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

2014 ◽  
Vol 598 ◽  
pp. 202-205 ◽  
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.

scholarly journals Nonlinear Dynamic Behaviors of a Marine Rotor-Bearing System Coupled with Air Bag and Floating-Raft

2015 ◽  
Vol 2015 ◽  
pp. 1-18 ◽  
Author(s):  
W. Zhao ◽  
M. Li ◽  
L. Xiao
Keyword(s):  
Nonlinear Dynamic ◽  
Largest Lyapunov Exponent ◽  
Steady State Response ◽  
Dynamic Effects ◽  
State Response ◽  
Floating Raft ◽  
Rotor Bearing ◽  
Vibration Mechanism ◽  
Air Bag ◽  
Bearing System

To understand the nonlinear dynamic mechanism of a rotor-bearing system coupled with air bag and floating-raft, the dynamic characteristics of the system are investigated. This work has two key objectives. First, the vibration mechanism of rotor-bearing system coupled with air bag and floating-raft is investigated by developing a numerical model. Then, the nonlinear dynamics of the system and the effect of several parameters are studied, which includes the steady-state response and its spectrum, the orbit and its Poincaré map, the bifurcation diagram, and largest Lyapunov exponent (LLE). The results show that at low speed the dynamic behavior appears in a single periodic motion, and, with the increase of the speed, the motion becomes quasi-periodic and chaotic. These performances indicate that the air bag and floating-raft introduce some dynamic effects of marine rotor-bearing system.

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

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
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.

Nonlinear dynamic characteristics of a three-dimensional rod-fastening rotor bearing system

2014 ◽  
Vol 229 (5) ◽  
pp. 882-894 ◽  
Author(s):  
Yi Liu ◽  
Heng Liu ◽  
Xin Wang ◽  
Minqing Jing
Keyword(s):  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Three Dimensional ◽  
Dynamic Features ◽  
Stability Margins ◽  
Mass Eccentricity ◽  
Nonlinear Dynamic Characteristics ◽  
Rotor Bearing ◽  
Rod Fastening 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.

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

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.

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

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.

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

Nonlinear Dynamic Behavior of a Rotor Bearing System With Nonlinear Viscous Damping Suspension

2017 ◽  
Author(s):  
Shuai Yan ◽  
Bin Lin ◽  
Jixiong Fei ◽  
Pengfei Liu
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
Vibration Isolation ◽  
Lubricating Oil ◽  
Viscous Damping ◽  
Oil Viscosity ◽  
Speed Range ◽  
Rotor Bearing ◽  
Nonlinear Dynamic Behavior ◽  
Bearing System

Nonlinear damping suspension has gained attention owing to its excellent vibration isolation performance. In this paper, a cubic nonlinear viscous damping suspension was introduced to a rotor bearing system for vibration isolation between the bearing and environment. The nonlinear dynamic response of the rotor bearing system was investigated thoroughly. First, the nonlinear oil film force was solved based short bearing approximation and half Sommerfeld boundary condition. Then the motion equations of the system was built considering the cubic nonlinear viscous damping. A computational method was used to solve the equations of motion, and the bifurcation diagrams were used to display the motions. The influences of rotor-bearing system parameters were discussed from the results of numerical calculation, including the eccentricity, mass, stiffness, damping and lubricating oil viscosity. The results showed that: (1) medium eccentricity shows a wider stable speed range; (2) rotor damping has little effect to the stability of the system; (3) lower mass ratio produces a stable response; (4) medium suspension/journal stiffness ratio contributes to a wider stable speed range; (5) a higher viscosity shows a wider stable speed range than lower viscosity. From the above results, the rotor bearing system shows complex nonlinear dynamic behavior with nonlinear viscous damping. These results will be helpful to carrying out the optimal design of the rotor bearing system.

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