Design analysis of a rail trolley frame

Substantiation of an existing design against new requirements for a manufacturer of rail track equipment THE CHALLENGE Our client had an existing product which was being sold to a new market and had to meet a new set of requirements laid out in RIS-1530-PLT (a rail industry standard). The trolley's frame is subject to high acceleration and cornering loads which were used to perform a fatigue analysis. The aim was to substantiate the frame considering a working life of 5000 hours. OUR SOLUTION An initial analysis highlighted a fatigue issue with the seat posts caused by rapid 2g acceleration, which it has to meet as part of the standard. A modification was required and this involved adding a new support bar underneath the seat which reduced the stresses in the posts. Figure 1 - displacement plot Using sound engineering practice, the materials can be considered as ductile and the maximum allowable stress was taken to be 80% of yield for the low cycle fatigue (LCF) cases. For high cycle fatigue (HCF) a displacement was applied to account for an out-of-roundness wheel load. The analysis showed that, following the modifications, the design met the requirements of RIS-1530-PLT.

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