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The effect of superimposed high-cycle fatigue on thermo-mechanical fatigue in cast iron
Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
Scania CV AB, Materials Technology, Södertälje, Sweden.
Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
2015 (English)In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 88, 121-131 p.Article in journal (Refereed) Published
Abstract [en]

The eect of superimposing a high-cycle fatigue strain load on an out-ofphase thermo-mechanical fatigue test of a lamellar, compacted and spheroidal graphite iron, has been investigated. In particular, dierent total mechanical strain ranges, maximum temperatures and high-cycle fatigue strain ranges have been studied. From this, a new property has been identied, measured and compared, namely the thermo-mechanical and high-cycle fatigue threshold, dened as the high-cycle fatigue strain range at which the life is reduced to half. Using a model developed earlier, the lifetimes and the threshold have been successfully estimated for the lamellar and compacted graphite iron, however underestimated for the spheroidal graphite iron. Nevertheless, an expression of the threshold was deduced from the model, which possibly can estimate its value in other cast irons and its high-cycle fatigue frequency dependence.

Place, publisher, year, edition, pages
Elsevier, 2015. Vol. 88, 121-131 p.
Keyword [en]
Cast iron, Thermo-mechanical fatigue, High-cycle fatigue, Fatigue crack growth, Life prediction
National Category
Mechanical Engineering Other Engineering and Technologies
Identifiers
URN: urn:nbn:se:liu:diva-121030DOI: 10.1016/j.ijfatigue.2016.03.020ISI: 000375817000013OAI: oai:DiVA.org:liu-121030DiVA: diva2:850969
Note

Funding agencies: Scania CV AB; Swedish Governmental Agency for Innovation Systems [FFI - 2012 - 03625]; Swedish Foundation for Strategic Research [SM12 - 0014]; Linkoping University [2009 - 00971]

Vid tiden för disputation förelåg publikationen endast som manuskript

Available from: 2015-09-03 Created: 2015-09-03 Last updated: 2016-06-09Bibliographically approved
In thesis
1. Fatigue of Heavy-Vehicle Engine Materials: Experimental Analysis and Life Estimation
Open this publication in new window or tab >>Fatigue of Heavy-Vehicle Engine Materials: Experimental Analysis and Life Estimation
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The heavy-vehicle automotive industry is constantly subjected to higher demands. In particular, new European emission standards are formulated with the intention of improving the environmental friendliness of newly-produced vehicles through reduced exhaust emission. In one way or another, this implies a successive improvement of the engine efficiency, which in turn, inevitably will require a higher combustion pressure and temperature. This is a respectable challenge for future engine constructions, but also for the engineering materials used to embody them. As higher thermal and mechanical loads must be sustained, there is a higher rate of wear, and consequently, a negative effect on the extent of the engine lifetime.

The aim of the present thesis is to confront the expected increase in rate of wear, henceforth referred to as fatigue, by studying the effect on materials typically employed in heavy-vehicle engines, namely cast irons. Foremost, the intention has been to improve the understanding of the physical mechanisms of fatigue in these materials, in order to develop a lifetime estimation method designated to assist the mechanical design of heavy-vehicle engines.

In essence, a large set of thermo-mechanical fatigue (TMF) and combined thermo-mechanical and high-cycle fatigue (TMF-HCF) tests has been conducted at engine load conditions on laboratory specimens of lamellar, compacted and spheroidal graphite irons. In this way, these three different material groups have been experimentally compared and the associated fatigue mechanism has been studied. In particular, a new property related to TMF-HCF conditions has been identified and measured, . Regarding the fatigue mechanism, it has been affirmed to consist of the initiation, propagation and coalescence of numerous microcracks. Based on this, a successful lifetime assessment model was formulated, allowing good estimations of the fatigue life of laboratory specimens subjected to both TMF and TMF-HCF conditions.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2015. 36 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1719
National Category
Mechanical Engineering Materials Engineering
Identifiers
urn:nbn:se:liu:diva-121031 (URN)10.3384/lic.diva-121031 (DOI)978-91-7519-023-5 (print) (ISBN)
Presentation
2015-09-18, ACAS, Hus A, Campus Valla, Linköpings universitet, Linköping, 10:15 (Swedish)
Opponent
Supervisors
Available from: 2015-09-03 Created: 2015-09-03 Last updated: 2015-09-28Bibliographically approved

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Norman, ViktorLeidermark, DanielMoverare, Johan
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