https://cyberleninka.org/article/n/544115.pdf

Hydrodynamic lubrication of textured surfaces: A review of modeling techniques and key findings

Coupling transient mixed lubrication and wear for journal bearing modeling

Numerical analyses of finite journal bearings operating with large eccentricity ratios were conducted to better understand the mixed lubrication phenomena in conformal contacts. The average Reynolds equation derived by Patir and Cheng was utilized in the lubrication analysis. The influence function, calculated numerically using the finite element method, was employed to compute the bearing deformation. The effects of bearing surface roughness were incorporated in the present analysis for the calculations of the asperity contact pressure and the asperity contact area. The numerical solutions of the hydrodynamic and asperity contact pressures, lubricant film thickness, and asperity contact area were evaluated based on a simulated bearing-journal geometry. The calculations revealed that the asperity contact pressure may vary significantly along both the width and the circumferential directions. It was also shown that the asperity contacts and the lubricant film thickness were strongly dependent on the bearing width, asperity orientation, and operating conditions.

Mixed-lubrication study of journal bearing conformal contacts

Numerical investigation of journal misalignment on the static and dynamic characteristics of aerostatic journal bearings

Accurate dynamic characteristic coefficients of water-lubricated rubber bearings are necessary to research vibration of ship propulsion system. Due to mixed lubrication state of water-lubricated rubber bearings, normal test rig and identification method are not applicable. This paper establishes a test rig to simulate shaft misalignment and proposes an identification method for water-lubricated rubber bearings, which utilizes rotor unbalanced motion to produce self-excited force rather than artificial excitation. Dynamic performance tests under different conditions are operated. The results show that when rotational speed is less than 700 r/min, even if specific pressure is 0.05 MPa, it is difficult to form complete water film for the rubber bearing which was investigated, and contact friction and collision of the shaft and bearing are frequent. In the mixed lubrication, water film, rubber, and contact jointly determine dynamic characteristics of water-lubricated rubber bearings. The contact condition has a significant effect on the bearing stiffness, and water film friction damping has a significant effect on bearing damping. As for the particular investigated bearing, when rotational speed is in the range of 400~700 r/min and specific pressure is in the range of 0.03~0.07 MPa, bearing stiffness is in the range of 5.6~10.06 N/μm and bearing damping is in the range of 1.25~2.02 Ns/μm.

/pdf/experimental-study-on-the-dynamic-performance-of-water-3clg2ib6zp.pdf

Experimental Study on the Dynamic Performance of Water-Lubricated Rubber Bearings with Local Contact

A mixed elastohydrodrynamic (EHL) model for journal bearings considering an axial flow due to shaft axial motion and misalignment is developed for lubrication performance evaluation A new, faster mixed EHL computing technology utilizing the odd–even successive overrelaxation (OESOR) parallel numerical iterative method is proposed based on the red–black successive overrelaxation (RBSOR) method to minimize the execution time prolonged by the complexity caused by the axial flow and misalignments The multithreaded computing scheme conducted by the OpenMP directive using different meshes and threads suggests that the OESOR method exhibits better efficiency A series of transient analyses was conducted to solve the mixed EHL model with the parallel OESOR method The results show that the axial flow and misalignments significantly affect the average pressure, hydrodynamic and asperity contact pressure, elastic deformation, and other characteristics of the journal bearings

Effects of Shaft Axial Motion and Misalignment on the Lubrication Performance of Journal Bearings Via a Fast Mixed EHL Computing Technology

In this study, the solution methods suitable for use in a workstation to solve the discretized incompressible and compressible fluid Reynolds equations are examined. The workstation used for computing consists of dual six-core central processing units (CPUs) and a 256-core graphics processing unit (GPU) dedicated for computing. To compare the computational performance, the Reynolds equations are solved by a parallel iterative method using multithreaded and GPU computing. Multithreaded computing is conducted by OpenMP directives and GPU computing is executed using either NVIDIA's compute unified device architecture (CUDA) programming or the accelerator programming model (APM). The lubrication models used are an inclined surface slider with or without a central recess and an air journal bearing. In GPU computing, both the CUDA and APM are subjected to communication latency to achieve efficient fine-grained computations. The results show that the performance of the less expensive GPU computing is close to th...

Chia-Wen Chan

Papers

Effects of Shaft Axial Motion and Misalignment on the Lubrication Performance of Journal Bearings Via a Fast Mixed EHL Computing Technology

Workstation Computing of Discretized Reynolds Equations