Study on A Novel Nonlinear Vibration Feature-based Method for Fault Diagnosis in Ring-like Engineering Structures

In aerospace, mechanical, and civil engineering, ring-like structures such as satellite panels, pipes, and truss bridges often exhibit complex dynamic behaviors due to their closed-loop vibration paths. Traditional nonlinear vibration-based methods for diagnosing bolt-loosening faults in these structures face limitations like reliance on benchmark structures and neglect of nonlinear boundaries. To address this, a new method is proposed in this paper. It models the nonlinear dynamics of ring-like structures using a multi-degree-of-freedom (MDOF) system with nonlinear damper-spring connections, simulating bolt-loosening faults. By applying two harmonic excitations, local fault features are defined, leading to a fault diagnosis method. Simulations confirm the method's effectiveness in detecting single and multiple bolt-loosening faults.