An experiment and a corresponding simple model were constructed to explore whether modal analysis is an appropriate tool for detecting bolted joint degradation. For the study, a beam is bolted to supports at its edges, and the spring encase the bolts such that greater control over the clamping force is retained. It was observed that the resonant frequencies and mode shapes are relatively insensitive to clamping force changes over wide ranges with a narrow region of sudden transition where there is greater sensitivity. It was suggested that the insensitivity may lead to poor prognostic capability if the modal properties are being used to track joint functionality loss for either maintenance or repair applications.
Degradation;Modal analysis;Natural frequencies;Vibrations (mechanical);Nondestructive examination;Radiography;Thermography (imaging);Boundary conditions;