Thermal-mechanical damage in railroad wheels due to hot spotting

Michael C. Fec, Huseyin Sehitoglu

Research output: Contribution to journalArticlepeer-review


As a railroad wheel is heated during a brake application, a compressive stress is developed in the tread surface. Free thermal expansion is partially or completely constrained by the cooler underlying material. If yielding of the surface material occurs, a residual tensile stress could be developed. Constraint of thermal expansion can cause stresses which may eventually initiate and propagate fatigue cracks. Constraint of free thermal expansion is a necessary ingredient in the thermal fatigue process. The number of cycles that produces cracks would classify this process under the more general heading of "low cycle fatigue". It has been observed that a phenomenon known as "hot spotting" develops on the tread surface as braking occurs. These areas of contact, roughly 20-40 mm in diameter, experience high localized stresses as a result of the severe temperature gradients associated with them. Thermal strains of these hot spots were calculated and in the case of total constraint all this strain is converted to mechanical strain. Thermomechanical fatigue testing provided the necessary data for the fatigue analysis. The result of this work provides a life prediction of railroad wheels experiencing hot spotting.

Original languageEnglish (US)
Pages (from-to)31-42
Number of pages12
Issue number1-2
StatePublished - Mar 1985

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry


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