Abstract
This work studied the effect of kissing bond defects on the fatigue strength of friction stir welded (FSW) specimens and assessed fatigue life prediction approaches for the fatigue strength evaluation of friction stir welded specimens. For specimens with inherent kissing bond defects prepared by friction stir welding process made of AA5083 aluminum alloy thin sheets, constant amplitude fatigue tests under different loading levels were carried out on MTS test frame. Profiles of kissing bond defects at weld toes as well as the fatigue fracture morphologies were observed with scanning electron microscopy. According to the experimental observations, finite element models based on both the virtual notch radius theory and the crack propagation conception were built, respectively, to calculate the stress and strain in the weld zone. Correspondingly, fatigue lives were predicted by these two methods and compared with experimental results.
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Abbreviations
- R:
-
Loading ratio, R = Fmin/Fmax
- Fmin :
-
Minimum load
- Fmax :
-
Maximum load
- Δσ:
-
Stress amplitude
- Ne :
-
Experimental fatigue life
- Hv:
-
Vickers hardness
- d:
-
Kissing bond depth
- rref :
-
Reference radius
- Fm :
-
Mean load
- Fa:
-
Load amplitude
- E:
-
Elastic modulus
- v:
-
Poisson ratio
- FAT:
-
Characteristic fatigue strength at N 2×106
- C:
-
Constant in equation of S-N curve
- m:
-
Exponent in equation of S-N curve
- S:
-
Stress
- KI :
-
Mode I crack stress intensity factor
- F:
-
Crack shape function
- a:
-
Crack length
- b:
-
Plate width
- C0 :
-
Constant of the power law
- ΔK :
-
Range of cyclic stress intensity factor
- ΔKth :
-
Threshold value of stress intensity
- Np :
-
Predicted fatigue life
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Acknowledgments
This work is partially funded by the National Natural Science Foundation of China (Grant No. 51065012), China.
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Ruijie Wang is an Associate Professor in Faculty of Mechanical and Electrical Engineering at Kunming University of Science and Technology. He received his B.S. in Machinery Manufacturing Process and Technology from Kunming University of Science and Technology in 1995. He received his Ph.D. from Beijing University of Technology in 2008. Dr. Wang’s current research interests include fatigue strength welded structures, fracture mechanics, finite element analysis.
Peng Mi is a graduate student in Mechanical and Electrical Engineering at Kunming University of Science and Technology. He received his B.S. in Mechanical Design and Manufacture & Automation from Yulin University in 2017. His current research interests include fatigue strength welded structures, finite element analysis.
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Wang, R., Mi, P. Study on fatigue strength of FSW joints of 5083 aluminum alloy with kissing bond defect. J Mech Sci Technol 34, 2761–2766 (2020). https://doi.org/10.1007/s12206-020-0608-3
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DOI: https://doi.org/10.1007/s12206-020-0608-3