Fatigue Life Prediction of Friction Stir Linear Welds for Magnesium Alloys

2016 ◽  
Author(s):  
HongTae Kang ◽  
Abolhassan Khosrovaneh ◽  
Xuming Su ◽  
Mingchao Guo ◽  
Yung-Li Lee ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Magnesium Alloys ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
Friction Stir

Fatigue Life Prediction for Overlap Friction Stir Linear Welds of Magnesium Alloys

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Ruijie Wang ◽  
Hong-Tae Kang ◽  
Chonghua (Cindy) Jiang
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Magnesium Alloys ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Fatigue Life Prediction ◽  
Structural Stress ◽  
Stress Strain ◽  
Friction Stir ◽  
Damage Equation

This work was undertaken to analyze the stress/strain state at the critical sites in friction stir welded specimens and, further, to assess the fatigue strength of friction stir welded specimens with conventional fatigue life prediction approaches. Elastoplastic and elastic finite-element stress/strain analyses were carried out for friction-stir-linear-welded (FSLW) specimens made of magnesium alloys. The calculated stress/strain at the periphery of the weld nugget was used to evaluate the fatigue life with local life prediction approaches. First, elastoplastic finite-element models were built according to experimental specimen profiles. Fatigue life prediction was conducted with Morrow's modified Manson–Coffin (MC) damage equation and the Smith–Watson–Topper (SWT) damage equation, respectively, for different specimens under different loading cases. Life prediction results showed that both equations can to some extent give reasonable results, especially within a low-cycle fatigue life regime, with the SWT damage equation giving more conservative results. As for high-cycle life, predicted results were much longer and scattered for both methods. Shell element elastic models were then used to calculate the structural stress at the periphery of the weld nuggets. The correlation between structural stress amplitude and experimental life showed the appropriateness of the structural stress fatigue evaluation for friction stir welds. The effect of the notches at the periphery of the faying surface on life prediction was further discussed.

Fatigue Life Prediction of Magnesium Alloys for Structural Applications

Magnesium ◽  
2005 ◽  
pp. 450-455
Author(s):  
Yukio Miyashita ◽  
Zainuddin bin Sajuri ◽  
Takashi Umehara ◽  
Yoshiharu Mutoh
Keyword(s):  
Fatigue Life ◽  
Magnesium Alloys ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
Structural Applications

Fatigue Life Prediction of Al-Li Alloy Butt-Welded Joints in Aerospace Structures

2009 ◽  
Author(s):  
Muhammad A. Wahab ◽  
Vinay Raghuram
Keyword(s):  
Fatigue Life ◽  
Crack Propagation ◽  
Life Prediction ◽  
Space Shuttle ◽  
Fatigue Behavior ◽  
Fatigue Life Prediction ◽  
Fatigue Properties ◽  
Interface Element ◽  
Aerospace Structures ◽  
Friction Stir

Friction-Stir-Welding (FSW) has been adopted as a major process for welding Aluminum aerospace structures. AA-2195 is one of the new generations Aluminum alloy (Al-Li) that has been used on the new super lightweight external tank of the space shuttle. The Lockheed Martin Space Systems (LMSS), Michaud Operations in New Orleans is continuously pursuing FSW technologies in its efforts to advance fabrication of the external tanks of the space shuttle. The future launch vehicles which will have to be reusable, mandates the structure to have good fatigue properties, which prompts an investigation into the fatigue behavior of the friction-stir-welded aerospace structures. The butt-joint specimens of Al-2195 are fatigue tested according to ASTM-E647. The effect of Stress ratios, Corrosion-Preventive-Compound (CPC), and periodic Overloading on fatigue life is investigated. Scanning Electron Microscopy (SEM) is used to examine the failure surfaces and examine the different modes of crack propagation i.e. tensile, shear, and brittle modes. It is found that fatigue life increases with the increase in stress ratio, the fatigue life increases from 30–38% with the use of CPC, the fatigue life increases 8–12 times with periodic overloading; crack closure phenomenon dominates the fatigue facture. Numerical Analysis using FEA has also been used to model fatigue life prediction scheme for these structures, the interface element technique with critical bonding strength criterion for formation of the new surfaces has been used to model crack propagation. The fatigue life predictions made using this method are within the acceptable ranges of 10–20% of the experimental fatigue life. This method overcomes the limitation of the traditional node-release scheme and closely follows the physics of crack propagation.

Fatigue-Life Prediction of Magnesium Alloys for Structural Applications

2003 ◽  
Vol 5 (12) ◽  
pp. 910-916 ◽  
Author(s):  
Z. Bin Sajuri ◽  
T. Umehara ◽  
Y. Miyashita ◽  
Y. Mutoh
Keyword(s):  
Fatigue Life ◽  
Magnesium Alloys ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
Structural Applications

A Fatigue Life Prediction Method of Laser Assisted Self-Piercing Rivet Joint for Magnesium Alloys

2015 ◽  
Vol 8 (3) ◽  
pp. 789-794 ◽  
Author(s):  
Hong Tae Kang ◽  
Abolhassan Khosrovaneh ◽  
Xuming Su ◽  
Yung-Li Lee ◽  
Mingchao Guo ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Magnesium Alloys ◽  
Life Prediction ◽  
Prediction Method ◽  
Fatigue Life Prediction
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