Effects of contact between rough surfaces on the dynamic responses of bolted composite joints: Multiscale modeling and numerical simulation

A multiscale numerical model, considering both microscopic interfacial properties and macroscopic composite properties, has been developed to model the dynamic responses of bolted composite structures using the elastic-viscoelastic correspondence principle. The complex contact moduli of the uneven interfaces of the joints, featuring multi-asperity contact at the micro perspective, were derived using the fractal contact theory. The frequency-dependent complex moduli of composite materials were ascertained through modal impact tests on unidirectional composites. The damping and stiffness of the composite specimens were solved within ABAQUS software using the complex eigenvalue method. The damping ratios of the joints decreased by over 8.5% while the resonant frequencies increased by more than 0.59% when the bolts of the joints were adjusted from fully loose to fully tightened. Results from the numerical prediction and the experiment were found to be in good agreement, whereby the influence of the interfacial contact conditions on the dynamic responses of the bolted composite structures was revealed through the multiscale analysis.