Influencing factors of steel wire fatigue crack propagation based on fracture mechanics

Abstract

Because of their advantages of a compact structure and uniform force, parallel wire bundles are often used in the fabrication of cable stays. This study investigated the stress intensity factor (SIF) of a surface crack of a steel wire in service, with the aim of addressing the issue of fatigue damage in cables. Specifically, the fatigue-damaged area of a cable easily cracks following prolonged exposure to alternating vehicular loads and temperatures. On the basis of the theory of fracture mechanics, steel wires with elliptical surface cracks were considered as research objects. This study employed the ABAQUS and FRANC3D applications to simulate crack propagation, and the variation in the crack SIF under the influence of different crack sizes, initial crack angles, stress ratios, and corrosion craters was studied. The results revealed a positive correlation between crack size expansion and the SIF increase. When the crack length was constant and the crack depth was in the range of 0.8–1.2 mm, the maximum SIF increased from 494.04 $\mathrm{MPa}\bullet {\mathrm{mm}}^{\frac{1}{2}}$ to 701.47 $\mathrm{MPa}\bullet {\mathrm{mm}}^{\frac{1}{2}}$. For the same crack shape, the SIF of the crack front decreased as the initial crack angle increased. The greater the stress ratio, the greater the SIF. The presence of corrosion pits caused the SIF to exhibit a decreasing trend with increasing pit width. The results of this study can provide guidelines for wire life evaluation and reliability analyses.