Fatigue Life Research on Coupler Knuckle of Freight Car on Universal Railway Lines

No. 17 coupler is the object of this paper. The load spectrum of coupler was obtained from the load-time process which was experimented on universal railway lines. Dangerous parts of coupler knuckle occurred in the surface S in front of coupler knuckle and the transition zone by finite element analysis. The relationship of stress-strain was clear by the tensile experiment of grade E steel specimen which was finished on MTS810 fatigue experiment machine. Considering the casting defects of coupler knuckle, the fatigue life of coupler knuckle was evaluated applying the steady-state method of local stress-strain approach and Miner linear cumulative damage theory. The results coincide with the actual situation. The fatigue life of coupler knuckle reduces significantly with the increase of fatigue strength reduction coefficient.