Session: CT-04-02 Assembly of Bolted Joints-2

Paper Number: 155062

155062 - Numerical and Experimental Analysis of the Tightening Process of Self-Locking Nuts 

Abstract: 

Self-locking nuts exhibit excellent anti-loosening properties and are commonly used in the assembly and connection of aircraft engine rotors. However, their non-circular structure results in complex tribological behavior during tightening, making it difficult to accurately control the preload and establish a clear relationship between bolt torque and preload. To address these challenges, this paper develops a finite element model (FEM) of self-locking nuts to analyze the stress-strain behavior under torque application, investigate the contact stress distribution between threads, and examine the correlation between torque and preload under different friction coefficients. An experimental platform was established to study the torque-preload relationship of self-locking nuts under varying lubrication conditions using both the torque method and the torque-angle method. The dispersion of bolt preload under these two tightening methods was compared, leading to recommendations for the optimal tightening process. The results show that the torque factor of self-locking nuts using the torque method is approximately 0.2, significantly higher than that of standard bolts and nuts. Additionally, compared to the torque method, the torque-angle method produces less variability in bolt preload, suggesting that it improves the accuracy of preload control. The fitting torque and torsion angle of the self-locking nut under the torque-angle method are two key process parameters, which need to be determined by combining experiments and theoretical analysis. This study provides a basis for optimizing the tightening procedure for self-locking nuts.

Presenting Author: Linbo Zhu Xi'an Jiaotong University

Presenting Author Biography: Linbo Zhu, Ph.D., Xi'an Jiaotong University. He focuses on stress analysis, finite element analysis, bolted flange joints, and optimization design.

Authors:

Linbo Zhu Xi'an Jiaotong University
Hanwen Zhang Xi’an Jiaotong University
Junqi Zhou Xi’an Jiaotong University
Junqi Xu Xi’an Jiaotong University
Jixun Shi Xi’an Jiaotong University
Jun Hong Xi’an Jiaotong University