Tilting-Pad Journal Bearing Subjected to Fuzzy Type-2 Uncertain Parameters

This paper evaluates the effects of uncertainties on the load capacity of a four-pad tilting-pad journal bearing, in which the pad radius, oil viscosity, and radial clearance are considered as uncertain information. The hydrodynamic supporting forces at the bearing pads are obtained by solving the Reynolds equation. In this case, the uncertain parameters are modeled as fuzzy type-2 variables. Fuzzy type-2 sets have been widely used due to their ability to model higher orders of uncertainties as compared with the fuzzy type-1 approach. They allow for inaccurate knowledge to be included in the membership functions used to describe the uncertain parameters. In the present contribution, the so-called alpha-level optimization was associated with the fuzzy type-2 technique for uncertainty analysis purposes. A sensitivity analysis was also carried out as an additional assessment of the considered uncertain parameters. The numerical results allowed to understand how the uncertain parameters affect the bearing supporting forces for three shaft speeds, namely, 3000, 9000, and 15,000 rpm. It was demonstrated that the effect of the uncertain parameters on the supporting forces increases according to the shaft speed. Additionally, the load capacity revealed to be more sensitive to variations on the oil viscosity and radial clearance than to the pad radius concerning the adopted uncertain interval. Consequently, the obtained results can provide suitable information for the design, manufacturing, and maintenance of tilting-pad journal bearings.