Failure analysis and design optimization of shrouded fan blade

Abstract

In this study, a failure analysis and design optimization of a shrouded blade in a transonic fan were performed. A visible crack was observed on the pressure side of the shroud, and its origin was located using scanning electron microscopy. The results indicate that the initial crack originated from the pressure-side contact surface edge, and several small cracks were observed in the source region. To determine the reasons for the failure, a shroud-cutting model with a three-dimensional displacement harmony boundary was established. The crack propagation process was simulated, and the stress intensity factor values along the crack front were calculated. Subsequently, a nonlinear static strength analysis was performed, which indicated that stress concentration at the crack origin led to crack initiation. Design optimization considering the pre-deformation angle, friction factor, and initial tightness was performed to determine the figure of merit of the design. The wear pattern of the refined shrouded fan blade demonstrated that the optimized design was effective, with a satisfactory contact state after the engine test. The proposed optimization method is cost-effective and can be used in practical engineering applications.