Numerical study of influences of hard particles in lubricant on tribological performances of the piston ring

2007 ◽  
Vol 221 (3) ◽  
pp. 361-372 ◽  
Author(s):  
F M Meng ◽  
Y Y Zhang ◽  
Y Z Hu ◽  
H Wang
Keyword(s):  
Friction Force ◽  
Contact Stress ◽  
Piston Ring ◽  
Reynolds Equation ◽  
Numerical Study ◽  
Cylinder Wall ◽  
Finite Element Program ◽  
Hard Particles ◽  
Element Program ◽  
Maximum Contact

Influences of hard particles lying in the lubrication region between piston ring face and cylinder wall, including the effects of a non-contact particle and contact particle, on tribological performances of the piston ringwere numerically analysed. A modified Reynolds equation incorporating a non-contact particle effect was presented. The total friction force, deformation, and contact stress of the ring, with a non-contact particle and contact particle consideration, were solved separately by using finite-element program code of the authors and software ANSYS 5.7. The numerical results show that obvious changes in the total friction force and deformation of the ring can occur, if the diameter and height across the film thickness of a non-contact particle and axial velocity difference between the non-contact particle and ring are considered. The maximum contact stress of the ring is obviously affected by the contact particle's interfering time and velocity, and hardness value of the plastically deformed particle.

Piston-Ring Lubrication Problems for Refrigeration Compressors Considering Combined Effects of Supply Oil Quantity and Surface Roughness

1996 ◽  
Vol 118 (2) ◽  
pp. 286-291 ◽  
Author(s):  
H. Nakai ◽  
N. Ino ◽  
H. Hashimoto
Keyword(s):  
Surface Roughness ◽  
Friction Force ◽  
Piston Ring ◽  
Reynolds Equation ◽  
Numerical Procedure ◽  
Cylinder Wall ◽  
Combined Effects ◽  
One Dimensional ◽  
Modified Reynolds Equation ◽  
Piston Ring Lubrication

Reciprocating-type compressors are widely used for refrigeration systems, and an understanding of piston-ring lubrication in the compressor is vital for designers in reducing the energy losses due to friction because a substantial portion of friction in the compressors is attributable to the piston-ring assembly. This study aimed at developing a one-dimensional analysis for lubrication between the piston-ring and cylinder of refrigeration compressors considering the combined effects of supply oil quantity and surface roughness on piston-ring face and cylinder wall. In the theoretical model, the piston-ring is treated as a one-dimensional dynamically loaded bearing with combined sliding and squeezing motion. The one-dimensional modified Reynolds equation based on the average flow model by Patir and Cheng is used as a governing equation. In the analysis of the modified Reynolds equation, two-types of inlet boundary conditions, flooded condition and starvation condition, are applied at the leading edge according to the supply oil quantity, and the Reynolds boundary condition is applied at the trailing edge. A numerical procedure is then developed to estimate the cyclic variation of minimum film thickness, inlet and outlet positions of lubrication film and friction force, and the combined effects of supply oil quantity and surface roughness height are examined for a typical refrigeration compressor. It is clarified from the numerical results that the supply oil quantity and surface roughness affect significantly the friction force of the piston-ring for refrigeration compressors.

Friction Force and Stresses Analysis for Contact of Assembled Details

2006 ◽  
Vol 113 ◽  
pp. 334-338
Author(s):  
Z. Dreija ◽  
O. Liniņš ◽  
Fr. Sudnieks ◽  
N. Mozga
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Plastic Deformation ◽  
Friction Force ◽  
Sliding Friction ◽  
Friction Model ◽  
Contact Interface ◽  
Finite Element Program ◽  
Elastic Plastic ◽  
Element Program

The present work deals with the computation of surface stresses and deformation in the presence of friction. The evaluation of the elastic-plastic contact is analyzed revealing three distinct stages that range from fully elastic through elastic-plastic to fully plastic contact interface. Several factors of sliding friction model are discussed: surface roughness, mechanical properties and contact load and areas that have strong effect on the friction force. The critical interference that marks the transition from elastic to elastic- plastic and plastic deformation is found out and its connection with plasticity index. A finite element program for determination contact analysis of the assembled details and due to details of deformation that arose a normal and tangencial stress is used.

An Experimental and Numerical Study to Analysis and Design of Sheet Hydroforming Process for an Automobile Fender Shell

2006 ◽  
Author(s):  
Mohammad Habibi Parsa ◽  
Payam Darbandi
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Fluid Pressure ◽  
Finite Element Program ◽  
New Approach ◽  
Explicit Finite Element ◽  
Sheet Hydroforming ◽  
Analysis And Design ◽  
Hydroforming Process ◽  
Element Program

A new approach for manufacturing of shell fender is proposed and has been examined numerically and experimentally. The new suggested method is based on sheet hydroforming process, which has a lot of advantages over conventional deep drawing process. After defining the shape of initial blank using an inverse finite element program, numerical evaluation of the proposed sheet hydroforming process for production of shell fender has been carried out using an explicit finite element code considering fluid pressure, boundary conditions and tools. Then experimental evaluation has been carried out using down sized specimen and the results have been compared with results of previous simulations. It has been shown that there are similar trends between finite element and experimental results.

Experimental and Numerical Study of Laterally Loaded Pile Groups with Pile Caps at Variable Elevations

2000 ◽  
Vol 1736 (1) ◽  
pp. 12-18 ◽  
Author(s):  
Michael C. McVay ◽  
Limin Zhang ◽  
Sangjoon Han ◽  
Peter Lai
Keyword(s):  
Numerical Study ◽  
Ground Surface ◽  
Pile Group ◽  
Special Device ◽  
Pile Groups ◽  
Finite Element Program ◽  
Lateral Resistance ◽  
Pile Cap ◽  
Element Program ◽  
Pile Caps

A series of lateral load tests were performed on 3×3 and 4×4 pile groups in loose and medium-dense sands in the centrifuge with their caps located at variable heights to the ground surface. Four cases were considered: Case 1, pile caps located above the ground surface; Case 2, bottom of pile cap in contact with the ground surface; Case 3, top of pile cap at the ground surface elevation; and Case 4, top of pile cap buried one cap thickness below ground surface. All tests with the exception of Case 1 of the 4×4 group had their pile tips located at the same elevation. A special device, which was capable of both driving the piles and raining sand on the group in flight, had to be constructed to perform the tests without stopping the centrifuge (spinning at 45 g). The tests revealed that lowering the pile cap elevation increased the lateral resistance of the pile group anywhere from 50 to 250 percent. The experimental results were subsequently modeled with the bridge foundation-superstructure finite element program FLPIER, which did a good job of predicting all the cases for different load levels without the need for soil–pile cap interaction springs (i.e., p-y springs attached to the cap). The analyses suggest that the increase in lateral resistance with lower cap elevations may be due to the lower center of rotation of the pile group. However, it should be noted that this study was for pile caps embedded in loose sand and not dense sands or at significant depths. The experiments also revealed a slight effect for the case of the pile cap embedded in sand with a footprint wider than the pile row. In that case the size of the passive soil wedge in front of the pile group, and consequently the group’s lateral resistance, increased.

Nonlinear Numerical Study of Cold-Formed Lipped Channel Beam-Columns

2014 ◽  
Vol 919-921 ◽  
pp. 183-187
Author(s):  
Ming Chen ◽  
Zhi Bin Feng ◽  
Zhou Zhou ◽  
Ya Long Wang ◽  
Qiang Zhang
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Engineering Practice ◽  
Time Saving ◽  
Finite Element Program ◽  
Beam Columns ◽  
Load Carrying ◽  
Element Program ◽  
Channel Beam ◽  
Overall Buckling

Cold-formed lipped channel sections may fail in local, distortional and overall buckling under compression. With the development of computer technology, finite element analyses of these sections play increasing important roles in engineering practice for economic design and time-saving purpose. A kind of typical cold-formed lipped channel beam-column with varying load eccentricity was analyzed in this paper by using the finite element program of ANSYS to observe the buckling modes and load carrying capacities of the columns. All the results can be the reference for further studies.

Finite Element Analysis of Grooved Gas Thrust Bearings and Grooved Gas Face Seals

1993 ◽  
Vol 115 (3) ◽  
pp. 348-354 ◽  
Author(s):  
D. Bonneau ◽  
J. Huitric ◽  
B. Tournerie
Keyword(s):  
Finite Element ◽  
Reynolds Equation ◽  
Weak Form ◽  
Oscillating Solution ◽  
Element Analysis ◽  
Finite Element Program ◽  
Thrust Bearings ◽  
Face Seals ◽  
Element Program ◽  
Gas Seals

A finite element method enabling the Reynolds equation solution for any face geometry of gas thrust bearing or of gas seal is presented. Difficulties due to thickness discontinuities are reduced by integration by parts of the terms involving derivatives. The weak form of the finite element Reynolds equation is then solved and the nonlinearity of the equation leads to the use of Newton-Raphson procedure. The process is fast convergent. The problem of oscillating solution is solved by the use of an upwind procedure. Some numerical examples show the accuracy and efficiency of the procedures. It is shown that the developed finite element program provides a numerical tool, more efficient than the method used until now, for the grooved gas seals design.

The Effect of Viscous and Hysteretic Damping on Rotor Stability

2000 ◽  
Author(s):  
Anthony M. Cerminaro ◽  
Frederick C. Nelson
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Rotor System ◽  
Viscous Damping ◽  
Finite Element Program ◽  
Hysteretic Damping ◽  
Element Program

A rotordynamic finite element program has been modified to include internal viscous and hysteretic damping. A numerical study has been done on a rotor system with variable external damping to predict the effect of various amounts of internal viscous and hysteretic damping on rotor stability. Three cases are considered: (1) external viscous damping with internal viscous damping; (2) external hysteretic damping with internal hysteretic damping; and (3) external viscous damping with internal hysteretic damping.

Slipping Effects of Simple Combination Beam under the Action of Negative Bending Moment

2011 ◽  
Vol 243-249 ◽  
pp. 1117-1121
Author(s):  
Xu Hong Zhang ◽  
He Wu ◽  
Jian Ping Cao
Keyword(s):  
Numerical Study ◽  
Bending Moment ◽  
Composite Beams ◽  
Slip Effect ◽  
Finite Element Program ◽  
Shear Connection ◽  
Distribution Rules ◽  
Element Program ◽  
Negative Bending ◽  
Simple Combination

A numerical study on slip effect of simply supported composite beams under negative bending moment is conducted by means of finite element program of ANSYS based on the feasibility verification of ANSYS. The research contents include: slip distribution rules; slip effect on deflection in service stage and ultimate bearing capacity; relationship between slip effect and shear connection、lognitudinal percentage of reinforcement and working behavior of composite beams with partial shear connection under negative bending moment .

Improvement of the Calculation of Hydrodynamic Systems by Considering the Dynamic Deformation Caused by Vibration

2011 ◽  
Author(s):  
Sebastian Kukla ◽  
Tim Sadek
Keyword(s):  
Reynolds Equation ◽  
Coefficient Matrix ◽  
Influence Coefficient ◽  
Finite Element Program ◽  
Hydrodynamic System ◽  
Element Program ◽  
Dynamic Components ◽  
Stiffness And Damping ◽  
Hydrodynamic Systems ◽  
Surface Dynamic

In order to improve the calculation of stiffness and damping coefficients (SDC) for hydrodynamic systems, this paper proposes the consideration of both static and dynamic deformations of the running surface. Dynamic deformations are caused by rotor vibration and corresponding unbalanced forces. A lubrication wedge was used to exemplify the significant influence of these dynamic deformations in SDC calculations. This basic hydrodynamic system was calculated considering material elasticity. First of all, an influence coefficient matrix, which describes the correlation of pressure and deformation, was calculated with the finite element program ANSYS. Using this matrix, small dynamic deformations of the running surface were considered in solving the Reynolds equation for the lubrication wedge. The analysis of the vibration response of this basic hydrodynamic system considering elastic material deformation demonstrated that both static and dynamic components of deflection significantly affect the SDC. These coefficients were also proved to be highly dependent on the stimulation frequency.

Finite Journal Bearing With Nonlinear Stiffness and Damping. Part 1: Improved Mathematical Models

1982 ◽  
Vol 104 (2) ◽  
pp. 397-405 ◽  
Author(s):  
E. Hashish ◽  
T. S. Sankar ◽  
M. O. M. Osman
Keyword(s):  
Mathematical Models ◽  
Reynolds Equation ◽  
Nonlinear Dynamic Analysis ◽  
Upper And Lower Bounds ◽  
Finite Element Program ◽  
Cavitation Phenomenon ◽  
Dynamic Case ◽  
Element Program ◽  
Stiffness And Damping ◽  
Film Profile

Two mathematical models for the nonlinear hydrodynamic film forces in a finite bearing are developed including a practical adaptation of the cavitation phenomenon. Using the linearity of the Reynolds equation for incompressible film, the pressure components are effectively decomposed and the Reynolds equation is rearranged for general solution by a finite element program in which only the L/d ratio and the eccentricity ratio are to be specified. The different possibilities of partial film profile location in a general dynamic case are demonstrated. The two partial film models possess the required accuracy of the finite bearing approach with the simplicity of the known long and short bearing approximations which are shown as the upper and lower bounds for the present case. The finite bearing approach presented are particularly suitable for nonlinear dynamic analysis.

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