Numerical and experimental investigation on influence of compound dimple on tribological performances for rough parallel surfaces

Abstract

Purpose This study aims to explore the superiority of the compound dimple (e.g. the rectangular-rectangular dimple) and compare its tribological performance for rough parallel surfaces with those of the traditional one-layer dimple (simple dimple). Design/methodology/approach A mixed-lubrication model for a rough textured surface is established and solved using the finite difference method for film pressure and contact pressure. To accelerate the evaluation of surface deformation, the efficient Continuous convolution fast Fourier transform algorithm is applied. The effects of the compound dimple on the tribological performance for the rough parallel surfaces is numerically investigated. And these effects are compared with those of the simple dimple. Furthermore, a reciprocating friction test is conducted to verify the superiority of the compound dimple. Findings The compound dimple exhibits better tribological performances in comparison with the traditional simple dimple, that is, a larger load-carrying capacity and a smaller friction coefficient. To achieve the best tribological performances for the rough parallel surfaces, the depth ratio of the lower pore to the total pore of the compound dimple and the dimple interval should be reasonably chosen. For the surface with compound dimples, there exists an optimal surface roughness to simultaneously maximize the load-carrying capacity and minimize the friction coefficient. The smaller friction coefficient of the surface with compound dimples is verified by the reciprocating friction test. Originality/value The compound dimple is proposed and the superiority of this novel surface texture is confirmed. This study is expected to provide a new texturing method to improve the tribological performances of the traditional simple dimple.

Comparative study of spherical dimple and bump effects on the tribological performances of journal bearing

“…The dimensionless composite elastic deformation V e ( θ , Z ) for an unknown point ( θ , Z ) of the shaft and bearing bush can be calculated by the following equation 16,36,37 where P ( S , T ) denotes the dimensionless hydrodynamic pressure at the known point ( S,T ). E * is the composite Young’s modulus of the shaft and bearing bush, which is calculated by the expression 1/E*=(1-ν1 2)/E1+(1-ν2 2)/E2.…”

“…E * is the composite Young’s modulus of the shaft and bearing bush, which is calculated by the expression 1/E*=(1-ν1 2)/E1+(1-ν2 2)/E2. 16,36,37 Here, E 1 and E 2 are the Young’s moduli of the shaft and bearing bush whose Poisson’s ratios are v 1 and v 2 , respectively.…”

“…To shorten the computation time, the CC-FFT method was applied by Meng et al. 16,38 and Liu et al. 39 for the elastic deformation analysis.…”

“…Besides, Meng et al. 14–16 also found that the compound dimple, characterized by two-layer pores, can better improve the load-carrying capacity and reduce the friction of parallel surfaces in comparison to the simple dimple with only one-layer pore. Further, dimple effects on the tribological performances of journal bearings are also studied by researchers.…”

“…[9][10][11] By applying surface texturing to the piston ring of an engine, Meng et al 12,13 found that surface texturing can reduce the friction force and wear of the piston-ring system. Besides, Meng et al [14][15][16] also found that the compound dimple, characterized by two-layer pores, can better improve the load-carrying capacity and reduce the friction of parallel surfaces in comparison to the simple dimple with only one-layer pore. Further, dimple effects on the tribological performances of journal bearings are also studied by researchers.…”