Multiobjective optimization of a journal bearing using the Pareto optimality concept

This paper deals with multiobjective optimization (minimization of temperature rise, minimization of oil feed flow, minimization of power loss) and discrete design variables (lubricant viscosity, radial clearance, length-diameter ratio) related to the design of a journal bearing. The aim of this paper is to show the sensitivity of radial clearance, oil viscosity and length-diameter ratio on bearing power loss and oil flow. The paper attempts to remove the difficulty of selecting the weighting factor in multiobjective journal bearing optimization problems. The optimization model is based on a hybrid solution scheme for journal bearings. The objective of bearing optimization is to minimize a linear combination (weighted sum) of power loss and oil flow. Constraints are imposed on the maximum fluid film pressure, minimum film thickness, maximum temperature rise and critical speed. A generic algorithm is used as the optimization tool with a penalty to those solutions that violate constraints. The three-level Taguchi method is used to measure the effect of design variables on the optimum solution. The Pareto-optimal set approach is adapted to segregate the superior design vectors. The results of power loss, oil flow, temperature rise, maximum pressure and minimum film thickness are presented in tabular and graphical form for comparative study. Three journal bearing design examples are included, demonstrating the effectiveness of the proposed method.