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.

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.

Vibration Analysis And Rotating Systems

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.

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.

Vibration Analysis And Rotating Systems
Vibration Analysis And Rotating Systems

BENEFITS—With the aid of FEA we were able to identify a problem and using value engineering resolve the issue using a minimal amount of material in the modification. We were also able to design a modification which could easily be retrofitted to existing models which were already on the market. The use of FEA for design optimisation helps a client find the best solution without having to spend the time producing multiple physical prototypes.

BENEFITS—With the aid of FEA we were able to identify a problem and using value engineering resolve the issue using a minimal amount of material in the modification. We were also able to design a modification which could easily be retrofitted to existing models which were already on the market. The use of FEA for design optimisation helps a client find the best solution without having to spend the time producing multiple physical prototypes.