scholarly journals Investigation on the dynamic behaviors of a rod fastening rotor based on an analytical solution of the oil film force of the supporting bearing

2020 ◽  
pp. 146134842091285
Author(s):  
Di Hei ◽  
Meiru Zheng
Keyword(s):  
Analytical Solution ◽  
Contact Stiffness ◽  
Small Error ◽  
Motion Equation ◽  
Liouville Theory ◽  
Dynamic Behaviors ◽  
Oil Film ◽  
Period 2 ◽  
Bearing Stiffness ◽  
Rod Fastening Rotor

The dynamic characteristics of rod fastening rotor supported by a finite journal bearing are investigated in this study. To model the dynamic behaviors of the bearing-rotor system, the oil film force of bearing is calculated by approximately solving the Reynolds equation with the variables separation method and Sturm–Liouville theory, and then a motion equation is developed with consideration of the contact and gyro effects of the disks of the rotor. To solve the motion equation with small error and excellent stability, an improved Newmark method is proposed. On this basis, the dynamics characteristics of the rod fastening rotor are analyzed for different rotor speeds, disk eccentricities, shaft bearing stiffness, and contact stiffness. And the orbits of the rod fastening rotor and integral rotor are compared. The numerical results indicate that the analytical solution of the oil film force has higher computational efficiency than the finite difference method. The rod fastening rotor shows higher stability than the integral rotor, and exhibits rich dynamic behaviors, such as periodic, qusi-periodic, period-2, period-4, and period-6.

Study on bearing stiffness characteristics with residual stress in carburized layer

2020 ◽  
pp. 095440622096079
Author(s):  
Junshuai Liang ◽  
Ning Li ◽  
Jingyu Zhai ◽  
BaoGang Wen ◽  
Qingkai Han ◽  
...  
Keyword(s):  
Residual Stress ◽  
Contact Stiffness ◽  
Roller Bearing ◽  
High Load ◽  
Axial Stiffness ◽  
Fe Model ◽  
Low Load ◽  
Bearing Stiffness ◽  
Carburized Layer ◽  
Stiffness Characteristics

In this study, a layering method of carburized ring is presented. A finite element (FE) model for analyzing bearing stiffness characteristics is established considering the residual stress in the carburized layer. The residual stress in the carburized layer of a double-row conical roller bearing is tested and the influence of the distribution of residual stress in carburized layer on the bearing stiffness is investigated. Results show that the residual stress in the carburized layer increases the contact stiffness of the bearing by 5% in the low-load zone and 3% in the high-load zone. The radial stiffness of the bearing is increased by 5% in the low-load zone and 3% in the high-load zone. The axial stiffness is increased by 6%, and the angular stiffness increased by 4%. The larger the thickness of the carburized layer, the greater the residual compressive stress in the carburized layer, the deeper the position of the maximum residual stresses in the carburized layer will lead to the greater stiffness of the bearing.

Analysis of Bouncing Vibrations of a 2-DOF Tripad Contact Slider Model With Air Bearing Pads Over a Harmonic Wavy Disk Surface

1999 ◽  
Vol 121 (4) ◽  
pp. 939-947 ◽  
Author(s):  
Kyosuke Ono ◽  
Kan Takahashi
Keyword(s):  
Contact Stiffness ◽  
Disk Surface ◽  
Design Parameters ◽  
Air Bearing ◽  
Static Contact ◽  
Tracking Ability ◽  
The Coefficient Of Friction ◽  
Bearing Stiffness ◽  
Perfect Contact ◽  
Contact Slider

In this study, the authors numerically analyzed the bouncing vibrations of a two-degree-of-freedom (2-DOF) model of a tripad contact slider with air bearing pads over a harmonic wavy disk surface. The general features of bouncing vibrations were elucidated in regard to the modal characteristics of a 2-DOF vibration system and design parameters such as contact stiffness, contact damping, air hearing stiffness, the rear to front air bearing stiffness ratio, static contact force and the coefficient of friction. The design of a contact slider was discussed in terms of tracking ability and wear durability. In addition, two sample designs of a perfect contact slider with sufficient wear durability were also presented.

Load Influence on Hydrostatic Oil Film Journal Bearing Stiffness Characteristics

2021 ◽  
Author(s):  
Leonid Moroz ◽  
Leonid Romanenko ◽  
Roman Kochurov ◽  
Evgen Kashtanov
Keyword(s):  
Journal Bearing ◽  
Oil Film ◽  
Bearing Stiffness ◽  
Stiffness Characteristics

Dynamic Analysis and Optimization on Assembly Parameters of Rod Fastening Rotor System With Manufacturing Tolerances

2019 ◽  
Author(s):  
Bingxi Zhao ◽  
Qi Yuan ◽  
Pu Li
Keyword(s):  
Contact Pressure ◽  
Timoshenko Beam ◽  
Contact Stiffness ◽  
Beam Element ◽  
Normal Contact ◽  
Tightening Force ◽  
Mass Imbalance ◽  
Rod Fastening Rotor ◽  
Bearing System ◽  
Timoshenko Beam Element

Abstract Rod fastening rotor (RFR), as a typical rotor structure of gas turbine which is different from the integral rotor, is comprised of a set of discs clamped together by a central tie rod or several tie rods on the pitch circle diameters. In process of machining, tolerances of the disc are inevitable, of which the parallelism error and mass imbalance are focused on in this paper. Firstly, the complex bending of RFR by accumulation of parallelism errors of discs is derived through the coordinate transmission. Then the static analysis of RFR is performed to obtain the additional pressure by the effect of unbalanced forces, which is related to the assembly angles and rotating speed, on contact surfaces using a linear hypothesis, based on which the distribution of contact pressure considering the original pre-tightening force is obtained. Then the Bifractal-Regular theory is adopted to acquire the micro-topography of the contact interface and derive the contact stiffness related to normal contact pressure, fractal upper length limit and regular shape of the contact interfaces. After that, the zero thickness element is introduced to obtain the equivalent stiffness matrices of the contact surface. In addition, the circumferential uniformly distributed rods are modeled as a spring element which provides additional bending stiffness for the RFR. Based on the analysis above, the dynamic model of the RFR-bearing system containing 10 discs is established using the Timoshenko beam element where the continuous part of the shaft is modeled by Timoshenko beam element considering shear effect. Finally, the multi-optimization is carried out on the vibration response by the coupled effects of both initial bending and mass imbalance of the RFR-bearing system through which the optimal assembly angles are obtained. The results show a good performance in decreasing vibration as well as bending of the RFR system.

Improved Analysis of Unstable Bouncing Vibration and Stabilizing Design of Flying Slider in Near-Contact Regime

2005 ◽  
Author(s):  
Kyosuke Ono ◽  
Masami Yamane
Keyword(s):  
Parametric Study ◽  
Adhesion Force ◽  
Design Method ◽  
Contact Stiffness ◽  
Frictional Coefficient ◽  
Disk Surface ◽  
The Self ◽  
Air Bearing ◽  
Excited Vibration ◽  
Bearing Stiffness

We proposed a design method of a flying head slider that can suppress the bouncing vibration in a near-contact regime, based on parametric study using an improved slider and contact models. At first, we numerically calculated the characteristics of contact force and adhesive force between air bearing pad and disk surface under the current small roughness conditions and found that the contact characteristics can be modeled by constant contact stiffness, a constant adhesion force and the separations of beginning and end of contact. Next we numerically computed the slider dynamics of a 2-DOF slider model by using these contact characteristics and nonlinear air-bearing stiffness. As a result, we could get the self-excited bouncing vibration whose general characteristics are more similar to the experimented results compared to our previous study. Parametric study shows that the frictional coefficient, attractive force and contact stiffness should be decreased and front and rear air-bearing stiffness and ratio of rear to front air-bearing stiffness should be increased in order to realize a stable flying slider in a smallest possible spacing. Moreover, we elucidated the effect of micro-waviness on the self-excited vibration of the slider.

The Effects of Bearing Stiffness on Nonlinear Dynamic Behaviors of Multi-Mesh Gear Train

2012 ◽  
Author(s):  
T. N. Shiau ◽  
T. H. Young ◽  
J. R. Chang ◽  
K. H. Huang ◽  
C. R. Wang
Keyword(s):  
Chaotic Motion ◽  
Nonlinear Dynamic ◽  
Equations Of Motion ◽  
Nonlinear Dynamic Analysis ◽  
Gear Train ◽  
Time Varying ◽  
Kutta Method ◽  
Dynamic Behaviors ◽  
Runge Kutta Method ◽  
Bearing Stiffness

In this study, the nonlinear dynamic analysis of the multi-mesh gear train with elastic bearing effect is investigated. The gear system includes the three rigid shafts, two gear pairs and elastic bearings. The stiffness and damper coefficient of elastic bearing are considered. The equations of motion of nonlinear time-varying system are derived using Lagrangian approach. The Runge-Kutta Method is employed to determine the system dynamic behaviors including the bifurcation and chaotic motion. The results show that the periodic motion, quasi-periodical motion and chaos can be excited with the elastic bearing effect. Especially, the results also indicate the dynamic response will go from periodic to quasi-periodical before the chaotic motion when the bearing stiffness is increased.

Influence of lubrication starvation and surface waviness on the oil film stiffness of elastohydrodynamic lubrication line contact

2016 ◽  
Vol 24 (5) ◽  
pp. 924-936 ◽  
Author(s):  
Yuanyuan Zhang ◽  
Huaiju Liu ◽  
Caichao Zhu ◽  
Chaosheng Song ◽  
Zufeng Li
Keyword(s):  
Film Thickness ◽  
Contact Stiffness ◽  
Elastohydrodynamic Lubrication ◽  
Force Balance ◽  
Line Contact ◽  
Surface Waviness ◽  
Regular Surface ◽  
Normal Contact ◽  
Oil Film ◽  
Film Stiffness

Stiffness properties of interfacial engineering surfaces are of great importance to the dynamic performance of relevant mechanical systems. Normal contact stiffness and oil film stiffness of line contact problems are studied in this work analytically and numerically. The Hertzian contact theory and the Yang–Sun method are applied to predict the contact stiffness, while the empirical elastohydrodynamic lubrication (EHL) film thickness method and the complete numerical EHL model are used to predict the oil film stiffness. The numerical model mainly consists of the Reynolds equation; the film thickness equation, in which the regular surface roughness is taken into consideration; the force balance equation; and the viscosity-pressure equation. The effects of the normal load, rolling speed, regular surface waviness, and starved lubrication level on the oil film stiffness are investigated.

Coupling Effect of Flexible Geared Rotor on Quick Return Mechanism

2005 ◽  
Author(s):  
J. R. Chang ◽  
W. C. Hsu
Keyword(s):  
Integration Method ◽  
Coupling Effect ◽  
Three Dimensional ◽  
Coupled System ◽  
System Model ◽  
Parameter Study ◽  
Dynamic Behaviors ◽  
Gear Mesh ◽  
Bearing Stiffness ◽  
Stiffness And Damping

Regarding the quick return mechanism, some researchers have neglected the rotor-mechanism coupling effect, and other researchers have combined the quick return mechanism with the motor but only considered the rotational motion of the rotor by assuming the rotor to be rigid and neglected the gear mesh dynamics. In the study, the rotor-mechanism coupling effect is investigated to find that the dynamic behaviors of the coupled system are different from those uncoupled systems. The coupling effect is mainly due to the flexibility of the shaft, the bearing, and the gear mesh. When the quick return mechanism is driven with the flexible geared rotor, the vibrations of the geared rotor have significant influences on the dynamic behaviors of the quick return mechanism. The traditional studies formulated the quick return mechanism only under the consideration of planar motion. However, the three dimensional vibration has to be considered for establishing the physical model of the coupled system. The main objective of this study is focused on the investigation of the coupling effect of the geared rotor on the quick return mechanism. The system model is formulated by using finite element method and following Hamiltonian approach. The numerical integration method is applied to obtain the dynamic response. The coupling effect of the geared rotor on the quick return mechanism is discussed by the parameter study. It is shown that the bearing stiffness and damping and the shaft radius have significant influences on the dynamic behavior of the mechanism.

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