A Ritz Model of Unsteady Oil-Film Forces for Nonlinear Dynamic Rotor-Bearing System

2004 ◽  
Vol 71 (2) ◽  
pp. 219-224 ◽  
Author(s):  
Tiesheng Zheng ◽  
Shuhua Yang ◽  
Zhonghui Xiao ◽  
Wen Zhang
Keyword(s):  
Free Boundary ◽  
Ritz Method ◽  
Computing Time ◽  
Force Model ◽  
The Finite Element Method ◽  
Oil Film ◽  
Great Saving ◽  
Cavitation Region ◽  
The Given ◽  
Oil Film Pressure

Based on the free boundary theory and variational method, this paper presents a Ritz method to compute the instantaneous hydrodynamic forces of a real bearing subject to any perturbed motions of the rotor. The given method manipulates the cavitation region by simply introducing a parameter to match the free boundary condition and, as a result, a very simple approximate formula of oil-film pressure were obtained leading to great saving of computing time. The numerical examples show the high accuracy of the proposed formulas. This oil-film force model is also used to analyze the nonlinear dynamics of a rigid unbalanced rotor with elliptical bearing support. The results well agree with those of the oil-film force model computed by the finite element method and the computing time is saved greatly.

Effect of Lubrication Status of Bearing on Crankshaft Strength

2007 ◽  
Vol 129 (4) ◽  
pp. 887-894 ◽  
Author(s):  
Jun Sun ◽  
Changlin Gui
Keyword(s):  
Combustion Engine ◽  
Direct Interaction ◽  
Local Area ◽  
Present Calculation ◽  
The Finite Element Method ◽  
Film Pressure ◽  
Oil Film ◽  
Bearing Load ◽  
Oil Film Pressure ◽  
Element Method

There is direct interaction between crankshaft and bearing in an internal combustion engine. The effect of lubrication status of bearing was not considered in the present calculation of crankshaft strength. A given oil film pressure distribution of bearing was generally used as load acted on journal. In this paper, a crankshaft-bearing system was taken as the study object. On the basis of lubrication analysis of misaligned bearing caused by crankshaft deformation, the stress and strength of-crankshaft were calculated using analytical oil film pressure of bearing as the load boundary condition. Crankshaft deformation and bearing load were calculated by whole crankshaft beam-element method. The lubrication of crankshaft bearing was analyzed by the kinetics method. Crankshaft stress was calculated by the finite-element method. The results show that when the effect of crankshaft deformation under load is considered, the offset distribution of oil film pressure of bearing appears and the highest oil film pressure increases remarkably, which result in the stresses of local area on fillet surface of crankshaft journal increase obviously and the safety factor of crankshaft decreases.

Calculation of Equilibrium Position and Dynamic Coefficients of a Journal Bearing Using Free Boundary Theory

1999 ◽  
Vol 122 (3) ◽  
pp. 616-621 ◽  
Author(s):  
Tiesheng Zheng ◽  
Norio Hasebe
Keyword(s):  
Finite Element ◽  
Equilibrium Position ◽  
Static Load ◽  
Journal Bearing ◽  
Computing Time ◽  
Oil Film ◽  
Dynamic Coefficients ◽  
Newton Raphson ◽  
Raphson Method ◽  
Oil Film Pressure

A finite element method, which is based on the variational inequality approach, is introduced to calculate the oil film pressure distribution of a journal bearing. The cavitation zone is found by solving a linear complementary problem. By means of this approach a perturbation can be performed directly on the finite element equation and, consequently, the Jacobian matrices of the oil film forces are obtained concisely. The equilibrium position of the bearing at a given static load is found by the Newton-Raphson method and, as byproducts, dynamic coefficients are obtained simultaneously without any extra computing time. Numerical examples show that the method works satisfactorily. [S0742-4787(00)02302-X]

Lubricating Characteristics of Circular Tilting Pad Thrust Bearing

2010 ◽  
Vol 148-149 ◽  
pp. 267-270
Author(s):  
Xiao Dong Yu ◽  
Hui Jiang ◽  
Xiu Li Meng ◽  
Hong Jun Xiang ◽  
Hai Peng Yu ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Power Loss ◽  
Thrust Bearing ◽  
Thickness Distribution ◽  
The Finite Element Method ◽  
Oil Film ◽  
Heavy Equipment ◽  
Tilting Pad ◽  
Actual Design ◽  
Oil Film Pressure

In order to solve lubricating problem of circular tilting pad thrust bearing in the heavy equipment, lubricating characteristics mathematical model is established based on the Computational Fluid Dynamics and lubricating theory, the Finite Element Method is used to compute the lubricating characteristics of a circular tilting pad thrust bearing, and figure out thickness distribution of oil film, pressure distribution of oil film, temperature distribution of oil film, power loss and fluid flow, etc. lubricating characteristics parameters by self-compiling software program. Experiments testify the validity of the lubricating characteristics mathematical model. Through this method, the safety of a circular tilting pad thrust bearing can be forecasted, and the optimal design of such products can be achieved, and provides reasonable data for actual design and experiment, and decreases economy loss.

scholarly journals Improvement of Transverse-Flux Machine Characteristics by Finding an Optimal Air-Gap Diameter and Coil Cross-Section at the Given Magneto-Motive Force of the PMs

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 755
Author(s):  
Grebenikov Viktor ◽  
Oleksandr Dobzhanskyi ◽  
Gamaliia Rostislav ◽  
Rupert Gouws
Keyword(s):  
Cross Section ◽  
Computer Model ◽  
Single Phase ◽  
Air Gap ◽  
Laboratory Measurements ◽  
The Finite Element Method ◽  
Power Characteristics ◽  
Transverse Flux ◽  
Output Characteristics ◽  
The Given

This paper presents analysis and study of the single-phase transverse-flux machine. The finite element method results of the machine are compared with the laboratory measurements to confirm the accuracy of the computer model. This computer model is then used to investigate the effect of the machine’s geometry on its output characteristics. Parametric analysis of the machine is carried out to find the optimal air-gap diameter at which the cogging torque of the machine is minimal. In addition, the influence of the coil cross-section on the torque and output power characteristics of the machine is investigated and discussed.

scholarly journals Numerical Evaluation of Structural Safety of Linear Actuator for Flap Control of Aircraft Based on Airworthiness Standard

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 104
Author(s):  
Dong-Hyeop Kim ◽  
Young-Cheol Kim ◽  
Sang-Woo Kim
Keyword(s):  
Numerical Analysis ◽  
Analytical Method ◽  
Safety Evaluation ◽  
Experimental Tests ◽  
Structural Safety ◽  
Linear Actuator ◽  
The Finite Element Method ◽  
Margin Of Safety ◽  
Verification Methodology ◽  
The Given

Airworthiness standards of Korea recommend verifying structural safety by experimental tests and analytical methods, owing to the development of analysis technology. In this study, we propose a methodology to verify the structural safety of aircraft components based on airworthiness requirements using an analytical method. The structural safety and fatigue integrity of a linear actuator for flap control of aircraft was evaluated through numerical analysis. The static and fatigue analyses for the given loads obtained from the multibody dynamics analysis were performed using the finite element method. Subsequently, the margin of safety and vulnerable area were acquired and the feasibility of the structural safety evaluation using the analytical method was confirmed. The proposed numerical analysis method in this study can be adopted as an analytical verification methodology for the airworthiness standards of civilian aircraft in Korea.

Numerical Simulation on Velocity Profiles of Mill Bearing Lubrication

2010 ◽  
Vol 145 ◽  
pp. 282-286
Author(s):  
Qing Xue Huang ◽  
Jian Mei Wang ◽  
Yu Gui Li ◽  
Li Feng Ma ◽  
Chun Jiang Zhao
Keyword(s):  
Cross Section ◽  
Velocity Profiles ◽  
Flow State ◽  
Oil Film ◽  
Velocity Gradients ◽  
Oil Flow ◽  
The Mathematical Model ◽  
The Relationship ◽  
General Velocity ◽  
Oil Film Pressure

No 460 oil-film bearing oil as the dedicated lubricant is regarded as the incompressible Newtonian fluid. To comprehensively analyze the real oil flow state, the mathematical model on velocity profiles, together with its dimensionless equations, is established, and the calculating program is developed to simulate the 3D velocity profiles and velocity gradients at different oil flow layers. The relationship between velocity profiles and the oil film pressure is discussed, and the velocity tendency is consistent with the general velocity profile of wedge cross section. The conclusions are beneficial to the further study on lubricating performances of heavy contact components and to prolong their service lives.

scholarly journals Isospectrals of non-uniform Rayleigh beams with respect to their uniform counterparts

2018 ◽  
Vol 5 (2) ◽  
pp. 171717 ◽  
Author(s):  
Srivatsa Bhat K ◽  
Ranjan Ganguli
Keyword(s):  
Boundary Condition ◽  
Cross Section ◽  
Natural Frequencies ◽  
Rectangular Cross Section ◽  
Beam Equation ◽  
The Finite Element Method ◽  
Rayleigh Beam ◽  
Uniform Beam ◽  
Governing Differential Equation ◽  
The Given

In this paper, we look for non-uniform Rayleigh beams isospectral to a given uniform Rayleigh beam. Isospectral systems are those that have the same spectral properties, i.e. the same free vibration natural frequencies for a given boundary condition. A transformation is proposed that converts the fourth-order governing differential equation of non-uniform Rayleigh beam into a uniform Rayleigh beam. If the coefficients of the transformed equation match with those of the uniform beam equation, then the non-uniform beam is isospectral to the given uniform beam. The boundary-condition configuration should be preserved under this transformation. We present the constraints under which the boundary configurations will remain unchanged. Frequency equivalence of the non-uniform beams and the uniform beam is confirmed by the finite-element method. For the considered cases, examples of beams having a rectangular cross section are presented to show the application of our analysis.

Influence of Surface Waviness on the Thermal Elastohydrodynamic Lubrication of an Eccentric-Tappet Pair

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
J. Wang ◽  
C. H. Venner ◽  
A. A. Lubrecht
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Surface Waviness ◽  
Film Pressure ◽  
Oil Film ◽  
Working Cycle ◽  
Temperature Oscillations ◽  
Minimum Film Thickness ◽  
Traction Coefficient ◽  
Oil Film Pressure

The effect of single-sided and double-sided harmonic surface waviness on the film thickness, pressure, and temperature oscillations in an elastohydrodynamically lubricated eccentric-tappet pair has been investigated in relation to the eccentricity and the waviness wavelength. The results show that, during one working cycle, the waviness causes significant fluctuations of the oil film, pressure, and temperature, as well as a reduction in minimum film thickness. Smaller wavelength causes more dramatic variations in oil film. The fluctuations of the pressure, film thickness, temperature, and traction coefficient caused by double-sided waviness are nearly the same compared with the single-sided waviness, but the variations are less intense.

Stress Distribution Analysis on Alloy Layer of High Power Marine Diesel Engine Bearing Bush

2013 ◽  
Vol 331 ◽  
pp. 148-152
Author(s):  
Xiu Xu Zhao ◽  
Zhi Xiang Hu ◽  
An Jian Huang
Keyword(s):  
Diesel Engine ◽  
High Power ◽  
Alloy Layer ◽  
Marine Diesel Engine ◽  
Oil Film ◽  
Marine Diesel ◽  
Bearing Alloy ◽  
Stress And Strain Distribution ◽  
Engine Bearing ◽  
Oil Film Pressure

According to the characteristics of large size, small clearance ratio, high oil film pressure and thin oil film thickness in the actual conditions of high power marine diesel engine bearing, this Paper analyzes oil film pressure distribution on inner surface of bearing bush based on the finite difference method, uses finite element method to establish the hierarchical model, and analyzes stress and strain distribution on bearing alloy. In addition, this Paper researches the changes of stress and strain distribution on bearing alloy layer when alloy layer thickness changes for the optimization design of high power marine diesel engine bearing bush.

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