The purpose of this thesis is to determine the optimal shape of lubricated axisymmetric spherical bearing cups and symmetric journal bearing sleeves under transient pure squeeze conditions using a genetic algorithm. The objective is to maximize the load impulse of a perfectly spherical ball or perfectly cylindrical journal interacting through a thin lubricant film with a generally non-spherical cup or non-cylindrical sleeve to achieve a specified minimum film thickness value. A generation is a set of bearing shapes over the design space encoded as binary chromosomes. A finite element model simulates the normal approach of the ball or journal to the cup or sleeve and the fitness of each shape is measured by load impulse. A new generation is formed by splitting and recombining chromosomes while conserving the top two fittest solutions and applying random mutations to the rest. This process is repeated for a fixed number of generations, after which the fittest design is selected as the "optimal" shape. It was found that optimal shapes produced by the genetic algorithm yielded generally higher impulse values than those obtained with perfectly spherical or cylindrical bearings, but the gain in performance over specified elliptical shapes was mixed over the design space.

Library of Congress Subject Headings

Bearings (Machinery)--Design and construction; Genetic algorithms

Publication Date


Document Type


Student Type


Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)


Stephen Boedo

Advisor/Committee Member

Hany Ghoneim

Advisor/Committee Member

Sarilyn Ivancic


RIT – Main Campus

Plan Codes