A Novel Nonlinear Transmissibility Function-Based Method for Diagnosing Shaft Cracks of Rotating Machineries

Fault diagnosis of shaft cracks plays an important role for the safety and reliability of rotating machineries such as aero-engine, turbopump, wind power generator and internal combustion turbine in modern industrial applications. In this paper, a novel method for diagnosing shaft cracks of rotating machineries based on nonlinear transmissibility function is proposed. In the new method, a nonlinear dynamic model is built to describe the nonlinear behavior of a simply supported rotor with breathing cracks and nonlinear supports (nonlinear bearing damping and stiffness coefficients). Damage features for benchmark and cracked structures are derived respectively, and damage indicator for crack diagnosis is defined as the relative change between damage features. Through two numerical studies simulated by the Matlab software, procedures of proposed method are demonstrated and method’s effectiveness and availability are verified. In the future study, the proposed nonlinear transmissibility function-based crack diagnosis method could be extended and applied for other faults in rotating machineries like unbalance, misalignment, stator-to-rotor rub and support structure looseness and so forth.