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Transient rolling of cylindrical contacts with constant and linearly increasing applied slip
KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).ORCID iD: 0000-0001-6896-1834
2009 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 266, no 1-2, 316-326 p.Article in journal (Refereed) Published
Abstract [en]

The transient start problem of a rolling cylindrical contact has been studied. The transient conditions were controlled by the applied relative slip. Two cases with start of rolling from stationary contact were investigated, with constant and with linearly increasing applied slip. At each instant during the transition stage, it was assumed that the traction distribution could be approximated with the Carter traction for steady-state tractive rolling. Based on this distribution, approximate expressions were derived for the transient rolling distance and transient behaviour of the tangential load. The transient period could end in gross sliding or steady-state creep with the Carter traction distribution and stick-slip regions in the contact. The expressions and the transient traction distributions were validated numerically using FEM. Simulations with constant applied slip showed that when rolling started from a tangentially unloaded and unstrained position, the steady-state traction distribution by Carter was a good approximation of the actual transient traction distribution. The solution was accurate for transient rolling lengths longer than a quarter of the contact width. The transient behaviour depended on the bulk geometry of the structures. For the relatively stiff structure with two elastic steel cylinders, small amounts of relative slip and high coefficients of friction, the transient rolling distance, L-0, could become large. In the present study, examples with L-0 approximate to 40 . a were identified. Thus, situations exist for which the transient conditions might be important. The transient distance increased with smaller slip, larger coefficient of friction, lower bulk stiffness, higher contact normal loads and for more compliant materials. The spur gear contact interaction with varying slip was considered as a case study.

Place, publisher, year, edition, pages
2009. Vol. 266, no 1-2, 316-326 p.
Keyword [en]
Transient rolling, Stick-slip, Sliding contact, Contact traction, Spur gear
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-7772DOI: 10.1016/j.wear.2008.07.008ISI: 000261538800037ScopusID: 2-s2.0-55249116733OAI: diva2:12897
QC 20100702. Uppdaterad från Submitted till Published i DiVA 20100702.Available from: 2007-12-10 Created: 2007-12-10 Last updated: 2011-11-11Bibliographically approved
In thesis
1. On the asperity point load mechanism for rolling contact fatigue
Open this publication in new window or tab >>On the asperity point load mechanism for rolling contact fatigue
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Rolling contact fatigue is a damage process that may arise in mechanical applications with repeated rolling contacts. Some examples are: gears; cams; bearings; rail/wheel contacts. The resulting damage is often visible with the naked eye as millimeter sized surface craters. The surface craters are here denoted spalls and the gear contact served as a case study.

The work focused on the asperity point load mechanism for initiation of spalls. It was found that the stresses at asperity level may be large enough to initiate surface cracking, especially if the complete stress cycle was accounted for.

The gear contact is often treated as a cylindrical contact. The thesis contains experimental and numerical results connected to rolling contact fatigue of cylindrical contacts. At the outset a stationary cylindrical contact was studied experimentally. The stationary test procedure was used instead of a rolling contact. In this way the number of contact parameters was minimized. The cylindrical contact resulted in four different contact fatigue cracks. The two cracks that appeared first initiated below the contact. The other two cracks developed at the contact surface when the number of load cycles and the contact load increased.

The influence of a surface irregularity (asperity) was studied numerically with the Finite Element Method (FEM). Firstly, the stationary contact was modelled and investigated numerically. At the cylindrical contact boundary a single axisymmetric was included. The partially loaded asperity introduced a tensile surface stress, which seen from the asperity centre was radially directed. Secondly, FE simulations were performed where a single axisymmetric asperity was over-rolled by a cylindrical contact. The simulations were performed for pure rolling and rolling with slip. For both situations, tensile forward directed stresses in front of the asperity were found. The presence of slip and a surface traction greatly increased the stresses in front of the asperity. Finally, when rolling started from rest with applied slip, the distance to steady-state rolling was determined for elastic similar cylindrical rollers.

Place, publisher, year, edition, pages
Stockholm: KTH, 2007. 14 p.
Trita-HFL. Report / Royal Institute of Technology, Solid mechanics, ISSN 1654-1472 ; 0440
Rolling contact fatigue, Spalling, Asperity contact, Point load; Micro-cracks, Traction, Applied slip
National Category
Engineering and Technology
urn:nbn:se:kth:diva-4569 (URN)
Public defence
2007-12-17, F3, Lindstedsvägen 26, Stockholm, KTH, 10:15

QC 20100702

Available from: 2007-12-10 Created: 2007-12-10 Last updated: 2013-01-14Bibliographically approved

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