Modeling and analysis of an impact-acoustic method for bolt looseness identification

Bolted joints are fundamental building blocks and have been widely used to hold multiple structural components together, while their looseness may lead to costly disasters in industries. Compared to current bolt loosening detection methods that are often hampered due to the need for highly experienced personnel or an overly complex sensor-structure interaction, a new percussion-based method using analytical modeling and numerical simulation was proposed to reduce cost and avoid contact-type sensor installation, which is a great contribution. Analytically, the bolted joint was modeled equivalently as a laminated plate by using the virtual material method and the layer-wise theory, and its percussion-induced sound pressure level (SPL) can be obtained via the acoustic radiation mode approach. The corresponding numerical simulation was developed with the focus on the acoustic-structure coupling, and the acoustic boundary conditions were satisfied through a perfectly matched layer (PML). Compared to prior work, another contribution of this paper is that the proposed method further considers the critical effect of bolted interfacial roughness, which affects radiation sound signals significantly. Finally, acoustic tests were carried out, and the good agreement between results of modeling, simulation, and experiments demonstrate the effectiveness of the proposed method. As a rapid and non-invasive bolt looseness detection method, the investigations in this paper can provide guidance for the future development of bolt looseness detection methods. Published by Elsevier Ltd.