Hydrostatic Thrust Bearing Research Articles

Modeling of Textured Hydrostatic Thrust Bearings and Lubricating Films with Variable Thickness

Modeling of Textured Hydrostatic Thrust Bearings and Lubricating Films with Variable Thickness

Research on the Lubrication Performance of Hydrostatic Thrust Bearings Considering Dynamic Pressure Effect and Oil Film Pressure Loss

A lubrication performance mathematical model considering the dynamic pressure effect and pressure loss is proposed for stepped hydrostatic thrust bearings. The influence mechanism of rotational speed and load on the static pressure, dynamic pressure, pressure loss, total pressure, and total temperature of the clearance oil film is systematically discussed through a combination of theory, simulation, and experiment. The investigation found that the total temperature of the oil film decreases with increasing load and increases with increasing rotational speed. The pressure loss also becomes increasingly significant with higher rotational speeds. The dynamic pressure is not limited by the load but increases with the increase in rotation speed. The oil film pressure loss is jointly borne by static pressure and dynamic pressure within the range of 0 to 160 rpm and mainly borne by static pressure within the range of 160 to 200 rpm. Additionally, the trends of static pressure, dynamic pressure, total pressure, and temperature in the experiment are nearly consistent with those predicted by numerical simulations, thereby validating the effectiveness of the research methodology employed in this article.

Effect and optimization of triangular textures on lubrication performance of hydrostatic and hydrodynamic hybrid thrust bearings

Effect and optimization of triangular textures on lubrication performance of hydrostatic and hydrodynamic hybrid thrust bearings

Optimal design of structural engineering components using artificial neural network-assisted crayfish algorithm

Abstract Optimization techniques play a pivotal role in enhancing the performance of engineering components across various real-world applications. Traditional optimization methods are often augmented with exploitation-boosting techniques due to their inherent limitations. Recently, nature-inspired algorithms, known as metaheuristics (MHs), have emerged as efficient tools for solving complex optimization problems. However, these algorithms face challenges such as imbalance between exploration and exploitation phases, slow convergence, and local optima. Modifications incorporating oppositional techniques, hybridization, chaotic maps, and levy flights have been introduced to address these issues. This article explores the application of the recently developed crayfish optimization algorithm (COA), assisted by artificial neural networks (ANN), for engineering design optimization. The COA, inspired by crayfish foraging and migration behaviors, incorporates temperature-dependent strategies to balance exploration and exploitation phases. Additionally, ANN augmentation enhances the algorithm’s performance and accuracy. The COA method optimizes various engineering components, including cantilever beams, hydrostatic thrust bearings, three-bar trusses, diaphragm springs, and vehicle suspension systems. Results demonstrate the effectiveness of the COA in achieving superior optimization solutions compared to other algorithms, emphasizing its potential for diverse engineering applications.

Multiobjective optimization of hydrostatic thrust bearing operating with electrorheological lubricant using Taguchi-fuzzy technique

An electrorheological (ER) fluid falls in the category of a smart lubricant. In an ER lubricant, the dielectric microparticles are suspended in an insulating lubricant like silicon oil. The properties of ER fluids change when they encounter an external electric field. In the present study, the ER lubricant is modeled using a continuous Bingham model. The finite element method is utilized to solve the Reynolds equation to compute fluid film pressure and associated performance indices like load-carrying capacity, stiffness, and damping parameters of hydrostatic thrust bearing. In the present study, the influencing variables, that is, recess shapes, compensating elements, and strength of an electric field have been optimized using the fuzzy-based Taguchi optimization technique. The optimal combination of recess shape, compensating element, and electric field is required to enhance the performance of the hydrostatic thrust bearing. The authors attempt to see the interaction of the input variable by the trade-off study graph. A Taguchi fuzzy-based multipurpose optimization was proposed to optimize the performance indices and an optimal combination of compensating elements, recess shape, and electric field has been presented.

Research on the Support Performance of Internal Feedback Hydrostatic Thrust and Journal Bearing Considering Load Effect

This study aims to analyze the impact of uniform and eccentric load conditions on the performance of internal feedback hydrostatic thrust and journal bearing. Two distinct models are established: a three-degrees-of-freedom uniform load model and a five-degrees-of-freedom eccentric load model. The support stiffness, overturning stiffness, and flow rate for both thrust and journal bearings are calculated. Additionally, numerical analysis is conducted to examine the influence of oil film thickness, inlet pressure, and restrictor size on the operational characteristics of the bearings, revealing the interplay between an eccentric load and journal bearing speed. The validity of the theoretical algorithm is verified through finite element simulation. The research outcomes hold significant guiding implications for the design and application of internal feedback hydrostatic bearings.

The evaluation of two analytical solutions for a compliant single-recess hydrostatic thrust bearing

Employing flexible elements within the geometry of bearings has shown enhanced performance. This paper aims to validate numerically two original analytical models corresponding to two design solutions of a structurally compliant hydrostatic thrust bearing. Assessing the bearing performance relies on a fluid-structure interaction modelling. The analytical models consider a series of simplifications, which ensure simplicity without significantly sacrificing accuracy. Their numerical validation confirms their reliability, with acceptable relative differences between analytical and numerical outcomes—1–5 % at low and medium loads, attaining roughly 13 % at higher loads for either configuration; this allows further fast and elegant parametric analyses for design optimization.

A circular hydrostatic shallow recess thrust bearing integrating a micro-range tilting axis

This article investigates the integration of a micro-range (± 10 µrad) tilting axis into a shallow recess hydrostatic thrust bearing. The working principle relies on pressure taps machined into the bearing geometry, enabling the external manipulation of the local pressure distribution, causing a change in film geometry to restore equilibrium. To estimate the possibilities and limitations, the article presents a theoretical approach to calculate the properties of the integrated tilting axis and the influence on the inherent tilting stiffness of the bearing. Furthermore, performed measurements at 10 µm film height and 10 MPa supply pressure validate the proposed theory. This technology enables the extension of a conventional hydrostatic bearing by a robust, highly sensitive, and low-cost micro-range tilting axis.

Simulation and Experimental on Thermal Behavior of Hydrostatic Thrust Bearing Based on Superhydrophobic/oleophobic Surface

Abstract The temperature rises of oil film in hydrostatic bearings at high-speed lead to a reduction in load capacity, accuracy and stability. In this paper, a superhydrophobic/oleophobic surface with micro-bulges structure is proposed. The surface is prepared by laser cross-scanning and chemical modification. The contact angle (CA) of surface is 138° and the boundary condition of surface modificated from non-slip to slip condition. The relationship between the slip length and the height of the micro-bulges structure is established by rheological experiments. By the simple partial simulations, validity of the temperature rise reduction on the superhydrophobic/oleophobic surface is verified. Then a bearing test rig was set up to measure temperature and load capacity of bearings at multiple points, the performance of smooth primary surface/structured oleophobic surface thrust bearings was compared. Results show that the structured bearing has lower oil film temperature and higher load capacity than the smooth bearing. The prepared oleophobic surface can effectively suppress the temperature rise at high speed conditions, and significantly increase the bearing load capacity.

Investigation on the Dynamic Pressure Effect of Clearance Oil Film at a Stepped Hydrostatic Thrust Bearing Working in Heavy Loading Duty

The dynamic pressure effect of the clearance oil film of stepped hydrostatic thrust bearing is studied by taking the double rectangular cavity oil cushion as an example. According to the hydrodynamics theory, the dynamic pressure of lubricating oil film in different clearance height regions is theoretically deduced and calculated. The dynamic pressure effect of the clearance oil film in the stepped hydrostatic thrust bearing is studied through the combination of theoretical calculation, simulation, and experimental verification. It is found that the experimental value of the dynamic pressure is between the theoretical value and the simulated value, which is basically not affected by the load. In the speed range of 0 r/min–200 r/min, compared with the viscosity of lubricating oil, the speed is the main factor affecting the dynamic pressure of the oil film of the stepped hydrostatic thrust bearing. The dynamic pressure value of the clearance oil film increases in a stepped fashion along the radial direction of the double rectangular cavity oil cushion. The dynamic pressure value has an obvious upward trend at the junction of the circumferential right oil cavity and the sealing edge and then decreases to 0 after reaching the peak value.

Research on influencing factors of oil film temperature field characteristics for adaptive hydrostatic thrust bearing

Adaptive hydrostatic thrust bearing represents a mechatronic answer to the fast-growing industrial needs of high-performance rotary machineries. The aim of this research is to study the influencing factors of the temperature field characteristics of the adaptive hydrostatic thrust bearing, such as rotational speed, load, viscosity, and inlet flow rate. The temperature rise equation of the micro-gap oil film is derived, and a three-dimensional model of micro-gap oil film is established. Finite Volume Method and ANSYS FLUENT are used to explore the influence factors of the temperature rise of the micro-gap oil film based on the principle of Computational Fluid Dynamic. The results show that temperature rise on the downstream side of the oil cavity is higher than that on the countercurrent side, and the temperature rise on the edge of the outer oil sealing edge is higher than that on the inner oil sealing edge. The rotational speed has the greatest impact on the oil film temperature rise, followed by viscosity, inlet flow rate, and then load. The increment of oil film temperature rise with the load less than 16 t is higher than the increment of oil film temperature rise with the load greater than 16 t. When the rotational speed is lower than 80 rpm, the temperature rise of the oil film increases faster with the increase of the rotational speed than when the rotation speed is above 80 rpm. The inlet flow rate increases, the maximum temperature and average temperature rise of the oil film decreases, but there is little variation. The maximum temperature and average temperature rise increase with the increase of viscosity, and the greater the viscosity, the more obvious nonlinear.

Study on static and dynamic characteristics of water-lubricated hydrostatic thrust bearings – Effect of feed hole inlet shape on bearing characteristics

Recently, water-lubricated hydrostatic bearings have been attracting attention. However, when water is used as the lubricating fluid, the flow velocity of the feed hole used as a restrictor is higher than that of conventional oil-lubricated hydrostatic bearings, resulting in a larger feed hole inlet flow velocity, making it difficult to analyze its characteristics using conventional hydrostatic bearing analysis methods. Therefore, in this study, a general-purpose fluid analysis tool has been used to numerically analyze the internal flow of two types of pocket-type water-lubricated hydrostatic thrust bearings with different feed hole inlet geometries and found that the pressure loss at the feed hole inlet is large for water-lubricated bearings and that the flow inside the feed hole is different from that of oil-lubricated hydrostatic bearings. The orifice effect at the feed hole inlet is found to account for most of the restrictor function. Furthermore, it was shown that the pressure loss at the feed hole inlet can be increased by adopting a right-angle inflow structure for the feed hole inlet geometry, which can improve the static and dynamic characteristics of the bearing.

Research on influencing factors of deformation of hydrostatic thrust bearings

When the hydrostatic thrust bearings operate under conditions of high speed and heavy load, the oil film will be strongly sheared and squeezed, which will increase the temperature of the hydrostatic oil film, resulting in uneven deformation of the workbench and tribology in serious cases. The deformation of the friction pair greatly affects the stability of the workbench during operation, and then affects the machining accuracy. Taking the hydrostatic thrust bearings as the research object, the model of hydrostatic thrust bearings was established based on the fluid–thermosolid coupling theory, and the influencing factors of the deformation of the hydrostatic thrust bearings are analyzed using ANSYS Workbench software, and the influencing laws are discussed. Finally, the correctness of the simulation method is verified by experiments. The results show that the larger the lubricating oil viscosity, the greater the deformation of the guide surface and the oil pad. With the increase in the rotation rate, the deformation of the guide surface and the oil pad increases continuously. With the increase in the inlet flow rate, the deformation of the guide surface and the oil pad is continuously reduced. In engineering practice, on the premise of ensuring the bearings capacity, low-viscosity lubricating oil should be used as much as possible, the rotation rate should be lower, or the inlet flow rate should be increased.

Experimental Force Coefficients of a Hydrostatic Thrust Bearing and Comparisons to Predictions

Abstract Reliable fluid film bearings for high-performance turbomachinery provide significantly extended operating life with controllable stiffness and damping force coefficients at low cost. Hydrostatic thrust bearings support thrust loads and control axial motions. This paper reports measurements and predictions of static and dynamic load characteristics of a hydrostatic thrust bearing fed with pressurized air. The current bearing model uses dynamic axial periodic motion amplitudes, that is, models as a function of the initial film thickness, to predict the dynamic force coefficients. Note that, presently, the recorded frequencies and their amplitudes of pneumatic hammer instability along the axial direction are implemented as an external excitation source. The measured and predicted static stiffnesses increase as the film thickness decrease and supply pressure into the bearing increase. The predicted dynamic force coefficients show a favorable agreement with the test data. Analysis reveals the negative damping coefficients and damping ratios as a distinctive onset condition of the present pneumatic hammer instability of the test bearing. A careful recess design and adequate operation conditions along with an accurate prediction can avoid or prevent undesirable pneumatic hammer instability in hydrostatic thrust bearings. This work extends the knowledge database of hydrostatic thrust bearings with pneumatic hammer instability and provides their design guideline for various operating conditions.

A novel hybrid Fick’s law algorithm-quasi oppositional–based learning algorithm for solving constrained mechanical design problems

Abstract In this article, a recently developed physics-based Fick’s law optimization algorithm is utilized to solve engineering optimization challenges. The performance of the algorithm is further improved by incorporating quasi-oppositional–based techniques at the programming level. The modified algorithm was applied to optimize the rolling element bearing system, robot gripper, planetary gear system, and hydrostatic thrust bearing, along with shape optimization of the vehicle bracket system. Accordingly, the algorithm realizes promising statistical results compared to the rest of the well-known algorithms. Furthermore, the required number of iterations was comparatively less required to attain the global optimum solution. Moreover, deviations in the results were the least even when other optimizers provided better or more competitive results. This being said that this optimization algorithm can be adopted for a critical and wide range of industrial and real-world challenges optimization.

Feasibility Analysis of Adopting the Hydrogen Hydrostatic Thrust Bearing

The hydrogen hydrostatic thrust bearing (HHTB) is a key component of hydrogen liquefaction that impacts turbo-expander characteristics. To analyze the feasibility of using the HHTB in this application, characteristics of HHTBs were calculated using a CFD model. To upgrade the performance of the HHTB, the impacts of bearing structure and operating parameters on static performance were investigated. Dynamic characteristics of the HHTB were studied using the dynamic grid method. It was found that the load capacity of the HHTB is less than that of helium-lubricated bearings but higher than that of air- and methane-lubricated bearings. The turbulent kinetic energy of hydrogen is higher than that of other gases. Load capacity can be enhanced through boosting supplied pressure, expanding the diameter of supply orifices, reducing gas film clearance, increasing the orifices quantity and setting a circumferential groove. A reduction in disturbance amplitude slightly increased the bearing’s dynamic stiffness. The dynamic stability of the HHTB was improved by a small film clearance in response to disturbance.

Investigation of the Static Performance of Hydrostatic Thrust Bearings Considering Non-Gaussian Surface Topography

The dynamic and static characteristics of hydrostatic thrust bearings are significantly affected by the bearing surface topography. Previous studies on hydrostatic thrust bearings have focused on Gaussian distribution models of bearing surface topography. However, based on actual measurements, the non-Gaussianity of the distribution characteristics of bearing surface topography is clear. To accurately characterize the non-Gaussian distribution of bearing surface topography, the traditional probability density function of Gaussian distribution was modified by introducing Edgeworth expansion. The non-Gaussian surface was then reflected by two parameters: kurtosis and skewness. This had an effect on the static characteristics of hydrostatic thrust bearings with both circumferential and radial surface topographies. The comparison between the Gaussian distribution results and those of the non-Gaussian model showed that errors between the two models could reach more than 10%. Therefore, it is important to take into account the non-Gaussianity of bearing surface when discussing static characteristics of hydrostatic thrust bearings considering the surface topography.

Comparative study on single-objective optimization and multi-objective optimization of convex textured friction couple performance

To improve the friction property of the friction pair of the hydrostatic thrust bearing, the surface with convex textures is designed at the bottom of the oil cavity, and the effect of convex textures on the interstitial oil film performance is analyzed. The interstitial oil film in contact with convex textures is simulated and studied by the computational fluid dynamics method. The study shows that the oil cavity with the convex structures can significantly improve the friction characteristics of the gap oil film in the hydrostatic thrust bearing. In order to further study the effect of texture parameters (texture radius, texture spacing , texture quantity and texture area ratio ) on its performance, the method based on the full factor test is used for single objective optimization, and the methods based on the BBD response surface and the NSGA-II algorithm are used for multiple target collaborative optimization. The full factor test with the main effect shows that the best combination with the bearing capacity is 0.5 mm, 7 mm, 7 and 1.6%, and the best combination with the rigidity is 0.3 mm, 5 mm, 5 and 1.13%. The influence of textures on the maximum temperature of oil film is basically unchanged and the bearing capacity is in inverse proportion to the friction factor. When considering the interaction between texture parameters, the BBD response surface method is used for multi-objective optimization. The study shows that the texture radius is 0.7 mm, the texture spacing is 7 mm, the quantity of textures is 6.2, and the area ratio is 3.14%, the optimal response values can be obtained, which the bearing capacity is 8519.31 N and the rigidity is 1.31868 E + 12 N m−1. The multi-objective optimization analysis of the NSGA-II algorithm based on the BBD response surface model shows that the algorithm can obtain a Pareto solution set. Each set of solutions obtained by the NSGA-II algorithm is the optimal solution. Both the BBD response surface method and the NSGA-II algorithm can be used to solve multi-objective problems.

Experimental and theoretical study on the dynamic stiffness of circular oil hydrostatic shallow recess thrust bearings

The dynamic stiffness of traditional (deep recess) hydrostatic bearings decreases due to the fluid compressibility between the bearing and a compensation device, e.g., a capillary. Shallow recess bearings, on the other hand, reduce the influence of fluid compressibility on dynamic stiffness through a reduced compressible volume and inherent stiffness. This article outlines a theoretical and experimental study of the dynamic stiffness of oil hydrostatic shallow recess thrust bearings without external compensation devices and in combination with external capillaries. The measurements performed in the study validate the theoretical models and the potential to increase dynamic stiffness. In addition, analytical solutions are proposed for the stiffness and damping of a circular shallow recess thrust bearing.

A novel hybrid flow direction optimizer-dynamic oppositional based learning algorithm for solving complex constrained mechanical design problems

Abstract In this present work, mechanical engineering optimization problems are solved by employing a novel optimizer (HFDO-DOBL) based on a physics-based flow direction optimizer (FDO) and dynamic oppositional-based learning. Five real-world engineering problems, viz. planetary gear train, hydrostatic thrust bearing, robot gripper, rolling bearing, and multiple disc clutch brake, are considered. The computational results obtained by HFDO-DOBL are compared with several newly proposed algorithms. The statistical analysis demonstrates the HFDO-DOBL dominance in finding optimal solutions relatively and competitiveness in solving constraint design optimization problems.