Fatigue Behavior of Dissimilar Ultrasonic Spot Welds in Lap-Shear Specimens of Magnesium and Steel Sheets

2011 ◽  
Vol 4 (1) ◽  
pp. 581-588 ◽  
Author(s):  
Teresa J. Franklin ◽  
Jwo Pan ◽  
Michael Santella ◽  
Tsung-Yu Pan
Keyword(s):  
Fatigue Behavior ◽  
Spot Welds ◽  
Steel Sheets ◽  
Lap Shear

Fatigue Behavior of Magnesium AZ31 in Friction Stir Spot Welds

2009 ◽  
Author(s):  
J. B. Jordon ◽  
M. F. Horstemeyer ◽  
H. Badarinarayan ◽  
J. Grantham
Keyword(s):  
Fatigue Life ◽  
Crack Growth ◽  
Fatigue Behavior ◽  
Spot Welds ◽  
Friction Stir ◽  
Lap Shear ◽  
Magnesium Az31 ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Crack Growth Modeling

In this study, the fatigue behavior of AZ31 magnesium friction stir spot welded joints is experimentally investigated. The friction stir spot welds employed here are representative of preliminary welds made in developing the joining process for potential use in automobile manufacturing. Load control cyclic tests were conducted on single weld lap-shear coupons and were fatigued until failure to determine stress-life properties. The fractured coupons were examined under optical and scanning electron microscopes with the intent to determine fatigue crack characteristics. Fractography analysis suggests that long crack growth accounts for a majority of the fatigue life. To predict the fatigue life of the lap-joint coupons, a long crack growth modeling approach, based on a kinked crack stress intensity solution, was employed. The fatigue model predictions compared well to the experimental stress-life results.

Fatigue behavior of friction spot welds in lap shear specimens of AA5754 and Ti6Al4V alloys

2016 ◽  
Vol 91 ◽  
pp. 149-157 ◽  
Author(s):  
A.H. Plaine ◽  
U.F.H. Suhuddin ◽  
N.G. Alcântara ◽  
J.F. dos Santos
Keyword(s):  
Fatigue Behavior ◽  
Spot Welds ◽  
Lap Shear

Failure Mode and Fatigue Behavior of Dissimilar Friction Stir Spot Welds in Lap-Shear Specimens of Transformation-Induced Plasticity Steel and Hot-Stamped Boron Steel Sheets

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
S. H. Hong ◽  
S.-J. Sung ◽  
J. Pan
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Behavior ◽  
Boron Steel ◽  
Loading Conditions ◽  
Test Results ◽  
Spot Welds ◽  
Transformation Induced Plasticity ◽  
Friction Stir ◽  
Lap Shear ◽  
Cycle Loading

Failure mode and fatigue behavior of dissimilar friction stir spot welds in lap-shear specimens of transformation-induced plasticity steel (TRIP780) and hot-stamped boron steel (HSBS) sheets are examined in this paper. Optical micrographs of the dissimilar TRIP780/HSBS friction stir spot welds made by a concave silicon nitride tool before and after testing are obtained and examined. These micrographs indicate that subject to quasi-static and cyclic loading conditions, the TRIP780/HSBS welds fail from cracks growing through the TRIP780 sheets where the tool was plunged into and the thickness was reduced. The bending moments and the transverse shear force near the welds are derived with consideration of the load offset, the weld gap, and the bend distance for calculation of analytical global stress intensity factor solutions for the welds in lap-shear specimens. A fatigue model of kinked crack growth is used to estimate fatigue lives based on the local stress intensity factor solutions for kinked cracks. The estimated fatigue lives with consideration of the weld gap and the bend distance are in agreement with the fatigue test results under low-cycle loading conditions and lower than the fatigue test results under high-cycle loading conditions. The estimated fatigue lives suggest that the weld gap and the bend distance can significantly affect fatigue lives of the friction stir spot welds in lap-shear specimens under cyclic loading conditions.

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