scholarly journals Nonlinear vibration behaviors of marine rotor system coupled with floating raft-airbag-displacement restrictor under ship heaving motion

2021 ◽  
Vol 13 (12) ◽  
pp. 168781402110673
Author(s):  
Xuan Xie ◽  
Ming Li ◽  
Junwei Wang
Keyword(s):  
Nonlinear Vibration ◽  
Rotor System ◽  
Rotating Speed ◽  
Floating Raft ◽  
Runge Kutta Method ◽  
Axis Orbit ◽  
Steady State Responses ◽  
Time Domain Response ◽  
Frequency Domain Response ◽  
State Responses

To study the nonlinear vibration behaviors of rotor system coupled with floating raft-airbag-displacement restrictor under ship heaving motion, the dynamic model is established considering the effect of heaving motion, its steady-state responses are numerically obtained using Runge-Kutta method and the results are surveyed by tools such as the spectrum waterfall diagram, time-domain response, frequency-domain response, axis orbit, and Poincaré map. The effects of rotating speed, ship heaving amplitude, and its frequency on the nonlinear dynamic behavior of the system are mainly studied. The results show that the responses of the rotor and raft are of obvious nonlinear behaviors such as amplitude jumping, bifurcation, and chaos due to the effects of nonlinear oil film force and ship heaving motion. With the increase of rotating speed, the motion of rotor and raft presents quasi-periodic and chaotic vibrations. Ship heaving amplitude and its frequency all have great effect on the vibration of rotor and raft; as heaving amplitude or frequency increases, the motion state of rotor and raft changes, and the amplitude of raft increases significantly. The displacement restrictor can effectively limit the vibrating displacements of the raft when ship heaving amplitude or its frequency is large.

scholarly journals Nonlinear Vibration Analysis of Rotor considering Cogging and Harmonic Effects

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Shanle Li ◽  
Feng Liu ◽  
Hongyan Wang ◽  
Haijun Song ◽  
Kuilong Yu
Keyword(s):  
Nonlinear Vibration ◽  
Vibration Analysis ◽  
Magnetic Force ◽  
Rotor System ◽  
Kutta Method ◽  
Rotor Vibration ◽  
Motion Equations ◽  
Runge Kutta Method ◽  
Static Eccentricity ◽  
New Formula

This paper aims to investigate nonlinear vibration characteristics of rotor system considering cogging and harmonic effects. Firstly, relative permeance with eccentric was established and then corrected by correction factor caused by the cogging effect. Based on the new formula of relative permeance, the expression of unbalanced magnetic force was obtained, and the coefficient of cogging effect was defined. Motion equations of rotor system were established, and Runge–Kutta method was used to solve the equations. Results showed that errors between finite and analytical results were smaller considering cogging and harmonic effects. When the harmonics were taken into consideration, the vibration of rotor increases sharply. When the cogging and harmonics were taken into consideration simultaneously, the vibration of rotor decreased instead, which means that stator slots have the effect of reducing vibration in rotor system. Rotor vibration was axis symmetry with static eccentricity rather than central symmetry with no eccentricity, and double, four times, and six times supply frequency always existed in the components of main frequency with eccentric.

scholarly journals Theoretical and Experimental Study on the Transient Time-Frequency Characteristics of the Bending-Torsional Coupling Motions of a Rub-Impact Dual-Rotor System

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Tian Gao ◽  
Shuqian Cao ◽  
Tiancheng Zhang
Keyword(s):  
Friction Coefficient ◽  
Fault Detection ◽  
High Speed ◽  
Rotor System ◽  
Bending Vibration ◽  
Transient Time ◽  
Rotating Speed ◽  
Time Frequency ◽  
Runge Kutta Method ◽  
Torsional Coupling

This paper focuses on the fault characteristics of the bending and torsional motions of a rub-impact dual-rotor system caused by aircraft flight maneuvers. The equations of the bending-torsional coupling motion of a dual-rotor system are established considering a low-pressure rotor rub-impact fault and the transient barrel roll flight of an aircraft. The 4th Runge-Kutta method with varied steps is used to obtain the bending and torsional responses. Then, the influences of the system parameters, including the rub-impact stiffness, friction coefficient, and rotating speed, on the bending and torsional motions of the dual-rotor system are investigated in detail. At last, a rotor rubbing experiment is carried out, verifying the validity of the simulation results. The results show that the rub-impact stiffness affects bending vibration significantly and the torsional motion is sensitive to the friction coefficient. Correspondingly, the torsional responses show apparent fractional fault frequencies and rotating fault frequencies within the whole region of the rub-impact stiffness. The bending responses can only display fault frequencies at certain rub-impact stiffness. As for the rotating speed, the torsional responses are also more effective than the bending responses for the rub-impact fault detection at the low- and high-speed regions. The results will contribute to a comprehensive basis for the rub-impact fault detection.

Non-Linear Dynamics of a Flexible Multi-Rotor Bearing System with a Fault of Parallel Misalignment

2011 ◽  
Vol 138-139 ◽  
pp. 104-110 ◽  
Author(s):  
Zi Gang Li ◽  
Ming Li
Keyword(s):  
Steady State ◽  
Dynamic Characteristics ◽  
Numerical Technique ◽  
Rotor System ◽  
Lagrange Equations ◽  
Lateral Direction ◽  
Rotating Speed ◽  
Nonlinear Properties ◽  
Parallel Misalignment ◽  
Steady State Responses

The dynamic behaviors of a flexible multi-rotor system with a fault of parallel misalignment are investigated on the basis of assumptions, such as the long journal bearings, small rotor misalignment and mass disk unbalance. Firstly, based on the Lagrange equations with undetermined multiplier, the dynamic model of a rotor system under the action of the nonlinear oil film forces is developed after taking into account the holonomic constraint, which describes the misalignment relation between two rotors, and the theoretical analysis reveals that the system with eleven DOF is of strong nonlinear properties. Then the nonlinear dynamic characteristics on numerical technique, such as steady state response, rotor orbit, Poincaré section and the largest Lyapunov exponent, are paid more attention in this study. The results show that at low speed the components of the steady-state responses in lateral direction is of the synchronous frequency with rotating speed as well as its integer multiples frequencies. As the speed increases the dynamic characteristics become complicated, and the nT-period, quasi-period and chaotic oscillations occur.

Nonlinear Dynamic Behaviors of Rotor System with Misaligned Journal Bearings

2012 ◽  
Vol 271-272 ◽  
pp. 1032-1038 ◽  
Author(s):  
Ming Li ◽  
Zi Gang Li ◽  
Ping Xue
Keyword(s):  
Nonlinear Dynamic ◽  
Degrees Of Freedom ◽  
Journal Bearings ◽  
Rotor System ◽  
Lateral Direction ◽  
Dynamic Behaviors ◽  
Rotating Speed ◽  
Mass Unbalance ◽  
Bifurcation Phenomena ◽  
Steady State Responses

The dynamic modeling of a rotor system on misaligned journal bearings is discussed and its nonlinear dynamic behaviors are considered in this paper. Firstly, a dynamic model of six degrees of freedom system is established under the conditions of the long bearings, small bearing misalignment and mass unbalance. Then, the nonlinear dynamics of the rotor-bearing system, such as the displacement response and its frequency spectrum, rotor orbit and its Poincare map are analyzed by the Runge-Kutta method. The results show that at low speed the steady-state responses of the rotor system in lateral direction is synchronous, as the speed increases a serious of bifurcation phenomena and chaotic oscillations occur. In many cases, there exist the integer multiples components of the rotating speed except the synchronous one in displacement responses.

Research on Lateral Nonlinear Vibration Behavior of Composite Shaft-Disk Rotor System

2018 ◽  
Vol 875 ◽  
pp. 149-161 ◽  
Author(s):  
Chun Jin Zhang ◽  
Yong Sheng Ren ◽  
Shu Juan Ji
Keyword(s):  
Nonlinear Vibration ◽  
Strain Energy ◽  
Nonlinear Deformation ◽  
Lagrange Equation ◽  
Rotor System ◽  
Kutta Method ◽  
Response Curves ◽  
Runge Kutta Method ◽  
Composite Shaft ◽  
Ihb Method

The characteristics of the lateral nonlinear vibration in composite shaft-disk rotor system with nonlinear deformation are studied. Firstly, the equations of the kinetic energy of the composite shaft, the disk and the eccentric mass as well as the equations of the strain energy of the composite shaft are derived. Based on these equations, the nonlinear vibration equations are deduced by using the Lagrange equation. Then, the frequency response curves and time response curves of the system are obtained by using the IHB method and verified by the fourth order Runge-Kutta method. Experimental results show that the external damping coefficient, the size of eccentric mass only influences the nonlinear amplitude. Moreover, the ply-angle, thickness to diameter(T/D) ratio, length to diameter (L/D) ratio, and the position of disk in the shaft not only produce an effect on the nonlinear amplitude, but also influence the nonlinear vibration frequency.

scholarly journals Vibration characteristics of triple-gear-rotor system in compressed air energy storage under variable torque load

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042098705
Author(s):  
Xinran Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xuehui Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Element Model ◽  
Rotor System ◽  
Dynamic Responses ◽  
System Response ◽  
Rotating Speed ◽  
Torque Load ◽  
Set Up ◽  
Two Stages

This paper focuses on the effects of the off-design operation of CAES on the dynamic characteristics of the triple-gear-rotor system. A finite element model of the system is set up with unbalanced excitations, torque load excitations, and backlash which lead to variations of tooth contact status. An experiment is carried out to verify the accuracy of the mathematical model. The results show that when the system is subjected to large-scale torque load lifting at a high rotating speed, it has two stages of relatively strong periodicity when the torque load is light, and of chaotic when the torque load is heavy, with the transition between the two states being relatively quick and violent. The analysis of the three-dimensional acceleration spectrum and the meshing force shows that the variation in the meshing state and the fluctuation of the meshing force is the basic reasons for the variation in the system response with the torque load. In addition, the three rotors in the triple-gear-rotor system studied show a strong similarity in the meshing states and meshing force fluctuations, which result in the similarity in the dynamic responses of the three rotors.

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