Abstract
There are several fatigue-based approaches that estimate the evolution of rolling contact fatigue (RCF) on rails over time and built to be used in tandem with multi-body simulations of vehicle dynamics. However, most of the models are not directly comparable with each other since they are based on different physical models even though they shall predict the same RCF damage at the end. This article studies different approaches to quantifying RCF and puts forward a measure for the degree of agreement between them. The methodological framework studies various steps in the RCF quantification procedure within the context of one another, identifies the ‘primary quantification step’ in each approach and compares results of the fatigue analyses. In addition to this, two quantities—‘similarity’ and ‘correlation’—have been put forward to give an indication of mutual agreement between models. Four widely used surface-based and sub-surface-based fatigue quantification approaches with varying complexities have been studied. Different operational cases corresponding to a metro vehicle operation in Austria have been considered for this study. Results showed that the best possible quantity to compare is the normalized damage increment per loading cycle coming from different approaches. Amongst the methods studied, approaches that included the load distribution step on the contact patch showed higher similarity and correlation in their results. While the different approaches might qualitatively agree on whether contact cases are ‘damaging’ due to RCF, they might not quantitatively correlate with the trends observed for damage increment values.
Highlights
Results showed that the best possible quantity to compare is the normalized damage increment per loading cycle coming from different approaches
Rail surface damage caused by rolling contact fatigue (RCF) is a major problem faced by several railway networks across the world with increasing operational requirements such as heavier axle loads, higher line capacities and vehicle running speeds
The selection of a suitable damage model is limited by calculation constraints arising due to the trade-off between damage model complexity and system complexity
Summary
Rail surface damage caused by rolling contact fatigue (RCF) is a major problem faced by several railway networks across the world with increasing operational requirements such as heavier axle loads, higher line capacities and vehicle running speeds. The damage quantification is done for varying service conditions and a measure for the degree of agreement between the methods is put forward This will allow researchers working on damage models to compare their results with other models in a systematic way. The use of a simpler model for a relatively small parameter space over-generalizes the wheel–rail contact problem by neglecting specific phenomena at play that influence damage (e.g. partial slip) and might not be accurate enough. This is relevant when studying RCF damage models because of the differing physical phenomena they are modelled on.
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