A novel nonlinear vibration feature-based approach for evaluating bolt-loosening faults in aerospace structures

Aerospace structures such as aircraft and satellites are frequently subjected to bolt-loosening faults in service, which will seriously affect structural integrity, reliability and safety. In this paper, the development of a novel approach based on nonlinear vibration features is presented to evaluate potential bolt-loosening faults in these structures. Firstly, the complex aerospace structure is decomposed into some simple T-type substructures based on structural configurations and features. Then, a general T-type multi-degree-of-freedom (MDOF) model simulating bolt-loosening faults and nonlinear boundaries as nonlinear damper-spring components is built for nonlinear vibration analysis. After that, two novel fault features, which are functions of structural properties, nonlinear output spectra and bolt-loosening fault-induced forces, are defined to form a novel bolt-loosening fault indicator. Finally, a novel approach with detailed operational procedures is proposed, and its effectiveness and superiority are verified through experimental studies on a simple lab structure with bolt-loosening faults and nonlinear boundaries. © 2023, Hong Kong Institution of Engineers. All rights reserved.