Damage Tolerance Assessment of Heavy-Duty Freight Railway Axles with Artificial Defects

Abstract Heavy-duty freight railway axles are no less important than those of passenger trains, owing to the potentially catastrophic results caused by the derailment of trains carrying hazardous substances. Intrinsic and extrinsic imperfections challenge classical design theories built based on the safe life concept, and damage tolerance assessment becomes vital for the safety and reliability of long-term serviced railway axles, as pits and scratches are common defects for heavy-duty railway axles. In this work, four-point rotating bending fatigue tests of AAR-CM railway axle steel specimens with semicircular and circumferential groove notches are conducted. The fatigue limit of the semi-circular notched specimens was evaluated based on fracture mechanics theory, in which non-conservative results are obtained by the El Haddad model and the S–N curves of circumferential groove notched specimens are correlated by the theory of critical distance (TCD).