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This paper aim to take the ship shaft stern bearing as the research object, and studies the influence of journal axial vibration on bearing dynamic characteristics under different misaligned angles and rotation speeds.

Computational fluid dynamics (CFD) and harmonic excitation method were used to build bearing unstable lubrication model, and the dynamic mesh technology was used in calculation.

The results indicate that journal axial vibration has a significant effect on bearing dynamic characteristics, like maximum oil film pressure, bearing stiffness and damping coefficients, and the effect is positively correlated with journal misaligned angle. The effect of shaft rotation speed and journal axial vibration on bearing dynamics characteristics are independent; they have no coupling. Bearing axial stiffness is mainly affected by the journal axial displacement, bearing axial damping is mainly affected by journal axial velocity and they are positively correlated with the misaligned angle. The influence of rotational speed on bearing axial stiffness and axial damping is not obvious.

This paper establishes the bearing dynamic model by CFD and harmonic excitation method with consideration of cavitation effect and analyzing the influence of journal axial vibration on the dynamic characteristics. The results are benefit to the design of ship propulsion shaft and the selection of stern bearing. Also, they are of great significance to improve the operation stability of the shaft bearing system and the vitality of the ship.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2022-0337/

The purpose of this paper is to discuss the calculation problem of the real carrying capacity of slewing bearings. The selection of slewing bearing to heavy-duty machine according to catalogue carrying capacity and also according to locally determined real carrying capacity is insufficient and it can be the cause of the damage of machine during exploitation.

The concepts of the local, total and general capacities is defined. The general capacity is a logical product of the local capacities. It is particularly useful in an analysis of slewing bearings incorporated into machines with complex structures. The FEM is applied in computations. The formation method of the mathematical model of a bearing is presented.

The computations of the local capacities and general capacity of a bearing for the limiting load of the bearing traces and the limiting tension of the bolts fastening the bearing were carried out. Considerations were illustrated by an example of the bearing of a mobile crane.

The paper presented in the methodology of the calculation of general bearing carrying capacity and the obtained results of calculations can be used already by designers of bearings and machine engines to elimination of the potential damages of machine on the stage of projecting.

The general capacity of a bearing into machines with complex and irregulars structure is considerably lower than the bearing catalogue capacity and then the local teal capacity. The reasons for the differences between the catalogue capacity and the general capacity of slewing bearings were given.

Currently, there is a lack of fast and highly accurate on analytical solution of Reynolds equation for evaluating the characteristics of surface textured bearing. This paper aims to develop such an analytical solution of Reynolds equation for an effective analysis of the characteristics of surface textured bearings.

By using the separation of variables method and mean eigenvalue method, the analytical solution is constructed. The CFD simulations and experimental results are used to validate the correctness of the analytical solution.

The analytical solution can accurately evaluate the characteristics of textured bearings. It is found that the larger the eccentricity ratio and aspect ratio, the greater the oil film force. It also found that the smaller the eccentricity ratio, the larger the Sommerfeld number S. When eccentricity ratio e = 0.65, the attitude angles of different oil boundaries are same. The effect of different aspect ratios on dynamic stiffness and damping coefficient generally follows a same trend. It is numerically shown that the critical speed of rotor-bearing is 3500 rpm.

The analytical solution provides a simple yet effective way to study the characteristics of surface textured bearings.

The well-operating condition of journal bearing is the assurance to keep superior performance of water-lubricated twin-screw compressor. To design the journal bearing more reasonably for this type of compressor, this paper aims to study the effects of rotating speed and design parameters on bearing characteristics, considering surface roughness and bending deformation of the shaft at the same time.

The average Reynolds equation considering the effect of surface roughness is adopted and solved by finite difference method and successive over-relaxation method to calculate pressure distribution with real bearing shapes and boundary conditions. The bending deformation of the shaft is calculated using simply supported beam model of variable cross-section.

The dynamic lubrication characteristics of four water-lubricated journal bearings in twin-screw air compressor are calculated and analyzed. In addition, the static characteristics of journal bearing including friction coefficient, film thickness ratio distribution and water film pressure distribution are calculated numerically with different rotating speed and design parameters. Moreover, some design principles of water-lubricated bearing for twin-screw compressor are put forward.

The lubrication characteristics of the water-lubricated journal bearing in twin-screw air compressor are calculated considering surface roughness and bending deformation of the shaft at the same time. The paper’s results may provide design guidelines for journal bearing in this kind of twin-screw compressor.

This study aims to investigate the rarefaction effects on flow and thermal performances of an equivalent sand-grain roughness model for aerodynamic thrust bearing.

In this study, a model of gas lubrication thrust bearing was established by modifying the wall roughness and considering rarefaction effect. The flow and lubrication characteristics of gas film were discussed based on the equivalent sand roughness model and rarefaction effect.

The boundary slip and the surface roughness effect lead to a decrease in gas film pressure and temperature, with a maximum decrease of 39.2% and 8.4%, respectively. The vortex effect present in the gas film is closely linked to the gas film’s pressure. Slip flow decreases the vortex effect, and an increase in roughness results in the development of slip flow. The increase of roughness leads to a decrease for the static and thermal characteristics.

This work uses the rarefaction effect and the equivalent sand roughness model to investigate the lubrication characteristics of gas thrust bearing. The results help to guide the selection of the surface roughness of rotor and bearing, so as to fully control the rarefaction effect and make use of it.

The present paper aims to analyse the synergistic effect of pocket orientation and piezo-viscous-polar (PVP) lubrication on the performance of multi-recessed hybrid journal bearing (MHJB) system.

To simulate the behaviour of PVP lubricant in clearance space of the MHJB system, the modified form of Reynolds equation is numerically solved by using finite element method. Galerkin’s method is used to obtain the weak form of the governing equation. The system equation is solved by Gauss–Seidal iterative method to compute the unknown values of nodal oil film pressure. Subsequently, performance characteristics of bearing system are computed.

The simulated results reveal that the location of pressurised lubricant inlets significantly affects the oil film pressure distribution and may cause a significant effect on the characteristics of bearing system. Further, the use of PVP lubricant may significantly enhances the performance of the bearing system, namely.

The present work examines the influence of pocket orientation with respect to loading direction on the characteristics of PVP fluid lubricated MHJB system and provides vital information regarding the design of journal bearing system.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2023-0241/

This paper aims to give the guidance for the design of the bearing.

The finite element method, the multi-body dynamics method, the finite difference method and the tribology are combined to analyze the lubrication.

The performance parameters of crankshaft-bearing system such as the misalignment, the oil filling ratio and the oil groove are also investigated. Misalignment causes the pressure to incline on one side and the pressure increases obviously. Filling ratio has great relationship with pressure distribution; the factors influencing the filling ratio are also analyzed. Different oil groove models are investigated, as it can provide the theory for oil groove design, and three factors above are always combined to influence the lubrication characteristics.

The optimization of bearing system is conducted by orthogonal test and neural network, unlike the linear optimization theory. Neural network uses the nonlinear theory to optimize crankshaft-bearing system.

The purpose of this paper is to study the influence of pivot stiffness on the dynamic characteristics of tilting-pad journal bearings (TPJBs) and the stability of the bearing-rotor system.

A theoretical numerical model is established, and the influences of pivot stiffness on TPJBs and a bearing-rotor system are analyzed. Then, two kinds of pivot structures with different stiffness are designed and the vibration characteristics are tested on the vertical rotor bearing test bench.

The pivot stiffness has an obvious effect on the dynamic characteristics of the TPJBs and the stability of the bearing-rotor system. As a result of appropriate pivot stiffness, the critical speed and the vibration amplification factor can be reduced, the logarithmic decay rate and the stability of the rotor system can be effectively increased. While the journal whirl orbit is smoother and the rubbing is obviously reduced when the bearings have flexible pivots.

The influence of pivot stiffness on TPJBs and a vertical rotor-bearing system is studied by theoretical and experimental methods.

This paper aims to describe the theoretical study concerning the effect of non‐linear behavior of the lubricant on the performance of symmetric constant flow valve compensated hole‐entry hybrid journal bearing. The bearing performance characteristics have been computed for various values of non‐linearity factor, land width ratio, aspect ratio and external load.

The analysis considers the generalized Reynolds equation governing the flow of lubricant having variable viscosity in the clearance space and equation of flow of lubricant through constant flow valve restrictor. The non‐Newtonian lubricant is assumed to follow the cubic shear stress law.

The study indicates that for generation of accurate bearing characteristics data, the inclusion of non‐linear effects of lubricant in the analysis is essential.

The performance characteristics in terms of minimum fluid‐film thickness, fluid‐film stiffness and damping coefficients, critical mass and threshold speed for a wide range of values of the non‐linearity factor and external load are presented. The results presented are expected to be quite useful to bearing designers.

The purpose of this paper is to present the effect of the preload on the static characteristics of three-lobe bearings lubricated with a fluid blended with high polymer additives modeled as a couple stress fluid.

Based on the micro-continuum theory, the modified Reynolds equation for couple stress fluids is solved using a finite difference method to obtain the distribution of the pressure, the load-carrying capacity, the attitude angle, the friction coefficient and the side leakage for various values of the couple stress parameter and the preload factor.

The results show that the presence of a couple stress in the lubricants improves the static characteristics of this type of bearing compared to those lubricated with Newtonian fluids for any value of the preload factor. Thus, it is found that the preload significantly affects the performance of the three-lobe journal bearing lubricated with a couple stress fluid or a Newtonian fluid. Moreover, the investigation showed that increasing the preload factor exhibits an increase in the load carrying capacity and the attitude angle, but it decreases the friction coefficient and the side leakage especially at a lower preload factor. Furthermore, using a couple stress fluid and a higher preload factor led to a significant rise in the load carrying capacity and a significant reduction in the friction coefficient.

This study helped improve the performance characteristics of the three-lobe journal bearing.

The presence of couple stress in the lubricants improves the static characteristics of this type of bearing compared to those lubricated with Newtonian fluids for any value of the preload factor. The usage of the couple stress fluid and the higher preload factor led to a significant rise in the load carrying capacity and a significant reduction in the friction coefficient.