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A statistical measure of the non-proportionality of stresses – investigations and applications*

  • Christian Gaier
Published/Copyright: May 28, 2013
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Materials Testing
From the journal Materials Testing Volume 48 Issue 3

Abstract

In mechanical engineering, fatigue assessment based on Finite Element analysis of components, where complex non-proportional loads are acting on, plays an important role in identifying critical spots, and predicting the lifetime, till crack initiation. In this contribution the life time analysis of a dynamically loaded crankshaft of a V6 diesel engine is demonstrated. Finite Element method, multi-body system simulation and an elasto-hydrodynamic simulation of the oil film have been combined for a modal analysis in the frequency domain. Based on these results a fatigue analysis follows to identify the critical engine speed range. In notches rotating principal stresses can be found, which reduce the lifetime significantly. To quantify the non-proportionality of stresses and the resulting decrease of the fatigue limit, a statistical measure originally proposed by Chu et al. is applied. The critical plane criterion has been used in conjunction with a stress based method (concept of synthetic S/N-curves, influence parameter concept) and linear damage accumulation according to Miner's rule.

Kurzfassung

Für die Auslegung von komplexen, nicht proportional belasteten Bauteilen spielt die Betriebsfestigkeitsanalyse auf Basis von Finite Elemente Methode-Ergebnissen eine kaum zu überschätzende Rolle, einerseits um kritische Stellen zu identifizieren, andererseits um die Dauerbruchsicherheit oder die Lebensdauer bis zum technischen Anriss abschätzen zu können. Im vorliegenden Beitrag wird die Betriebsfestigkeitsanalyse einer dynamisch belasteten Kurbelwelle eines V6 Dieselmotors gezeigt. Finite Elemente Methode, Mehrkörpersimulation und elasto-hydrodynamische Simulation des Ölfilms wurden für eine modale Analyse im Frequenzbereich kombiniert. Basierend auf diesen Ergebnissen erfolgte eine Betriebsfestigkeitsanalyse, um kritische Motordrehzahlen identifizieren zu können. In Kerben konnten dabei Richtungsschwankungen der Hauptnormalspannungen festgestellt werden, welche zu einer nicht unwesentlichen Lebensdauerreduktion führen können. Um die Nicht-Proportionalität von Spannungen und die damit verbundene Reduktion der Dauerfestigkeit quantifizieren zu können, wurde ein statistisches Maß angewandt, welches ursprünglich von Chu et al. vorgeschlagen wurde. Die Betriebsfestigkeitsanalyse erfolgte im weiteren durch Anwendung eines kritischen Schnittebenenverfahrens basierend auf Spannungen (Konzept der synthetischen Wöhlerlinien, Einflussparameterkonzept) und der linearen Schadensakkumulation nach Miner.

Dr. Christian Gaier, born 1965 studied from 1984 to 1992 electrotecnology at the Technical University of Vienna. After post-graduate, he worked as an assistant at the “Institut für Grundlagen und Theorie der Elektrotechnik” at the Technical University of Vienna where he wrote his dissertation about “Numerische Berechnung magnetischer Felder mit Finiten Kantenelementen”. Since 1996 he works on the field of Fatigue asessment at the Engineering Center Steyr, Magna Powertrain, St. Valentin. He is responsible for the development of the software FEMFAT.

*

Contribution to the 7th International Conference on Biaxial/Multiaxial Fatigue and Fracture (7ICBMFF)

References

1 Gaier, C.; Steinwender, G.; Dannbauer, H.: FEMFAT-MAX: A FE-Postprocessor for Fatigue Analysis of Multiaxially Loaded Components, NAFEMS-Seminar Fatigue Analysis, Wiesbaden (2000)Search in Google Scholar

2 Gaier, C.; Pramhas, G.; Steiner, W.: An Extended Critical Plane Criterion for General Load Situations, Proc. of the 8th International Fatigue Congress 2002, pp. 259–266Search in Google Scholar

3 Gaier, C.; Dannbauer, H.: Fatigue Analysis of Multiaxially Loaded Components with the FE-Postprocessor FEMFAT-MAX, ESIS Publication31 (2003), pp. 223–240Search in Google Scholar

4 Chu, C. C.; Conle, F. A.; Huebner, A.: An Integrated Uniaxial and Multiaxial Fatigue Life Prediction Method. VDI Berichte Nr.1283 (1996), pp. 337–348Search in Google Scholar

5 Gaier, C.; Lukacs, A.; Hofwimmer, K.: Investigations on a statistical measure of the non-proportionality of stresses, International Journal of Fatigue26 (2004), No. 4, pp. 331–33710.1016/j.ijfatigue.2003.08.023Search in Google Scholar

6 Prandstötter, M.; Riener, H.; Steinbatz, M.: Simulation of an Engine Speed-UP Run: Integration of MBS – FE – EHD – Fatigue, ADAMS User Conference – Europe (2002)Search in Google Scholar

7 Craig, R. R.; Bampton, M. C. C.: Coupling of Substructures for Dynamics Analysis, AIAA Journal6 (1968), pp. 1313–131910.2514/3.4741Search in Google Scholar

8 Craig, R. R.: Structural Dynamics – An Introduction to Computer Methods, John Wiley & Sons (1981)Search in Google Scholar

Published Online: 2013-05-28
Published in Print: 2006-03-01

© 2006, Carl Hanser Verlag, München

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  10. A statistical measure of the non-proportionality of stresses – investigations and applications*
  11. Multiaxial fatigue life and strength criteria for non-proportional loading*
  12. Predicting fatigue life of welded aluminium joints with combined bending and torsion using energy based criteria*
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  14. Vorschau/Preview
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https://doi.org/10.3139/120.100716

Articles in the same Issue

  1. Inhalt/Contents
  2. Inhalt
  3. DGZfP-Mitteilungen
  4. Organschaft
  5. Fachbeiträge/Technical Contributions
  6. Normung von Prüfverfahren in der Bauakustik
  7. Fatigue damage of weld seams with and without postweld treatment under multiaxial loading*
  8. On ratchetting-based models of Wear and Rolling Contact Fatigue* (RCF)
  9. A constitutive high cycle fatigue damage model – based on the interaction between microplasticity and local damage*
  10. A statistical measure of the non-proportionality of stresses – investigations and applications*
  11. Multiaxial fatigue life and strength criteria for non-proportional loading*
  12. Predicting fatigue life of welded aluminium joints with combined bending and torsion using energy based criteria*
  13. Reliability evaluation of NDT techniques for Cu-welds for risk assessment of nuclear waste encapsulation
  14. Vorschau/Preview
  15. Vorschau
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