A Method for Analyzing Correlation Grades of Factors Influencing the Behavior of Bolted Connections Based on the Grey Correlation Degree

Failure caused by loosening of bolted connections is a common problem in practice. To reasonably optimize the factors influencing the behavior of bolted connections, this paper proposed a method for analyzing the correlation grades of factors influencing the behavior of bolted connection based on the grey correlation degree. First, Deng's correlation degree is optimized from three different perspectives: dimensionless factors, resolution coefficient, and weight assignment. Then, a model of the bolted connection is established based on the degrees of correlation of influencing factors. To avoid inverse correlation of influencing factors caused by fluctuation of the residual preload, a difference classification method based on qualitative analysis is proposed. By grading the correlation degree of each influencing factor, optimal selection of parameters in bolted connections can be achieved. Finally, the bolted connection on a third-rail current collector slide was taken as an example and residual preload analysis was performed. It can be concluded that reasonably selecting the bolt material and size and optimizing the friction condition of various contact surfaces is necessary to effectively improve the reliability of the bolted connection. The method was verified by simulations.