The Stability Analysis of Hydrodynamic Journal Bearings Allowing for Manufacturing Tolerances. Part I: Effect Analysis of Manufacturing Tolerances by Taguchi Method

2009 ◽  
Author(s):  
Wubin Xu ◽  
Peter J. Ogrodnik ◽  
Mike J. Goodwin ◽  
Gordon A. Bancroft
Keyword(s):  
Stability Analysis ◽  
Taguchi Method ◽  
Journal Bearings ◽  
Effect Analysis ◽  
Manufacturing Tolerances ◽  
The Stability

Non-linear stability analysis of micropolar fluid lubricated journal bearings with turbulent effect

2019 ◽  
Vol 71 (1) ◽  
pp. 31-39
Author(s):  
Subrata Das ◽  
Sisir Kumar Guha
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Micropolar Fluid ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Turbulent Regime ◽  
Content Type ◽  
Non Linear ◽  
The Stability ◽  
Bearing System

Purpose The purpose of this paper is to investigate the effect of turbulence on the stability characteristics of finite hydrodynamic journal bearing lubricated with micropolar fluid. Design/methodology/approach The non-dimensional transient Reynolds equation has been solved to obtain the non-dimensional pressure field which in turn used to obtain the load carrying capacity of the bearing. The second-order equations of motion applicable for journal bearing system have been solved using fourth-order Runge–Kutta method to obtain the stability characteristics. Findings It has been observed that turbulence has adverse effect on stability and the whirl ratio at laminar flow condition has the lowest value. Practical implications The paper provides the stability characteristics of the finite journal bearing lubricated with micropolar fluid operating in turbulent regime which is very common in practical applications. Originality/value Non-linear stability analysis of micropolar fluid lubricated journal bearing operating in turbulent regime has not been reported in literatures so far. This paper is an effort to address the problem of non-linear stability of journal bearings under micropolar lubrication with turbulent effect. The results obtained provide useful information for designing the journal bearing system for high speed applications.

Non-Linear Transient Stability Analysis of a Rigid Rotor Supported on Journal Bearings With Rectangular Dimples

2015 ◽  
Author(s):  
Ram Turaga
Keyword(s):  
Stability Analysis ◽  
Surface Texture ◽  
Transient Stability ◽  
Equations Of Motion ◽  
Journal Bearings ◽  
Pressure Curve ◽  
Rigid Rotor ◽  
Non Linear ◽  
The Stability ◽  
Transient Stability Analysis

The influence of deterministic surface texture on the sub-synchronous whirl stability of a rigid rotor has been studied. Non-linear transient stability analysis has been performed to study the stability of a rigid rotor supported on two symmetric journal bearings with a rectangular dimple of large aspect ratio. The surface texture parameters considered are dimple depth to minimum film thickness ratio and the location of the dimple on the bearing surface. Journal bearings of different Length to diameter ratios have been studied. The governing Reynolds equation for finite journal bearings with incompressible fluid has been solved using the Finite Element Method under isothermal conditions. The trajectories of the journal center have been obtained by solving the equations of motion of the journal center by the fourth-order Runge-Kutta method. When the dimple is located in the raising part of the pressure curve the positive rectangular dimple is seen to decrease the stability whereas the negative rectangular dimple is seen to improve the stability of the rigid rotor.

Nonlinear Simulation Analysis and Experiment of Fluid Plain Journal Bearing With Incompressible Fluid

2003 ◽  
Author(s):  
Katsuhisa Fujita ◽  
Atsuhiko Shintani ◽  
Koji Yoshioka ◽  
Kouhei Okuno ◽  
Hiroaki Tanaka ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Incompressible Fluid ◽  
Journal Bearing ◽  
Simulation Analysis ◽  
Journal Bearings ◽  
Stable Region ◽  
Flexible Rotor ◽  
Nonlinear Simulation ◽  
Fluid Forces ◽  
The Stability

Recently, in many areas such as computers and information equipments etc., the fluid journal bearings are required to rotate at higher speed. To satisfy this requirement, the strictly stability analysis of the journal is indispensable. In this paper, we investigate the stability analysis of the dynamic behavior of the fluid plain journal bearing with an incompressible fluid considering the nonlinear terms of fluid forces. The stability analysis is examined by the numerical simulations on each model of a rigid rotor and a flexible rotor. The stable regions by nonlinear analysis are compared with the regions by classical linear analysis. Performing the nonlinear simulation analysis, it becomes clear that there is rather a stable region which amplitude does not grow up abruptly, and this phenomenon can not only be pointed out, but also is judged to be unstable by linear stable analysis. Finally, the experiment using actual bearings is performed and compared with the numerical results.

Comparison of Effects of Dimensional Manufacturing Tolerances and Journal Out-of-Roundness on Stability of Hydrodynamic Journal Bearing System

2011 ◽  
Vol 121-126 ◽  
pp. 1966-1971
Author(s):  
Wu Bin Xu ◽  
De Jian Zhou ◽  
Peter Ogrodnik ◽  
Mike Goodwin
Keyword(s):  
Theoretical Analysis ◽  
Taguchi Method ◽  
Journal Bearing ◽  
Journal Bearings ◽  
System Stability ◽  
Design Stage ◽  
Analysis Method ◽  
Manufacturing Tolerances ◽  
Hydrodynamic Journal Bearing ◽  
Bearing System

The manufacturing tolerances of a hydrodynamic journal bearing system are inevitable in manufacturing process. To examine and understand the effect of manufacturing tolerances on the system stability can help engineers to confidently choose reasonable tolerances at design stage. This study presented a theoretical analysis method to determine and compare the effects of dimensional manufacturing tolerances and journal out-of-roundness on system stability by Taguchi method. The results show that the journal out-of-roundness has the most significant effect on the system stability and the journal out-of-roundness appears to stabilize the system. The authors suggest that both dimensional manufacturing tolerances and journal roundness should be taken into account in the design of cylindrical journal bearings.

Stability Analysis of a Complex Geared Rotor-Bearing System in a Turbine Reduction Gearbox

2013 ◽  
Author(s):  
Yuanhong Guan ◽  
Edward W. Sieveking ◽  
Varad Sampathkumar
Keyword(s):  
Stability Analysis ◽  
High Speed ◽  
Low Frequency ◽  
Stability Margin ◽  
Journal Bearings ◽  
Root Cause ◽  
Rotor Bearing ◽  
Noise Vibration ◽  
The Stability ◽  
Load Conditions

It is well known that the rotor system will meet several critical speeds or unstable regions as its rotation speed increases, especially when the rotor system is supported by journal bearings, since there exists a strong fluid-structure coupling which is rather prone to stability issues. Stability analysis of rotor-bearing systems (such as turbine-compressor) has been extensively studied in the literatures over the past 50 years. However, few studies have been performed on geared rotor-bearing systems, especially for complex multi-stage gear train systems. In this paper, the abnormal noise/vibration problem on a high speed 2 stage epicyclic reduction gearbox of a turbine-generator system is studied. This gearbox showed abnormal low frequency vibrations at low speed cranking and high speed partial load conditions. Further detailed probe testing showed that the gear bodies which were supported by 6 journal bearings had quite large sub-synchronized vibrations and shaft whirls were developed when the abnormal noise was present. In order to better understand the root cause and to fully eliminate such low frequency noise/vibration, a detailed finite element model for the whole turbine-gearbox-generator was developed under different speed / load conditions. The linearized journal bearing stiffness and damping matrix were calculated using a separate tool and then plugged into the above FE model. The gears are modeled as rigid bodies and connected by gear mesh stiffness. Gyroscopic force terms have also been included in the model. The stability of the whole system was evaluated by a complex eigenvalue analysis and the stability margin evaluated by the corresponding damping factor (or log decrement). The model predicts a range of instability regions and has good correlation with testing data. The root cause of this abnormal noise/vibration is due to the strong torsional-lateral coupling of gear systems, and further coupling with the fluid dynamics of the journal bearings under certain speed/load conditions. Some sensitivity studies are also performed in order to increase the stability margin and eliminate the sub-synchronized vibrations.

scholarly journals Stability analysis of long hydrodynamic journal bearings based on the journal center trajectory

Friction ◽  
2020 ◽  
Author(s):  
Yu Huang ◽  
Haiyin Cao ◽  
Zhuxin Tian
Keyword(s):  
Stability Analysis ◽  
Equilibrium Point ◽  
Journal Bearing ◽  
Stability Boundary ◽  
Initial Point ◽  
Journal Bearings ◽  
Bearing Surface ◽  
Rotating Speed ◽  
Stability Threshold ◽  
The Stability

AbstractIn this study, we observe that there are two threshold speeds (stability threshold speed and second threshold speed) for the long journal bearing, which is different for the short bearing. When the rotating speed is below the stability threshold speed, the stability boundary nearly coincides with the clearance circle, and the journal center gradually returns to the equilibrium point after being released at an initial point. If the rotating speed is between the stability threshold speed and the second threshold speed, after being released at an initial point, the journal center converges to a contour containing the equilibrium point. In this situation, for a higher rotating speed, the corresponding contour is also larger. When the rotating speed exceeds the second threshold speed, the journal gradually moves towards the bearing surface after being released at an initial point.

scholarly journals Analisis Stabilitas Lereng Dengan Perkuatan Geotekstil Woven Akibat Pengaruh Termal Menggunakan Metode Elemen Hingga. (Hal. 61-72)

2019 ◽  
Vol 5 (2) ◽  
pp. 61
Author(s):  
Imron Maulana Fauzi ◽  
Indra Noer Hamdhan
Keyword(s):  
Thermal Expansion ◽  
Stability Analysis ◽  
Slope Stability ◽  
Thermal Effect ◽  
Thermal Capacity ◽  
Soil Reinforcement ◽  
Effect Analysis ◽  
Soil Parameter ◽  
Embankment Slope ◽  
The Stability

ABSTRAKAda beberapa jenis perkuatan tanah untuk mengantisipasi longsoran yang sering digunakan di Indonesia seperti halnya geotekstil. Analisis stabilitas dilakukan pada lereng timbunan dengan kemiringan 1V:1H, 1V:1,5H dan 1V:2H dengan membandingkan kondisi lereng timbunan tanpa perkuatan geotekstil, lereng timbunan dengan perkuatan geotekstil serta lereng timbunan dengan perkuatan geotekstil yang dipengaruhi oleh termal menggunakan software PLAXIS 2D 2017. Analisis pengaruh termal dilakukan dengan memvariasikan besaran nilai suhu dan parameter termal tanah (kapasitas, konduktivitas dan ekspansi). Terjadi penurunan stabilitas lereng timbunan dengan perkuatan geotekstil yang diakibatkan oleh semakin besarnya nilai suhu termal dan terjadi peningkatan stabilitas lereng dengan perkuatan geotekstil akibat meningkatnya nilai ekspansi termal, sedangkan nilai konduktivitas dan kapasitas termal tidak berpengaruh.   Kata kunci: lereng timbunan, geotekstil, stabilitas, suhu, parameter termal tanah. ABSTRACTThere are several types of soil reinforcement to anticipate landslide that are often used in Indonesia as well as geotextile. The stability analysis is carried out on the slope of the embankment with a slope of 1V:1H, 1V:1,5H and 1V:2H by comparing the slope conditions of the embankment without geotextile reinforcement, slope of embankment with geotextile reinforcement and slope of embankment with geotextile reinforcement that influenced by thermal using PLAXIS 2D 2017. The thermal effect analysis is carried out by varying the value of temperature and soil thermal parameters (capacity, conductivity and expansion). There is a decrease in the stability of the embankment slopes with geotextile reinforcement caused by the increasing thermal temperature value and an increase in slope stability with geotextile reinforcement due to the increase of thermal expansion value, while the conductivity and thermal capacity have no effect.Keywords:  embankment slope, geotextile, stability, temperature, thermal soil parameter.

Stability Analysis of the Nanjung Water Diversion Twin Tunnels based on Convergence Measurement

2019 ◽  
Vol 1 (1) ◽  
pp. 49-60
Author(s):  
Simon Heru Prassetyo ◽  
Ganda Marihot Simangunsong ◽  
Ridho Kresna Wattimena ◽  
Made Astawa Rai ◽  
Irwandy Arif ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Convergence Rate ◽  
Critical Strain ◽  
Convergence Rates ◽  
Strain Analysis ◽  
Water Diversion ◽  
Tunnel Face ◽  
Tunnel Stability ◽  
The Stability ◽  
Twin Tunnels

This paper focuses on the stability analysis of the Nanjung Water Diversion Twin Tunnels using convergence measurement. The Nanjung Tunnel is horseshoe-shaped in cross-section, 10.2 m x 9.2 m in dimension, and 230 m in length. The location of the tunnel is in Curug Jompong, Margaasih Subdistrict, Bandung. Convergence monitoring was done for 144 days between February 18 and July 11, 2019. The results of the convergence measurement were recorded and plotted into the curves of convergence vs. day and convergence vs. distance from tunnel face. From these plots, the continuity of the convergence and the convergence rate in the tunnel roof and wall were then analyzed. The convergence rates from each tunnel were also compared to empirical values to determine the level of tunnel stability. In general, the trend of convergence rate shows that the Nanjung Tunnel is stable without any indication of instability. Although there was a spike in the convergence rate at several STA in the measured span, that spike was not replicated by the convergence rate in the other measured spans and it was not continuous. The stability of the Nanjung Tunnel is also confirmed from the critical strain analysis, in which most of the STA measured have strain magnitudes located below the critical strain line and are less than 1%.

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