Inductances Evaluation of a Squirrel-Cage Induction Motor with Curved Dynamic Eccentricity

Lv, Qiang,Bao, Xiaohua,He, Yigang,Fang, Yong,Cheng, Xiaowei The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.5

Eccentricity faults more or less exist in all rotating electrical machines. This paper establishes a more precise model of dynamic eccentricity (DE) in electrical machines named as curved dynamic eccentricity. It is a kind of axial unequal eccentricity which has not been investigated in detail so far but occurs in large electrical machines. The inductances of a large three-phase squirrel-cage induction machine (SCIM) under different levels of curved DE conditions are evaluated using winding function approach (WFA). These inductances include the stator self and mutual inductances, rotor self and mutual inductances, and mutual inductances between stator phases and rotor loops. A comparison is made between the calculation results under curved DE and the corresponding pure DE conditions. It indicates that the eccentricity condition will be more terrible than the monitored eccentricity based on the conventional pure DE model.

편심을 가진 스퍼 기어의 동적 하중 특성

박찬일 대한기계학회 2023 大韓機械學會論文集A Vol.47 No.1

Gear eccentricity changes the dynamic characteristics of a gear system and generates unnecessary dynamic excitation force that affects the premature failure of gears. This study analyzed the dynamic load characteristics of spur gears with eccentricity. Accordingly, the six-DOF equations of motion of the spur gear system owing to eccentricity were derived. Applying to a numerical example, the equations of motion were solved using the Newmark beta and Newton-Raphson methods. The dynamic mesh and bearing loads of the spur gear system with eccentricity were analyzed. The effects of the gear eccentricity, transmission error, and mode on mesh and bearing loads were investigated.

Inductances Evaluation of a Squirrel-Cage Induction Motor with Curved Dynamic Eccentricity

Qiang Lv,Xiaohua Bao,Yigang He,Yong Fang,Xiaowei Cheng 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.5

Eccentricity faults more or less exist in all rotating electrical machines. This paper establishes a more precise model of dynamic eccentricity (DE) in electrical machines named as curved dynamic eccentricity. It is a kind of axial unequal eccentricity which has not been investigated in detail so far but occurs in large electrical machines. The inductances of a large three-phase squirrel-cage induction machine (SCIM) under different levels of curved DE conditions are evaluated using winding function approach (WFA). These inductances include the stator self and mutual inductances, rotor self and mutual inductances, and mutual inductances between stator phases and rotor loops. A comparison is made between the calculation results under curved DE and the corresponding pure DE conditions. It indicates that the eccentricity condition will be more terrible than the monitored eccentricity based on the conventional pure DE model.

Dynamic propagation of a finite eccentric crack in a functionally graded piezoelectric ceramic strip

신정우,김태욱,김성준,황인희 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.1

The dynamic propagation of an eccentric Griffith crack in a functionally graded piezoelectric ceramic strip under anti-plane shear is analyzed using the integral transform method. A constant velocity Yoffe-type moving crack is considered. Fourier transform is used to reduce the problem to a pair of dual integral equations, which is then expressed in a Fredholm integral equation of the second kind. We assume that the properties of the functionally graded piezoelectric material vary continuously along the thickness. The impermeable crack boundary condition is adopted. Numerical values on the dynamic stress intensity factors are presented for the functionally graded piezoelectric material to show the dependence of the gradient of material properties, crack moving velocity, and eccentricity. The dynamic stress intensity factors of a moving crack in functionally graded piezoelectric material increases when the crack moving velocity, eccentricity of crack location, material property gradient, and crack length increase.

회전 실린더의 편심이 테일러-쿠에트 유동에 미치는 영향

전동협(Dong Hyup Jeon) 대한기계학회 2021 大韓機械學會論文集B Vol.45 No.2

테일러 반응기 내 회전 실린더의 편심에 따른 테일러-쿠에트 유동의 영향을 알아보기 위하여 전산유체해석을 수행하였다. TTVF 영역에서 편심 변화에 따른 유동 특성과 전단률 분포를 알아보았다. 편심 발생 시 비대칭적 유동 분포와 불안정한 테일러 와류가 형성되었다. 편심이 커질수록 유동의 비대칭성이 커지고 외부 실린더 표면에 높은 압력이 분포되었으나 테일러 와류의 개수에는 변화가 없었다. 편심비가 60%인 경우, 테일러 와류가 사라지고 불규칙한 유선이 나타났다. We conducted a computational fluid dynamics simulation to understand the effect of the eccentricity of a rotating cylinder on the Taylor-Couette flow in a Taylor reactor. We investigated the flow characteristics and shear rate distributions at the TTVF region according to the variation of eccentricity. When the eccentricity occurs, an asymmetric flow distribution and unstable Taylor vortex appear. As the eccentricity increases, the asymmetry of the flow increases and high pressure is distributed at the surface of the outer cylinder, however, the number of Taylor vortices does not change. When the eccentric ratio is 60%, the Taylor vortices disappear and irregular streamlines are observed.

The effect of mass eccentricity on the torsional response of building structures

Georgoussis, George K.,Mamou, Anna Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.6

The effect of earthquake induced torsion, due to mass eccentricities, is investigated with the objective of providing practical design guidelines for minimizing the torsional response of building structures. Current code provisions recommend performing three dimensional static or dynamic analyses, which involve shifting the centers of the floor masses from their nominal positions to what is called an accidental eccentricity. This procedure however may significantly increase the design cost of multistory buildings, due to the numerous possible spatial combinations of mass eccentricities and it is doubtful whether such a cost would be justifiable. This paper addresses this issue on a theoretical basis and investigates the torsional response of asymmetric multistory buildings in relation to their behavior when all floor masses lie on the same vertical line. This approach provides an insight on the overall seismic response of buildings and reveals how the torsional response of a structure is influenced by an arbitrary spatial combination of mass eccentricities. It also provides practical guidelines of how a structural configuration may be designed to sustain minor torsion, which is the main objective of any practicing engineer. A parametric study is presented on 9-story common building types having a mixed-type lateral load resisting system (frames, walls, coupled wall bents) and representative heightwise variations of accidental eccentricities.

The effect of mass eccentricity on the torsional response of building structures

George K. Georgoussis,Anna Mamou 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.6

The effect of earthquake induced torsion, due to mass eccentricities, is investigated with the objective of providing practical design guidelines for minimizing the torsional response of building structures. Current code provisions recommend performing three dimensional static or dynamic analyses, which involve shifting the centers of the floor masses from their nominal positions to what is called an accidental eccentricity. This procedure however may significantly increase the design cost of multistory buildings, due to the numerous possible spatial combinations of mass eccentricities and it is doubtful whether such a cost would be justifiable. This paper addresses this issue on a theoretical basis and investigates the torsional response of asymmetric multistory buildings in relation to their behavior when all floor masses lie on the same vertical line. This approach provides an insight on the overall seismic response of buildings and reveals how the torsional response of a structure is influenced by an arbitrary spatial combination of mass eccentricities. It also provides practical guidelines of how a structural configuration may be designed to sustain minor torsion, which is the main objective of any practicing engineer. A parametric study is presented on 9-story common building types having a mixed-type lateral load resisting system (frames, walls, coupled wall bents) and representative heightwise variations of accidental eccentricities.

Vibration analysis of electric motors considering rotating rotor structure using flexible multibody dynamics-electromagnetic-structural vibration coupled analysis

Cho Seunghyeon,전경훈,김창완 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.2

In this study, we develop flexible multibody dynamic-electromagnetic-structural vibration coupled analysis method to accurately predict motor vibration by considering the electromagnetic force characteristics, rotating characteristics of rotating motor motors, and their interactions at the no-load rated speed and operating speed range. The structural characteristics are accurately reflected by developing a three-dimensional (3D) finite element model considering the entire components of the motor. The reliability of the 3D finite element model of the motor is verified using the impact hammer test. In addition, to consider the rotational characteristics of the rotor structure, we develop a flexible multibody dynamics model that connects the flexible rotor and the bearing with revolute joint. The vibration of the motor at the no-load rated speed is analyzed using flexible multibody dynamics-electromagnetic-structural vibration coupled analysis. Comparing the vibration test results, it is confirmed that the flexible multibody dynamics-electromagnetic-structural vibration coupled analysis result predicts the actual motor vibration more accurately than the conventional finite element analysis-based electromagnetic-structural vibration coupled analysis result. By using flexible multibody dynamics-electromagnetic-structural vibration coupled analysis in the operating speed range, it is confirmed that not only electromagnetic force harmonics but also sideband harmonics caused by rotor eccentricity-induced large vibrations, and also confirmed that it accurately predicts the vibration characteristics of actual motors with rotating rotors.

Effect of aortic spiral blood flow on wall shear stress in stenosed left main coronary arteries with varying take-off angle, stenosis severity and eccentricity

Abouzar Moshfegh,Ashkan Javadzadegan,Zhaoqi Zhang,Hamid Hassanzadeh Afrouzi,Mohammad Omidi 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.8

It is well accepted that blood flow in the human aorta is spiral by nature, with beneficial impacts for the cardiovascular system in the form of improved haemodynamics and efficient perfusion. This study investigates the effect of aortic spiral blood flow on wall shear stress (WSS) in computer-generated models of the left main trunk (LMT), also known as left main coronary artery, with varying take-off angle, stenosis severity and eccentricity. The results show that the spirality effect causes a substantial reduction in maximum WSS (WSS max ), average WSS (WSS ave ) and size of regions with low WSS. The effects of spiral flow on WSS max become more significant with increasing LMT take-off angle and stenosis eccentricity, and they become less significant with increasing stenosis severity. The aortic spiral blood flow intensity, LMT take-off angle, stenosis severity and eccentricity statistically significantly predict the WSS; however, the strongest predictor of WSS is stenosis severity (F(4, 399) = 3653.85, p < 0.001 for WSS max and F(4, 399) = 913.46, p < 0.001 for WSS ave ), followed by LMT take-off angle (F(4, 399) = 582.735, p < 0.001 for WSS max and F(4, 399) = 163.16, p < 0.001 for WSS ave ), stenosis eccentricity (F(4, 399) = 230.15, p < 0.001 for WSS max and F(4, 399) = 52.94, p < 0.001 for WSS ave ) and blood flow spirality (F(4, 399) = 112.37, p < 0.001 for WSS max and F(4, 399) = 32.18, p < 0.001 for WSS ave ). Our findings suggest that naturally or artificially induced spiral flow in the aorta potentially has atheroprotective effects in the LMT.

Vibration characteristic analysis of gearbox based on dynamic excitation with eccentricity error

Wen Liu,Hang Zhao,Tengjiao Lin,Biao Gao,Yun Yang 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.11

In this study, the vibration characteristics of gearbox considering the eccentricity error and the friction excitation of helical gear pair were evaluated theoretically and experimentally. A geometric model of a single-stage helical gear pair with eccentricity error was established to obtain the calculation formula of the length of the dynamic contact line and the friction excitation. The multi-degree-of-freedom dynamic model of the transmission system was established considering the influences of tooth friction, support stiffness and damping, meshing stiffness and damping, static error, and dynamic tooth backlash. Then, the dynamic meshing forces of the system were obtained and applied to the gearbox for vibration response analysis using mode superposition method. A correlation test rig was developed to measure vibration under different operating conditions for verifying the correctness of the simulation models. Comparison between simulation and test was performed to demonstrate the accuracy of the proposed model in predicting vibrations. Results showed that eccentricity greatly influenced the overall vibration characteristics. The relative error between measurement and prediction can be significantly reduced by considering the eccentricity error in the dynamic model of transmission system.