ANALYSIS OF FATIGUE CRACK GROWTH IN ROTARY BEND SPECIMENS AND RAILWAY AXLES

Fatigue crack growth tests have been carried out on pre-cracked specimens of steel AFNOR XC 38 under rotary bending conditions. The semi-elliptical surface crack shape evolution was determined and the results were analyzed by da/dN = f(ΔK) using a stress intensity factor solution for semi-elliptical surface cracks in round bars subjected to a bending stress modified to take into account the rotatary bending conditions. Results show a very good correlation with fatigue crack growth data obtained in standard centre cracked tension specimens of the same steel. An application to the sensitivity of design parameters to an analysis of cracked railway axles is proposed, allowing an improvement in maintenance procedures.