STUDY ON NONLINEAR DYNAMIC CHARACTERISTICS OF A GEARED ROTOR BEARING SYSTEM

The nonlinear dynamic characteristics of three-dimensional rod-fastening rotor bearing system are investigated in this paper. The rod-fastening rotor includes discontinuous shaft, rotating disks, circumferentially distributed rods, and macrointerfaces between disks. The first three parts are discretized by three dimensional elements, and the macrointerfaces are connected by some springs whose stiffness is determined by a proposed linear partition method. For comparison, the three-dimensional dynamic model of a corresponding complete rotor bearing system is also built. After the rod-fastening and complete rotor bearing system are reduced by a component mode synthesis, periodic motions and stability margins are calculated by using the shooting method and path-following technique, and the local stability of system is obtained by using the Floquet theory. Comparative results show the both systems have a resemblance in the bifurcation features when mass eccentricity and rotating speed are changed. The vibration response has the identical frequency components when typical bifurcations occur. The dynamic stress is obtained by regarding the displacements of all nodes as load. Moreover, the unbalanced and insufficient of the pre-tightening forces lead to obvious disadvantageous influence on the stability and vibration of the both systems. Generally, this paper considers the interfacial effect of the rod-fastening rotor bearing system and the relative nonlinear dynamic features are obtained.

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Nonlinear dynamic characteristics of marine rotor-bearing system under coupled heave and pitch ship motions

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406220977566 ◽

2020 ◽

pp. 095440622097756

Author(s):

Wenzhuo Zhang ◽

Ming Li

Keyword(s):

Dynamic Characteristics ◽

Nonlinear Dynamic ◽

Ship Motions ◽

Analytical Mechanics ◽

Periodic State ◽

Head Waves ◽

Nonlinear Dynamic Characteristics ◽

Rotor Bearing ◽

The Stability ◽

Bearing System

The coupled heave and pitch motions of a ship sailing in head waves affect the stability of the marine rotor-bearing system. Based on the theory of analytical mechanics, this study establishes a dynamic model of the rotor-bearing system subjected to the coupled motions of heave and pitch, considering nonlinear oil film moments produced by the tilting of the rotor in the bearings. The nonlinear dynamic behaviours of the system are analysed using numerical methods to obtain Poincaré sections, bifurcation diagrams, and the largest Lyapunov exponents. The results show that dynamic bifurcation characteristics reveal complex quasi-periodic motion of upper and lower branches after the initial instability of the system, and the speed of second instability increase markedly. At high speeds, the amplitude of the rotor system increases sharply, which can cause the rotor to touch the inner wall of the bearings in the quasi-periodic state and a failure to transition to the chaotic state. Additionally, the effects of heave and pitch amplitude variations on the dynamic characteristics of the system are also discussed.

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Nonlinear Characteristics of Two-Span Rotor-Bearing System with Three-Coupling Faults

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.52-54.303 ◽

2011 ◽

Vol 52-54 ◽

pp. 303-307

Author(s):

Yue Gang Luo ◽

Song He Zhang ◽

Zhao Hui Ren ◽

Bang Chun Wen

Keyword(s):

Dynamic Characteristics ◽

Nonlinear Dynamic ◽

Nonlinear Characteristics ◽

Coupling Faults ◽

Comprehensive Method ◽

Nonlinear Dynamic Characteristics ◽

Speed Range ◽

Rotor Bearing ◽

Set Up ◽

Bearing System

The dynamic model of two-span rotor-bearing system with three-coupling faults of rub-impact, crack and pedestal looseness faults was set up, and the influences of faults to nonlinear dynamic characteristics of the system were studied by mapping and continuation comprehensive method. There are many harmonic elements of 1/3, 1/2, 2/3, 1, 3/2 and 2 et al within the sub-critical rotate speed range. But the 3/2 and 2-harmonic elements decrease within the super-critical rotate speed range. It may the main characteristics of the system with three-coupling faults of rub-impact, crack and pedestal looseness. It should notice to diagnosis the three-coupling faults of the system when running within the super-critical rotate speed range.

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Nonlinear Dynamic Characteristics of Marine Rotor-Bearing System under Heaving Motion

Shock and Vibration ◽

10.1155/2019/7683952 ◽

2019 ◽

Vol 2019 ◽

pp. 1-16 ◽

Cited By ~ 1

Author(s):

Yongchao Han ◽

Ming Li

Keyword(s):

Dynamic Characteristics ◽

Nonlinear Dynamic ◽

Dynamic Performance ◽

Chaotic Oscillation ◽

Mathematic Model ◽

Rotating Speed ◽

Period 2 ◽

Rotor Bearing ◽

Motion Period ◽

Bearing System

In this paper, the influence of the heaving motion on the nonlinear dynamic behavior of the rotor-bearing system is considered. First, a mathematic model of the marine rotor-bearing system is developed on the short bearing theory in the noninertial reference system, in which the heaving motion is taken into account. Then its dynamic characteristics are analyzed based on the numerical integration method, such as the bifurcation diagram, the largest Lyapunov exponents (LLE), the steady-state response, and the rotor orbit and its Poincaré map. The results indicate that heaving motion has a great effect on the dynamics of the rotor system, which exhibits a period 1 motion at low rotating speed, with the increase of the rotating speed, the phenomena of the quasiperiodic, period 2, and double Hopf bifurcations appear. Its dynamic performance presents a period 1 motion, period 2, quasiperiodic, and chaotic oscillation.

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Study of Nonlinear Dynamics of Rotor-Bearing System Coupled with a Floating Raft Isolation Device

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.598.202 ◽

2014 ◽

Vol 598 ◽

pp. 202-205 ◽

Cited By ~ 2

Author(s):

Wen Zhao ◽

Ming Li

Keyword(s):

Periodic Motion ◽

Nonlinear Dynamic ◽

Basic Assumption ◽

Mathematic Model ◽

State Response ◽

Floating Raft ◽

Nonlinear Dynamic Characteristics ◽

Rotor Bearing ◽

Isolation Device ◽

Bearing System

The mathematic model of rotor-bearing system coupled with floating raft isolation device is developed and its nonlinear dynamic characteristics are mainly discussed in this paper. First, on the basic assumption theory of short bearing, the nonlinear dynamic motions of the system with 4 DOF is deduced after considering the vertical and horizontal deformation and the nonlinear vibrating behaviors are analyzed such as the steady state response and its spectrum, orbit and its Poincaré map. The results show that the responses at a low speed appear single periodic motion, with increasing the speed it indicates the doubling and quasi periodic motion, etc.

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Research on Rubbing Fault in a Dual-Disc Overhung Rotor-Bearing System

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.353-358.977 ◽

2007 ◽

Vol 353-358 ◽

pp. 977-980

Author(s):

Zhao Hui Ren ◽

Tao Yu ◽

Yue Gang Luo ◽

Nai Hui Song ◽

Bang Chun Wen

Keyword(s):

Dynamic Characteristics ◽

Mechanical Model ◽

Reference Value ◽

Rotating Machinery ◽

Force Model ◽

Nonlinear Dynamic Characteristics ◽

Rotor Bearing ◽

Simulation Results ◽

Set Up ◽

Bearing System

Mechanical model and rubbing force model of a dual-disc overhung rotor-bearing system are set up respectively. By using an experiment rig to simulate rubbing fault, the nonlinear dynamic characteristics of rubbing rotor system are investigated and the dynamic characteristics of mid-disc and overhung disc are analyzed respectively. The numerical simulation results coincide with the experiment results and the research in this paper has practical reference value to the safe and stable run of the practical rotating machinery.

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