Study On the Bistable Vibration Behaviour of a Rod Fastened Rotor-Bearing System

2021 ◽  
Author(s):  
Jiaqi Li ◽  
YANG Zhongyu ◽  
REN Qingzhao ◽  
MO Guyun ◽  
ZHONG Wenyuan ◽  
...  
Keyword(s):  
Test Bench ◽  
Dynamic Behaviour ◽  
Lagrange Equation ◽  
Phase Spectrum ◽  
Contact Interface ◽  
Transient Responses ◽  
Rotor Bearing ◽  
Acceleration And Deceleration ◽  
Bearing System ◽  
Eccentric Distance

Abstract Based on the Lagrange equation, the motion equation of a rod fastened rotor-bearing system considering the damping of the contact interface is established. The numerical method is employed for numerical analysis. The bifurcation diagram, time series, frequency waveform, phase spectrum and Poincare map are used to illustrate the nonlinear dynamic behaviour. The transient responses during acceleration and deceleration are calculated to reveal the dynamic behaviour of the system. The numerical results hold that since the oil film is nonlinear, the system presents obvious bistable behaviour and a jumping phenomenon. In addition, a test bench of the rod fastened rotor-bearing system is built. The bistable behaviour and jumping phenomenon are experimentally proven, and the effect of the eccentric distance of the rotor on the bistable behaviour is experimentally explored. The results of this paper can be used for the basic design and fault diagnosis of rod fastened rotors.

Dynamic Characteristics of a Squeeze Film Damped Rotor System Considering Instantaneous Static Eccentricity in Maneuvering Flight

2020 ◽  
Author(s):  
Xi Chen ◽  
Xiaohua Gan ◽  
Shuyun Jiang ◽  
Guangming Ren
Keyword(s):  
Rotor System ◽  
Elastic Support ◽  
Squeeze Film ◽  
Forward Speed ◽  
Transient Responses ◽  
Transient Characteristics ◽  
Maneuvering Flight ◽  
Rotor Bearing ◽  
Static Eccentricity ◽  
Bearing System

Abstract An on-board rotor-bearing system operating at high speed is inevitably subjected to additional inertial forces and parametric excitations caused by aircraft maneuvering flights. The differential equations of motion for a squeeze film damped rotor system moving with the aircraft during maneuvering flight are derived based on Lagrange’s principle. Transient characteristics of the rotor system considering instantaneous static eccentricity of journal in turning maneuver are calculated by Newmark-HHT integration method. The effects of forward speed, radius of curvature, and elastic support stiffness on transient responses are discussed subsequently. The results indicate that when the aircraft conducts a maneuvering flight, the whirl orbit of journal deviates from the center of the damper, and the deviation direction is determined by the centrifugal acceleration of aircraft and the additional gyroscopic moment. The journal performs a nonsynchronous whirl around the instantaneous static eccentricity. Its magnitude is related to the additional maneuvering loads and the stiffness of elastic support. Increasing forward speed or decreasing maneuvering radius, the rotor vibration will enter earlier into or withdraw later from the relatively large eccentric condition. The stiffness of elastic support has a great impact on transient characteristics of rotor-bearing system during maneuvering flight. Overall, using finite element modeling combined with mechanism analysis, a flexible and efficient approach is proposed to predict transient responses of engine rotor systems during aircraft maneuvering flights.

Dynamic Behaviors of a Rotor-Bearing System under Base-Transferred Shock Excitations Considering Journal-Bearing Clearance

2010 ◽  
Vol 29-32 ◽  
pp. 703-708 ◽  
Author(s):  
Shao Hua He ◽  
Ping Hao Zhang ◽  
Xin Yue Wu
Keyword(s):  
Journal Bearing ◽  
Inhibitory Effect ◽  
Time Varying ◽  
Transient Responses ◽  
Oil Film ◽  
The Past ◽  
Bearing Clearance ◽  
Rotor Bearing ◽  
Residual Response ◽  
Bearing System

The past researches on the transient responses of rotor-bearing systems under shock excitations paid little attention on impact-contact-rub forces which would arise when taking journal- bearing clearance into account, and these forces’ influences on the overall responses remain unknown until now. In this paper, models of impact-contact force, rub force and oil-film force in a rotor-bearing system were built respectively. Numerical calculation was performed to obtain time-varying responses of those forces while the system suffers base-transferred shock excitations. Influences of those forces on system overall responses were investigated. The main conclusion is that the rub force has no obvious influence on the system responses during shock lasting time, whereas it shows an obvious inhibitory effect on the residual response, making time-varying amplitudes be smoother. Rub force maybe bigger in x direction than in y direction although shock energy in x direction is less than in the y direction. Influences of the oil-film force on response is similar to that of rub force but more severely. It has obvious influences on overall responses both during shock lasting time and residual time.

An FE Transient Response Analysis Model of a Flexible Rotor-Bearing System With Mount System to Base Shock Excitation

2007 ◽  
Author(s):  
An Sung Lee ◽  
Byung Ok Kim
Keyword(s):  
Transient Response ◽  
Transportation Systems ◽  
Integration Scheme ◽  
Response Analysis ◽  
Flexible Rotor ◽  
Analysis Model ◽  
Transient Responses ◽  
Transient Response Analysis ◽  
Rotor Bearing ◽  
Bearing System

Turbomachinery such as turbines, pumps and compressors, which are installed in transportation systems such as warships, submarines and space vehicles, etc., often perform crucial missions and are exposed to potential dangerous impact environments such as base-transferred shock forces. To protect turbomachinery from excessive shock forces, it may be needed to accurately analyze transient responses of rotors, considering the dynamics of mount designs to be applied with. In this study a generalized FE transient response analysis model, introducing relative displacements, is firstly proposed to accurately predict transient responses of a flexible rotor-bearing system with mount systems to base-transferred shock forces. In the transient analyses the state-space Newmark method of a direct time integration scheme is utilized, which is based on the average velocity concept. Results show that for the identical mount systems considered, the proposed FE-based detailed flexible rotor model yields more reduced transient vibration responses to the same shocks than a conventional simple model or a Jeffcott rotor. Hence, in order to design a rotor-bearing system with a more compact light-weighted mount system, preparing against any potential excessive shock, the proposed FE transient response analysis model herein is recommended.

Analysis of dynamic behaviour of rotor-bearing system

2013 ◽  
Vol 228 (12) ◽  
pp. 2141-2161 ◽  
Author(s):  
Janko D Jovanović ◽  
Radoslav N Tomović
Keyword(s):  
Mathematical Model ◽  
Dynamic Behaviour ◽  
Direct Determination ◽  
Rolling Bearing ◽  
Plane Motion ◽  
Radial Clearance ◽  
Largest Lyapunov Exponent ◽  
Non Linear ◽  
Rotor Bearing ◽  
Bearing System

This paper deals with a non-linear mathematical model for simulation and analysis of a dynamic behaviour of a rotor-bearing system. The model is used for the simulation of plane motion of a centre of rotor’s cross-section which makes the model convenient for the analysis of vibrations generated in a rolling bearing as well as for the analysis of accuracy of the revolution of rotor supported on a rolling bearing. The model takes into account the following quantities: internal radial clearance, external radial load and unbalanced load. Differential equations of a motion are derived using Lagrange’s equations. The contacts between the balls and the rings are considered to be non-linear with a stiffness derived by the Hertzian theory of an elastic contact. The proposed model enables direct determination of local contact deformations which significantly reduces needed computations and CPU time. The results obtained by the model are used to reconstruct phase-space trajectories and Poincaré maps and to calculate the largest Lyapunov exponent in order to establish the stability of rotor-bearing system motion. A computer program is developed based on the mathematical model for the simulation and analysis of a dynamic behaviour of a rotor-bearing system.

Analysis of faults in rotor-bearing system using three-level full factorial design and response surface methodology

2021 ◽  
pp. 095745652110307
Author(s):  
Hara P Mishra ◽  
Arun Jalan
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Fault Analysis ◽  
Vibration Response ◽  
Effect Analysis ◽  
Outer Race ◽  
Surface Plot ◽  
Rotor Bearing ◽  
Full Factorial ◽  
Bearing System

This article presents the experimental and statistical methodology for localized fault analysis in the rotor-bearing system. These defects on outer race, on inner race, and on a combination of ball and outer race are considered. In this study speed, load and defects were considered as the essential process variables to understand their significance and effects on vibration response for the rotor-bearing system. Three factors at three levels were considered for experimentation, and the experiment was designed for L27 based on design of experiments (DOE) methodology. From the experiments, the vibration response results are recorded in terms of root mean square value for the analysis. Response surface methodology (RSM) is used for identifying the interaction effect of varying process parameters upon the response of vibrations by response surface plot. The rotor-bearing test setup is used for experimentation and is analyzed by using DOE. This study establishes the prediction of fault in the rotor-bearing system in combined parametric effect analysis and its influence with DOE and RSM.

Natural frequency analysis of a functionally graded rotor-bearing system with a slant crack subjected to thermal gradients

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Arnab Bose ◽  
Prabhakar Sathujoda ◽  
Giacomo Canale
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Power Law ◽  
Beam Theory ◽  
Functionally Graded ◽  
Thermal Gradients ◽  
Element Analysis ◽  
Rotor Bearing ◽  
Natural Frequency Analysis ◽  
Bearing System

Abstract The present work aims to analyze the natural and whirl frequencies of a slant-cracked functionally graded rotor-bearing system using finite element analysis for the flexural vibrations. The functionally graded shaft is modelled using two nodded beam elements formulated using the Timoshenko beam theory. The flexibility matrix of a slant-cracked functionally graded shaft element has been derived using fracture mechanics concepts, which is further used to develop the stiffness matrix of a cracked element. Material properties are temperature and position-dependent and graded in a radial direction following power-law gradation. A Python code has been developed to carry out the complete finite element analysis to determine the Eigenvalues and Eigenvectors of a slant-cracked rotor subjected to different thermal gradients. The analysis investigates and further reveals significant effect of the power-law index and thermal gradients on the local flexibility coefficients of slant-cracked element and whirl natural frequencies of the cracked functionally graded rotor system.

Stability of periodic motion on the rotor-bearing system with coupling faults of crack and rub-impact

2007 ◽  
Vol 21 (6) ◽  
pp. 860-864 ◽  
Author(s):  
Yue-Gang Luo ◽  
Zhao-Hui Ren ◽  
Hui Ma ◽  
Tao Yu ◽  
Bang-chun Wen
Keyword(s):  
Periodic Motion ◽  
Coupling Faults ◽  
Rotor Bearing ◽  
Bearing System
Sign in / Sign up

Export Citation Format

Share Document