Surface texturing has proved to be very efficient in full and mixed lubrication, reducing the friction coefficient and the wear rate of mating surfaces. By partially texturing the inlet zone of a thrust washer pad load carrying capacity is generated in the system. In the present paper, a partially textured thrust bearing with square dimples is analysed theoretically using a thermohydrodynamic model. The equations are solved numerically by the finite-difference method. The bearing was realized by the photolithographic method and the theoretical results (fluid film thickness and friction torque) were compared with the experimental data obtained on the test rig. It is found that an optimal number of 12 sectors maximize the load carrying capacity of the bearing. The optimal textured fraction, which maximizes the load carrying capacity is 0.5 on the circumferential direction and 0.9-1 on the radial direction. A good correlation was found between the theoretical and experimental results for the two measured parameters (fluid film thickness and friction torque).

In this article, a laser partially textured thrust bearing is theoretically and experimentally analyzed. An adiabatic model is developed in order to theoretically investigate the performances of the bearing. The bearing sample is partially textured both in radial and circumferential direction using the laser texturing process. The performance of the bearing (fluid film thickness and friction torque) is evaluated on a specially adapted test rig and the experimental results are compared with the theoretical model. A good agreement is found between the theoretical model and the experimental data. Also a comparison between a laser textured bearing and a bearing textured using the photolithographic method is presented.

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A theoretical model that evaluates the frictional properties of an infinitely wide rigid cylinder rotating over a grooved surface in a hydrodynamic lubrication regime is presented in this article. The parabolic approximation of the film thickness is used in order to analytically compute the pressure distribution in the fluid film. At the discontinuities of the grooved surface, the conservation of the flowrate is applied. The pressure distribution was also computed using a commercial CFD software. Different groove depths are tested using the two methods in order to establish whether the Reynolds equation is valid for low dimple aspect ratios. It is found that the Reynolds equation is not valid when the depth of the groove is comparable with its width. In the case where the width of the grooves is much larger than their depth, the obtained results (CFD and analytical) are perfectly similar. The load-carrying capacity and the friction force of the couple are also computed.

The process of liquid flow takes place inside a highly compressible porous layer (HCPL) many times. In these cases, elastic forces of the HCPL solid phase are negligible, compared with hydrodynamic (HD) forces. Such processes were named ex-poro-HD (XPHD). A study of the impact process under XPHD conditions for circular and rectangular aligned plates was recently performed and presented by the authors. The impact of a rigid sphere on an HCPL, imbibed with a Newtonian liquid, under XPHD conditions, is analysed in the present paper. The Kozeny—Carman equation was used to compute the permeability variation as a function of compacticity/porosity. The Bowden and Tabor model for squeeze under impact was extended for XPHD conditions. The obtained model gives the impact pressure and force variations as the layer thickness decreases, so the damping capacity of the HCPL was evaluated. The maximum value of the absorbed energy, given by the optimal compacticity/porosity of the HCPL, is established. A comparison with the impact of a rigid sphere on a Newtonian liquid film under HD conditions is also done, keeping the same geometry and same kinematic and dynamic parameters, inherited from the XPHD model. The damping capacity of an HCPL is several orders of magnitude greater than that of the Newtonian liquid layer. The theoretical model was validated by two experiments, in which the HCPL is impacted by free falling ball tests.

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