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Martin Ertz

Bio: Martin Ertz is an academic researcher from Technical University of Berlin. The author has contributed to research in topics: Contact mechanics & Tribology. The author has an hindex of 2, co-authored 3 publications receiving 180 citations.

Papers
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Journal ArticleDOI
01 Aug 2002-Wear
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.

128 citations

Journal ArticleDOI
20 Oct 2006-Wear
TL;DR: In this article, a model of dry friction is established based on the method of movable cellular automata (MCA) and the influence of pressure and sliding velocity has been investigated by means of a large number of numerical simulations.

62 citations

01 Jan 2003
TL;DR: In this article, a survey on different kinds of static, dynamic and thermal loadings in wheel/rail contact is presented, including tractive or braking forces transmitted through the contact patch.
Abstract: Rail surfaces are subjected to extreme stresses. In this paper, a survey on different kinds of static, dynamic and thermal loadings in wheel/rail contact is presented. Besides the static wheel load, tractive or braking forces are transmitted through the contact patch. If a wheel rolls on a corrugated rail, dynamic oscillations of contact forces occur up to the short-term loss of contact. Driving at high creepages causes increased contact temperature and gives rise to severe thermal stresses. The surfaces of wheel and rail are always rough. If measured roughness profiles are taken into account, the surface stresses are much higher than in the smooth case. Compared with these high stresses, bending stresses in the rail can nearly be neglected. The stresses due to the different kinds of loading have to be superimposed. Material laws should be able to describe the behaviour of rail steel subjected to cyclic loading. It seems to be reasonable that the extreme stresses in the rail surface contribute to the formation of the so-called White Etching Layers.

1 citations


Cited by
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Journal ArticleDOI
01 Jun 2004
TL;DR: In this paper, twin-disc wear testing has been carried out to study the wear characteristics of R8T railway wheel steel and three wear regimes were identified; mild, severe, and catastrophic.
Abstract: The need to improve safety and reduce costs means that new specifications are being imposed on railway wheel wear. These mean that more durable wheel steels are required. In order to develop such materials, a greater understanding is needed of the wear mechanisms and transitions occurring in wheel steels. In this work, twin-disc wear testing has been carried out to study the wear characteristics of R8T railway wheel steel. The results have indicated that, compared with previous wheel steels, R8T offers greater wear resistance. Three wear regimes were identified; mild, severe, and catastrophic. Wear rates were seen to increase steadily initially and then to level off, before increasing rapidly as the severity of the contact conditions increased. This paper is concerned with the form of the data and the reasons for the transitions. Analysis of the contact conditions indicated that the first transition in the wear rate was caused by the change from partial slip to full slip conditions at the disc interface. Temperature calculations for the contact showed that the large increase in wear rates seen at the second wear transition may result from a thermally induced reduction in yield strength and other material properties. This improved understanding will help in progressing towards the aim of eventually attaining a wear modelling methodology reliant on material properties rather than wear constants derived from testing.

162 citations

Journal ArticleDOI
30 Oct 2008-Wear
TL;DR: In this paper, the effects of a number of contaminants, such as oil, dry and wet leaves and sand, on wheel/rail adhesion were investigated using a twin disc simulation.

158 citations

Journal ArticleDOI
TL;DR: A review of the literature on the numerical tribology of dry contacts by analysing the different scales involved can be found in this article, where the authors propose an exhibition of numerical results.

116 citations

Journal ArticleDOI
10 Sep 2007-Wear
TL;DR: In this article, the surface changes induced by repeated brake applications and how such material modifications might affect friction and wear properties of automotive disc brakes were investigated by using a focused ion beam instrument (FIB).

111 citations

Journal ArticleDOI
TL;DR: In this article, a multi-scale approach is used to make an attempt to understand the sources of elastomere friction in a more rigorous way, where the elastomer undergoes large deformations during contact, such that the frictional properties result for the main part from internal energy dissipation and not just from the combination of surfaces in contact.

106 citations