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Severe stress concentration occurs around circular vent holes of an industrial turbine sealing disk.This paper investigates the structural design and optimization for the vent holes to effectively reduce the maximum yon Mises stress and improve the fatigue life of the turbine sealing disk.An efficient integrated design optimization method is presented based on a novel non-circular vent hole design method in combination with a variable dimension sub-model method,a self-developed modeling and meshing tool,and the Multi-Island Genetic Algorithm.The proposed non-circular vent hole is biaxial symmetric and consists of four smoothly connected arcs.The variable dimension sub-model method is utilized to obtain accurate results in the fields around the vent holes within the computationally acceptable time.The modeling and meshing tool is developed by using the Tcl/Tk Scripts to rebuild the geometry and generate the high-quality hexahedral mesh automatically.The Multi-Island Genetic Algorithm is adopted to solve the studied constrained optimization problem.After optimization,the maximum von Mises stress is reduced from 1305.644 MPa to 963.435 MPa,and the fatigue life is increased from 3091 cycles to 30,297 cycles.The results show that the proposed design and optimization methods can significantly improve the performance of the turbine sealing disk along with the remarkable drop in stress concentration.