Analysis of Thermal Stresses and Residual Stress Changes in Railroad Wheels Caused by Severe Drag Braking
01 Feb 1977-Journal of Engineering for Industry (American Society of Mechanical Engineers)-Vol. 99, Iss: 1, pp 18-23
TL;DR: In this article, a finite element computer program was used to analyze the thermal stresses in railroad freight car wheels subjected to severe drag brake heating, and the resulting changes in the residual stress field after the wheel has cooled to ambient temperature have also been calculated.
Abstract: A finite-element computer program, which takes into consideration nonlinear material behaviour after the yield point has been exceeded, has used to analyze the thermal stresses in railroad freight car wheels subjected to severe drag brake heating. The analysis has been used with typical wheel material properties and wheel configurations to determine the thermal stress field and the extent of regions in the wheel where the yield point is exceeded. The resulting changes in the residual stress field after the wheel has cooled to ambient temperature have also been calculated. It is shown that severe drag braking can lead to the development of residual circumferential tensile stresses in the rim and radial compressive stresses in the plate near both the hub and rim fillets.
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TL;DR: In this paper, the maximum surface temperature during rolling contact of railway wheels with sliding friction can be estimated using Blok's flash temperature formula, and an efficient approach is proposed for Hertzian contact.
Abstract: The maximum surface temperature during rolling contact of railway wheels with sliding friction can be estimated using Blok’s flash temperature formula. For a more detailed investigation, semi-analytical and numerical methods are available. A survey of various methods is given and an efficient approach is proposed for Hertzian contact. The actual contact temperature is confined to a very thin surface layer. Due to continuous frictional heating, the bulk temperature of the wheel increases with time. For the long-term behaviour of the wheel temperature, not only the convection at the free wheel surfaces but also the heat conduction from the wheel into the colder rail has to be considered. Practical consequences of the theoretical results are discussed.
128 citations
TL;DR: In this paper, an approximate analytical solution for a line contact model is presented for a wheel and rail, and the increased bulk temperature of the wheel after a long period of constant operating conditions is also taken into account.
Abstract: Sliding friction between railway wheels and rails results in considerable contact temperatures and gives rise to severe thermal stresses at the surfaces of the wheels and rails. An approximate analytical solution is presented for a line contact model. The increased bulk temperature of the wheel after a long period of constant operating conditions is also taken into account. The thermal stresses have to be superimposed on the mechanical contact stresses. They reduce the elastic limit of the wheel and rail, and yielding begins at lower mechanical loads. When residual stresses build up during the initial cycles of plastic deformation, the structure can carry higher loads with a purely elastic response in subsequent load cycles. This phenomenon is referred to as shakedown. Due to the distribution of temperature, the rail surface is generally subjected to higher stresses than the wheel surface. This can cause structural changes in the rail material and hence rail damage.
42 citations
TL;DR: In this paper, the authors show that the kind of hardening observed for rail steel has a considerable influence on the shakedown limit and the residual stresses provide the structure to shake down to pure elastic behaviour in subsequent load cycles up to a shakedown.
Abstract: Sliding friction between railway wheels and rails results in elevated contact temperatures and gives rise to severe thermal stresses at the wheel and rail surfaces. The thermal stresses have to be superimposed on the mechanical contact stresses. Due to the distribution of stresses, the rail surface is generally subjected to higher stresses than the wheel surface. The elastic limit is reduced and yield begins at lower mechanical loads. During the first cycles of plastic deformation, the material hardens and residual stresses build up. The residual stresses provide the structure to shake down to pure elastic behaviour in subsequent load cycles up to a shakedown limit. The kind of hardening observed for rail steel has a considerable influence on the shakedown limit. The shakedown limit is dropped to lower mechanical loads due to the thermal stresses in the rail surface as well. This might cause structural changes in the rail material and rail damage.
25 citations
TL;DR: The "common neighbor analysis," based on planar graphs is used to obtain information about the transient structures accompanying viscoplastic behavior on an atomic level, and a simple analytical expression for the isotropic pressure at finite temperatures is proposed.
Abstract: We study equilibrium and nonequilibrium properties of a simple ``generic embedded-atom model'' (GEAM) for metals. The model allows to derive simple analytical expressions for several zero-temperature constitutive properties---in overall agreement with real metals. The model metal is then subjected to shear deformation and strong flow via nonequilibrium molecular dynamics simulation in order to discuss the origins of some qualitative properties observed using more specific embedded-atom potentials. The ``common neighbor analysis,'' based on planar graphs is used to obtain information about the transient structures accompanying viscoplastic behavior on an atomic level. In particular, pressure tensor components and plastic yield are investigated and correlated with underlying structural changes. A simple analytical expression for the isotropic pressure at finite temperatures is proposed. A nonequilibrium phase diagram is obtained by semianalytic calculation.
19 citations
01 Nov 2016
TL;DR: In this paper, the authors present a part of a research project that aims to develop a technology of freight wagons modernization during their periodic repair, which can solve the problem of corrosion of the wagon's body shell.
Abstract: Rail transport is a very important part of the modern economy, one of the components determining its dynamic development. It is therefore important to conduct research and taking action aimed at the development and refinement of this branch of industry. Such actions directly translate into an increase in its effectiveness, safety, reduction of burden on the environment and society. Nowadays numerous studies are conducted, aimed at introducing new technologies and solutions, both in terms of railway infrastructure and logistics management systems, as well as in traction vehicles themselves. Introduction of modern technology helps eliminate or reduce nuisance problems associated with the implementation of any kind of transport or the operation of the used technical means. Presented paper concerns an issue of freight wagon modernization using composite materials. It presents a part of a research project that aim is to develop a technology of freight wagons modernization during their periodic repair. The main problem during exploitation of concerned types of freight wagons designed for coal transport is corrosion of the wagon's body shell. The goal of the project is to elongate the period between periodic repairs (by better corrosion protection) and improve conditions of exploitation of modernized freight wagons (for example easier unloading during winter conditions - no freezes of the charge to the freight wagon body shell). One of elements of the project is also to develop a system for diagnosing the technical condition of the modernized shell of wagon body during operation. For this purpose the use of non-destructive testing methods of technical state of constructions will be used, including methods that use the analysis of dynamic response of the object. Application of the composite panels to the freight wagon's body shell was proposed as the solution that can solve mentioned problems during exploitation of freight wagons. The composite panels composed of fiberglass and epoxy resin were proposed. They will be mounted on the body shell using blind rivet nuts. What is more the body shell of the modernized freight wagon will be painted using an anticorrosion agent. The research project is realized by a consortium composed by research units and industry and supported by the Polish National Centre for Research and Development.
19 citations