Wear and Fatigue of Railway Track Caused by Contamination, Sanding and Surface Damage

The wheel rail contact operates in an arduous environment. Damage to the surface of either component is possible during manufacture, installation, or operation. The question arises as to how tolerant is the railway wheel or section of track to surface indentation or damage. In this work a twin disc simulation has been used to relate the level of surface damage (as well as the way it is generated) to the fatigue life of the surfaces. A related problem is the presence of solid contamination on the track. Sand (applied for improved adhesion) or track ballast material can cause damage to the rail and wheel surfaces. These mechanisms have been explored to assess the effect on contact fatigue life and wear. The disc specimens have been either artificially damaged (with dents and scratches) or run with particles of sand or ballast material. The discs were then loaded and rotated at realistic conditions of contact pressure and controlled slip. For normal operation of the contact, either dry or with water lubrication, surface dents and scratches have little effect on fatigue life. The normal plastic flow in the rail surface layer acts to close up dents. The failure of the disc is then by fatigue cracking across the whole surface with no particular preference to the dent location. Alternatively, if the contact is lubricated with oil then this plastic flow is greatly reduced and the dents act as stress raisers and fatigue cracks initiate from their trailing edge. Sand or ballast particles are crushed as they enter the wheel/rail contact. The fragments indent the surfaces and rapidly roughen the contact faces. The surface indentation is relatively minor, but the presence of particles increases the level of traction (over the wet case) and promotes further surface plastic flow. This can reduce the residual fatigue life of the contact. Further, high concentrations of sand were shown to promote a low cycle fatigue process that caused very high wear by the spallation of material. The twin disc simulations have shown that, under conditions similar to that of wheel/rail operation, surface damage is not a primary cause of fatigue failure. However, wear is greatly accelerated by the presence of solid contaminants and some evidence of a low cycle fatigue process was observed for sanded contacts

A numerical model of twin disc test arrangement for the evaluation of railway wheel wear prediction methods

Twin disc tests are commonly used to study wear in railway materials. In this work the implementation of a numerical model of the twin disc arrangement is given, which reproduces the distribution of tangential forces over the contact patch between the two discs. Wear is subsequently calculated by relating the forces and creepage between the two discs using three different wear functions found in the literature. The resulting wear rates are compared with experimental data for discs made of common railway wheel and rail steels. This allows a comparison and assessment of the validity of the different wear algorithms considered

Special Lagrangian cones with higher genus links

For every odd natural number g=2d+1 we prove the existence of a countably infinite family of special Lagrangian cones in C^3 over a closed Riemann surface of genus g, using a geometric PDE gluing method.Comment: 48 page

Reinterpreting the UK Response to Hate Crime

This paper considers the motivation and function of the UK’s hate-crime framework, offering a historically located interpretation. It discusses the development of legislation to combat discrimination- and prejudice-motivated harassment and offending before examining recent assessments of the UK’s approach. It then provides a cursory examination of the historical context in which the UK’s legislative and policy developments emerged. After exposing the limitations of the current UK response and framing this in a wider domestic and international context, the paper concludes by arguing that the UK’s evolving hate-crime policy framework currently remains partial and serves to obfuscate its social control objectives, along with the political anxieties related to the ideological and political threats and disorder that underpinned its development. The article concludes by arguing that the current framework has recently downgraded – and increasingly sidesteps – the need to address internal manifestations of illiberalism, including institutional discrimination, workforce representativeness, racial and religious disparity, and equal opportunities

Is there a link between regional planning and economic growth?

An aging population directly influences the activities of community planners. Planning issues have a bearing on the quality of life older people experience living in the community. By consciously involving older citizens in the plan-making process, planners can better understand the visions and unique needs of this sector of the population. A questionnaire was developed to measure the degree of effort planners make to involve older citizens in the planning process. It was administered to planners in a sample of 30 jurisdictions in Florida. The results indicate that planners have generally neglected older adults as part the citizen participation process. Since planners have an important role to play in planning for communities as they age, increased participation of older adults throughout the plan-making process could result in plans and over time, in communities, that are more elder-friendly and therefore more livable for everyone