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Fatigue life assessment of welded joints under variable amplitude loading. State of the present knowledge and recommendations for fatigue design regulations

 
: Sonsino, C.; Maddox, S.J.; Hobbacher, A.

International Institute of Welding -IIW-; IIS; JWS Japan Welding Society; JWES The JApan Welding Engineering Society:
IIW International Conference on Technical Trends and Future Prospectives of Welding Technology for Transportation, Land, Sea, Air and Space 2004. Proceedings : Osaka, Japan, 15.-16. July 2004
London: IIW, 2004 (Welding in the world 48.2004, Special issue)
S.84-99
International Conference on Technical Trends and Future Prospectives of Welding Technology for Transportation, Land, Sea, Air and Space <2004, Osaka>
Englisch
Konferenzbeitrag, Zeitschriftenaufsatz
Fraunhofer LBF ()
Schweißverbindung; welded joint; Mehrstufenbeanspruchung; variable amplitude loading; laser welding

Abstract
Investigations of cumulative damage were carried out on two types of welded joints (butt welds and transverse stiffeners) of four structural steels, S355M, S690Q and S960Q in the thickness of t = 10 and 25 mm. Further investigations were performed with laser beam welded hollow hat specimens of an automotive steel DC04 and an aluminium alloy AA 5083 with sheet thicknesses of 2 and 3 mm. The random spectra used were of Gaussian type.
By applying the Palmgren-Miner rule modified by Haibach most fatigue life estimations with the conventional damage sum D=1.0 were on the unsafe side. For cumulative fatigue design the evaluation of the results suggest the use of an allowable damage sum of Dal = 0,5 with the slope of k =3 up to the knee point of the SN-curve at 1 * 107 cycles and k´ = 5 after the knee point. This applies for steel as well as for aluminium welded joints.

: http://publica.fraunhofer.de/dokumente/N-22091.html