Fatigue crack propagation model and life prediction for pantographs on High-Speed trains under different service environments

The fatigue crack growth of a weld toe on the upper arm of a pantograph was investigated to predict the fatigue crack propagation life of the pantograph under normal and corrosive conditions. First, samples were subjected to four-point bending tests and simulations under the two conditions, and Paris law parameters were obtained. Second, constant-amplitude loads were determined through the equivalent treatment of variable-amplitude loads. Based on the Paris model, crack propagation was simulated using the finite element method for the two environments, and results showed a relationship between the crack length a and the stress intensity factor KI. The service life of the pantograph was predicted using the Paris law. Results indicated that the pantograph could run about 958,000 km and 7,660 km in normal and corrosive environments, respectively, after the development of its fatigue crack from a surface crack into a through-thickness crack.