by the Exact Point-Speed Influence Coefficient Method

1972 ◽  
Vol 94 (1) ◽  
pp. 148-158 ◽  
Author(s):  
J. M. Tessarzik ◽  
R. H. Badgley ◽  
W. J. Anderson
Keyword(s):  
Influence Coefficient ◽  
Flexible Rotor ◽  
Critical Speeds ◽  
Angle Measurements ◽  
Flexible Rotors ◽  
Speed Range ◽  
Influence Coefficient Method ◽  
Rotor Balancing ◽  
Exact Point ◽  
Coefficient Method

A test program was conducted to confirm experimentally the validity of the exact point-speed influence coefficient method for balancing rotating machinery, and to assess the practical aspects of applying the method to flexible rotors. Testing was performed with a machine having a 41-in. long, 126-lb rotor. The rotor was operated over a speed range encompassing three rotor-bearing system critical speeds: two “rigid-body” criticals and one flexural critical. Rotor damping at the flexural critical was very low due to the journal bearings being located at the nodal points of the shaft. The balancing method was evaluated for three different conditions of initial rotor unbalance. The method was found to be effective and practical. Safe passage through all the critical speeds was obtained after a reasonable number of balancing runs. Success of the balancing method was, in large part, due to the accuracy of the instrumentation system used to obtain phase-angle measurements during the balancing procedure.

Extended Influence Coefficient Method for Rotor Active Balancing During Acceleration

2004 ◽  
Vol 126 (1) ◽  
pp. 219-223 ◽  
Author(s):  
Shiyu Zhou ◽  
Stephen W. Dyer ◽  
Kwang-keun Shin ◽  
Jianjun Shi ◽  
Jun Ni
Keyword(s):  
Fatigue Life ◽  
Gain Scheduling ◽  
Rotor System ◽  
Influence Coefficient ◽  
Resonant Vibration ◽  
Active Balancing ◽  
Look Up Table ◽  
Influence Coefficients ◽  
Influence Coefficient Method ◽  
Coefficient Method

Imbalance-induced vibration of rotating machineries is an important factor limiting the performance and fatigue life of a rotor system. Particularly, the severe resonant vibration of a rotor when it passes through its critical speeds could damage the rotor system. To avoid this peak vibration, this paper presents an active balancing method to offset the imbalance of the rotor system during acceleration by using an electromagnetic balancer. In this method, “instantaneous” influence coefficients at different speeds are obtained and stored in a look-up table. Then, a gain scheduling strategy is adopted to suppress the imbalance-induced vibration during acceleration based on the “instantaneous” influence coefficient table. A comprehensive testbed is built to validate this scheme, and the validation results are presented.

Practical Balancing of Flexible Rotors for Power Generation

2007 ◽  
Author(s):  
Zlatan Racic ◽  
Juan Hidalgo
Keyword(s):  
Power Plants ◽  
Influence Coefficient ◽  
Theoretical Derivation ◽  
Flexible Rotors ◽  
Influence Coefficients ◽  
Turbo Generator ◽  
Mass Moment ◽  
Practical Standpoint ◽  
Influence Coefficient Method ◽  
Generator Sets

Balancing technology is still relatively new. Thirty years ago it was primarily still part of the skilled trade and was often obscured. Today there is enough reference literature printed during the last 20 years alone on general balancing and balancing of flexible rotors, that could fill a room, (Ref: N. Rieger). The majority of papers and other references deal with theoretical derivation of equations based on Jeffcott rotor model. With the growth of rotor sizes specifically of electric generators in power plants, so grew the need to develop not only a theory, but also the way to practically balance these rotors. The economy of manufacturing required pushing the rotors to more and more slender; lower and lower stiffness (∝ EIxx/L3) designs, in relation to its mass moment of inertia (Im), these rotors were more difficult to balance. The first to encounter the problem of balancing these rotors were the OEMs. On two different shores of the Atlantic Ocean, two basic balancing theories known as balancing in “N”, or in “N+2” balancing planes and operating rotor modes were developed. Later, with the development of the microcomputer the influence coefficient method had gained popularity among the power plant community and despite good experiences from both sides the controversy over which one produces better results was left open. In this paper a review of the “N” and “N+2” methods including notes on influence coefficients (IC) is conducted from a practical standpoint. The conclusion by the Authors is that there is no “better” or “worse” balancing method, only the more or less economical in a given situation, and neither gives a unified method to satisfy every rotor. General guidance is also provided over which method to use for best results in balancing large turbo-generator sets.

scholarly journals On a programme for the balancing calculation of flexible rotors with the influence coefficient method

2000 ◽  
Vol 22 (4) ◽  
pp. 235-247
Author(s):  
Nguyen Van Khang ◽  
Tran Van Luong
Keyword(s):  
Computer Software ◽  
Rotor System ◽  
Influence Coefficient ◽  
Flexible Rotor ◽  
C Language ◽  
Flexible Rotors ◽  
University Of Technology ◽  
Influence Coefficient Method ◽  
Coefficient Method

This paper presents the influence coefficient method of determining the locations of unbalances on a flexible rotor system and the correction weights. A computer software for calculating the at-the-site balancing of a flexible rotor system was created using C++ language at the Hanoi University of Technology. This software can be used by balancing flexible rotors in Vietnam.

Prototype design and size optimization of a hybrid lower extremity exoskeleton with a scissor mechanism for load-carrying augmentation

2014 ◽  
Vol 229 (1) ◽  
pp. 155-167 ◽  
Author(s):  
Yunjie Miao ◽  
Feng Gao ◽  
Dalei Pan
Keyword(s):  
Lower Extremity ◽  
Influence Coefficient ◽  
Input And Output ◽  
Flexion Extension ◽  
Load Carrying ◽  
Influence Coefficient Method ◽  
Prototype Design ◽  
Coefficient Method ◽  
Length Optimization ◽  
Scissor Mechanism

A hybrid lower extremity exoskeleton SJTU-EX which adopts a scissor mechanism as the hip and knee flexion/extension joint is proposed in Shanghai Jiao Tong University to augment load carrying for walking. The load supporting capabilities of a traditional serially connected mechanism and the scissor mechanism are compared in detail. The kinematic influence coefficient method of the kinematic and dynamic analysis is applied in the length optimization of the scissor sides to minimize the transmitting errors between the input and output motions in walking and the load capacities of different scissor mechanisms are illustrated. The optimization results are then verified by the walking simulations. Finally, the prototype of SJTU-EX is implemented with several improvements to enhance the working performances.

scholarly journals A method to select correcting faces of a double-face dynamic balancing rotor

2016 ◽  
Vol 8 (12) ◽  
pp. 168781401668289
Author(s):  
Shihai Zhang ◽  
Zimiao Zhang
Keyword(s):  
Influence Coefficient ◽  
Axial Distribution ◽  
Dynamic Balancing ◽  
The Real ◽  
Influence Coefficients ◽  
Total Phase ◽  
Influence Coefficient Method ◽  
Phase Variations ◽  
Distribution Laws ◽  
Design And Practice

Considering the sensitivity and installing position limitation, the real positions for two correcting faces must be selected first in the process of double-face dynamic balancing design and practice for rigid rotor system. According to the principle of influence coefficient method, series of testing weight experiments are conducted in this article. Based on the experimental results, the axial distribution laws of the amplitudes and phases of influence coefficients are found and summarized as follows: the amplitude variations of influence coefficients are very small and the phase variations of influence coefficients are obvious when the correcting positions are changed along shaft, so the phases of influence coefficients have the key effect on the correcting vector in correcting faces. Based on this fact, the total phase difference maximum method of influence coefficients is proposed to select the real axial positions for correcting faces. The principle of the method is analyzed in theory, and the application effect is tested by double-face dynamic balancing experiments.

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