Nonlinear Dynamic Analysis and Experiment Verification of Rotor-Ball Bearings-Support-Stator Coupling System for Aeroengine With Rubbing Coupling Faults

2009 ◽  
Vol 132 (2) ◽  
Author(s):  
G. Chen ◽  
C. G. Li ◽  
D. Y. Wang
Keyword(s):  
Nonlinear Dynamic Analysis ◽  
Coupling Model ◽  
Hertzian Contact ◽  
Squeeze Film ◽  
Ball Bearings ◽  
Rotating Speed ◽  
Coupling Faults ◽  
Coupling System ◽  
Experiment Verification ◽  
Effect Of Support

In this paper, a new rotor-ball bearings-support-stator coupling system dynamic model with rubbing coupling faults is established for practical aeroengine. In the model, the rubbing fault is modeled, the stator motion is considered, the flexible support and squeeze film damper are established, and the nonlinear factors of ball bearing, such as the clearance of the bearing, the nonlinear Hertzian contact force between balls and races, and the varying compliance vibration because of the periodical variety of the contact position between balls and races, are modeled. The numerical integral method is used to obtain the system responses, the effect of support stiffness on rotor responses is studied using a vibration amplitude-rotating speed plot, and the characteristics of the rubbing fault is analyzed using a 3D cascade plot. An aeroengine tester with a stator is established to carry out the rubbing fault experiments, the simulation results from the rotor-ball bearings-support-stator coupling model are compared with the experimental results, and the consistency of the results show fully the effectiveness of the new rotor-ball bearings-support-stator coupling model with rubbing fault.

A New Rotor-Ball Bearing-Stator Coupling Dynamics Model for Whole Aero-Engine Vibration

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
G. Chen
Keyword(s):  
Ball Bearing ◽  
Coupling Effect ◽  
Coupling Model ◽  
Hertzian Contact ◽  
Squeeze Film ◽  
Dynamics Model ◽  
New Model ◽  
Engine Vibration ◽  
Coupling System ◽  
Aero Engine

In this paper, a new rotor-ball bearing-stator coupling system dynamics model is established for simulating the practical whole aero-engine vibration. The main characteristics of the new model are as follows: (1) the coupling effect between rotor, ball bearing, and stator is fully considered; (2) the elastic support and the squeeze film damper are considered; (3) the rotor is considered as an Euler free beam of equal-section model, and its vibration is analyzed through truncating limited modes; (4) nonlinear factors of ball bearing such as the clearance of bearing, nonlinear Hertzian contact force, and the varying compliance vibration are modeled; and (5) rubbing fault between rotor and stator is considered. The Zhai method, which is a new explicit fast numerical integration method, is employed to obtain system’s responses, and the whole aero-engine vibration characteristics are studied. Finally, aero-engine tester including casing is established to carry out rubbing fault experiment, the simulation results from rotor-ball bearing-stator coupling model are compared with the experiment results, and the correctness of the new model is verified to some extent.

Nonlinear Dynamic Response Analysis of Rotor-Ball Bearing-Stator Coupling System Including Unbalance-Rubbing Coupling Faults

2007 ◽  
Author(s):  
Guo Chen ◽  
Rong Tao Hou
Keyword(s):  
Ball Bearing ◽  
Dynamic Responses ◽  
Response Analysis ◽  
Nonlinear Dynamic Response ◽  
Rotating Speed ◽  
Coupling Faults ◽  
Mass Unbalance ◽  
Coupling System ◽  
Chaos Motion ◽  
Rotor Mass

In this paper, a new rotor-ball bearing-stator coupling system dynamic model is established. In the model, the rotor mass unbalance and rubbing faults are included, and the nonlinear factors of ball bearing such as the clearance of bearing, nonlinear Hertzian contract force between balls and races, and the varying compliance vibration coming from the periodical variety of contact positions between balls and races are modeled. The numerical integral method is employed to obtain system’s responses, and the vibration amplitude-rotating speed curve, bifurcation plot, phase plane plot, shaft centre orbits, frequency spectrum and Poincare´ map are used to carry out the analysis of bifurcation and chaos motion, and the effects of rotational speed, rubbing stiffness, rotor eccentricity, bearing house-stator stiffness, and stator-foundation stiffness on dynamic responses are analyzed, and the non-linear dynamic characteristics of rotor-ball bearing-stator system under unbalance and rubbing coupling faults are discovered.

Nonlinear Dynamic Analysis of an Asymmetric Ball Bearing Rotor System

2019 ◽  
Author(s):  
Doğancan Bahan ◽  
Ender Ciğeroğlu
Keyword(s):  
Ball Bearing ◽  
Nonlinear Dynamic Analysis ◽  
Harmonic Balance Method ◽  
Beam Theory ◽  
Hertzian Contact ◽  
Radial Clearance ◽  
Ball Bearings ◽  
Algebraic Equations ◽  
Rotor Systems ◽  
Nonlinear Algebraic Equations

Abstract Performance of ball bearing–rotor systems are highly dependent on and often limited by characteristics of ball bearings. Several studies are available in the literature, investigating varying compliance and subharmonic resonances of ball bearings. Most of the studies are carried out with rigid rotors to focus on modelling of the bearings. There exist few studies which take flexibility of rotors into account. Furthermore, even if the rotor flexibility is modelled, most of the time symmetrical rotors are considered. However, rotors are rarely symmetric in realistic applications due to different locations of bearings and different weights of rotor components (compressors, turbines etc.). In this study, an asymmetric, balanced, flexible rotor supported by ball bearings considering Hertzian contact and radial clearance is investigated. Rotor shaft is modelled with Nelson finite rotor elements using Timoshenko beam theory and disks are considered as rigid masses. Harmonic Balance Method (HBM) is used to obtain nonlinear algebraic equations in the frequency domain and Alternating Frequency Time (AFT) method is utilized to find Fourier coefficients of nonlinear bearing forces. In order to decrease the number of nonlinear equations to be solved, Receptance Method (RM) is applied. Resulting set of nonlinear algebraic equations is solved by using Newton’s method with arclength continuation. Several case studies are performed and effects of asymmetry on nonlinear periodic vibration response of rotors are studied.

Vibration Modelling and Verification for Rotor-Support-Casing Coupling System with Misalignment Fault

2019 ◽  
Vol 24 (3) ◽  
pp. 511-519
Author(s):  
Nanfei Wang ◽  
Dongxiang Jiang ◽  
Yizhou Yang
Keyword(s):  
Coupling Model ◽  
Hertzian Contact ◽  
Force Model ◽  
Lumped Mass ◽  
Oil Film ◽  
Coupling System ◽  
Lumped Mass Method ◽  
Unique Nature ◽  
Rotor Support ◽  
Misalignment Fault

Misalignment is one of the common malfunctions that occur in rotating machines. Effects of misalignment on the casing vibration response of a rotor-support-casing (RSC) coupling system is investigated in detail. The model of an RSC coupling system is established using the lumped mass method. The coupling effects between the rotor, support and casing are fully considered. A misalignment model is proposed, and equivalent misalignment force is applied on corresponding lumped mass points. Nonlinear factors of bearing, such as the clearance of bearing, oil film force, nonlinear Hertzian contact force, and the varying compliance vibration are developed. The influences of oil film thickness and bearing size are considered in the nonlinear oil film force model. By using a numerical method, the governing equations of the system are solved to obtain the steady-state vibration. The simulation results from a coupling model are compared with the experimental results and the effectiveness of the new model is verified. It has been found that spectrums and orbit plots are effectively used to reveal the unique nature of misalignment faults, leading to reliable misalignment diagnostic information.

Research on rotating speed of a squeeze-film driven rotor based on near-field acoustic driving

2012 ◽  
Vol 19 (12) ◽  
pp. 1872-1880
Author(s):  
Bing Jia ◽  
Chao Chen ◽  
Chunsheng Zhao
Keyword(s):  
Near Field ◽  
Squeeze Film ◽  
Rotating Speed

Additively Manufactured Compliant Hybrid Gas Thrust Bearing for SCO2 Turbomachinery: Design and Proof of Concept Testing

2021 ◽  
Author(s):  
Bugra Ertas
Keyword(s):  
Thrust Bearing ◽  
Nonlinear Behavior ◽  
Squeeze Film ◽  
Outer Diameter ◽  
Proof Of Concept ◽  
Unit Load ◽  
Rotating Speed ◽  
Load Carrying ◽  
New Type ◽  
Turbomachinery Design

Abstract The following paper presents a new type of gas lubricated thrust bearing fabricated using additive manufacturing or direct metal laser melting (DMLM). The motivation for the new bearing concept is derived from the need for highly efficient supercritical carbon dioxide turbomachinery in the mega-watt power range. The paper provides a review of existing gas thrust bearing technologies, outlines the need for the new DMLM concept, and discusses proof of concept testing results. The new concept combines hydrostatic pressurization with individual flexibly mounted pads using hermetic squeeze film dampers in the bearing-pad support. Proof-of-concept testing in air for a 6.8" (173mm) outer diameter thrust bearing was performed; with loads up to 1,500 lbs (6.67kN) and a rotating speed of 10krpm (91 m/s tip speed). The experiments were performed with a bent shaft resulting in thrust runner axial vibration magnitudes of 2.9mils (74microns) p-p and dynamic thrust loads of 270 lbs (1.2kN) p-p. In addition, force deflection characteristics of the bearing system are presented for an inlet hydrostatic pressure of 380psi (2.62MPa). Results at 10krpm show that the pad support architecture was able to sustain high levels of dynamic misalignment equaling 6 times the nominal film clearance while demonstrating a unit load carrying capacity of 55psi (0.34Mpa). Gas-film force-deflection tests portrayed nonlinear behavior like a hardening spring, while the pad support stiffness was measured to be linear and independent of film thickness.

scholarly journals Extended Hertz Theory of Contact Mechanics for Case-Hardened Steels With Implications for Bearing Fatigue Life

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Nikhil D. Londhe ◽  
Nagaraj K. Arakere ◽  
Ghatu Subhash
Keyword(s):  
Elastic Modulus ◽  
Fatigue Life ◽  
Contact Pressure ◽  
Effective Elastic Modulus ◽  
Hardened Steel ◽  
Hertzian Contact ◽  
Design Parameters ◽  
Case Hardening ◽  
Ball Bearings ◽  
Subsurface Stress

The analytical expressions currently available for Hertzian contact stresses are applicable only for homogeneous materials and not for case-hardened bearing steels, which have inhomogeneous microstructure and graded elastic properties in the subsurface region. Therefore, this article attempts to determine subsurface stress fields in ball bearings for graded materials with different ball and raceway geometries in contact. Finite element models were developed to simulate ball-on-raceway elliptical contact and ball-on-plate axisymmetric contact, to study the effects of elastic modulus variation with depth due to case hardening. Ball bearings with low, moderate, and heavy load conditions are considered. The peak contact pressure for case-hardened steel is always more than that of through-hardened steel under identical geometry and loading conditions. Using equivalent contact pressure approach, effective elastic modulus is determined for case-carburized steels, which will enable the use of Hertz equations for different gradations in elastic modulus of raceway material. Nonlinear regression tools are used to predict effective elastic modulus as a weighted sum of surface and core elastic moduli of raceway material and design parameters of ball–raceway contact area. Mesh convergence study and validation of equivalent contact pressure approach are also provided. Implications of subsurface stress variation due to case hardening on bearing fatigue life are discussed.

Nonlinear Dynamic Analysis and Experimental Verification of an Unbalanced Rotor Supported by Ball Bearings

2011 ◽  
Author(s):  
S. H. Upadhyay ◽  
Satish C. Sharma ◽  
S. P. Harsha
Keyword(s):  
Dynamic Properties ◽  
Nonlinear Dynamic Analysis ◽  
Peak Frequency ◽  
Nonlinear Damping ◽  
Rotor System ◽  
System Stability ◽  
System Response ◽  
Ball Bearings ◽  
Unbalanced Rotor ◽  
Radial Forces

In this paper, a dynamic model is presented for studying the dynamic properties of unbalanced rotor system supported by ball bearings under the effects of radial internal clearance and unbalanced rotor effect. The Newmark-β method is used to solve the nonlinear equations. The dynamics behaviors of a rigid rotor system are studied through frequency responses of the system. Clearances, nonlinear stiffness & nonlinear damping, radial forces and unbalanced forces—all these bring a significant influence to bear on the system stability. The validity of the proposed model verified by comparison of frequency components of the system response with those obtained from experiments. The peak-to-peak frequency response of the system for each speed is obtained.

A numerical train–floating slab track coupling model based on the periodic-Fourier-modal method

2016 ◽  
Vol 232 (1) ◽  
pp. 315-334 ◽  
Author(s):  
Longxiang Ma ◽  
Weining Liu
Keyword(s):  
Numerical Model ◽  
Dynamic Response ◽  
Moving Load ◽  
Coupling Model ◽  
Principle Of Superposition ◽  
Fourier Modal Method ◽  
Slab Track ◽  
Model Based ◽  
Coupling System ◽  
Modal Method

A numerical model based on the periodic-Fourier-modal method is proposed for the dynamic analysis of a train-floating slab track coupling system with random track irregularity. In the model, each vehicle of the train is modeled as a multiple-degree-of-freedom vibration system consisting of one car body, two bogies, four wheelsets, and two groups of spring-damper suspension devices. The floating slab track is modeled as a periodic-infinite structure with discrete supports and discontinuous slabs. Linear springs are used to couple the train and the track. In order to establish this numerical model, an efficient periodic approach named periodic-Fourier-modal method for solving the dynamic response of the floating slab track under a harmonic moving load is first developed. Based on this, a strategy is then proposed which can couple the moving train to the track with random irregularity and express the wheel–rail force as a superposition of a series of harmonic loads. With the solved wheel–rail force, the vehicle response can be directly calculated through vehicle dynamics, while track response can be calculated through the principle of superposition and the reuse of the initially proposed periodic-Fourier-modal method. Using this train–floating slab track coupling model, the solution of the dynamic response of the infinite track can be transformed to perform only within a single periodic range, which can save the calculation time significantly. The numerical results of the Beijing subway, based on the proposed model, are discussed in detail, and some important conclusions are drawn.

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