Digital shearography approach for stress intensity factors calculation in friction stir welded nugget of AA2024 aluminum alloy

In this research paper, the unstable fracture of 2024-T351 aluminum alloy is studied under a variety of in-plane and out-of-plane mixed-mode loading conditions including pure mode I and pure mode III loadings. A recently proposed loading device with compact tension shear tearing (CTST) specimens is employed for performing fracture experiments. Three-dimensional finite element analyses using the M-integral approach are conducted to derive the stress intensity factors distributions along the crack front for different mixed-mode configurations. The numerical results reveals that the coupled effect of modes II and III can be observed under mixed-modes I/II, I/III and I/II/III loading conditions. Furthermore, the values of stress intensity factors at the midsection of the specimens are used to predict the critical loads based on different mixed-mode criteria. A good consistency is observed between the theoretical predictions of the criteria and the experimental results for different loading conditions.

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Effects of Bonded Crack Retarders on Fatigue Parameters of FSWed Integral Panel

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.891-892.627 ◽

2014 ◽

Vol 891-892 ◽

pp. 627-632

Author(s):

Yu E Ma ◽

Pan Fu Xu

Keyword(s):

Residual Stress ◽

Finite Element ◽

Stress Intensity ◽

Stress Intensity Factors ◽

Damage Tolerance ◽

Weld Zone ◽

Finite Element Models ◽

Cohesive Elements ◽

Intensity Factors ◽

Friction Stir

As known, friction stir welded (FSWed) joints are mature to be applied in aircraft structure. However, the weld creates local discontinuity in property and local tensile residual stress, which harm the damage tolerance of welded panels. So crack retarders were bonded in the weld zone to improve damage tolerance. Finite element method was used to calculate stress intensity factors by ABAQUS software. Finite element models were built to simulate the function of bonded retarder. Cohesive elements were used between the substrate panel and bonded retarder. A Fortran program was made to input residual stress to finite element models. Stress intensity factors from residual stress with and without bonded retarders were calculated and compared. Effects of residual stress on stress intensity factors and redistribution of residual stress were taken into considered. Effective R ratios were calculated with crack growing through the weld. Effects of bonded retarder on stress intensity factors were calculated. The results were compared with the experimental findings.

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Evaluating Stress Distributions and Stress Intensity Factors of a Crack under Mixed-Mode conditions in Aluminum Alloy

2010 International Conference on Measuring Technology and Mechatronics Automation ◽

10.1109/icmtma.2010.229 ◽

2010 ◽

Author(s):

Youli Ma

Keyword(s):

Aluminum Alloy ◽

Stress Intensity ◽

Stress Intensity Factors ◽

Mixed Mode ◽

Stress Distributions ◽

Intensity Factors

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Thermoelastic Analysis of Crack Propagation in AA6082 Friction Stir Welded Joints

Materials Science Forum ◽

10.4028/www.scientific.net/msf.561-565.2221 ◽

2007 ◽

Vol 561-565 ◽

pp. 2221-2224 ◽

Cited By ~ 1

Author(s):

Raffaella Di Sante ◽

Pasquale Cavaliere ◽

Gian Luca Rossi ◽

Antonio Squillace

Keyword(s):

Stress Intensity ◽

Stress Distribution ◽

Crack Propagation ◽

Stress Intensity Factors ◽

Measurement Techniques ◽

Welding Process ◽

Crack Tip ◽

Fe Model ◽

Intensity Factors ◽

Friction Stir

Thermolastic Stress Analysis (TSA) has been recently developed as a direct investigating method for the study of the stress field around the crack tip of a cyclically loaded structure. The advantage of using measurement techniques based on the thermoelastic effect lays in the fact that stress intensity factors may be determined based on the effective stress distribution around the crack tip rather than calculated from the crack length and amplitude of cyclic loads. This paper reports results related to fatigue tests on Friction Stir Welded alluminium alloys sheets. Fatigue crack propagation experiments were performed by employing single-edge notched specimens, in tensiontension condition with R=0.1, up to failure. The application of TSA allowed the monitoring of crack formation and growth in real time, providing the actual stress distribution around the crack tip for the different technological parameters used in the welding process. Stress intensity factors were determined based on the TSA data and compared to those calculated using an ABAQUS FE model.

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