This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Improvements in the Fatigue Assessment of Large Welded Structures Using the Nominal Stress Approach
ISSN: 0148-7191, e-ISSN: 2688-3627
Published September 24, 2012 by SAE International in United States
Annotation ability available
By the fatigue assessment of large welded steel structures such as construction machines structures, the calculation engineer is confronted with a difficulty: the local stress approaches with fictitious notch radius that are very accurate cannot be used on the global structure because of the current computer limitations. Only a nominal stress can be estimated on the whole structure. The accuracy of the current commercial code methods that are using the nominal stress approach is not satisfying for most of the cases. The major problems are the following:
- only one SN-Curve (FAT-class) can be chosen for a weld
- the stress used for the calculation is based on the critical plane concept, not taking into account the direction of the weld (anisotropy of notch effects) and the geometrical weld parameters (e.g. weld throat thickness and penetration)
- choice of the FAT-class when the structural detail is not available in the IIW guideline.
The investigations that have been made in collaboration with LMS Durability development team in the last two years have permitted to elaborate a new nominal stress approach that improves the three issues above. The validation on some weld joints and geometries has shown that this new method allows making a big step forward in the accuracy without affecting the time required for the analysis.
CitationKarge, M., "Improvements in the Fatigue Assessment of Large Welded Structures Using the Nominal Stress Approach," SAE Technical Paper 2012-01-1910, 2012, https://doi.org/10.4271/2012-01-1910.
- Karge, M. Methode zur Berechnung der Schädigung von Schweissnähten mobiler Arbeitsmaschinen (Method for the fatigue assessment of the seam welds from mobile construction, machines) Diploma Thesis Technische Universität Dresden 2011
- Hobbacher, A. Recommendations for Fatigue design of welded joints and components International Institute of Welding June 2008
- Issler, L. Schwingfestigkeitsversuche an Kastenprofilen aus Baustahl S 355 für Liebherr-Hydraulikbagger (fatigue testing from box profiles of steel S 355 for Liebherr-Hydraulikbagger), STZ Bauteilfestigkeit und -sicherheit, Werkstoff- und Fügetechnik (BWF) Fachhochschule Esslingen October 2008
- ICE Flow: DesignLife theory guide 5.0 nCode International Ltd. 2008
- LMS Virtual.Lab Rev 11 LMS International N.V. 2012
- Hofwimmer, K. Gaier, C. Dannbauer, H. Zhang, S. Weisner, R. Eppler, R. Hempel, H. Force Based Fatigue Assessment of Weldings ATZautotechnology 8 April 2008
- Dong, P. Hong, J.K. The master S-N curve approach to fatigue evaluation of welded structures OMAE 2004-51324
- Fricke, W. Guideline for the Fatigue Assessment by notch stress analysis for welded structures, IIW-Doc. XIII-2240-08/XV-1289-08 June 2008
- Karge, M. Improvements in the fatigue assessment of large welded structures using the nominal stress approach Liebherr fatigue and simulation meeting Ehingen June 2011
- Sonsino, C.M. Kaßner, M. Fricke, W. Stand von Bemessungskonzepten zur schwingfesten Auslegung von Schweißverbindungen (status from the fatigue assessment of weld connections), Festigkeit geschweißter Bauteile DVS conference in Braunschweig May 2009
- Koettgen, V. Zingsheim, F. Hack, M. Speckert, M. “A New Approach for Numerical Fatigue Life Prediction of Parts or Systems with Seam Welds,” SAE Technical Paper 2003-01-2772 2003 10.4271/2003-01-2772