scholarly journals Analysis of Dynamic Characteristics for a Rotor System with Pedestal Looseness

2011 ◽  
Vol 18 (1-2) ◽  
pp. 13-27 ◽  
Author(s):  
Hui Ma ◽  
Xueyan Zhao ◽  
Yunnan Teng ◽  
Bangchun Wen
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Rotational Speed ◽  
Element Model ◽  
Rotor System ◽  
High Order Harmonic ◽  
Bifurcation Phenomenon ◽  
Frequency Components ◽  
Increasing Process ◽  
Harmonic Components

This paper presents a finite element model of a rotor system with pedestal looseness stemming from a loosened bolt and analyzes the effects of the looseness parameters on its dynamic characteristics. When the displacement of the pedestal is less than or equal to the looseness clearance, the motion of the rotor varies from period-one through period-two and period-three to period-five with the decreasing of stiffness of the non-loosened bolts. The similar bifurcation phenomenon can be also observed during the increasing process of the rotational speed. But the rotor motion is from period-six through period-three to period-four with the decreasing of the foundation stiffness. When the stiffness of the foundation is small and the displacement of pedestal is greater than the looseness clearance, the response of the rotor exhibits period-one and high order harmonic components with the decreasing of looseness clearance, such as 2X, 3X etc. However, when the stiffness of the foundation is great, the spectrum of the response of the rotor will be from combined frequency components to the continuous spectrum with the decreasing of the looseness clearance.

Dynamics of Multi-Disk Rotor System with Rub-Impact Fault

2009 ◽  
Vol 16-19 ◽  
pp. 1082-1086
Author(s):  
Ji Shuang Dai ◽  
Hui Ma ◽  
Xue Jun Wang ◽  
Bang Chun Wen
Keyword(s):  
Finite Element ◽  
Contact Region ◽  
Element Model ◽  
Rotor System ◽  
Nonlinear Finite Element Method ◽  
Fractional Frequency ◽  
Theoretical Support ◽  
Frequency Components ◽  
Stage 1 ◽  
The Finite Element Model

In this paper, a multi-disk rotor system is studied. The rotor system is properly simplified and the finite element model is established. Assuming that contact region is an arc when the practical rotor-stator rub-impact fault occurs. Contact analysis and nonlinear finite element method are adopted to carry out numerical simulation of rub-impact. The results show that 1/2 fractional frequency components appear in slight rub-impact stage; 1/3 fractional frequency components appear in moderate rub-impact stage and 1/4 fractional frequency components appear in serious rub-impact stage. The research results will provide theoretical support for fault diagnosis of rub-impact.

scholarly journals Dynamic Characteristics and Experimental Research of Dual-Rotor System with Rub-Impact Fault

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Hongzhi Xu ◽  
Nanfei Wang ◽  
Dongxiang Jiang ◽  
Te Han ◽  
Dewang Li
Keyword(s):  
Dynamic Characteristics ◽  
Element Model ◽  
Rotor System ◽  
Rotor Vibration ◽  
Double Frequency ◽  
Fundamental Frequencies ◽  
Outer Rotor ◽  
Dimensional Finite Element ◽  
Frequency Components ◽  
Collision Force

Rub-impact fault model for dual-rotor system was further developed, in which rubbing board is regarded as elastic sheet. Sheet elastic deformation, contact penetration, and elastic damping support during rubbing of sheet and wheel disk were considered. Collision force and friction were calculated by utilizing Hertz contact theory and Coulomb model and introducing nonlinear spring damping model and friction coefficient. Then kinetic differential equations of rub-impact under dry rubbing condition were established. Based on one-dimensional finite element model of dual-rotor system, dynamic transient response of overall structure under rub-impact existing between rotor wheel and sheet was obtained. Meanwhile, fault dynamic characteristics and impact of rubbing clearance on rotor vibration were analyzed. The results show that, during the process of rub-impact, the spectrums of rotor vibration are complicated and multiple combined frequency components of inner and outer rotor fundamental frequencies are typical characteristic of rub-impact fault for dual-rotor system. It also can be seen from rotor vibration response that the rubbing rotor’s fundamental frequency is modulated by normal rotor double frequency.

Parametric Modeling and Dynamic Characteristics Analysis of a Power Turbine Rotor System

2019 ◽  
Vol 36 (4) ◽  
pp. 359-365
Author(s):  
Jingjing Huang ◽  
Lu Cui ◽  
Suobin Li ◽  
Bingbing Han ◽  
Longxi Zheng
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Element Model ◽  
Turbine Rotor ◽  
Parametric Modeling ◽  
Rotor System ◽  
Analysis Model ◽  
Element Analysis ◽  
The Real ◽  
Power Turbine

Abstract With the increasing requirements of aeroengine performance and working stability, the primary research task of the rotor system dynamics is to build a rotor system model that can reflect the actual situation and obtain the calculation results which can reflect the real dynamic characteristics of the rotor system. In this paper, the finite element analysis model of a power turbine rotor was established, and the dynamic model and dynamic characteristics of the complex rotor system were studied. The results indicated that the finite element model could reflect the real dynamic characteristics of the power turbine rotor. For the given design rotational speed, the critical speed had enough margin and the rotor system worked safely and smoothly. This research provided a reference and theoretical basis for the calculation of the dynamic characteristics of the similar rotor system.

Static and Dynamic Characteristics Analysis of Precise Composite CNC Grinding Machine

2011 ◽  
Vol 411 ◽  
pp. 88-93
Author(s):  
Hong Lin Zhao ◽  
Yun Fei Sun ◽  
Rui Chen ◽  
Yu Mei Huang ◽  
Guang Peng Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Element Model ◽  
Machine Model ◽  
Static And Dynamic Characteristics ◽  
Cnc Grinding ◽  
Characteristics Analysis ◽  
The Subject ◽  
Grinding Machine ◽  
Cnc Grinding Machine

The parameters of joint parts must be included in the finite element model of a whole grinding machine. The subject investigated in this paper is B2-K3000 high-precision composite flexible grinding machine. Through finite element modeling, the joint part parameters are integrated into the whole grinding machine model to establish a dynamic model and then analyze its static and dynamic characteristics. The result shows that the whole grinding machine possesses good features, but it still needs to be improved. This paper gives suggestions for its structure development and application.

Dynamic Characteristics of a Long-Span Cable-Stayed Bridge

2011 ◽  
Vol 480-481 ◽  
pp. 1496-1501
Author(s):  
Liu Hui
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Iteration Method ◽  
Natural Frequencies ◽  
Element Model ◽  
Vibration Modes ◽  
Cable Stayed Bridge ◽  
Long Span ◽  
Subspace Iteration ◽  
Floating System

In order to study the dynamic characteristics of a super-long-span cable-stayed bridge which is semi-floating system, the spatial finite element model of this cable-stayed bridge was established in ANSYS based on the finite element theory.Modal solution was conducted using subspace iteration method, and natural frequencies and vibration modes were obtained.The dynamic characteristics of this super-long-span cable-stayed bridge were then analyzed.Results showed that the super-long-span cable-stayed bridge of semi-floating system has long basic cycle, low natural frequencies, dense modes and intercoupling vibration modes.

Weak-Points Diagnosis and Optimization of Shield Machine Cutter Tool Based on Characteristic Parameters

2016 ◽  
Vol 693 ◽  
pp. 1479-1485 ◽  
Author(s):  
Jian Zhao ◽  
Xue Wu Hong ◽  
Ming Yu ◽  
Zhi Peng Gao ◽  
Wen Jin Wang
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Optimization Design ◽  
Weak Link ◽  
Human Life ◽  
Element Model ◽  
Ring Structure ◽  
Modal Parameters ◽  
Underground Engineering ◽  
Shield Machine

Shield machine plays an indispensable role in the mining, transportation, underground engineering, hydraulic engineering and municipal construction. Shield cutters of shield construction process often appears serious deformation, damage that leads to engineering accident, or even a threat to human life and safety. In order to provide high precise data for shield machine cutter tool dynamic modification and to diagnose the shield machine cutter tool fault, the dynamic characteristic of the shield machine cutter tool system, which is the main component of a shield machine cutter tool, has to be obtained precisely. The compute modal parameters identification method base on the finite element method is proposed to identify the modal parameters of the shield machine cutter tool. By means of Solidwords software, the knife ring structure of the shield machine tool and the tool is designed; then build the tool the finite element model, modal analysis, obtained the dynamic characteristics, and find out the weak link, put forward the improvement measures and prolong its life. Therefore, the study on dynamic characteristics of shield machine cutter, for the optimization design of domestic tool, has an important significance improve tool life.

scholarly journals Seismic Failure Pattern Prediction in a Historical Masonry Minaret under Different Earthquakes

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Halil Nohutcu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Nonlinear Analysis ◽  
Dynamic Characteristics ◽  
Time History ◽  
Element Model ◽  
Ambient Vibration ◽  
Tension Stress ◽  
Historical Structures ◽  
Ambient Vibration Tests

Historical structures are the values that are of great importance to that country, showing the roots of a country, and must be passed on from generation to generation. This study attempts to make a contribution to this goal. Seismic damage pattern estimation in a historical brick masonry minaret under different ground motion levels is investigated by using updated finite element models based on ambient vibration data in this study. Imaret Mosque which was built in 1481 AD is selected for an application. Surveying measurement and material tests were conducted to obtain a 3D solid model and mechanical properties of the components of the minaret. Firstly, the initial 3D finite element model of the minaret was analyzed and numerical dynamic characteristics of the minaret were obtained. Then, ambient vibration tests as well as operational modal analysis were implemented in order to obtain the experimental dynamic characteristics of the minaret. The initial finite element model of the minaret was updated by using the experimental dynamic results. Lastly, linear and nonlinear time-history analyses of the updated finite element model of the minaret were carried out using the acceleration records of two different level earthquakes that occurred in Turkey, in Afyon-Dinar (1995) and Çay-Sultandağı (2002). A concrete damage plasticity model is considered in the nonlinear analyses. The conducted analyses indicate that the compressive and tension stress results of the linear analyses are not as realistic as the nonlinear analysis results. According to the nonlinear analysis, the Çay-Sultandağı earthquake would inflict limited damage on the minaret, whereas the Dinar earthquake would damage some parts of the elements in the transition segment of the minaret.

scholarly journals Spectrum Analysis of a Coaxial Dual-Rotor System with Coupling Misalignment

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Hongxian Zhang ◽  
Liangpei Huang ◽  
Xuejun Li ◽  
Lingli Jiang ◽  
Dalian Yang ◽  
...  
Keyword(s):  
Spectral Characteristics ◽  
Element Model ◽  
Rotor System ◽  
Harmonic Frequencies ◽  
Coaxial Rotor ◽  
Outer Rotor ◽  
Frequency Components ◽  
Harmonic Resonance ◽  
The Finite Element Model ◽  
Engine Rotor

The finite element model of a dual-rotor system was established by Timoshenko beam element. The dual-rotor system is a coaxial rotor whose supporting structure is similar to that of an aero-engine rotor system. The inner rotor is supported by three bearings, which makes it a redundantly supported rotor. The outer rotor connects the inner rotor by an intershaft bearing. The spectrum characteristics of the dual-rotor system under unbalanced excitation and misalignment excitation were analysed in order to study the influence of coupling misalignment of the inner rotor on the spectral characteristics of the rotor system. The results indicate that the vibration caused by the misaligned coupling of the inner rotor will be transmitted to the outer rotor through the intershaft bearing. Multiple harmonic frequency components, mainly 1x and 2x, will be excited by the coupling misalignment. The amplitudes of all harmonic frequencies increase with the misalignment in both the inner and outer rotors. The vibration level of the outer rotor affected by the misalignment is lower than that of the inner rotor because it is far from the misaligned coupling. Harmonic resonance occurs when any harmonic frequencies of the misalignment response coincide with a natural frequency of the system. In order to verify the theoretical model, experiments are performed on a test rig. Both the experimental and simulation results are in good accordance with each other.

Simulation and Test Study on Dynamic Characteristic of Air Spring with Auxiliary Chamber

2013 ◽  
Vol 341-342 ◽  
pp. 391-394 ◽  
Author(s):  
Li Qing Sun ◽  
Zhong Xxing Li ◽  
Xu Feng Shen ◽  
Jia Yi Zhu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Characteristic ◽  
Dynamic Characteristics ◽  
Excitation Frequency ◽  
Initial Pressure ◽  
Element Model ◽  
Air Spring ◽  
Chamber Volume ◽  
Lower Excitation

In order to improve dynamic characteristics of air spring with auxiliary chamber, finite element model of air spring R1A390-295 with auxiliary chamber connected with pipe is established,and through analysis to the dynamic characteristics of the model, influence discipline of sitffness characteristics to air spring with different pipe, different auxiliary chamber or different initial pressure are analysed under different excitation. The result show that:minor dynamic sitffness is obtained by using larger pipe or under lower excitation frequency,and as volume of auxiliary chamber increases, the spring dynamic sitffness will decrease accordingly and its amplitude tends to gentle,and influence for decreasing the spring dynamic sitffness is not obvious by continuing to increase the auxiliary chamber volume; the spring dynamic sitffness will increases as initial pressure increases. The validity of Finite element model is verified through dynamic characteristic test .

Simulation of Crank-Rocker Mechanism on Finite Element by ANSYS

2012 ◽  
Vol 605-607 ◽  
pp. 626-629
Author(s):  
Xin Yu Zhang
Keyword(s):  
Finite Element ◽  
Theoretical Analysis ◽  
Finite Element Model ◽  
Dynamic Characteristics ◽  
Element Model ◽  
Analysis And Design

This paper has analyzed the movement of the crank-rocker mechanism by a simple finite element model, to study the establishing of the model and the constraints imposed. It has simulated the movement by software ANSYS, and gets the results which is consistent to the theoretical analysis. It accesses kinematical and dynamic characteristics for the mechanism, and provides the necessary foundation to analysis and design of the complex machinery.

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