The present study deals with the experimental determination of the performance of a 100 mm diameter plain journal bearing submitted to a misalignment torque. Hydrodynamic pressure and temperature fields in the mid-plane of the bearing, temperatures in two axial directions, oil flow rate, and minimum film thickness, were all measured for various operating conditions and misalignment torques. Tests were carried out for rotational speeds ranging from 1500 to 4000 rpm with a maximum static load of 9000 N and a misalignment torque varying from 0 to 70 N.m. The bearing performances were greatly affected by the misalignment. The maximum pressure in the mid-plane decreased by 20 percent for the largest misalignment torque while the minimum film thickness was reduced by 80 percent. The misalignment caused more significant changes in bearing performance when the rotational speed or load was low. The hydrodynamic effects were then relatively small and the bearing offered less resistance to the misalignment.

Textured surfaces are the subject of a great deal of research work in tribology, which mainly involves numerical studies of lubricated contacts. A variety of shapes and arrangements of textures can be found, these being as numerous as the different authors. Depending on the configuration, it has been shown that the presence of the texture can provide better lubrication efficiency through both a reduction of friction and an increase in load-carrying capacity. However, improving bearing performance implies a specific geometrical configuration for given operating conditions. The improvement in lubricated contact performance by texturing the active surface has been demonstrated using experimental studies concerning, for example, pin-on-disk, mechanical seal, camshaft, journal bearing, thrust bearing, and piston ring set-ups. The objective of the present experimental analysis is to provide, using local measurements, a better understanding of the influence of surface texturing on the steady-state behavior of thrust bearings. To achieve this goal, the experimental device is equipped with 80 sensors such as thermocouples and pressure transducers which allowed a proper assessment of the phenomenology at the film/pad interface. The tests are conducted on five hydrodynamic thrust bearings, among which four are textured. Results show that, for the studied configurations, the textured thrust bearings can help to reduce friction up to 30% at low loads while for heavy loads, their performance is equivalent or even lower than that of an untextured planar bearing.

The behavior of the hydrodynamic journal bearings is now very well known because of the many experimental and numerical studies that have been carried out on the topic. This interest in two-lobe journal bearings is due to the fact that their simplicity, efficiency, and low cost have led to them being widely used in industry. These mechanical components tend to be subjected to numerous startups and stops. During transient periods, direct contact between the journal and bearing induces high friction in the lubricated contact and hence wear of the lining. The aim of this work is, first, to present experimental data obtained on a journal lobed bearing subjected to numerous starts and stops. Then, a comparison is made between the measured bearing performance and numerical results, these being obtained on the assumption that the regime is a thermohydrodynamic one. The wear after more than 2000 cycles was measured and used to generate numerical simulations. The aim here was to compare experimental data with theoretical results. It was observed that hydrodynamic pressure increases, whereas the temperature at the film/bush interface slightly decreases on both the upper and lower lobes. These trends are confirmed by the numerical simulations, with theoretical results being very close to experimental data. The final value for wear was measured, the maximum being found to be located at an angular coordinate of $180deg$ and reaching nearly $9μm$. The present study demonstrates that, for the case studied, while the bearing behavior is clearly affected by wear, the bearing still remains useable and safe.

Hydrodynamic journal bearings are essential components for supporting and guiding the rotating shafts of high-speed machinery. Manufacturing defects in assembly or thermal distortions may introduce problems during running, such as misalignment. The destructive effects of this kind of running problem have justified the development of a numerical model to predict the bearing operating characteristics under steady-state conditions. The present work presents in detail the three-dimensional thermohydrodynamic approach adopted in this study in order to consider the thermal field variations. This model also includes lubricant film rupture and reformation phenomena by conserving the mass flow rate. In addition, an experimental validation is made by comparison with measurements carried out on our test device for various operating conditions and misalignment torques. The influence of misalignment direction is also investigated by considering numerical and experimental approaches used in the study of bearing behavior variations.