Experimental Study of Constant-Amplitude Fatigue Performance of M39 High-Strength Bolts in Grid Structures with Bolt-Sphere Joints

Abstract

Grid structures with bolt-sphere joints are widely used in industrial plants. With the installation of suspension cranes, high-strength bolts are subjected to repeated alternating loads and cause fatigue problems. Due to their dispersive nature, the degree of difficulty and cost of fatigue tests are extremely high. Due to the lack of a recognized fatigue design method, engineering designers have encountered great difficulties, and the promotion and application of such methods are severely restricted. In this paper, we successfully implemented a constant-amplitude fatigue test of M39 high-strength bolt specimens on an American MTS Landmark 370.50 fatigue testing machine and obtained the corresponding S-N curve from the statistical analysis of the test data. Using the nominal stress amplitude Δσ and the hot point stress amplitude Δσk as the design parameters, we established a corresponding constant-amplitude fatigue design method. We performed a microscopic analysis of the fracture surface using a TESCAN Mira3 LMH scanning electron microscope and revealed the fatigue failure mechanism of the high-strength bolts.

Comprehensive Fatigue Analysis and Practical Design Methodology for Weld Toes in the Sphere of Welded Hollow Spherical Joints in Grid Structures

“…For example, Qiu et al [8,9] conducted fatigue tests under constant and variable amplitude conditions on M30 high-strength bolts used in spatial grids, deriving the corresponding fatigue S-N curves. Moreover, to comprehensively investigate the fatigue performance of BSJs, fatigue tests were carried out on M20, M39, and M60 high-strength bolts [10][11][12].…”

Experimental Study on Variable-Amplitude Fatigue Performance of M60 High-Strength Bolts of Grid Structures with Bolted Spherical Joints

“…In addition, Yang [13], Qiu [14], and Zhou [15,16] conducted constant-amplitude fatigue tests on M20, M30, M39, and M60 high-strength bolts of grid structures with bolted spherical joints to study their fatigue performance. They obtained the corresponding stressfatigue life (S-N) curves.…”