On the characteristics of gas foil conical bearings considering misalignment

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hongyang Hu ◽  
Ming Feng ◽  
Tianming Ren
Keyword(s):  
Film Thickness ◽  
Peer Review ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Critical Role ◽  
Friction Torque ◽  
Misalignment Angle ◽  
Content Type ◽  
Stiffness Model ◽  
Dynamic Performances

Purpose The purpose of this paper is to study the characteristics of gas foil conical bearings (GFCBs) considering the misalignment, the static and dynamic performances with different misalignment cases were studied. Design/methodology/approach A test rig on the air compressor supported by GFCBs has been developed to measure the practicability. A nonlinear bump stiffness model and one-dimensional beam top foil stiffness model were used as a basis for the calculation of static and dynamic performance. The finite element method and finite difference method are adopted to solve the Reynolds equation and the film thickness equation coupled, in which different misalignment cases were considered by changing the film thickness. Findings The supporting performance of GFCB is excellent, and the film clearance plays a critical role. The misalignment effects depend on the assembled angle and the misalignment angle. The load capacity, friction torque, temperature of GFCB decrease when the misalignment assembled angle is between 120° and 240°, while the dynamic bearing stability is improved. The static and dynamic performances show the opposite law for the other assembled angles, and the misalignment effect is more dramatic when there is a larger misalignment angle. Moreover, the bearing and running parameters largely affect the bearing performance. Originality/value The present study focuses on the static and dynamic characteristics of GFCB and investigates the effects of misalignment on the bearing performance. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0117

Effect of taper error on the performance of gas foil conical bearing

2020 ◽  
Vol 72 (10) ◽  
pp. 1189-1197
Author(s):  
Hongyang Hu ◽  
Ming Feng ◽  
Tianming Ren
Keyword(s):  
Peer Review ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Cone Angle ◽  
Nonlinear Structure ◽  
Content Type ◽  
Axial Load Capacity ◽  
Stiffness Model ◽  
Direct Stiffness ◽  
Conical Bearing

Purpose This paper aims to study the bearing performance with different cone angle errors, to study the effect law of manufacturing taper error on the properties of gas foil conical bearing (GFCB). Design/methodology/approach For the GFCB supported by separated bump foil strips, a nonlinear structure stiffness model considering Coulomb friction and arch characteristics was proposed. The finite element method and finite difference method were used to solve the Reynolds equation and the film thickness equation by coupling, and the properties of the GFCB were obtained. The effect of foil and bearing structure parameters on the static and dynamic performance under different taper error cases was analyzed. Moreover, a test on the air compressor supported by GFCBs was conducted to verify the practicability. Findings The taper error has a largely adverse effect on the load capacity of GFCB. When the taper error is −0.03°, the radial load capacity Fr and axial load capacity Fz decrease by 37.5 and 58.3%, respectively. The taper error decreases the direct stiffness and cross-coupled damping of GFCB, which will weaken the bearing stability. Moreover, the performance of GFCB is closely related to the foil and bearing parameters. Originality/value The taper error adversely affects the static and dynamic characteristics of GFCB, which should be concerned by bearing designers, researchers and academicians. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2020-0089/

Effect of roundness error on the performance of novel gas foil conical bearings

2020 ◽  
Vol 72 (7) ◽  
pp. 895-904
Author(s):  
Hongyang Hu ◽  
Ming Feng ◽  
Tianming Ren
Keyword(s):  
Peer Review ◽  
Dynamic Properties ◽  
Load Capacity ◽  
Dynamic Stiffness ◽  
Friction Torque ◽  
Roundness Error ◽  
Content Type ◽  
Stiffness Model ◽  
Static Performance ◽  
Stiffness And Damping

Purpose The purpose of this paper is to study the effect law of roundness error on the properties of gas foil conical bearing (GFCB), and the performance of bearings with different non-circular sleeve shapes are calculated. Design/methodology/approach For the bump-type GFCB, the nonlinear bump foil stiffness model and 1-D beam top foil stiffness model are built. On this basis, the finite element method and finite difference method are used to solve the Reynolds equation and the film thickness equation coupled, and the static and dynamic properties of GFCB are calculated. The effect law of sleeve roundness error on the static performance under different conditions is obtained. Moreover, the dynamic stiffness and damping characteristics under different errors are also studied. Findings The roundness error will decrease the load capacity and friction torque of GFCB, and increase the attitude angle. The error effect is more dramatic when there is larger eccentric, small nominal clearance, larger error value and more error lobes, and the static performance exhibits a periodic change in the circumferential direction. The roundness error can also decrease the direct stiffness and cross-coupled damping of GFCB, while the cross-coupled stiffness increases largely, which will reduce the bearing stability. Originality/value The roundness error adversely affects the static and dynamic characteristics of GFCB, which should be concerned by bearing designers, researchers and academicians. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0019/

Influence of wedge shape on the performance of air foil thrust bearings

2019 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hongyang Hu ◽  
Ming Feng
Keyword(s):  
Film Thickness ◽  
Load Capacity ◽  
Friction Torque ◽  
Distribution Area ◽  
Convex Shape ◽  
Concentrated Load ◽  
Content Type ◽  
Wedge Shape ◽  
Static Performance ◽  
Pitch Ratio

Purpose The purpose of this paper is to investigate the effect of different wedge shapes on the performance of air foil thrust bearing (AFTB). Design/methodology/approach During the study, a bump foil stiffness model considering slip deformation and a two-dimensional sheet top foil model is established, and the Reynolds equation and film thickness equation is solved using the finite difference method and finite element method. The static performance such as load carrying capacity, friction torque and power loss of AFTB under different taper parameters is obtained. The influence of different pitch ratio, film thickness ratio and wedge shapes on the bearing characteristics is studied. Findings There is an optimal height and a pitch ratio for the taper of AFTB with certain tile number. Compared to the plane and concave wedge shape, the upper convex shape can enhance the convergence effect of the wedge region, increase the effective film pressure distribution area of the bearing and reduce the local concentrated load of the top foil, which is more conductive to the increase of load capacity. Originality/value The wedge shape parameters bring a fundamental difference in the static performance of AFTB. The results are expected to be helpful to bearing designers, researchers and academicians concerned.

Effects of polymers concentration on EHL film-forming in point contacts

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Liangwei Qiu ◽  
Xiaoyang Chen ◽  
Fakai Dong
Keyword(s):  
Film Thickness ◽  
Peer Review ◽  
Point Contact ◽  
High Concentration ◽  
Content Type ◽  
Base Oils ◽  
Low Viscosity ◽  
Lubricant Oil ◽  
Pure Rolling ◽  
Film Forming

Purpose This paper aims to experimentally investigate the film-forming capability of base oils containing poly-methacrylate (PMA) and poly-isobutene (PIB), in a point contact under pure rolling. Design/methodology/approach By using the relative light intensity method, the film thickness is calculated from the interferometer images which are captured by multiple-contact optical elastohydrodynamic lubricated test rig. Findings The test results reveal that polymers, both PMA and PIB, have a significant contribution to the film-forming capability of base oils and the film thickness increases with concentration. The forming-film capabilities for PMA and PIB in base oils are similar at low concentration, while PIB gives a higher film thickness than PMA at high concentration. Shear-thinning phenomenon are observed in all polymer-based oils. Originality/value The polymer usually as an additive is added into the low viscosity base oils to improve the properties of lubricant oil. This paper reports the lubricated properties of PMA and PIB with different concentrations in base oils and to evaluate their functional mechanism in a point contact. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0263/

A thermal EHL investigation for size effect of finite line contact on bush-pin hinge pairs in industrial chains

2020 ◽  
Vol 72 (5) ◽  
pp. 695-701
Author(s):  
Mingyu Zhang ◽  
Jing Wang ◽  
Peiran Yang ◽  
Zhaohua Shang ◽  
Yi Liu ◽  
...  
Keyword(s):  
Film Thickness ◽  
Peer Review ◽  
Contact Zone ◽  
Line Contact ◽  
Equivalent Radius ◽  
Content Type ◽  
Oil Film ◽  
Finite Line Contact ◽  
Finite Line ◽  
Thermal Ehl

Purpose This paper aims to study the influence of the dimension change of bush-pin on the pressure, oil film thickness, temperature rise and traction coefficient in contact zone by using a thermal elastohydrodynamic lubrication (EHL) model for finite line contact. Concretely, the effects of the equivalent curvature radius of the bush and the pin, and the length of the bush are investigated. Design/methodology/approach In this paper, the contact between the bush and pin is simplified as finite line contact. The lubrication state is studied by numerical simulation using steady-state line contact thermal EHL. A constitutive equation Ree–Eyring fluid is used in the calculations. Findings It is found that by selecting an optimal equivalent radius of curvature and prolonging the bush length can improve the lubrication state effectively. Originality/value Under specific working conditions, there exists an optimal equivalent radius to maximize the minimum oil film thickness in the contact zone. The increase of generatrix length will weaken the stress concentration effect in the rounded corner area at both ends of the bush, which can improve the wear resistance of chain. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0448.

scholarly journals A Novel Stick-Slip Nanopositioning Stage Integrated with a Flexure Hinge-Based Friction Force Adjusting Structure

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 765
Author(s):  
Junhui Zhu ◽  
Peng Pan ◽  
Yong Wang ◽  
Sen Gu ◽  
Rongan Zhai ◽  
...  
Keyword(s):  
Friction Force ◽  
High Speed ◽  
Simulation Analysis ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Critical Role ◽  
Vertical Direction ◽  
Flexure Hinge ◽  
Stick Slip ◽  
Static Performance

The piezoelectrically-actuated stick-slip nanopositioning stage (PASSNS) has been applied extensively, and many designs of PASSNSs have been developed. The friction force between the stick-slip surfaces plays a critical role in successful movement of the stage, which influences the load capacity, dynamic performance, and positioning accuracy of the PASSNS. Toward solving the influence problems of friction force, this paper presents a novel stick-slip nanopositioning stage where the flexure hinge-based friction force adjusting unit was employed. Numerical analysis was conducted to estimate the static performance of the stage, a dynamic model was established, and simulation analysis was performed to study the dynamic performance of the stage. Further, a prototype was manufactured and a series of experiments were carried out to test the performance of the stage. The results show that the maximum forward and backward movement speeds of the stage are 1 and 0.7 mm/s, respectively, and the minimum forward and backward step displacements are approximately 11 and 12 nm, respectively. Compared to the step displacement under no working load, the forward and backward step displacements only increase by 6% and 8% with a working load of 20 g, respectively. And the load capacity of the PASSNS in the vertical direction is about 72 g. The experimental results confirm the feasibility of the proposed stage, and high accuracy, high speed, and good robustness to varying loads were achieved. These results demonstrate the great potential of the developed stage in many nanopositioning applications.

scholarly journals Influence of Temperature Effect on the Static and Dynamic Performance of Gas-Lubricated Microbearings

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 716
Author(s):  
Liangliang Li ◽  
Zhufeng Liu ◽  
Chongyu Wang ◽  
Yonghui Xie
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Operating Environment ◽  
Low Friction ◽  
Operating Stability ◽  
Comprehensive Performance ◽  
Different Temperatures ◽  
Dynamic Performances ◽  
The Difference

Gas-lubricated microbearings are widely applied in multiple fields due to their advantages of high-speed, low friction level and other features. The operating environment of microbearings is complex, and the difference of temperature has an important influence on their comprehensive performance. In this investigation, FEM (finite element method) is employed to investigate the static, dynamic and limit characteristics of microbearings lubricated by different kinds of gas at different temperatures. The results show that the rise of temperature leads to the decline of equivalent viscosity of gas, which weakens the load capacity of microbearings, and furthermore, affects the operating stability of microbearings. The dynamic performances of microbearings at different temperatures are very different, and the two dynamic limit characteristics are more sensitive to temperature when it changes.

Research on sealing performance of oil seals with micro-dimple texture on lips

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fuying Zhang ◽  
Yuanhao Zhang
Keyword(s):  
Peer Review ◽  
Surface Texture ◽  
Elastohydrodynamic Lubrication ◽  
Friction Torque ◽  
Pumping Rate ◽  
Content Type ◽  
Rotation Direction ◽  
Sealing Performance ◽  
Pumping Efficiency ◽  
Shaft Seals

Purpose The purpose of this paper is to study the pumping efficiency of oil seals with different surface textures at different speeds, and the influence of the rotation direction of triangular texture on the sealing performance was further analyzed. Design/methodology/approach Based on the theory of elastohydrodynamic lubrication and the pumping mechanism of rotary shaft seals, establishing a numerical model of mixed lubrication in oil seal sealing area. The model is coupled with the lip surface texture parameters and the two-dimensional average Reynolds equation considering the surface roughness. Findings The results show that the application of lip surface texture technology has obvious influence on the oil film thickness, friction torque and pumping rate of oil seal. The triangular texture has the most significant effect on the increase of pump suction rate. When the rotation direction of triangular texture is 315 degrees, the pumping rate of oil seal is the largest compared with the other seven directions. Originality/value The model has a comprehensive theoretical guidance for the design of new oil seal products, which provides a certain basis for the application of surface texture technology in the field of sealing in the future. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2020-0198/

Performance studies of textured race ball bearing

2019 ◽  
Vol 71 (9) ◽  
pp. 1116-1123 ◽  
Author(s):  
Vivek Bhardwaj ◽  
R.K. Pandey ◽  
V.K. Agarwal
Keyword(s):  
Ball Bearing ◽  
Dynamic Performance ◽  
Critical Role ◽  
Operating Conditions ◽  
Frictional Torque ◽  
Bulk Temperature ◽  
Back Side ◽  
Ball Bearings ◽  
Content Type ◽  
Long Duration

Purpose The purpose of this paper is to develop an energy-efficient and dynamically improved thrust ball bearing using textured race. A texture has been used on the stationary race of the test bearing to conduct the long-duration experiment for exploring its tribological and vibrational behaviours under starved lubricating condition using micro size MoS2 blended grease. The performance behaviours of the textured race bearing have been compared with conventional bearing (i.e. having both races without textures) under the identical operating conditions for demonstrating the advantages of textured race. Design/methodology/approach Texture was created on stationary race of the test ball bearing (51308) using nano-second pulsed Nd: YAG laser. Performance parameters (frictional torque, temperature rise and vibrations) of textured ball bearings were measured under severe starved lubricating conditions for understanding the critical role of texture in the long duration of the test. S-type load cell and miniature accelerometer were used for measuring the frictional torque and vibration, respectively. Bulk temperature at stationary races (at the back side) of test bearings was measured in operating conditions using a non-contact infrared thermometer. Findings Significant reduction in frictional torque and decrease in amplitude of vibration with textured ball bearing were found even under the severe starved lubricating condition in comparison to conventional bearing. Originality/value There is dearth of research pertaining to the performance behaviours of ball bearings using textures on the races. Therefore, an attempt has been made in this study to explore the tribo-dynamic performance behaviours of a thrust ball bearing using a texture on its stationary race under severe starved lubricating condition for the longer duration of the test.

An adjustable oil film thickness test rig for detecting lubrication characteristics of slipper/swash-pair in piston pumps

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Haiji Wang ◽  
Guanglin Shi
Keyword(s):  
Film Thickness ◽  
Peer Review ◽  
Relative Error ◽  
Mathematical Analysis ◽  
Test Rig ◽  
Content Type ◽  
Oil Film ◽  
Displacement Sensors ◽  
Measuring Machine ◽  
Lubrication Characteristics

Purpose The purpose of this paper is to propose an adjustable oil film thickness test rig for detecting lubrication characteristics of the slipper. The mathematical analysis of lubrication is introduced. Based on the results from the test rig, the results comparison from test rig and mathematical analysis is carried out. Design/methodology/approach This paper introduces a mechanism which can adjust the oil film thickness between the slipper and swash-plate. Feasibility is ensured, and the accuracy of test rig is guaranteed by the three-coordinate measuring machine. Three displacement sensors show the oil film thickness and its shape. The reacting force and torque resulting from oil film can be achieved by three S-type force sensors and a torque sensor, respectively. Findings The relative error of the reacting force is small. The relative error reduces and is acceptable when the deformation of retainer is taken into account. The thickness and tilt angle of oil film have less effect on the reacting force. However, they are significantly impact on torque. Originality/value The test rig proposed in this paper is able to adjust the oil film thickness, which is used to detecting the lubrication characteristics in pump design. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2020-0166/

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