Presentations and Papers
Summary - Iron Ore Freight Bogie - Remaining Fatigue Life and Operating Environment Evaluation
Presenter: Steve Gillespie
The original M-Series ore wagons operating in the Pilbara region are now over 40 years old and Rio Tinto Iron Ore were required to make decisions about their future extended operation or replacement. The economic benefit of deferring expenditure on replacement of up to 4800 bogies was recognised but the increased risk of unexpected fatigue failure of the aged bogies was unknown. A study was therefore initiated by Pilbara Iron Railways Division to evaluate the remaining fatigue life of the M-Series bogie fleet.
The methodology adopted in the study involved in the CAD model generation and finite element analysis of the cast bolster and sideframe components of two bogie types. This was followed by long term strain gauge monitoring of the bogies in revenue service. The stress spectrum data obtained from the tests was then used to calculate limiting bolster and sideframe fatigue design lives and crack growth rates.
The results of the evaluations showed that despite the bogie age, extended future operation was possible with a low risk of unexpected fatigue failure. A one off detailed inspection of the aged bogies to look for cracks in critical locations could be used to further reduce the risk of failures. The study also highlighted the effect of the gentle operating environment on fatigue life with fatigue damage accumulation rates being substantially lower than those obtained from AAR design loads.
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