On the Choice of Element for Solving Lubrication Problems

1998 ◽  
Vol 120 (3) ◽  
pp. 636-639
Author(s):  
Ram Turaga ◽  
A. S. Sekhar ◽  
B. C. Majumdar
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Journal Bearings ◽  
The Finite Element Method ◽  
High Eccentricity ◽  
Damping Coefficients ◽  
Significant Difference ◽  
The Stability ◽  
Stiffness And Damping ◽  
Element Method

This study deals with the stability characteristics of journal bearings using the finite element method. Two different elements, a 3-node linear triangle and a 6-node quadratic triangle, have been used. The results show a significant difference in (1) stiffness and damping coefficients and (2) stability characteristics at high eccentricity ratios due to the use of the two different elements.

An Experimental Investigation on the Static and Dynamic Characteristics of Journal Bearings Under the Influence of Twisting Misalignment

1997 ◽  
Vol 119 (1) ◽  
pp. 188-192 ◽  
Author(s):  
P. Arumugam ◽  
S. Swarnamani ◽  
B. S. Prabhu
Keyword(s):  
Finite Element Method ◽  
Vertical Direction ◽  
Journal Bearings ◽  
Response Functions ◽  
The Finite Element Method ◽  
Static And Dynamic Characteristics ◽  
Damping Coefficients ◽  
Stiffness And Damping ◽  
Different Levels ◽  
Bearing System

The misalignment between the journal and the bearing in a rotor-bearing system may be due to manufacturing error, elastic deflection, thermal expansion etc. In the present work, the eight linearized stiffness and damping coefficients of the cylindrical and three lobe bearings are identified at different levels of bearing misalignment (twisting misalignment) and at different speeds of the rotor. The identification method used here needs FRFs (Frequency Response Functions) obtained by the measurements and the finite element method. The twisting misalignment changes the stiffness and damping coefficients in the vertical and horizontal directions. In the case of three lobe bearings, for 0.7 degree of misalignment, the stiffness in the vertical direction is increased by about 12 percent.

Analysis of Aerodynamic Journal Bearings With Small Number of Herringbone Grooves by Finite Element Method

1994 ◽  
Vol 116 (4) ◽  
pp. 698-704 ◽  
Author(s):  
D. Bonneau ◽  
J. Absi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Study ◽  
Load Capacity ◽  
Journal Bearings ◽  
The Finite Element Method ◽  
Bearing Number ◽  
Comparison Of The Results ◽  
Herringbone Grooves ◽  
Element Method

A numerical study of gas herringbone grooved journal bearings is presented for small number of grooves. The compressible Reynolds equation is solved by use of the Finite Element Method. The nonlinearity of the discretized equations is treated with the Newton-Raphson procedure. A comparison of the results for a smooth bearing with previously published results is made and the domain of validity of the Narrow Groove Theory is analyzed. Load capacity, attitude angle, and stiffness coefficients are given for various configurations: groove angle and thickness of grooves, bearing number, and that for both smooth and grooved member rotating.

Stability Analyses of Western Slopes in Jointed Rock Masses for GuangYang Highway

2011 ◽  
Vol 368-373 ◽  
pp. 234-240
Author(s):  
Shu Li Wang ◽  
Man Gen Mu ◽  
Ran Wang ◽  
Wen Bo Cui
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Limit Equilibrium ◽  
Western Slope ◽  
Seismic Load ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Limit Equilibrium Methods ◽  
The Stability ◽  
Element Method

This paper presents the results of a study on a joint slope deformation affecting the western slope of the GuangYang highway (YangQuan, China). Fieldwork identified the ongoing deformational process and assisted in defining its mechanisms, evolution and controlling factors. Here we discuss how to use limit equilibrium methods to calculate the behavior of slopes and to use the finite element analysis to evaluate the stability, displacements of slopes and soil-slope stabilization interaction. The finite element method with shear strength reduction (SSR) technique is explained in Phase2D. This method is effective for the prediction of the stability of slope. Based on numerical comparisons between the limit equilibrium methods and finite element method, it is suggested that the finite element method with SSR technique is a reliable and maybe unique approach to evaluate the slope stability. The paper also took into account effectiveness of the large rain and seismic load. The results of the numerical analysis are consistent with the observed slope surface evidence.

Optimization Research on Workpiece Clamping Deformation Using Genetic Algorithm and Finite Element Method

2011 ◽  
Vol 189-193 ◽  
pp. 2153-2160
Author(s):  
Yu Wen Sun ◽  
Chuan Tai Zhang ◽  
Qiang Guo
Keyword(s):  
Genetic Algorithm ◽  
Finite Element Method ◽  
Finite Element ◽  
Machining Accuracy ◽  
Clamping Force ◽  
The Finite Element Method ◽  
Linear Programming Method ◽  
Fixture Layout ◽  
The Stability ◽  
Element Method

Optimal fixture involves fixture layout and clamping force determination. It is critical to ensure the machining accuracy of workpiece. In this paper, the clamping process is analyzed with the consideration of cutting forces and frictions using the finite element method. Then the fixture layout and clamping force are optimized by minimizing the workpiece deformation via a Genetic Algorithm (GA). Subsequently, linear programming method is used to estimate the stability of workpiece. It is shown through an example that the proposed method is proved to be efficient. The optimization result is not only far superior to the experiential one, but also the total optimization time can be reduced significantly.

DETERMINATION OF DELAMINATION SIZE IN HONEYCOMB SANDWICH PANEL USING FINITE ELEMENT METHOD

2015 ◽  
Vol 75 (8) ◽  
Author(s):  
Ramzyzan Ramly ◽  
Wahyu Kuntjoro ◽  
Wirachman Wisnoe ◽  
Rizal Effendy Mohd Nasir ◽  
Aman Mohd Ihsan Mamat ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Sandwich Panel ◽  
Bending Test ◽  
The Finite Element Method ◽  
Three Point Bending ◽  
Significant Difference ◽  
Honeycomb Sandwich ◽  
Element Method

This paper describes the determination of a relative delamination size of the skin to the honeycomb core of the honeycomb sandwich panel using the Finite Element Method approach. In the analysis, the honeycomb sandwich panel was modelled in the actual dimension using CATIA. The delamination of two different sizes (10 mm diameter and 30 mm diameter) were modelled to simulate the delamination cases. Using Nastran/Patran, the models underwent a three-point-bending test in order to simulate a result. The results were compared between the case of no delamination, 10 mm delamination, and 30 mm delamination. From the simulation, there was a significant difference of displacement of the skin (facing) between the 10 mm diameter delamination and the 30 mm diameter delamination.  

Modelling of the Behaviour of Dynamical Gas Seals: Calculation with a Finite Element Method Implicitly Assuring the Continuity of Flow

1995 ◽  
Vol 209 (3) ◽  
pp. 195-201 ◽  
Author(s):  
P Hernandez ◽  
R Boudet
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Results ◽  
The Body ◽  
Dynamical Model ◽  
The Finite Element Method ◽  
Flow Through ◽  
Gas Seals ◽  
Stiffness And Damping ◽  
Element Method

The objective of this paper is to present a model of the behaviour of dynamical seals and the corresponding numerical results. These seals are used in the mechanism to realize partial sealing when the relative rotating speeds are too high for usual solutions. The studied seals mainly include two discs: one is attached to the shaft and the other to the body, the last one being pushed and the first being attached by springs. During operation, a gaseous film is created between the discs, preventing any contact. The control of the film thickness allows the leakage flow to be controlled. For the behaviour of such mechanisms, an analytical formulation of the problem is firstly presented. Then a geometrical and kinematical model having one degree of freedom is proposed to model the mechanism having two discs in relative rotation, one of which is spirally grooved. A dynamical model associated with the motion of the disc attached to the body has been developed and the mechanics of thin viscous films is used to study the behaviour of the gaseous film at the interface. Utilization of the finite element method in the mechanics of thin viscous films is introduced and a description of the elements used is presented. The influence of the groove's angle and the groove's depth is shown through numerical results concerning leakage mass flow through the mechanism and the loading capacity of the fluid film, as well as the coefficients of stiffness and damping associated with the dynamical model.

Numerical investigation on the static performance of aerostatic journal bearings with different pocket shapes by the finite-element method

2020 ◽  
pp. 135065012097911
Author(s):  
Xinglong Chen ◽  
James K Mills ◽  
Kai Shi ◽  
Gang Bao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Film Thickness ◽  
Journal Bearings ◽  
Orifice Diameter ◽  
Eccentricity Ratio ◽  
The Finite Element Method ◽  
Area Formula ◽  
Static Performance ◽  
Element Method

In this work, to improve the static behavior of aerostatic journal bearings, we examine the effect of pockets with different shapes, including the square, rectangular 1, rectangular 2, and circular, manufactured on the surface of the aerostatic journal bearing. The effects of the pocket shapes, pocket area [Formula: see text], eccentricity ratio ɛ, orifice diameter df, average gas film thickness h0, and misalignment angles [Formula: see text] and [Formula: see text] on the static performance are investigated using simulations. The Reynolds equation is solved by the finite-element method in this work. Simulations reveal that the pocket area [Formula: see text], eccentricity ratio ɛ, gas film thickness h0, orifice diameter df, and misalignment angles [Formula: see text] and [Formula: see text] have a significant influence on the load force F and the stiffness K. In general, rectangular 2 pocket bearings are found to perform somewhat better than bearings with other pocket shapes, with the pocket depth set to one-half of h0, when the pocket area [Formula: see text] varies from one-twelfth to one. The pocket area [Formula: see text] should be set according to the average gas film thickness h0 and the orifice diameter df to achieve a better static performance for the bearings. For bearings operated with misalignment angles [Formula: see text] and [Formula: see text], different pocket areas [Formula: see text] should be set according to the pocket shapes for the optimal design.

scholarly journals Analysis of Spiral-Grooved Gas Journal Bearings by the Narrow-Groove Theory and the Finite Element Method At Large Eccentricities

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Elia Iseli ◽  
Eliott Guenat ◽  
Roger Tresch ◽  
Jürg Schiffmann
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Pressure ◽  
Journal Bearings ◽  
The Finite Element Method ◽  
Pressure Profiles ◽  
Stability Maps ◽  
Time Periodic ◽  
Good Agreement ◽  
Element Method

Abstract A finite groove approach (FGA), based on the finite element method (FEM), is used for analyzing the static and dynamic behavior of spiral-grooved aerodynamic journal bearings at different eccentricities, number of grooves, and compressibility numbers. The results of the FGA are compared with the narrow-groove theory (NGT) solutions. For the rotating-groove case, a novel time-periodic solution method is presented for computing the quasi-steady-state and dynamic pressure profiles. The new method offers the advantage of avoiding time-consuming transient integration, while resolving a finite number of grooves. The static and dynamic solutions of the NGT and FGA approach are compared, and they show good agreement, even at large eccentricities (ε=0.8) and high compressibility numbers (Λ = 40). Stability maps at different eccentricities are presented. At certain operation points, a stability decrease toward larger eccentricities is observed. The largest stability deviations of the NGT from the FGA solutions occur at large groove angle, low number of grooves, and large compressibility numbers.

scholarly journals Analytical and experimental research on stability of large slenderness ratio horizontal hydraulic hoist

2018 ◽  
Vol 10 (10) ◽  
pp. 168781401880347 ◽  
Author(s):  
Ji Zhou ◽  
Duan-Wei Shi ◽  
Zhi-Lin Sun ◽  
Tao Bi ◽  
Xiong-Hao Cheng ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Safety Factor ◽  
Slenderness Ratio ◽  
Hydraulic Cylinder ◽  
Ratio Test ◽  
The Finite Element Method ◽  
Sliding Bearing ◽  
The Stability ◽  
Element Method

Taking the hydraulic cylinder for the miter gate in Dateng Gorges Water Conservancy Project as the object, a large slenderness ratio test hydraulic cylinder was designed based on the similarity theory. The buckling analysis of the test hydraulic cylinder was carried out by the finite element method, considering the friction at the supports, the misalignments between piston rod and cylinder tube, and gravity. The results indicate that the stability safety factor is 10.55. A buckling experimental system was established, and the buckling stability of the test hydraulic cylinder was tested for the sliding bearing support and the rolling bearing support at the piston-rod end, respectively. The stability safety factor is over 9.01 and 6.82 relevantly. The similarities and differences among the results of the finite element method, experimental method, NB/T 35020-2013, and two-sections pressure bar method were analyzed. Experimental and analytical results clearly show that the friction at the supports is a key factor in determining the magnitude of the stability safety for large slenderness ratio horizontal hydraulic hoist and utilizing the sliding bearing can effectively improve the stability safety factor.

scholarly journals The Stability of a Steel Welded Girder with Bending and Shear Forces Included

2017 ◽  
Vol 11 (1) ◽  
pp. 14-19
Author(s):  
Ryszard Sygulski ◽  
Michał Guminiak ◽  
Łukasz Polus
Keyword(s):  
Finite Element Method ◽  
Integral Equation ◽  
Finite Element ◽  
Plate Boundary ◽  
Shear Loading ◽  
The Finite Element Method ◽  
Shear Forces ◽  
Shear Effects ◽  
The Stability ◽  
Element Method

Abstract The stability of the element of a steel welded girder subjected to bending and shear forces is considered. The considered element is a rectangular plate supported on boundary. The type of a plate boundary conditions depend on the types (thickness) of the stiffeners. Considered plate is loaded by in-plane forces causing bending and shear effects. The Finite Element Method was applied to carry out the analysis. Additionally the Boundary Element Method in terms of boundary-domain integral equation was applied to evaluate the critical shear loading.

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