Study on self-loosening of bolted joints excited by dynamic axial load

Loosening tests of bolted joints are carried out under various preloads and excitation amplitudes. Three coatings are utilized to treat bolts, and their effects on the anti-loosening performance are studied. For the MoS2 coated bolt, a reasonable preload is calculated, and its anti-loosening performance is also examined. It is found that the anti-loosening performance of MoS2 coating on bolt is better than that of the other two coatings. Under the same equivalent stress as that of the uncoated bolt at the thread root, both the preload and the anti-loosening performance of the MoS2 coated bolt are significantly greater. Additionally, a FE model is created to simulate the bolted joint, and very good agreement is found between numerical and experimental results. •The anti-loosening performance of the PTFE/MoS2/TiN coated bolts was studied.•The wear mechanisms of the thread surfaces were investigated.•Experimental observations were further explained using finite element method.