REPAIR EFFECT OF UIT ON WEB GUSSET WELDED JOINTS WITH FATIGUE CRACKS STAYING ALONG WELD TOES

The article presents the results of research on low cycle fatigue strength of welded joints of structural steel S960QL. Two types of butt welds were analysed: I-joints and V-joints. The tests were performed under load controlled using the total strain amplitude εac. Fatigue life analysis was conducted based on the Manson-Coffin-Basquin equation, which made it possible to determine fatigue parameters. High concordance was found of the adopted description model with experimental results. Studies have shown differences in the fatigue life of the various joints analysed, wherein I-joints showed about 20-50% higher fatigue life. Fractographic tests of fatigue fractures in joints revealed the details of fatigue cracking and differences in the propagation rate of fatigue cracks.

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Growth rate of fatigue cracks in fields of residual stresses in titanium welded joints with different content of embrittling impurities

Strength of Materials ◽

10.1007/bf00767140 ◽

1990 ◽

Vol 22 (11) ◽

pp. 1562-1569 ◽

Cited By ~ 1

Author(s):

V. T. Troshchenko ◽

V. V. Pokrovskii ◽

V. L. Yarusevich ◽

V. I. Mikhailov ◽

V. A. Sher

Keyword(s):

Growth Rate ◽

Residual Stresses ◽

Welded Joints ◽

Fatigue Cracks ◽

Different Content

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Effect of Forging Force on Fatigue Behavior of Spot Welded Joints of Aluminum Alloy 5182

Journal of Manufacturing Science and Engineering ◽

10.1115/1.2383071 ◽

2006 ◽

Vol 129 (1) ◽

pp. 95-100 ◽

Cited By ~ 10

Author(s):

B. H. Chang ◽

D. Du ◽

B. Sui ◽

Y. Zhou ◽

Z. Wang ◽

...

Keyword(s):

Residual Stress ◽

Aluminum Alloy ◽

Welded Joints ◽

Fatigue Behavior ◽

Fatigue Cracks ◽

Element Analysis ◽

Aluminum Alloy 5182 ◽

Forging Force ◽

Positive Effect ◽

Spot Welded

Using experimental and finite element analysis methods, the effects of electrode forging force are investigated on fatigue behavior and residual stress of spot welded joints of aluminum alloy 5182. Results show that applying forging force significantly reduces the residual stresses in the heat affected zone and the fatigue cracks no longer initiate from there; instead, all cracks begin from the nugget edge. In addition, the mitigation of residual stress by forging force decreases the driving force for crack propagation and leads to longer fatigue life. It can be concluded that applying forging force appropriately has a positive effect on the fatigue strength of resistance spot welded joints.

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Residual Stress and Strain Responses of Welded Piping Joints Under Low-Cycle Fatigue Loading

Volume 1: Codes and Standards ◽

10.1115/pvp2009-77813 ◽

2009 ◽

Author(s):

Pei-Yuan Cheng ◽

Tasnim Hassan

Keyword(s):

Residual Stress ◽

Finite Element ◽

Residual Stresses ◽

Fatigue Failure ◽

Welded Joints ◽

Low Cycle Fatigue ◽

Fatigue Cracks ◽

Stress And Strain ◽

Weld Toe ◽

Strain Responses

It is well known that residual stress of welded joints influence their fatigue lives. This influence of residual stress is manifested through strain ratcheting response at the weld toe. Among many other reasons, strain ratcheting at the weld toe is anticipated to be a reason of many premature fatigue failure of welded joints. Hence, accurate simulations of weld toe residual stress and strain responses are essential for fatigue life simulation of welded joints. This paper presents results form an ongoing study on fatigue failure of welded piping joints. A modeling scheme for simulating weld toe residual stress and strain response is developed. Uncoupled, thermo-mechanical, finite element analyses are employed for imitating the welding procedure, and thereby simulating the temperature history during welding and initial residual stresses. Simulated residual stresses are validated by comparing against the measured residual stresses. Finite element simulations indicate that both residual stress and resulting strain responses near the weld toe are the key factors in inducing fatigue cracks at the weld toe. Research needs in revealing the fatigue failure mechanisms at the weld toe are discussed.

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Characteristics of Fatigue Cracks Propagating in Different Directions of FSW Joints Made of 5754-H22 and 6082-T6 Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.794-796.371 ◽

2014 ◽

Vol 794-796 ◽

pp. 371-376 ◽

Cited By ~ 1

Author(s):

Ákos Meilinger ◽

János Lukács

Keyword(s):

Fatigue Crack ◽

Cyclic Loading ◽

Crack Propagation ◽

Fatigue Crack Propagation ◽

Welded Joints ◽

Fatigue Cracks ◽

Research Work ◽

Friction Stir ◽

Base Materials ◽

Welding Processes

The Friction Stir Welding (FSW) is a dynamically developing version of the pressure welding processes. High-quality welded joints can be created using this process for different engineering applications (e. g. automotive parts). Nowadays, the knowing of the properties and the behaviour of the welded joints is an important direction of the investigations, especially under cyclic loading. The research work aimed to demonstrate the behaviour of the friction stir welded joints under cyclic loading conditions. Fatigue Crack Propagation (FCG) experiments were performed on 5754-H22 and 6082-T6 aluminium alloys and their friction stir welded joints. The CT type specimens were cut parallel and perpendicular to the characteristic directions of the base materials and the welded joints, and the notch locations in the specimens of welded joints were different, too. Therefore, the propagating cracks represent the possible directions of the fatigue cracks both on the base materials and on the welded joints. The results of the fatigue crack propagation tests on the welded joints clearly demonstrate the different characteristics of the thermo-mechanically affected zone (TMAZ), the heat affected zone (HAZ), and the advancing (AS) and retreating sides (RS) of the weld nugget (WN). The investigations and their results were compared with each other and with the results can be found in the literature.

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