Railway Axle in Rotating Bending-Shoulder Fillets

1 Railway Axle in Rotating Bending-Shoulder Fillets 

The railway axle shown in Fig. 7.24 is made with UNI Aq50 (0.35 % C) steel of 550 MPa ultimate strength and 25 % RA. It sustains a static weight of 25 t. Verify its fatigue integrity. The most stressed regions are certainly the shoulders (sections I, II and III of detail A of Fig. 7.24) because they represent areas of discontinuity and act as stress raisers. The axle has a machine finish whose surface factor is Cs= 0.78 (see Fig. 3.11). 

The static load acting on the axle journal is 25/2 = 12.5 t. A lateral component L exists that is equal to 5 t. Let s assess the bending moments Mi, M2, M3 and M4 acting on sections 1, 11, 111 e IV  

Fatigue limit 5/for the steel is about 200 MPa, as it can be deducted from Figs. 3.34 and 3.35. The reduced fatigue limit S f that takes into consideration all the corrective factors is 

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