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.

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.

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.

Fault Diagnosis of Wind Turbine Gearboxes

2012 ◽  
Vol 512-515 ◽  
pp. 715-718
Author(s):  
Yu Bai Zhang ◽  
Hui Qun Yuan ◽  
Yin Xin Yu ◽  
Hai Jiang Kou ◽  
Ming Xuan Liang
Keyword(s):  
Wind Turbine ◽  
High Speed ◽  
Fault Location ◽  
Natural Frequencies ◽  
Experimental Tests ◽  
Element Model ◽  
Frequency Domain Analysis ◽  
Mode Shapes ◽  
Frequency Components ◽  
The Finite Element Model

Abnormal vibration appeared when experimental tests was carried out on gearboxes of a 1.5MW wind turbine. In this paper, Time-domain and frequency- domain analysis of test data was implemented based on the method of wavelet denoising, the fault location was determined, and the vibration fault indicators and frequency components were obtained. The finite element model of the gearboxes were established, and the natural frequencies and mode shapes were achieved by calculating. The results showed that the fault occurred in the high speed shaft parts, fault vibration frequency was caused by high-speed shaft eccentric resonance frequency and the frequency generated by the natural frequency and the edge frequency that caused by turning. The research layed the foundation for the study of noise reduction and optimization of the wind turbine gearboxes.

Interval Analysis on Aero-Engine Rotor System With Misalignment

2015 ◽  
Author(s):  
Cun Wang ◽  
Yanhong Ma ◽  
Dayi Zhang ◽  
Jie Hong
Keyword(s):  
Interval Analysis ◽  
Second Harmonic ◽  
Joint Stiffness ◽  
Element Model ◽  
Rotor System ◽  
Operating Conditions ◽  
Analysis Method ◽  
Interval Analysis Method ◽  
Frequency Components ◽  
Different Characteristics

Misalignment is a usual phenomenon in rotating machines. The rotor centerlines are not collinear at the couplings and the rotors operate in incorrect axial positions in a multi-span rotor. The effects of misalignment of flexible rotor system are summarized as the variation of joint stiffness and additional misalignment excitation force based on the dynamic model established. The variation of joints stiffness is difficult to describe, meanwhile the misalignment excitation and rotor unbalance changes with different assembly and operating conditions. The distributions of these parameters which have significant effect on rotor dynamics are unknown, but the intervals of uncertain parameters are usually easier to get. An interval analysis method based on Taylor expansion and direct integration, which solves the dynamic response of rotor system under complex excitations including misalignment and multi unbalance with different frequencies and excitation points is presented. The differential equation of rotor system is formulated by combination of the matrixes of an actual rotor system finite element model and interval excitation vectors. The responses of a single spool and two spools with misalignment and unbalance are calculated by the interval analysis method. The results indicate that the method is effective and reflects some dynamic influence of misalignment and unbalance on rotor system. Second harmonic frequency appears, and rotor orbit is irregular. The response reflects the uncertain interval distribution characteristics, and the frequency components on different locations of the rotor have different characteristics.

Redrawing Operation a Star Shape from Cylindrical Shape Using Experimental and FE Analysis

2020 ◽  
Vol 38 (1A) ◽  
pp. 25-32
Author(s):  
Waleed Kh. Jawad ◽  
Ali T. Ikal
Keyword(s):  
Finite Element ◽  
Effective Strain ◽  
Element Model ◽  
Cylindrical Shape ◽  
Element Analysis ◽  
Punch Force ◽  
Maximum Value ◽  
Element Simulation ◽  
Blank Sheet ◽  
The Finite Element Model

The aim of this paper is to design and fabricate a star die and a cylindrical die to produce a star shape by redrawing the cylindrical shape and comparing it to the conventional method of producing a star cup drawn from the circular blank sheet using experimental (EXP) and finite element simulation (FES). The redrawing and drawing process was done to produce a star cup with the dimension of (41.5 × 34.69mm), and (30 mm). The finite element model is performed via mechanical APDL ANSYS18.0 to modulate the redrawing and drawing operation. The results of finite element analysis were compared with the experimental results and it is found that the maximum punch force (39.12KN) recorded with the production of a star shape drawn from the circular blank sheet when comparing the punch force (32.33 KN) recorded when redrawing the cylindrical shape into a star shape. This is due to the exposure of the cup produced drawn from the blank to the highest tensile stress. The highest value of the effective stress (709MPa) and effective strain (0.751) recorded with the star shape drawn from a circular blank sheet. The maximum value of lamination (8.707%) is recorded at the cup curling (the concave area) with the first method compared to the maximum value of lamination (5.822%) recorded at the cup curling (the concave area) with the second method because of this exposure to the highest concentration of stresses. The best distribution of thickness, strains, and stresses when producing a star shape by

scholarly journals Vibration characteristics of triple-gear-rotor system in compressed air energy storage under variable torque load

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042098705
Author(s):  
Xinran Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xuehui Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Element Model ◽  
Rotor System ◽  
Dynamic Responses ◽  
System Response ◽  
Rotating Speed ◽  
Torque Load ◽  
Set Up ◽  
Two Stages

This paper focuses on the effects of the off-design operation of CAES on the dynamic characteristics of the triple-gear-rotor system. A finite element model of the system is set up with unbalanced excitations, torque load excitations, and backlash which lead to variations of tooth contact status. An experiment is carried out to verify the accuracy of the mathematical model. The results show that when the system is subjected to large-scale torque load lifting at a high rotating speed, it has two stages of relatively strong periodicity when the torque load is light, and of chaotic when the torque load is heavy, with the transition between the two states being relatively quick and violent. The analysis of the three-dimensional acceleration spectrum and the meshing force shows that the variation in the meshing state and the fluctuation of the meshing force is the basic reasons for the variation in the system response with the torque load. In addition, the three rotors in the triple-gear-rotor system studied show a strong similarity in the meshing states and meshing force fluctuations, which result in the similarity in the dynamic responses of the three rotors.

Durability Analysis of the Reduction Gear for High Speed Train Considering Driving Histories

2012 ◽  
Vol 586 ◽  
pp. 269-273
Author(s):  
Chul Su Kim ◽  
Gil Hyun Kang
Keyword(s):  
Fatigue Life ◽  
High Speed ◽  
Element Model ◽  
Rolling Stock ◽  
Reduction Gear ◽  
High Speed Train ◽  
Analysis Software ◽  
Tractive Effort ◽  
Durability Analysis ◽  
The Finite Element Model

To assure the safety of the power bogies for train, it is important to perform the durability analysis of reduction gear considering a variation of velocity and traction motor capability. In this study, two types of applied load histories were constructed from driving histories considering the tractive effort and the train running curves by using dynamic analysis software (MSC.ADAMS). Moreover, this study was performed by evaluating fatigue damage of the reduction gears for rolling stock using durability analysis software (MSC.FATIGUE). The finite element model for evaluating the carburizing effect on the gear surface was used for predicting the fatigue life of the gears. The results showed that the fatigue life of the reduction gear would decrease with an increasing numbers of stops at station.

Analysis of Hydroelectric Unit’s Upper Bracket Based on Test and FEM

2014 ◽  
Vol 721 ◽  
pp. 131-134
Author(s):  
Mi Mi Xia ◽  
Yong Gang Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Element Model ◽  
The Finite Element Method ◽  
Ansys Software ◽  
Element Analysis ◽  
Hydroelectric Unit ◽  
The Finite Element Analysis ◽  
Strain Rosette ◽  
The Finite Element Model

To research the load upper bracket of Francis hydroelectric unit, then established the finite-element model, and analyzed the structure stress of 7 operating condition points with the ANSYS software. By the strain rosette test, acquired the data of stress-strain in the area of stress concentration of the upper bracket. The inaccuracy was considered below 5% by analyzing the contradistinction between the finite-element analysis and the test, and match the engineering precision and the test was reliable. The finite-element method could be used to judge the stress of the upper bracket, and it could provide reference for the Structural optimization and improvement too.

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