Electro-mechanical contact characterization model for bolted interfaces

The threaded contact interface is difficult to detect because of its complexity and internal contact characteristics, such as the squeezing contact between the thread of a shear bolt and the hole wall. How to non-destructively detect the contact force of the thread contact interface is the key issue to solve the problem of thread damage detection, which is highly important for the normal use of bolts. This paper aims to explore a new electrical measurement method that measures the contact force state between the thread of a shear bolt and the hole wall by measuring the squeezing contact electrical signal. However, owing to the influence of the helical structure, the contact force between the thread and the hole wall is very complex and includes both normal and shear forces. In this paper, contact forces are measured by measuring electrical signals under pressure. By combining the electrical contact model, a thread/hole wall electro-mechanical contact model is established, forming the principle of contact force measurement. Compared with traditional contact mechanics theory, this paper considers the influence of the helical configuration on the interface contact behavior, providing a theoretical reference for predicting bolt thread failure. The accuracy of the model was verified through experiments, with a maximum error of less than 10%. Further research and analysis were conducted on the parameters of the electro-mechanical contact model and actual engineering. This model can be used to measure the normal contact force between the shear thread and the hole wall, laying the foundation for detecting thread failure.