Optimum shape design of rotor shafts using genetic algorithm

In general, the dynamic design of a rotor system is to optimize the system in stability at the operating speed, unbalance response in the vicinity of the rotor critical speeds, and minimize the system weight considering economics. This paper deals with the optimum shape design of the rotor shaft to change the critical speeds under the constraints of the constant mass. As to the design procedures, the genetic algorithm was applied to find the optimum diameters of a rotor shaft so that the optimized rotor system can yield the critical speeds as far from the operating speed as possible. Genetic algorithm is a search algorithm based on the natural world, which states that the individual with the superior character creates the superior descendant because of having excellent adaptability, high survivability, and more crossing chance, and the natural genetics that repeatedly perform the process of reproduction, crossover, and mutation. The results show that the critical speeds of the rotor-bearing systems can be significantly improved by slight modification of the shaft diameters, even without increasing the total mass of a rotor system.