Turbine blade straddle root and rim structural optimization using finite element contact analysis

The development of turbine blade root style is one of the key problems in the blade design technology as the root carries most of the loads of the whole blade. The optimal design problem and the corresponding numerical method were established for a straddle root structure with the minimum equivalent stress of the root and rim as the optimal objective. A multi-variable parametric model of the blade and rim, which took eight critical geometrical variables of the root and rim as design variables, was built by APDL (ANSYS parametric design language) and the optimal problem was numerically solved by combining pattern search algorithm with finite element method. The results indicate that the optimized structure has better strength performance, whose maximum equivalent stress of the root sharply decreased by 25.18% comparing with the original design. It eventually confirms the feasibility and validity of the proposed optimal design method.