An Attempt to Use the Results of Microtomographic Studies of the Surface After the Period of Operation in the Numerical Analysis of Wheel-Rail Contacts.

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Date: July-August 2020
From: Mechanika(Vol. 26, Issue 4)
Publisher: Kauno Technologijos Universitetas
Document Type: Article
Length: 3,396 words
Lexile Measure: 1390L

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Abstract :

Under the passing train in the rail, a three-dimensional state of stress is created. The mutual forces exerted by the wheel on the rail consist of the normal (vertical) and longitudinal and transverse forces of the tangential force. The vertical force has a static component derived from the weight of the rail vehicle, a quasi-static component derived from the unbalance in the curves and a random component resulting from the vibrations of the vehicle mass as a result of unevenness of the track and flange rim impacts due to serration. The distribution of tangential forces in the wheel-rail system depends on the shape and size of the contact area, the slip values and the state of the running surface (surface topography). During the contact of two bodies, their interaction causes an increase in stress and thus an increase in surface energy. Therefore, this energy, depending on the type of material, can cause physicochemical changes in it, which in turn lead to the phenomenon of decohesion. In order for the phenomenon to occur, it must be exceeded the limit of strength of the material is usually the yield point. Depending on the material's properties (especially hardness) the time in which contact surfaces stay in contact is extremely important because the longer it is, the more energy will be transferred to the other body. In the case of materials with a high hardness, the energy is first converted into elastic and then plastic impacts, causing plastic deformation and dislocation motion, leading to the separation of material layers and its defect. However, much more plastic materials are faster than the yield point and the separation of material in the form of flaky wear debris. The paper presents the influence of selected exploitation factors on the condition of the surface layer through the use of simulation tests using the Finite Element Method (FEM). The surface layer was mapped using a computer microtomograph and the influence of operational parameters on its condition was presented using simulation tests by means of FEM. Keywords: wear, microcontact rolling-sliding, FEM, tribological test, microtomography.

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Gale Document Number: GALE|A644456588