Numerical investigation and optimization of the geometric profiles of dimple bottom structure in frictional interaction pairs

Abstract

Dimple texture forming in the interaction pairs is a wear reduction technique like lubrication. Dimple-texturing is an efficient and sustainable way of altering the surface topography to improve the tribological characteristics of interacting surfaces. In this work, sliding interaction pairs with circular dimples, three different dimple bottom structures, namely flat, V-shaped and U-shaped, are selected for numerical investigation using the Reynolds equation to enhance the hydrodynamic characteristics. The numerical design and investigation on the dimple area density (ρ), aspect ratio (λ), and flow velocity (V) is done using unblocked central-composite design (UCD) under response surface methodology (RSM) along with multi-objective gray relation analysis method for individual dimple bottom structures to minimize the coefficient of friction and increase the load bearing capacity in the interaction pairs. The flat bottom structure exhibits excellent load-bearing capacity and minimum coefficient of friction when compared to V-shaped and U-shaped bottom structures. Compared to flat bottom structure, the V-shaped and U-shaped bottom structures has 40.37% and 7.81% lesser load-bearing capacity, respectively, and 54.08% and 7.81% higher coefficient of friction, respectively. In a flat bottom structure, the flow velocity is identified as an effective variable factor to improve the outcome characteristics, followed by dimple area density and aspect ratio. The optimal dimple area density and aspect ratio values are observed in the range of 30–40% and 0.025 – 0.030, respectively. In addition, the optimal value of flow velocity is observed to be 2.5 m/s.