Abstract: Different paths are generated by the same crank – rocker linkage through adjusting the fixed pivot position of the rocker. An optimal synthesis method of adjustable crank – rocker linkages for continuous path generation is put forward, which is based on the orientational structural error of the fixed link. The path flexibility is firstly determined, the optimal synthesis model is then set up, the optimal synthesis solution is obtained using modified genetic algorithm. The orientational structural error of the fixed link can effectively reflect the difference between the practical generated path and the desired path and can be calculated conveniently, avoid the difficulty of selecting corresponding comparison points of the two paths, The modified genetic algorithm guarantees that the optimal synthesis result is the global optimal solution. The number of independent design variables is reduced greatly compared with traditional optimal synthesis method. The result of a synthesis example verifies the effectiveness of the proposed method.

Key words: Adjustable linkages, Continuous path, Genetic algorithm, Optimal synthesis, Low cycle fatigue , Crack propagation life, High cycle fatigue, Rotor , Nuclear steam turbine