Diagnosis of loose pedestals in two-dimensional engineering structures with nonlinear vibration transmissibility functions

Referring to existing vibration transmissibility function-based approaches, which are frequently applied to diagnose fatigue crack and joint loosening faults in two-dimensional engineering structures such as aluminium plates and steel frames, a novel approach applying nonlinear vibration transmissibility functions is developed to diagnose potential loose pedestals in this paper. Firstly, the two-dimensional structural dynamic model, which simulates effects of loose pedestals as equivalent loads, is obtained through the lumped mass method. Secondly, exciting the dynamic model three times with different extra masses, the transmissibility function-based matrix of one sub-model to be diagnosed is obtained, and then a novel damage index is defined based on the matrix singularity. Lastly, a novel approach with particular procedures is proposed. Through three numerical cases on a two-dimensional dynamic model with multiple degrees of freedom (MDOFs), validity and applicability of the proposed approach are shown. As a result, this paper provides a totally new idea to diagnose loose pedestals, which can ensure structures’ smooth operation.