Under the suspended crane loading, the key to the fatigue of the grid structure with bolt-sphere joints is the fatigue of the higher strength bolt. By now, there are not any research reports about the fatigue properties of M27 higher strength bolt at home and abroad. With the aid of the fatigue-testing machine and the loading device, this paper will have 8 constant amplitude fatigue experiments on test-piece, and will get the S-N curve of the higher strength bolt. With the aid of the metallographic analysis, this paper studies the mechanism and influencing factors of the fatigue failure; and with the aid of the finite element software ABQUAS, it analyzes and gets the stress concentration factor of the M27 higher strength bolt, and verifies the position of the fatigue failure.
