Plain Bearings Research Articles

Assessment of the impact of 3D printed water-lubricated cutless bearings material on vibration parameters.

The tested bearings were subjected to equal loads and rotational speeds, using water as the lubricant. Analysis showed that they achieved the best vibration damping at lower speeds, between 600 and 1100 rpm. Comparative studies of bearings made of different materials, such as available on the market bearings made of rubber, bearings printed with a 3D printer from PETG, PLA, ABS or Tribo filament materials, revealed differences in their vibration damping ability and operational stability. Conclusions from the study suggest that higher vibration acceleration may increase the radius of the trajectory, which may affect the function and performance of the bearings. The importance of the operational stability of water-lubricated plain bearings cannot be assessed solely on the basis of the RMS of vibration acceleration or trajectory radius. Both of these parameters are crucial from the user's point of view, especially in the context of various applications such as electric boats.

Feasibility study on preloaded flexible conical plain bearings as wind turbine main bearings

Wind turbines (WT) are a key technology towards a carbon neutral energy production worldwide. Currently about 30 % of the Levelized Cost of Electricity (LCoE) consist of service and maintenance. Critical components are the main roller bearings which have a failure probability between 15 and 30 % within 20 years. Main bearing replacements are expensive maintenance procedures because an external crane is needed which cost about $250.000 per day for offshore WTs. Hence, a discussed countermeasure within the wind industry is to use segmented plain bearings in future WTs. These types of bearings allow an up-tower sub-component wise replacement of faulty parts without the need to dismantle the whole drivetrain. Therefore, the Chair for Wind Power Drives (CWD) developed, tested and validated a segmented conical plain bearing concept for the use as a main bearings for WTs. To function properly common plain bearings need a minimum clearance to allow the formation of a convergent lubrication gab. This initial clearance negatively influences run-out, as the shaft con move freely within the limits of the clearance. As WT drivetrain concepts become more integrated, main bearings for WTs need to fulfill higher requirements regarding the allowable run-out of the main shaft. Therefore, a fundamental design challenge arises for plain bearings as rotor main bearings. One approach to reduce run-out for roller main bearings is to use preloaded tapered roller bearings. For common plain bearings however preloading is not possible. However, the concept of preloading was successfully transferred to the flexible conical plain bearing concept developed at the CWD and the main shaft run-out severely reduced. In this work the feasibility of a preloaded flexible conical plain bearing as a WT rotor main bearing is evaluated and the advantages and disadvantages contrasted.

The influence of plasma spraying parameters on microstructure and hardness of aluminium-bronze-polyester-YSZ composite coatings for plain bearings applications

The influence of plasma spraying parameters on microstructure and hardness of aluminium-bronze-polyester-YSZ composite coatings for plain bearings applications

A simplified model for the wear prediction of plain bearings in the variable stator vane system

The wear of plain bearings in the variable stator vane (VSV) systems in a turbojet engine is a significant problem for compressor efficiency and stability requiring adapted models. The VSV bearings are located in a complex system and are exposed to combined and oscillating loads. This study aims to predict the wear evolution of the VSV bearings, considering the complexity of the system’s geometry and the loads with adapted computational time. This paper presents a three-dimensional formulation of this highly nonlinear wear problem under simplifying hypotheses in the objective to obtain a compromise between the quality of the prediction and the CPU time.

A Comprehensive Numerical Study of a Wedge-Shaped Textured Convergent Oil Film Gap

The modification of surface geometries to reduce friction is an omnipresent topic of research. In nature, different low-friction surfaces, such as fish skins, exist. To transfer this knowledge to technical applications, for example, to journal or plain bearings, many numerical and experimental studies of textured surfaces have been performed. In this work, the influence of the geometric parameters (texture length l, width b, angle α and start position xstart) of a wedge-shaped texture on three different convergent oil film gaps was analyzed in full-film lubrication and compared with untextured oil film gaps. With the aid of a CFD (computational fluid dynamics) model, a comprehensive variation study was conducted, and the best-performing wedge-shaped texture was determined. The results show that an open texture at the inlet provides the largest improvement. Furthermore, it can be observed that the optimal relative texture width and absolute inlet height for the three investigated oil film gaps are similar. In contrast to the volume flow of the untextured geometry, the volume flow of the textured one is significantly higher, especially that perpendicular to the movement direction.

Designing Large Segmented Flexible Conical Plain Bearings as Wind Turbine Main Bearings

Main bearings are failure-prone components in wind turbines, significantly increasing the LCOE of wind energy. Therefore, segmented plain bearings are being discussed as replacement for the currently used rolling bearings. Segmented plain bearings allow an up-tower replacement of faulty segments without the need to dismantle the WT drivetrain, as is required for rolling bearing replacements. One such bearing is the segmented, flexible, conical “FlexPad” plain bearing as alternative to existing double row tapered roller bearings. Designing the FlexPad bearing manually is very complex and thus time-consuming. Hence, during the research project a new holistic design method for large and highly loaded, conical plain bearings was developed. To prove the suitability of the method, two bearing prototypes were built and tested. The prototype, designed with the new method, outperformed the first, manually designed bearing, in terms of the design objectives. Most importantly, the friction losses were reduced by 32.1%. The project results show that the new method is able to efficiently design safely operating FlexPad bearing variants for wind turbines.

Impact of Oil Film Dynamics on the Performance of Aeroengine Plain Bearings

Impact of Oil Film Dynamics on the Performance of Aeroengine Plain Bearings

Influence of housing hole accuracy on the starting torque of self-lubricating spherical plain bearings

The accuracy of the housing hole mainly refers to the dimensional tolerance, ovality and surface roughness of the hole, which directly affects the swing flexibility and service life of the self-lubricating spherical plain bearings (SSPBs) after the bearing is fitted in the housing hole. The dimension tolerance between the bearing and the housing has been ordained in the aviation standard. However, it is found that the ovality and surface roughness of the housing hole also have a great influence on the interference fit state, thus affecting the starting torque. In this paper, the effects of the three indexes of the housing hole accuracy (dimensional tolerance, ovality and surface roughness) on the starting torque were studied. Firstly, a theoretical analysis of the liner deformation inside the bearing was carried out based on the Lame equation. Then, the concept of equivalent interference was proposed considering the interference fit caused by the ovality and surface roughness, and the amount of the equivalent interference was determined. Furthermore, the influences of the three indexes on the starting torque were studied quantitatively with theoretical solution, numerical analysis and experimental verification. The results showed that the proposed concept of the equivalent interference can analyze the influence of the ovality and the surface roughness effectively, and the ovality has a greater effect on the starting torque than the surface roughness. The three precision indexes of the housing hole are reasonably designed to ensure that the starting torque after fitted meets standard requirements.

Behavior of Lubricated Bearings in Electric Circuits

In recent years, electrical damage phenomena in rolling and plain bearings have become increasingly important due to the growing electrification of individual mobility and renewable energy technologies [...]

Checking the Mechanisms of Internal Combustion Engines for the Presence of Parasitic Forces Using a New Methodology

This article presents the results of a study of internal combustion engines equipped with a crank mechanism according to the efficiency criterion using a new method for determining the operating efficiency of machines and engines. The study revealed the presence of parasitic forces in internal combustion engines equipped with a crank mechanism. The occurrence of parasitic forces present in internal combustion engines and the law of their dependence on the movement of the piston have been studied. As well as the negative impact of parasitic forces on engine efficiency. This article presents the main results of the study. As a result of the research, it was revealed that when converting the thermal energy generated in the combustion chamber of internal combustion engines equipped with a crank mechanism into mechanical work, more than 30% of the energy of the pressure force is spent on parasitic forces. The influence of the mechanical friction force (friction of the plain bearings) with the crankshaft on the effective torque was also studied. Thus, the inefficiency of internal combustion engines equipped with a crank mechanism has been theoretically and practically proven. Finally, recommendations are given for eliminating parasitic forces when designing new internal combustion engines. It is proposed to equip new internal combustion engines with mechanisms without parasitic forces. Equipping internal combustion engines with a mechanism that does not contain parasitic forces (that is, equipping them with more efficient mechanisms) significantly increases the possibility of efficient use of the thermal energy of the fuel introduced into the combustion chamber in internal combustion engines. Consequently, this increases the engine efficiency by 130%. or more. For internal combustion engines, a new mechanism is recommended that eliminates the loss of force and allows the use of rolling bearings. This feature of the new mechanism makes it possible to increase the efficiency of internal combustion engines by another 4-6%. From previous studies it is known that the efficiency of a rolling bearing relative to a plain bearing is more than 2-3 times.

The Influence of Plasma Spraying Parameters on Microstructure and Porosity of Bronze-Polyester Coatings for Plain Bearings Applications

The plasma sprayed bronze coatings are widely used for repairing of plain bearing used in different applications. This type of coating was not deeply analyzed in state-of-art publications. In presented article we fill this gap in the case of plasma spraying process. The influence of power current (300/500/700A) and hydrogen flow (0/4/8 NLPM) on microstructure and thickness of aluminium bronze-polyester coating was investigated. The Thermico A60 plasma torch was used for thermal spray process of coating on flat carbon steel samples (grade S355). The Metco 604NS was sprayed with 20g/min powder feed rate. The obtained results showed the presence of local large pores formed by burning of polyester in plasma plume. This gap makes role of oil pockets in bearings. The obtained coatings were characterized by large deviation in thickness in range 200-350 micrometers. It might be concluded that in requires additional milling process after deposition.

Behavior of an aerodynamic sliding bearing with textured surface under turbulent conditions

Abstract Recent advancements in turbomachinery development aim to reduce components while improving performance and minimizing environmental impact. Aerodynamic bearings, supporting high-speed rotors by dissipating significant energies, are key elements requiring thorough understanding. In order to better predict the behavior of aerodynamic bearings operating under severe conditions, numerical models using computational fluid dynamics have been employed to study the thermal effect on the tribological behavior of these air-lubricated bearings. An analysis of surface texturing of the bearings has also been conducted to evaluate its influence on operational performance compared to non-textured surfaces, considering the influence of rotation speed, radial load, and textures on the tribological performance of plain bearings. The main results observed are as follows. First, there is a noticeable change in geometric characteristics, such as the application of micro-textures, lubrication and friction, compared with conventional plain bearings. This textured surface appears to have a significant influence on the pressure and velocity distribution of the lubricating fluid, leading to significant changes in the bearing's tribological and operational performance. In addition, numerical analysis also reveals significant variations in shear stresses in the vicinity of the bearing walls. These variations can potentially affect the strength and durability of the bearing under severe operating conditions. Additionally, the results show a downward trend in system temperature, suggesting improved thermal management thanks to the textured surface. Another essential aspect revealed by this analysis is the decrease in the coefficient of friction with increasing shaft speed. This observation underlines the importance of operating speed and applied radial load in the bearing's tribological behavior and suggests further optimization possibilities for reducing energy losses and extending the life of the aerodynamic sliding bearing.

Research on Improving the Tribological Properties of Bearings under Cryogenic Conditions

Bearings, as one of the most central components of rotating equipment, are widely used both in servo steering gear, aerospace and other fields. However, for extremely cryogenic conditions, the life of bearings is low, so it is necessary to carry out the tribological design of bearings to improve its cryogenic performance. In this paper, four kinds of optimized and improved plain bearings are designed. The tribological tests of these four bearings under extreme cryogenic working conditions were carried out using the developed bearing simulation test rig. The results show that under the same load and rotational speed conditions, the preparation of micro-weave structure on the surface of the shaft tile or the preparation of composite coating on the surface of the journal can improve the friction and wear performance of the bearings to a certain extent. When both methods are used at the same time, the friction reduction and anti-friction wear effect of the sliding bearing is better. This study not only provides theoretical guidance and technical support for improving the cryogenic tribological performance of bearings, but also has important practical significance for the future development of rotating equipment in the low-temperature field.

Tribological studies of materials for sliding bearings when lubricated with hydraulic fluid

Tribological research of materials BrOPh6.5-0.15, PH4M paired with 40X steel and lubricated with hydraulic fluid AMh-10 showed good antifriction properties. The results of the research on the influence of load, speed and temperature on the coefficient of friction of materials: BrOPh6.5-0.15 and PH4M when lubricated with AMh-10 hydraulic fluid. At a load of 0.5447 MPa, the coefficient of friction of BrOPh6.5-0.15 material at a temperature of 90°C is 1.58 times higher, and at a load of 2.003 MPa, the coefficient of friction of BrOPh6.5-0.15 material is 2.85 times higher than the coefficient of friction of BrOPh6.5-0.15 material at a temperature of 20°C. Materials BrOPh6.5-0.15 and PH4M are promising for application in plain bearings of pumps pumping hydraulic fluid AMh-10.

ОСОБЕННОСТЬ МЕХАНИЗИРОВАННОЙ ПОСАДКИ МАЛИНЫ САЖЕНЦАМИ С АСИММЕТРИЧНОЙ КОРНЕВОЙ СИСТЕМОЙ

An analysis of planting machines used in horticulture and forestry is given in the article. A version of the most simplified machine with the placement of a planting disk and support wheels on one axis mounted on plain bearings is proposed for planting raspberries. The results of studying an array of typical seedlings for the shape and overall dimensions of their root system are given. It has been established that up to half of the studied array of planting material has a root system close to the symmetrical type, and 37.5% of seedlings are characterized by a twofold or more degree of asymmetry. The nature of the interaction between the root system of a seedling and the soil covering it is shown. The seedling is placed in the seedling holder with the most developed part of the roots forward in the direction of rotation of the disk. The combined vertical and longitudinal pressure of the soil coming from the harrows overturns the seedling, as a result of which its stem can take a position close to horizontal. If, when placing a seedling in a seedling holder, the most developed part of its root system is oriented in the direction opposite to the direction of rotation of the planting disk, then, as a rule, in the final position the stem of the seedling is inclined from the vertical at a small angle. It has been established that the spatial orientation of the stem of a raspberry seedling has no practical significance, because the root shoots that grow after planting are bearing fruit, the quality of which is not related to the spatial orientation of the original stem. The planting machine has been successfully used on the farm for 25 years. It has been established that after its passage, about 5% of planted plants require additional manual trimming.

Improving the reliability of the turbocharger seal assembly by optimizing the elements of the seal assembly

Currently, most power units using internal combustion engines are equipped with turbocharging and that is explained by the requirements for efficiency, environmental safety and specific power characteristics. At the same time, the turbocompressor (TCR) is one of the resource-determining elements of power units, which accounts for a significant number of failures. Studies conducted towards the analysis of turbocompressor failures have shown that the main reason for it lies in a malfunction of the seal assembly, which is a consequence of extremely unfavorable conditions for its operation, consisting in a high (up to 800 оС) exhaust temperature, aggressive environment, a high (up to 120.000 min-1) rotor speed, the sliding speeds of the mating parts, up to 150 m/s. Oil for lubrication and cooling of the TCR is supplied through floating plain bearings, while the cavities of the turbine and compressor are isolated by means of the seal assemblies. Violation of their operability leads to the ingress of oil in a cavity of the impellers, to the imbalance of a rotor and, ultimately, to a turbocompressor failure. The determining factor affecting the operability of the seal assembly is a heat density of its parts. This factor is especially manifested in operating under forced conditions and engine shutdown, when cooling of a turbine volute is stopped by blown air, and a bearing assembly is stopped by circulating oil. In this case, a large part of the thermal energy is transferred from a heated turbine volute to the seal assembly and to the bearing assembly. The focus is on the temperature influence on performance of the turbocompressors’ sealing rings.

Investigation and application of EB-PVD and related processes for high-rate deposition of aluminum alloys

Electron beam physical vapor deposition (EB-PVD) with high power axial EB guns has high deposition rates and therefore is well suited for depositing comparatively thick coatings with high throughput in mass production processes. The top sliding layer on bearing shells is a well-known use case for this technology. In low-cost manufacturing, often semi-finished products such as sheets or strips are coated, from which final products with a broad range of dimensions can be manufactured.The adaptation of related processes such as pretreatment and substrate cooling of three different semi-finished products was the focus of the investigations. All process steps were optimized for high throughput. Deposition with AlSn or AlSnCu alloys was carried out at coating rates up to 1 μm/s. These alloys, containing elements with different vapor pressures, were evaporated out of one continuously fed crucible with long-term stability.The deposited coatings have finely dispersed tin clusters in the aluminum matrix. The tin clusters have linear dimensions in the range of 200 to 400 nm. This size range is a direct consequence of the high coating rate; it is thus process-specific for EB-PVD. Such coatings are highly beneficial for applications such as plain bearings. Initial load tests have impressively confirmed the advantages for EB-PVD processed bearings.

Bayesian inference-based wear prediction method for plain bearings under stationary mixed-friction conditions

This study introduces a method to predict the remaining useful life (RUL) of plain bearings operating under stationary, wear-critical conditions. In this method, the transient wear data of a coupled elastohydrodynamic lubrication (mixed-EHL) and wear simulation approach is used to parametrize a statistical, linear degradation model. The method incorporates Bayesian inference to update the linear degradation model throughout the runtime and thereby consider the transient, system-dependent wear progression within the RUL prediction. A case study is used to show the suitability of the proposed method. The results show that the method can be applied to three distinct types of post-wearing-in behavior: wearing-in with subsequent hydrodynamic, stationary wear, and progressive wear operation. While hydrodynamic operation leads to an infinite lifetime, the method is successfully applied to predict RUL in cases with stationary and progressive wear.

Investigation of Wear Resistance of Polyamide PA6 Based Composite Materials for Metal - Polymer Plain Bearings and Gears

Metal-polymer plain bearings and gears are becoming increasingly used in many areas of human activity. The wear resistance of one group of such materials - unreinforced polyamides PA6, PA66, and composites with fillers РА6+30GF, РА6+30CF, РА6+MoS2, РА6+Оil was studied. To determine their wear resistance indicators the author's method of model triboexperimental research according to the scheme of end friction at dry sliding friction paired with carbon steel (0.45%C) is used. According to the determined wear resistance indicators, are calculated as the basic parameters of the author's mathematical model of materials’ wear kinetics at sliding friction and the analytical method of the research of specified friction units. Based to the research, polymeric materials’ wear resistance diagrams are plotted as graphical indicators of wear resistance in the accepted range of specific friction forces. The qualitative and quantitative influence of the type and structure of the fillers on the wear resistance has been established. Qualitatively, the nature of the change in wear resistance of the indicated types of polyamides is similar, quantitatively the difference is significantly differentiated. It was found that PA6+Oil has the highest wear resistance compared to the РA6. It consistently increases in the following sequence: PA66, РA6+30GF, РA6+MoS2, РA6+30CF, РA6+Oil.

Application of Gas Saturation in Radial Plain Bearings

Application of Gas Saturation in Radial Plain Bearings