Railway axle

Page 1

Gussoni Enrico 804089 Olivari Laura 876599 DESIGN OF A RAILWAY WHEELSET ACCORDING TO BSI OBJECTIVES 1. According to the standard BS EN 13103 , define the forces and moments to be taken into account with reference to masses and braking conditions 2. Calculate the values of the forces and those of the reaction forces and moments taking into account the effect of: • the masses in motion • the braking system 3. Calculate the distribution of internal forces and moments for both cases 4. Apply the beam theory for the stress calculation in the most stressed section of the axle 5. Evaluate the theoretical stress concentration factor Kt by comparison of the analytical results with the numerical ones (from FE-model) 6. Fatigue assessment First of all we have to evaluate the vertical/horizontal forces on the journal due to coach weight and lateral acceleration. We found them by referring to the standard. P1=112.38 kN P2=78.65 kN H=26.74 kN Then we calculate the forces Fi exerted by the masses of the unsprung elements. These forces are dire cted as opposite to the gravity force, in order to represent the effect of inertia during vibrations. According to the standard we evaluate this case which is the worse one; in fact their effect on bending is added to the one due to the vertical forces. F1=1.1282 kN F2=1.3538 kN F3=F1 We are now able to calculate the reaction forces and moments due to the masses in motion, paying attention to the “transport” of the reaction forces onto the axle. Y1=53.487 kN Y2=26.744 kN Q1=124.02 kN Q2=63.394 kN The weight of the axle can be neglected because its effect is opposite to the one of the load (so we are in advantage for safety) and because most of the mass is concentrated in the wheels. Calculation of internal forces with masses in motion. Braking…