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1 – 10 of 55Linlin Li, Jiajun Yang and Wenwei Liu
The purpose of this paper is to explore the effect of surface roughness characterized by fractal geometry on squeeze film damping characteristics in damper of the linear rolling…
Abstract
Purpose
The purpose of this paper is to explore the effect of surface roughness characterized by fractal geometry on squeeze film damping characteristics in damper of the linear rolling guide, which has not been studied so far.
Design/methodology/approach
The stochastic model of film thickness between rail and damper is established by using the two-variable Weierstrass–Mandelbrot function defining multi-scale and self-affinity properties of the rough surface topography. The stochastically averaged Reynolds equation is solved by using the variables separation method to further derive the film pressure distribution, the damping coefficient, the damping force and squeeze film time. The effect of surface roughness on squeeze film damping characteristics of the damper is analyzed and discussed through simulation.
Findings
By comparing cases of the rough surface for different fractal parameters and the smooth surface, it is shown that for the isotropic roughness structure, the presence of surface roughness of the damper decreases the squeeze film damping characteristics. It is found that roughness effect on the damping coefficient is associated with the film thickness. In addition, the vibration amplitude effect is negligible for the damper of the linear rolling guide.
Originality/value
To investigate the random surface roughness effect, the rough surface topography of damper of the linear rolling guide is characterized by using the fractal method instead of the traditional mathematical statistics method.
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Mahmoud Hammou, Ahmed Bouzidane, Marc Thomas, Aboubakeur Benariba and Mohamed Bouzit
The purpose of this study is to examine the dynamic performance of an orifice-compensated three-pad hydrostatic squeeze film damper.
Abstract
Purpose
The purpose of this study is to examine the dynamic performance of an orifice-compensated three-pad hydrostatic squeeze film damper.
Design/methodology/approach
A numerical model has been developed and presented to study the effect of eccentricity ratio and pressure ratio on the static and dynamic characteristics of an orifice-compensated three-pad hydrostatic squeeze film damper. It is assumed that the fluid flow is incompressible, laminar, isothermal and steady-state. The finite difference method has been used to solve Reynolds equation governing the lubricant flow in film thickness of hydrostatic bearing. The numerical results obtained are discussed, analyzed and compared between three- and four-lobe hydrostatic journal bearings available in the literature.
Findings
It was found that the influence of eccentricity ratio on dynamic characteristics of an orifice-compensated three-pad hydrostatic squeeze film damper appears to be essentially controlled by the concentric pressure ratio. It was also found that the three-pad hydrostatic squeeze film damper has higher stiffness than three and four-lobe hydrostatic journal bearings.
Originality/value
In fact, the results obtained show that this type of hydrostatic squeeze film damper provides hydrostatic designers a new bearing configuration suitable to control rotor vibrations.
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Zhenlin Wang, Zhansheng Liu and Guanghui Zhang
The purpose of this paper is to present a numerical model to investigate the dynamic behavior and force coefficients of a compact squeeze film damper with dual film clearances…
Abstract
Purpose
The purpose of this paper is to present a numerical model to investigate the dynamic behavior and force coefficients of a compact squeeze film damper with dual film clearances adjusted by an elastic ring, known as elastic ring squeeze film damper (ERSFD).
Design/methodology/approach
The governing equations of ERSFD as well as the boundary conditions are obtained based on Reynolds equation. A simplified Greenwood–Williamson model is implemented to investigate the contact behavior between the elastic ring and the journal. The interactions between the films and the elastic ring are achieved by block iterative method.
Findings
The radial deformation as well as velocity of the elastic ring are captured to illustrate the pressure profiles of the inner and outer films. High-order frequency components related to the number of the boss N are observed on the frequency spectrum of the film force. The force coefficients of the ERSFD are constant for a wider range of non-dimensional whirling radius ε compared with conventional squeeze film damper.
Originality/value
The force coefficients of the ERSFD are obtained by assuming that the journal center moves in a circular centered orbit. High-order frequency components related to the number of bosses N are observed. These findings may provide helpful materials for the application of the ERSFD.
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Mohamed Benadda, Ahmed Bouzidane, Marc Thomas and Raynald Guilbault
This paper aims to propose a new hydrostatic squeeze film damper compensated with electrorheological valve restrictors to control the nonlinear dynamic behavior of a rigid rotor…
Abstract
Purpose
This paper aims to propose a new hydrostatic squeeze film damper compensated with electrorheological valve restrictors to control the nonlinear dynamic behavior of a rigid rotor caused by high unbalance eccentricity ratio. To investigate the effect of electrorheological valve restrictors on the dynamic behavior of a rigid rotor, a nonlinear model is developed and presented.
Design/methodology/approach
The nonlinear results are compared with those obtained from a linear approach. The results show good agreement between the linear and nonlinear methods when the unbalanced force is small. The effects of unbalance eccentricity ratio and electric field on the vibration response and the bearing transmitted force are investigated using the nonlinear models.
Findings
The results of simulation performed that the harmonics generated by high unbalance eccentricities can be reduced by using hydrostatic squeeze film damper compensated with electrorheological valve restrictors.
Originality/value
The numerical results demonstrate that this type of smart hydrostatic squeeze film damper provides to hydrostatic designers a new bearing configuration suitable to control rotor vibrations and bearing transmitted forces, especially for high speed.
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Aboubakeur Benariba, Ahmed Bouzidane, Hicham Aboshighiba and Mark Thomas
The purpose of this research is to study the dynamic behavior of hydrostatic squeeze film dampers made of four hydrostatic pads, fed through four capillary restrictors with…
Abstract
Purpose
The purpose of this research is to study the dynamic behavior of hydrostatic squeeze film dampers made of four hydrostatic pads, fed through four capillary restrictors with micropolar lubricant.
Design/methodology/approach
The modified version of Reynolds equation is solved numerically by the finite differences and the Gauss–Seidel methods to determine the pressure field generated on the hydrostatic bearing flat pads. In the first step, the effects of the pad dimension ratios on the stiffness and damping coefficients are investigated. In the second step, the damping factor is evaluated with respect to the micropolar properties.
Findings
The analysis revealed that the hydrostatic squeeze film dampers lubricated with micropolar lubricants produces the maximum damping factor for characteristic length of micropolar lubricant less than 5, while the same bearing operating with Newtonian lubricants reaches its maximum damping factor at eccentricity ratios larger than 0.4.
Originality/value
The results obtained show that the effects of micropolar lubricants on the dynamic performances are predominantly affected by the pad geometry and eccentricity ratio.
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Xin Qin, Xiaojing Wang, Zhengmao Qiu, Yifan Hao and Yan Zhu
This study aims to present a novel hydrostatic squeeze film-metal mesh journal bearing (HS-MMJB), which uses both hydrostatic squeeze film damper (HSFD) and metal mesh damper…
Abstract
Purpose
This study aims to present a novel hydrostatic squeeze film-metal mesh journal bearing (HS-MMJB), which uses both hydrostatic squeeze film damper (HSFD) and metal mesh damper (MMD), to suppress the vibration of rotor-bearing systems.
Design/methodology/approach
The lubrication equations were introduced to calculate the dynamic characteristics of HS-MMJB, and the response analyses of rotor systems were carried out. Experiments were conducted to study the vibration reduction of a rotor system with HS-MMJB. In addition, experiments for different oil supply pressures in the HS-MMJB were conducted.
Findings
The theoretical and experimental results show that the HS-MMJB exhibits excellent damping and vibration attenuation characteristics. Moreover, the stability of the rotor system can be improved by controlling the oil supply pressure.
Originality/value
There is a dearth of research on vibration characteristics of rotor system support by journal bearing combining HSFD and MMD. Moreover, the active oil pressure control is implemented to improve the stability of rotor system.
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Amina Nemchi, Ahmed Bouzidane, Aboubakeur Benariba and Hicham Aboshighiba
The purpose of this paper is to study the influence of different flow regimes on the dynamic characteristics of four-pad hydrostatic squeeze film dampers (SFDs) loaded between…
Abstract
Purpose
The purpose of this paper is to study the influence of different flow regimes on the dynamic characteristics of four-pad hydrostatic squeeze film dampers (SFDs) loaded between pads.
Design/methodology/approach
A numerical model based on Constantinescu’s turbulent lubrication theory using the finite difference method has been developed and presented to study the effect of eccentricity ratio on the performance characteristics of four-pad hydrostatic SFDs under different flow regimes.
Findings
It was found that the influence of turbulent flow on the dimensionless damping of four-pad hydrostatic SFDs appears to be essentially controlled by the eccentricity ratio. It was also found that the laminar flow presents higher values of load capacity compared to bearings operating under turbulent flow conditions.
Originality/value
In fact, the results obtained show that the journal bearing performances are significantly influenced by the turbulent flow regime. The study is expected to be useful to bearing designers.
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CholUk Ri, KwangChol Ri, ZhunHyok Zhang, ChungHyok Chae, Qiang Zhao, HyeIl Pak, JaeHun Kim, Hwan NamGung and ChangSop Kim
As a core rotating component of power machinery and working machinery, the rotor system is widely used in the fields of machinery, electric power and aviation. When the system…
Abstract
Purpose
As a core rotating component of power machinery and working machinery, the rotor system is widely used in the fields of machinery, electric power and aviation. When the system operates at high speed, the system stability is of great importance. To enhance the system stability, squeeze film damper (SFD) is being installed in the rotor system to alleviate vibration. The purpose of this paper is to first classify the rotor system into two types, the dual rotor system and the single rotor system, and to comprehensively and specifically mention the method of generating the dynamic model. Next, based on the establishment of a dynamic model with and without SFD in the rotor system, the optimization design of the rotor system with SFD was carried out using a genetic algorithm. Through sensitivity analysis, SFD clearance, shaft stiffness and oil viscosity were determined as design variables of the rotor system, and the objective function was the minimization of the maximum amplitude of the rotor system with SFD within the operation speed range.
Design/methodology/approach
In this paper, first, the rotor system was classified into two types, namely, the dual rotor system and the single rotor system, and the method of creating a dynamic model was comprehensively and specifically mentioned. Here, the dynamic model of the rotor system was derived in detail for the single rotor system and the dual rotor system with and without SFD. Next, based on the establishment of a dynamic model with and without SFD in the rotor system, the optimization design of the rotor system with SFD was carried out using a genetic algorithm. The sensitivity analysis of the unbalanced response was carried out to determine the design variables of the optimization design. Through sensitivity analysis, SFD clearance, shaft stiffness and oil viscosity were determined as design variables of the rotor system, and the objective function was the minimization of the maximum amplitude of the rotor system with SFD within the operation speed range.
Findings
SFD clearance, shaft stiffness and oil viscosity were determined as design variables of the rotor system through sensitivity analysis of the unbalanced response. These three variables are basic factors affecting the amplitude of the rotor system with SFD.
Originality/value
In the existing studies, only a dynamic model of a single rotor system with SFD was created, and the characteristic values of pure SFD were selected as optimization variables and optimization design was carried out. But in this study, the rotor system was classified into two types, namely, the dual rotor system and the single rotor system, and the method of creating a dynamic model was comprehensively and specifically mentioned. In addition, optimization design variables were selected and optimized design was performed through sensitivity analysis on the unbalanced response of factors affecting the vibration characteristics of the rotor system.
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Yifan Hao, Chengdong Zheng, Xiaojing Wang, Chao Chen, Ke Wang and Xin Xiong
This work aims to demonstrate the vibration suppression of the rotor system with localized defects on bearing using an integral squeeze film damper (ISFD).
Abstract
Purpose
This work aims to demonstrate the vibration suppression of the rotor system with localized defects on bearing using an integral squeeze film damper (ISFD).
Design/methodology/approach
Experiments were carried out to study the vibration characteristics of the rotor system with ISFD mounted on fault deep groove ball bearings. Three fault bearings including bearing with outer race defect, inner race defect and ball defect have been used in this paper. The results were compared by use of vibration acceleration level, continuous wavelet transform and envelope spectrum.
Findings
It was found that ISFD shows excellent damping and vibration attenuation characteristics of the rotor system with defective bearing. The fault bearing rotor system with external ISFD considerably reduces the vibration energy and amplitude compared with the system without ISFD.
Originality/value
There is a dearth of experimental research pertaining to vibration characteristics of rotor system support by defective bearings with ISFD. Besides, the test provides evidence for the application of ISFD in vibration control of the rotor system with incipient defects on bearing.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0144/
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Said Sobhi, Mohamed Nabhani, Khalid Zarbane and Mohamed El Khlifi
This study aims to present a numerical model to investigate cavitation effects on oscillatory porous squeeze film. This effect is able to cause considerable damage to the…
Abstract
Purpose
This study aims to present a numerical model to investigate cavitation effects on oscillatory porous squeeze film. This effect is able to cause considerable damage to the lubrication mechanisms, mainly in the form of surface erosion. The erosion process is caused by surface spalling due to alternating positive and negative contact stresses imposed by bubble collapse. If the process continues uncontrolled, the performance of the contact will rapidly deteriorate.
Design/methodology/approach
The study is conducted numerically using Elrod–Adams model for the modified Reynolds equation coupled with the Darcy’s law for the lubricant flow through the porous medium. The governing equations are numerically discretized and iteratively solved.
Findings
The numerical results show that frequency, amplitude and permeability have a significant influence on the generation of cavitation. A comparison of the present numerical results against available literature experimental data in particular case proved a good agreement.
Originality/value
The present paper is to develop a more realistic and efficient model. Indeed, the consideration of cavitation phenomena in this model will lead to a more accurate prediction of the squeeze film characteristics. The results of this paper are based on original work and have practical value.
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