Experimental results and fatigue life evaluation of magnesium laserbeam‐welded joints under proportional and non‐proportional multiaxial fatigue loading with variable amplitudes |
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| Authors: | A. Bolchoun C. M. Sonsino H. Kaufmann T. Melz |
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| Affiliation: | Fraunhofer LBF, Darmstadt, Germany |
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| Abstract: | Fatigue life of magnesium laserbeam‐welds (AZ31 and AZ61 alloys) was assessed experimentally under variable amplitude loadings. The specimens were subjected to load‐controlled cyclic loadings. The tests were carried out using a Gauss‐distributed amplitude sequence of length LS = 5 · 104 cycles and loading ratio R = –1 under pure axial, pure torsion as well as in‐phase and out‐of‐phase combined loadings. The notch stresses were obtained from a linear‐elastic FE‐model using the reference radius approach with rref = 0.05 mm. The stress‐based hypotheses were applied: Effective equivalent stress hypothesis (EESH), shear stress intensity hypothesis (SIH), Findley, and modified Gough‐Pollard. A non‐proportionality factor is introduced and steps required for computing are presented in order to improve fatigue life assessment under non‐proportional loadings. |
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| Keywords: | Magnesium dü nnwandige Schweiß verbindungen spannungsbasierte Hypothesen nichtproportionale Belastung Nichtproportionalitä tsfaktor Magnesium thin‐walled welded joints stress‐based hypothesis out‐of‐phase loading non‐proportionality factor |
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