The optimization method for designing the shape of the shank of an aeroengine fan blade was explored

and it was used to improve the vibration property of the fan blade without changing the aerodynamic design of the blade. First

the method for designing the shape of shank based on NURBS (nonuniform rational B-spline) bridging curves was established

and the smooth connection between the passage blade and the tenon sides was achieved. Then the parametric design of the shank shape was accomplished by adjusting the positions of the control points of the bridging curves

and 8 design variables which were required to completely define the shape of the shank were extracted on the basis of related assumptions. The maximization of resonance margin of the fan blade was chosen as the objective of shank design; the optimization process of shank shape design was established based on radial basis function network (RBFN) and particle swarm optimization (PSO)

and the principle is that an RBFN metamodel is constructed to approximate and predict the implicit objective function whose input and output are design variables of the shank and resonance margin of the fan blade respectively

and that PSO is used to find the best combination of shank design variable which achieves the maximum resonance margin. The above process was used in the design of a high bypass ratio widechord fan blade

and the shank shape was optimized so that the natural frequency of the axial first order bending mode for the fan blade was increased and that the resonance margin for the excitation frequency that was the triple of the rotation speed was increased by about 2%.