Fatigue Crack Growth in Integrally Stiffened Panels Joined Using Friction Stir Welding and Swept Friction Stir Spot Welding

2008 ◽  
Vol 5 (4) ◽  
pp. 101568 ◽  
Author(s):  
Dwight A. Burford ◽  
Bryan M. Tweedy ◽  
Christian A. Widener ◽  
R. W. Neu ◽  
K. R. W. Wallin ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Friction Stir Welding ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Spot Welding ◽  
Friction Stir Spot Welding ◽  
Stiffened Panels ◽  
Friction Stir ◽  
Integrally Stiffened Panels

Fatigue Crack Growth Behavior of Friction Stir Welding of 6063-T5 Aluminum Alloys

2010 ◽  
Vol 146-147 ◽  
pp. 1498-1501
Author(s):  
Supachai Surapunt
Keyword(s):  
Fatigue Crack ◽  
Friction Stir Welding ◽  
Aluminum Alloys ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Base Metal ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Fatigue Crack Growth Behavior ◽  
Friction Stir

The microstructure and fatigue crack growth behavior of friction stir welding of 6063-T5 aluminum alloys were investigated. For this propose, fatigue crack growth curves were determined in four different locations of notch, which are base metal, middle of welded zone (parallel to weld line), near interface and interface (shoulder limits). The crack initiation and crack propagation of the base metal specimens presented slower than those of stir welded specimens. The microstructure observations show that the grain sizes in stir welded zone are finer than that in the unaffected base material and in the heat affected zone.

Fatigue Crack Growth Rates in Friction Stir Welding Joints of 7075-T6 Al Alloy and Fatigue Life Prediction Based on AFGROW

2011 ◽  
Vol 337 ◽  
pp. 507-510 ◽  
Author(s):  
Bin Lian Zou ◽  
Xin Qi Yang ◽  
Jia Hua Chen
Keyword(s):  
Fatigue Crack ◽  
Friction Stir Welding ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Al Alloy ◽  
International Institute ◽  
Welding Seam ◽  
Friction Stir

In this work, a study of fatigue crack propagation (FCP) behavior of friction stir welding (FSW) joints of 7075-T6 aluminum alloy was carried out. Fatigue crack growth rate curves were determined for cracks growing in different locations of the welding lines, including prefabricated crack through welding seam center, advancing side (AS), retreating side (RS), and vertical to welding seam. A computational simulation of fatigue crack propagation was conducted by AFGROW with different stress ratios R, and the effects of R on FCP rate were analyzed. Results showed that the FCP rate in RS of the Heat Affected Zone (HAZ) was the lowest and the highest was in the region vertical to the welding seam. In the low stress intensity factor range (△K) region, the FCP rate in Nugget Zone (NZ) was lower than that in AS of the HAZ, but in the high △K region, the situation was contrary. Reasons of the results were analyzed. Compared with the standard of International Institute of Welding (IIW), FCP rates in all regions were lower and it concluded nice fatigue properties of FSW 7075-T6. The simulation made in terms of crack propagation rate (da/dN) versus △K generally showed a good agreement with the measured values. The study of effects of different R on FCP rates based on AFGROW indicated that FCP rates increased with increasing R.

scholarly journals Simulation of Fatigue Crack Growth in Integrally Stiffened Panels Under the Constant Amplitude and Spectrum Loadin

2009 ◽  
Vol 2009 (1) ◽  
pp. 5-19 ◽  
Author(s):  
Petr Augustin
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Experimental Program ◽  
Constant Amplitude ◽  
Load Spectrum ◽  
Stiffened Panels ◽  
Load Sequence ◽  
Integrally Stiffened Panels ◽  
Spectrum Loading

Simulation of Fatigue Crack Growth in Integrally Stiffened Panels Under the Constant Amplitude and Spectrum LoadinThe paper describes methodology of numerical simulation of fatigue crack growth and its application on integrally stiffened panels made of 2024-T351 aluminium alloy using high speed cutting technique. Presented approach for crack growth simulation starts by the calculation of stress intensity factor function from finite element results obtained using MSC. Patran/Nastran. Subsequent crack growth analysis is done in NASGRO and uses description of crack growth rates either by the Forman-Newman-de Koning relationship or by the table lookup form. Three crack growth models were applied for spectrum loading: non-interaction, Willenborg and Strip Yield model. Relatively large experimental program comprising both the constant amplitude and spectrum tests on integral panels and CCT specimens was undertaken at the Institute of Aerospace Engineering laboratory in order to acquire crack growth rate data and enable verification of simulations. First analyses and verification tests of panels were performed under the constant amplitude loading. For predictions of crack growth using the spectrum loading a load sequence representing service loading of the transport airplane wing was prepared. Applied load spectrum was measured on B737 airplane within the joint FAA/NASA collection program. The load sequence is composed of 10 flight types with different severity analogous to the standardized load sequence TWIST. Before application on the stiffened panels a calculation of crack growth under the spectrum loading was performed for simple CCT specimen geometry. The paper finally presents comparison of simulations of fatigue crack propagation in two-stringer stiffened panel under the spectrum loading with verification test carried out in the IAE lab. The work was performed within the scope of the 6th Framework Programme project DaToN - Innovative Fatigue and Damage Tolerance Methods for the Application of New Structural Concepts.

Fractographic analysis of fatigue crack growth in lightweight integral stiffened panels

2010 ◽  
Vol 1 (3) ◽  
pp. 233-258 ◽  
Author(s):  
Pedro M.G.P. Moreira ◽  
Paulo M.S.T. de Castro
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Testing ◽  
Content Type ◽  
Stiffened Panels ◽  
Friction Stir ◽  
Final Fracture ◽  
Striation Spacing ◽  
Macroscopic Crack

PurposeThe purpose of this paper is to complement available macroscopic fatigue crack growth measurements in flat stiffened panels with scanning electron microscopy (SEM) measurements of striation spacing.Design/methodology/approachThe paper's approach is fatigue testing of two‐stiffener flat panels manufactured using three different processes, with a central initial crack perpendicular to the stiffeners and load, in order to identify striation spacing during crack growth up to final fracture, using SEM.FindingsAn increase of striation spacing as cracks grow was quantified. Although when cracks approach the stiffeners the stress intensity factor decreases, there is no clear decrease of striation spacing in that region. Striation spacing is roughly similar to macroscopic crack‐propagation rate da/dN measured in the panels testing. This observation is no longer valid once the stiffeners are reached; this stage is characterized by fast acceleration of the cracking process until final complete rupture is verified, and macroscopic crack growth measurements are made difficult because of the “T” geometry in that region.Originality/valueA complete picture of the striation spacing during the fatigue crack growth up to final fracture of a two‐stiffener flat panel is provided for three different manufacturing processes: high‐speed machining, laser beam welding and friction stir welding.

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