Analysis on damage evolution and corrosion fatigue performance of high-strength steel wire for bridge cable: Experiments and numerical simulation
Corrosion fatigue (CF) failure is one of the typical failure modes of high-strength steel wires for bridge cables because the cables are subjected to the long-term cyclic loads and exposed to the heavy polluted environment at the same time. In this paper, the damage evolution process and CF performance were investigated, and the service life was predicted for steel wire with machine-cut notch via experiments and numerical simulation. Firstly, a novel experimental device was constructed to apply fatigue load and corrosive medium on multiple specimens simultaneously. With the constructed device, two groups of experiments were conducted to analysis the fatigue performance and CF performance of surface notched wire specimens, and the fatigue life and CF life of steel wire were obtained under fatigue load and the coupling effect of corrosive medium and fatigue load (CCF) respectively. Additionally, in order to study the fatigue damage evolution process and CF damage evolution process of surface notched steel wire under fatigue load and CCF respectively, a fatigue damage constitutive equation and a CF damage constitutive equation were proposed respectively according to continuum damage mechanics, and experimental data were used to determine the value of each parameter in these two equations. With the proposed model, damage evolution process in steel wire was simulated under fatigue loads and CCF respectively. The effect of corrosive medium on wire life was discussed. The results show that the fatigue life and CF life of surface notched wire obtained from simulation are consistent well with the experimental results, which shows that the simulation method can achieve the expected goal, and has high reliability in predicting the fatigue life and CF life, and simulating the fatigue damage evolution and CF damage evolution of surface notched wire. For the fatigue damage evolution process and CF damage evolution process, damage evolves gradually, and the damage evolution rate gradually increases. There are more and more damage elements at the bottom of machine-cut notch, and some elements inside the steel wire are also damaged. Comparing the damage distribution of steel wire subjected to fatigue load only and CCF, it can be found that corrosive medium will cause the damaged elements to appear earlier. Under the same stress range, the fatigue life and CF life of steel wire with machine-cut notch are significantly different, but the fatigue damage evolution rate and CF damage evolution rate are similar. It can be concluded that the difference in service life is mainly due to the corrosive medium that causes the damaged elements near the surface notch appear earlier, especially under higher stress ranges.