Nonlinear Dynamic Behavior Effect of Magnetorheological Damper on a Rotor System with Axial and Radial Rub-Impacts

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Liang Ma ◽  
Jun Wang ◽  
Chenghao Li
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
Rotor System ◽  
Magnetorheological Damper ◽  
Nonlinear Dynamic Behavior

Nonlinear Dynamic Study on Effects of Rub-Impact Caused by Oil-Rupture in a Multi-Shafts Turbine With a Squeeze Film Damper

2014 ◽  
Author(s):  
T. N. Shiau ◽  
C. R. Wang ◽  
D. S. Liu ◽  
W. C. Hsu ◽  
T. H. Young
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
Equations Of Motion ◽  
Rotor System ◽  
Squeeze Film ◽  
Speed Ratio ◽  
Frequency Spectra ◽  
Squeeze Film Damper ◽  
Assumed Mode Method ◽  
Nonlinear Dynamic Behavior

An investigation is carried out the analysis of nonlinear dynamic behavior on effects of rub-impact caused by oil-rupture in a multi-shafts turbine system with a squeeze film damper. Main components of a multi-shafts turbine system includes an outer shaft, an inner shaft, an impeller shaft, ball bearings and a squeeze film damper. In the squeeze film damper, oil forces can be derived from the short bearing approximation and cavitated film assumption. The system equations of motion are formulated by the global assumed mode method (GAMM) and Lagrange’s approach. The nonlinear behavior of a multi-shafts turbine system which includes the trajectories in time domain, frequency spectra, Poincaré maps, and bifurcation diagrams are investigated. Numerical results show that large vibration amplitude is observed in steady state at rotating speed ratio adjacent to the first natural frequency when there is no squeeze film damper. The nonlinear dynamic behavior of a multi-shafts turbine system goes in its way into aperiodic motion due to oil-rupture and it is unlike the usual way (1T = >2T = >4T = >8T etc) as compared to one shaft rotor system. The typical routes of bifurcation to aperiodic motion are observed in a multi-shafts turbine rotor system and they suddenly turn into aperiodic motion from the periodic motion without any transition. Consequently, the increasing of geometric or oil parameters such as clearance or lubricant viscosity will improve the performance of SFD bearing.

scholarly journals Nonlinear Dynamic Behavior of Double-Disk Isotropic Rotor System with Axial Rub-Impact

2011 ◽  
Vol 2-3 ◽  
pp. 678-682
Author(s):  
Y. Zhang ◽  
W.M. Wang ◽  
J.F. Yao
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
High Speed ◽  
Element Model ◽  
Rotor System ◽  
Self Healing ◽  
Rotor Bearing ◽  
Nonlinear Dynamic Behavior ◽  
Operation Stability ◽  
Bearing System

In the case of considering the shear effect and gyroscopic effect, a finite element model is developed to study the nonlinear dynamic behavior of a double-disk isotropic rotor- bearing system with axial rub-impact in this paper. The influences of rotational speed and initial phase difference on the operation stability of the rotor-bearing system are discussed. It transpires that the response of the rotor system with axial rub- impact is mainly synchronous periodic motion. The vibration signals of axial rub-impact include such as the synchronous signal and the multiple frequencies, in which the synchronous signal is dominating signal. There is no weakening wave phenomenon in time wave plot. All the results are in reasonable good agreement with those observed in engineering. The results of this paper could provide certain reference for fault diagnosis and self-healing of large high-speed rotating machinery system, thus ensuring the safe operation of the system.

Experimental and Numerical Studies on Nonlinear Dynamic Behavior of Rotor System Supported by Ball Bearings

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Changqing Bai ◽  
Hongyan Zhang ◽  
Qingyu Xu
Keyword(s):  
Finite Element ◽  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
High Speed ◽  
Ball Bearing ◽  
Rotor System ◽  
Hertzian Contact ◽  
Ball Bearings ◽  
Flexible Rotor ◽  
Nonlinear Dynamic Behavior

Ball bearings are important mechanical components in high-speed turbomachinery that is liable for severe vibration and noise due to the inherent nonlinearity of ball bearings. Using experiments and the numerical approach, the nonlinear dynamic behavior of a flexible rotor supported by ball bearings is investigated in this paper. An experimental ball bearing-rotor test rig is presented in order to investigate the nonlinear dynamic performance of the rotor systems, as the speed is beyond the first synchroresonance frequency. The finite element method and two-degree-of-freedom dynamic model of a ball bearing are employed for modeling the flexible rotor system. The discrete model of a shaft is built with the aid of the finite element technique, and the ball bearing model includes the nonlinear effects of the Hertzian contact force, bearing internal clearance, and so on. The nonlinear unbalance response is observed by experimental and numerical analysis. All of the predicted results are in good agreement with experimental data, thus validating the proposed model. Numerical and experimental results show that the resonance frequency is provoked when the speed is about twice the synchroresonance frequency, while the subharmonic resonance occurs due to the nonlinearity of ball bearings and causes severe vibration and strong noise. The results show that the effect of a ball bearing on the dynamic behavior is noticeable in optimum design and failure diagnosis of high-speed turbomachinery.

On the Nonlinear Dynamic Behavior of a Rotor-Bearing System

2002 ◽  
Author(s):  
Jianping Jing ◽  
Yi Sun ◽  
Songbo Xia ◽  
Guotai Feng
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
Rotor System ◽  
Careful Examination ◽  
Mode Superposition Method ◽  
Direct Integration Method ◽  
Oil Whirl ◽  
Rotor Bearing ◽  
Nonlinear Dynamic Behavior ◽  
Bearing System

The nonlinear dynamic behavior of a rotor-bearing system is analyzed based on a continuum model. The finite element method is adopted in the analysis. Emphasis is given on the so called “Oil-Whirl phenomena” which might lead to the failure of the rotor system. The dynamic response of the system in unbalanced condition is approached by direct integration method and mode superposition method, it is found that a typical “Oil-Whirl phenomenon” is successfully produced. Furthermore, the bifurcation behavior of the Oil-Whirl phenomenon that is much concerned in recent nonlinear dynamics research is analyzed. The rotor-bearing system is also examined by the simple discrete model. Significant differences are found between these two models. It is suggested that a careful examination should be made in modeling such nonlinear dynamic behavior of the rotor system.

Impact of blast and mechanical loads on the shear deformable stiffened sandwich plate with an auxetic core layer in thermal environment

2021 ◽  
pp. 109963622110219
Author(s):  
Vu Thi Thuy Anh ◽  
Vu Dinh Quang ◽  
Nguyen Dinh Duc ◽  
Pham Ngoc Thinh
Keyword(s):  
Dynamic Behavior ◽  
Elastic Foundation ◽  
Nonlinear Dynamic ◽  
Sandwich Plate ◽  
Thermal Environment ◽  
Core Layer ◽  
Mechanical Loads ◽  
Environment Temperature ◽  
Nonlinear Dynamic Behavior ◽  
Fgm Layer

By using the first order shear deformation theory (FSTD), this paper presents the results of the nonlinear dynamic behavior and natural frequencies of sandwich plate supported by elastic foundations in thermal environment and subjected to mechanical load and blast loading. This work takes advantage of the sandwich plate configuration with three layers: graphene platelet –reinforced composite (GPL) layer – auxetic layer – FGM layer, to analyze the dynamic and vibration problem, in which the auxetic core layer has a negative Poisson's ratios and the FGM layer is reinforced by stiffeners made of full metal or full ceramic depending on a situation of stiffeners at the metal-rich or ceramic-rich side of the plate respectively. Corresponding to the combination of material layers, the mechanical quantities of the problem are processed and calculated to suit the structure and reinforcement conditions. Numerical results are provided to explore the influences of geometrical parameters, elastic foundation parameters, GPL volume fraction, blast and mechanical loads on the nonlinear dynamic behavior and vibration of sandwich plate resting on elastic foundation and in thermal environment. In addition, the study is not only assumed that the material properties depend on environment temperature variation, but also considered the thermal stresses in the stiffeners, as well as considered the effect of imperfections in the original shape of the structure.

Sign in / Sign up

Export Citation Format

Share Document