Diagnosis of serious and initial faults in general ring-type engineering structures with vibration features

Nonlinearities caused by potential structural faults such as loose bolts or fatigue cracks commonly exist in almost all engineering structures like steel frames having ring shapes. In order to utilise these nonlinearities to perform fault diagnosis in structures with ring shapes, this paper presents a new method based on three sensitive and effective vibration features. Firstly, a general ring-type multiple degree of freedom (MDOF) model is applied to analyse related engineering structures’ nonlinear dynamic characteristics, and then, related differential equation of motion is built based on the Newton’s second law. After that, applying the local tuning approach (LTA) and harmonic response analysis, three novel vibration features are extracted for normal, seriously damaged and slightly damaged structures with nonlinear boundary conditions respectively. Finally, results of some numerical examples are studied to successfully demonstrate properties of newly proposed vibration features and verify the effectiveness of the new fault diagnosis method. Overall, this paper proposes a new method which can effectively diagnose potential serious and initial faults in engineering structures with ring shapes.