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•The fatigue resistance property of single- and double-sided welded joints in OBD is investigated by conducting experimental and numerical studies.•The prediction results will be more ...accurate considering effect factors of angular misalignments and stress ratio.•The specific united master S-N curve for the fatigue performance prediction of single- and double-sided welded joints in OBD is recommended.
In this study, the fatigue resistance properties of single- and double-sided welded joints in OBD are investigated using the traction structural stress method by conducting experimental and numerical investigations. Full-scale fatigue specimen tests are conducted to analyze the fatigue property validations and failure modes, considering the effects of length scale, residual stress relaxation, angular misalignment corrections, and stress ratio. Double-sided welded joints have been found to fail at the interior weld toe with the propagation direction of deck thickness, and the prediction results will be more accurate considering the effect factors of angular misalignments and stress ratio. The specific united master S-N curve for the fatigue performance prediction of single- and double-sided welded joints in OBDs is recommended with the combination of fatigue test data.
Abstract
The change in quality indicators when replacing traditional welded joints with glue-welded ones is considered. The classification of factors influencing the machines glue-welded joints ...destruction processes is given. The possible destruction causes are shown on the base of the glue-welded joints destruction nature analysis. The cause-and-effect relations that have the greatest impact on the quality when replacing traditional machines welded joints with glue-welded ones are established.
Sulfate-reducing bacteria (SRB) corrosion of X80 pipeline steel welded joints has been investigated. The larger diameter, deeper depth and higher density of the corrosion pits were detected in the ...heating affected zone (HAZ) than in the base metal (BM) and weld zone (WZ) in the sterile medium. However, in the inoculated medium, Desulfovibrio desulfuricans (D. desulfuricans) tended to attach primarily to the BM and WZ, and increased their local corrosion sensibilities. D. desulfuricans disliked to attach to the HAZ surface and only non-uniform corrosion dominated on the surface, which was an important phenomenon in D. desulfuricans corrosion of pipeline steel.
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•Corrosion rate and local corrosion sensibility of HAZ are larger in sterile medium.•SRB like to attach to BM and WZ surface, inducing local corrosion on them.•SRB cells resist to attach to HAZ surface, reducing its local corrosion sensibility.•Selected SRB attachment and local corrosion are confirmed in the welded joint.
•A fatigue evaluation framework based on the equivalent structural stress is presented to predict fatigue failure mode of the rib-to-deck welded joints.•An analytical model of root-weld crack is ...established to determine the critical cracking plane.•Effect of the weld penetration ratio on the fatigue failure mode transition is investigated.•Master S-N curve is employed to predict the fatigue life for rib-to-deck welded joint.
Rib-to-deck welded joints in orthotropic steel decks have demonstrated different fatigue failure modes that have different fatigue resistance. Among the different failure modes, the mode corresponding to the lowest fatigue resistance governs the fatigue resistance of the welded joint. The ability of determining the governing failure mode is essential for predicting the fatigue resistance of the welded joints. This research establishes a fatigue evaluation framework for determining the dominant failure mode of rib-to-deck welded joints. The framework is established based on the equivalent structural stress method and validated using model test data. The results indicate that the proposed framework provides accurate prediction of the dominant fatigue failure mode of rib-to-deck welded joints. Based on the presented framework, the fatigue resistance of the welded joints is reasonably predicted, and the effect of weld penetration ratio on the fatigue failure mode is investigated.
The objective of this paper was to investigate the fatigue performance of the thick plate structural steel butt‐welded joints influenced by its geometrical factors, such as the notch angles, ...incomplete penetration length, and plate thickness. Utilizing experimental tests, finite element calculations, and analytical models, the fatigue behavior of various weld joint shapes and dimensions was analyzed, and the discrepancy of fatigue strength for different incomplete penetration lengths was evaluated using the nominal stress method. Meanwhile, the local approaches, including notch stress intensity factor (NSIF), averaged strain energy density (SED), effective notch stress (ENS) method, peak stress method (PSM), and implicit gradient effective stress (IGES) method, are employed to assess the fatigue life of thick plate welded joints. According to the results, incomplete penetration ratios in butt‐welded joints led to a decrease in fatigue strength. The analytical solutions of butt‐welded joints in high cycle regime based on SED results were obtained to estimate the fatigue characteristic values for different plate thickness and incomplete penetration ratios. The proposed equations could illustrate the relationship between the nominal stress and local SED dealing with the variations of incomplete penetration length and geometrical dimensions. Moreover, the results obtained by the analysis of ENS, PSM, and IGES could be deduced by the analytical models to determine the fatigue life of welded joints.
Highlights
Geometry and fatigue strength of thickness butt‐welded joints have been evaluated.
Fatigue tests with different penetration lengths butt‐welded specimens have been conducted.
The analytical solutions for butt‐welded joints were developed for estimating the fatigue characteristic value.
Fatigue strength in nominal and notch stress was compared with other test data.
This study proposes an equivalent crack life prediction method for root cracks in T‐welded joints. An equivalent initial defect is used to describe the severity of the weld defect. Fatigue life ...prediction is achieved based on equivalent fracture parameters and high‐stress fatigue life reference points fitted to obtain a P‐S‐N curve for the entire stress range. Taking the 6082‐aluminum alloy T‐welded joints as the object, the test data under tensile load P‐S‐N curve fitting and crack growth simulation were carried out to compare and verify the applicability under constant and equivalent spectral load. This method enables deterministic fatigue life prediction with less testing and cost. Meanwhile, the approach incorporates the uncertainty of the physical model of the weld into the P‐S‐N curve, simplifying the process of calculating the probabilistic fatigue life.
Highlights
An equivalent crack life prediction method is developed to study T‐welded joints root cracks.
The suitability of using a set of high stress fatigue life reference points to predict P‐S‐N curves is discussed.
The applicability of the method for constant and equivalent spectral loads is verified.
The unique combination of very large strains, high temperatures and high strain rates inherent to friction stir welding (FSW) and friction stir processing (FSP) and their dependency on the processing ...parameters provides an opportunity to tailor the microstructure, and hence the performance of welds and surfaces to an extent not possible with fusion processes. While a great deal of attention has previously been focused on the FSW parameters and their effect on weld quality and joint performance, here the focus is on developing a comprehensive understanding of the fundamentals of the microstructural evolution during FSW/P. Through a consideration of the mechanisms underlying the development of grain structures and textures, phases, phase transformations and precipitation, microstructural control across a very wide range of similar and dissimilar material joints is examined. In particular, when considering the joining of dissimilar metals and alloys, special attention is focused on the control and dispersion of deleterious intermetallic compounds. Similarly, we consider how FSP can be used to locally refine the microstructure as well as provide an opportunity to form metal matrix composites (MMCs) for near surface reinforcement. Finally, the current gaps in our knowledge are considered in the context of the future outlook for FSW/P.
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