scholarly journals Vibration Analysis of Rotor - Coupling - Bearing System With Misaligned Shafts

1996 ◽  
Author(s):  
A. Sreenivasa Rao ◽  
A. S. Sekhar
Keyword(s):  
Theoretical Model ◽  
Finite Elements ◽  
Vibration Analysis ◽  
Rotating Machinery ◽  
Value Analysis ◽  
Flexible Coupling ◽  
Eigen Value ◽  
Shaft Misalignment ◽  
Reaction Forces ◽  
Bearing System

The shaft misalignment, even being a common fault in rotating machinery, is not sufficiently studied. The present work addresses effects of misalignment in rotating machinery. An attempt to give a theoretical model for a rotor-coupling-bearing system has been done. The rotor-bearing system including the flexible coupling is modelled using the finite elements. The reaction forces and moments developed due to flexible coupling misalignment both for parallel and angular are derived and introduced in the model. Vibration analyses such as eigen value analysis and unbalance response are carried out for the rotor system with misaligned shafts.

Vibration analysis of rotors for the identification of shaft misalignment Part 1: Theoretical analysis

2004 ◽  
Vol 218 (9) ◽  
pp. 971-985 ◽  
Author(s):  
P N Saavedra ◽  
D E Ramírez
Keyword(s):  
Finite Element ◽  
Stiffness Matrix ◽  
Vibration Analysis ◽  
Frequency Response Function ◽  
Mechanical Vibration ◽  
Element Analysis ◽  
Flexible Coupling ◽  
The Finite Element Analysis ◽  
Shaft Misalignment ◽  
Coupling Stiffness

Shaft misalignment in machinery causes preload forces to be generated in couplings which are then transmitted to the different machine components, thus reducing their lifetime. Shaft misalignment is a major cause of vibration in machines. Based on tests on coupling stiffness, a new coupling finite element stiffness matrix has been deduced. This has been used in the finite element analysis of a two-rotor system connected by a flexible coupling, to calculate the mechanical vibration resulting from mixed angular and parallel shaft misalignments with residual unbalance. The calculated vibration spectra were determined for two flexible couplings: a three-pin Renold coupling and a three-jaw Lovejoy coupling. The results and analysis indicate that the vibration generated by shaft misalignment is caused by the variation in coupling stiffness on rotation, and that the forcing frequencies generated are harmonics of the shaft's speed and directly depend on the frequency of the variation in coupling stiffness. In addition, the amplitudes of the measured vibratory components were found to rely directly upon the frequency response function that is related to the coupling and measurement points.

Modal synthesis method of lateral vibration analysis for rotor-bearing system

2002 ◽  
Vol 80 (32) ◽  
pp. 2537-2549 ◽  
Author(s):  
Chun-Ping Zou ◽  
Hong-Xing Hua ◽  
Duan-Shi Chen
Keyword(s):  
Vibration Analysis ◽  
Synthesis Method ◽  
Lateral Vibration ◽  
Modal Synthesis ◽  
Rotor Bearing ◽  
Bearing System

scholarly journals Established Numerical Techniques for the Structural Analysis of a Regional Aircraft Landing Gear

2018 ◽  
Vol 2018 ◽  
pp. 1-21 ◽  
Author(s):  
F. Caputo ◽  
A. De Luca ◽  
A. Greco ◽  
A. Marro ◽  
A. Apicella ◽  
...  
Keyword(s):  
Finite Elements ◽  
Numerical Models ◽  
Three Dimensional ◽  
Landing Gear ◽  
Point Of View ◽  
Fe Model ◽  
One Dimensional ◽  
Reaction Forces ◽  
Local Technique ◽  
Stick Model

Usually during the design of landing gear, simplified Finite Element (FE) models, based on one-dimensional finite elements (stick model), are used to investigate the in-service reaction forces involving each subcomponent. After that, the design of such subcomponent is carried out through detailed Global/Local FE analyses where, once at time, each component, modelled with three-dimensional finite elements, is assembled into a one-dimensional finite elements based FE model, representing the whole landing gear under the investigated loading conditions. Moreover, the landing gears are usually investigated also under a kinematic point of view, through the multibody (MB) methods, which allow achieving the reaction forces involving each subcomponent in a very short time. However, simplified stick (FE) and MB models introduce several approximations, providing results far from the real behaviour of the landing gear. Therefore, the first goal of this paper consists of assessing the effectiveness of such approaches against a 3D full-FE model. Three numerical models of the main landing gear of a regional airliner have been developed, according to MB, “stick,” and 3D full-FE methods, respectively. The former has been developed by means of ADAMS® software, the other two by means of NASTRAN® software. Once this assessment phase has been carried out, also the Global/Local technique has verified with regard to the results achieved by the 3D full-FE model. Finally, the dynamic behaviour of the landing gear has been investigated both numerically and experimentally. In particular, Magnaghi Aeronautica S.p.A. Company performed the experimental test, consisting of a drop test according to EASA CS 25 regulations. Concerning the 3D full-FE investigation, the analysis has been simulated by means of Ls-Dyna® software. A good level of accuracy has been achieved by all the developed numerical methods.

scholarly journals Power System Dynamic Stability Improvement with UPFC using LQR Technique

2019 ◽  
Vol 9 (1) ◽  
pp. 1714-1719
Keyword(s):  
Power Systems ◽  
Value Analysis ◽  
Systems Model ◽  
Eigen Value ◽  
Controller Performance ◽  
Power Oscillation Damping ◽  
Oscillation Damping ◽  
Power System Dynamic Stability ◽  
Simulation Condition ◽  
Damping Controller

Many damping controller devices based on other techniques have been proposed time to time. For the study of the damping performance, it has been proposed a power systems model with ‘UPFC’ and power oscillation damping controller in the present article. The proposed controller performance has been studied under different simulation condition results and that also includes various loading condition, i.e., normal with 100 percent, under loading 80 percent and overloading with 120 percent at different operational points. Finally, a better result has been observed by using the proposed damping controlling device than earlier available existing devices. However, the result obtained by using Eigen value analysis is supported by the facts obtained by the settling time analysis and the analysis of simulation results

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