Performance Evaluation of Single-dimple and Multi-dimple Textures under Varying Operating Conditions

Most publications in the field of surface texturing in full-film lubrication focus on a sharp-edged texture and a parallel oil film gap. Additionally, only specific operating conditions are examined, and the performance of single- and multi-dimple textures is not fully analysed in the literature. Therefore, this study aims to fill this research gap. First of all, the optimal geometrical parameters for a single- and multi-dimple textured convergent oil film gap under hydrodynamic lubrication conditions were determined using an optimization algorithm. To ensure manufacturability in a cost- and time-efficient manner, a rectangular shape was selected for the textures. The manufacturability of the surfaces was ensured by incorporating a fillet in the geometry, a crucial element of the manufacturing process. Based on this work, design recommendations for industrially manufacturable surface modifications can be framed. The lifting- and drag forces of these textures were evaluated under varying operating conditions, including external load, viscosity, relative velocity, and angle of the convergent oil film gap. Both, single- and multi-dimple textures, can increase the load carrying capacity more than 20 % and decrease the friction more than 25 %, depending on the operating conditions. Additionally, it was observed that single-dimple textures outperform multi-dimple textures, as long as the surface modifications outperform an untextured oil film gap. In terms of working conditions, it was discovered that textures enhance the examined tribological properties in non-high-loaded applications. This means that textures perform better at a low angle of convergence, a low external force, a high relative velocity and a high dynamic viscosity.