Abstract
In order to consider cyclic material behavior in the course of the design process of cyclically loaded components and safety relevant parts, the importance of local strain-based fatigue design approaches has been growing continually. For the damage impact of load-time histories on components such as chassis parts, standard service loads with amplitudes settled in the high cycle fatigue and very high cycle fatigue regimes as well as overloads and misuse with load amplitudes from the low cycle fatigue regime, have to be considered, in order to perform a reliable fatigue life estimation. Therefore, a continuous fatigue life curve from the LCF to the VHCF regime, which covers all relevant damage mechanisms, is required. Hence, a fatigue life curve from low cycle fatigue (LCF) across to high cycle fatigue (HCF), and culminating at very high cycle fatigue (VHCF), derived from a combined method using strain- and load-controlled fatigue tests, will be discussed. This continuous fatigue life curve for aluminum wrought alloys, based on the evolution of the behavior of elastic-plastic material as well as the results of high frequency testing up to VHCF, will be presented.
Kurzfassung
Damit das zyklische Werkstoffverhalten bereits während des Konstruktionsprozesses von zyklisch beanspruchten Bauteilen und sicherheitsrelevanten Komponenten berücksichtigt werden kann, nimmt die Bedeutung von lokalen dehnungsbasierten Bemessungskonzepten stetig zu. Im Rahmen eines numerischen Betriebsfestigkeitsnachweises für beispielsweise Fahrwerksbauteile sind die Schädigungen von Beanspruchungszeitfunktionen zu bewerten, deren maximalen Beanspruchungen im Bereich des Abknickpunktes der Wöhlerlinie von der Zeit- in die Langzeitfestigkeit liegen. Weiterhin ist der Einfluss von Überlasten und Missbrauch auf die Betriebsfestigkeit zu berücksichtigen, um einen zutreffenden Lebensdauernachweis führen zu können. Dafür wird eine kontinuierliche Wöhlerlinie von der Kurzzeitfestigkeit bis in den Very High Cycle Fatigue Bereich benötigt, die die Schädigungsmechanismen berücksichtigt und Einflüsse auf das Werkstoff- respektive Bauteilverhalten beschreibt. Im Folgenden wird die Fatigue Life Curve vorgestellt, die aus einer Kombination von dehnungs- und spannungsgeregelten Wöhlerversuchen besteht. Gezeigt wird die Ableitung dieser kontinuierlichen Wöhlerlinie von der Kurzzeitfestigkeit bis weit in die Langzeitfestigkeit am Beispiel von Aluminium-Knetlegierungen.
References
1 A.Palmgren: Fatigue life of bearings (Die Lebensdauer von Kugellagern), VDI-Zeitschrift58 (1924), pp. 339–341Search in Google Scholar
2 B. F.Langer: Fatigue failure from stress cycles of varying amplitude, Trans. ASME, Journal of Applied Mechanics4 (1937), No. 4, pp. 160–162Search in Google Scholar
3 M. A.Miner: Cumulative damage in fatigue, Journal of Applied Mechanics12 (1945) No. 3, pp. 159–16410.1115/1.4009458Search in Google Scholar
4 E.Haibach: Modified linear damage accumulation hypothesis with respect to the decreasing fatigue strength with ongoing damaging, Technische Mitteilungen TM50 (1970) (in German)Search in Google Scholar
5 R. B.Wehrspohn, M.Füting: Fraunhofer – Materials – Materials Data Space, Elbe Druckerei Wittenberg GmbH, Lutherstadt Wittenberg, Germany (2016)Search in Google Scholar
6 https://www.fraunhofer-materials-data-space.de/, accessed 30. 05. 2018Search in Google Scholar
7 J.Liu, H.Zenner: Suggestion to improve the fatigue approach according to the nominal stress method, Konstruktion44 (1992), pp. 9–17 (in German)Search in Google Scholar
8 L. F.Coffinjr.: A study on the effect of cyclic thermal stresses on a ductile metal, Trans. ASME76 (1954), pp. 931–95010.1115/1.4015020Search in Google Scholar
9 S. S.Manson: Fatigue: A complex subject – some simple approximations, Experimental Mechanics5 (1965), No. 7, pp. 45–8710.1007/BF02321056Search in Google Scholar
10 J. D.Morrow: Cyclic plastic strain energy and fatigue of metals, ASTM STP278 (1965), pp. 45–8710.1520/STP43764SSearch in Google Scholar
11 O. H.Basquin: The exponential law of endurance tests, Proc. of the ASTM10 (1910), pp. 625–630Search in Google Scholar
12 W.Ramberg, W. R.Osgood: Description of stress-strain curves by three parameters, National Advisory Committee for Aeronautics Technical Note No. 902, USA (1943)Search in Google Scholar
13 R.Wagener: Cyclic material behavior under constant and variable amplitude loading (Zyklisches Werkstoffverhalten bei konstanter und variabler Beanspruchungsamplitude), PhD-Thesis. (2007), TU ClausthalSearch in Google Scholar
14 R.Wagener, T.Melz: Deriving a continuous fatigue life curve from LCF to VHCF, SAE 2017-01-0330 (2017) 10.4271/2017-01-0330Search in Google Scholar
15 R.Wagener, T.Melz: Deriving a continuous SN-line from LCF to VHCF for dimensioning issues, H.Frenz, J. B.Langer (Eds.): Fortschritte in der Werkstoffprüfung Prüftechnik-Kennwertermittlung-Schadensvermeidung (2017), DVM, Berlin, pp. 83–90 (in German)Search in Google Scholar
16 T.Endo, J.Morrow: Cyclic stress-strain and fatigue behavior of representative aircraft metals, Journal of Materials4 (1969), No. 1, pp. 159–175Search in Google Scholar
17 T. H.Sandersjr., D. A.Mauney, J. T.Staley: Strain control fatigue as a tool to interpret fatigue initiation of aluminum alloys, R. I.Jaffee, B. A.Wilcox (Eds.): Fundamental aspects of structural alloy design, Plenum Publishing, New York, USA (1977) 10.1007/978-1-4684-2421-8_17Search in Google Scholar
18 W. A.Wong: Monotonic and cyclic fatigue properties of automotive aluminum alloys, SAE Technical Paper No. 840120, USA (1984) 10.4271/840120Search in Google Scholar
19 C. C.Wigant, R. I.Stephens: Low cycle fatigue of A356-T6 cast aluminum alloy, SAE Technical Paper No. 870096, USA (1987) 10.4271/870096Search in Google Scholar
20 R. I.Stephens, H. D.Berns, R. A.Chernenkoff, R. L.Indig, S. J.Koh, D. J.Lingenfelser: Low cycle fatigue of A356-T6 cast aluminum alloy – a round-robin test program, R. I.Stephens (Ed.): Fatigue and Fracture Toughness of A356-T6 Cast Aluminum Alloy, SAE SP-760, USA (1988) 10.4271/881705Search in Google Scholar
21 W. A.Wong, R. J.Bucci, R. H.Stentz, J. B.Conway: Tensile and strain-controlled fatigue data for certain aluminum alloys for application in the transportation industry, SAE Technical Paper No. 870094, USA (1987)10.4271/870094Search in Google Scholar
22 R. I.Stephens, S. K.Koh: Improvements in empirical representation of A356-T6 cast aluminum alloy, R. I.Stephens (Ed.): Bi-Linear Log-Log Elastic Strain-Life Model for A356-T6 Cast Aluminum Alloy Round-Robin Low Cycle Fatigue Data, Fatigue and Fracture Toughness of A356-T6 Cast Aluminum Alloy, SAE SP-760, (1998)Search in Google Scholar
23 A.Fatemi, A.Plaiseied, A. K.Khosrovaneh, D.Tanner: Application of bi-linear log-log S-N model to strain-controlled fatigue data aluminum alloys and its effect on life predictions, International Journal of Fatigue27 (2005), pp. 1040–105010.1016/j.ijfatigue.2005.03.003Search in Google Scholar
24 C. F.Jenkin, G. D.Lehmann: High Frequency Fatigue, Aeronautical Research Committee, Reports and Memoranda 1222 (M. 62), H. M. Stationery Office, London, UK (1930)Search in Google Scholar
25 W.Harris: Frequency, Metallic Fatigue, 1st Ed., pp. 91–135, Pergamon Press, Oxford, UK (1961)Search in Google Scholar
26 C.Fischer: The influence of test frequencies on the fatigue strength of the aluminum wrought alloy EN AW-6060, Dr.-Ing. Thesis, TU Darmstadt, Darmstadt, Germany (2017)Search in Google Scholar
27 C.Müller: About the statistical evaluation of experimental Wöhler-lines, Dr.-Ing. Thesis, TU Clausthal, Clausthal-Zellerfeld, Germany (2015),Search in Google Scholar
28 H.Mughrabi: Specific features and mechanisms of fatigue in the ultrahigh-cycle regime, International Journal of Fatigue28 (2006), pp. 1501–150810.1016/j.ijfatigue.2005.05.018Search in Google Scholar
© 2018, Carl Hanser Verlag, München
This work is licensed under the Creative Commons Attribution 4.0 International License.
