Traction stress-based fatigue failure mode identification of load-carrying welded cruciform joints

Various fatigue failure modes (i.e., cracking position and orientation with respect to a weld) can develop in welded rib to deck connections in orthotropic bridge deck structures. After demonstrating its effectiveness in correlating fatigue test data covering different failure modes, the master S-N curve method was then adopted in this study for determining the critical failure mode in welded U-rib to deck connections. These include considerations of additional failure modes potentially present in double-sided welds between U-rib and deck versus the traditional single-sided weld design. The effects of weld penetrations and test loading conditions on failure mode development have been quantitatively established by means of the master S-N curve method.

Section: Comparative and Parameterized Study On Fatigue Propertiesmentioning

confidence: 99%

“…In cases where traction structural stresses at weld root and weld toe are very close, the fatigue failure modes may be affected by random factors, such as material and geometric imperfections, in a transition zone region. 55…”

Section: Introduction Of the Analysis Schemementioning

confidence: 99%

Modeling of fatigue failure mode in U‐rib to deck joints in orthotropic bridge structures

Yang

Wang

Qian

et al. 2022

“…(1) Fatigue lives according to weld root failure is usually much lower than that associated with weld toe failure. As stipulated in EN‐1993‐1‐9, 4 the S‐N curve recommended for weld root failure falls into the worst possible category, namely, FAT36, which is lower than that of the weld toe failure 5 . (2) The weld root failure is usually difficult to address in the design stage due to its inherent weld quality and throat size variability.…”

Section: Introductionmentioning

confidence: 99%

“…As stipulated in EN-1993-1-9, 4 the S-N curve recommended for weld root failure falls into the worst possible category, namely, FAT36, which is lower than that of the weld toe failure. 5 Ziqi Zhao and Tairui Zhang contributed equally to this work and should be considered co-first authors.…”

mentioning

confidence: 99%

A data‐driven analysis for fatigue failure mode identification in load‐carrying fillet welded joint with mechanical data augmentation

Zhao

Zhang

Song

et al. 2022

Self Cite

Weld toe and weld root failures dominate the fatigue failures of the loadcarrying cruciform fillet welded joints. Compared to weld toe failure, the weld root failure is strongly affected by its inherent weld quality and throat size, which is more unpredictable and should be eliminated. This work proposes a weld sizing criterion in terms of two weld leg sizes and weld penetration to avoid root failure. The criterion is obtained by a data-driven approach with the help of the mechanical-directed data augmentation technique. The tractionstress-based method is applied for the data augmentation to identify the fatigue failure mode, which is statistically tested against 372 experimentally obtained fatigue data.cruciform joint, data augmentation, data driven, weld root failure, weld sizing | INTRODUCTIONThe load-carrying cruciform fillet welded joint (LCFWJ) is broadly applied to connect secondary components to main members in metal structures. [1][2][3] Two failure modes dominate the fatigue fractures of LCFWJ, namely, weld toe and root failure, depending on the load conditions and the joint geometry, as illustrated in Figure 1. Fatigue crack initiating from the weld root and propagating into the fillet weld is referred to as weld root failure, which should be eliminated during the design stage of the welded structures because of two reasons. (1) Fatigue lives according to weld root failure is usually much lower than that associated with weld toe failure. As stipulated in EN-1993-1-9, 4 the S-N curve recommended for weld root failure falls into the worst possible category, namely, FAT36, which is lower than that of the weld toe failure. 5 Ziqi Zhao and Tairui Zhang contributed equally to this work and should be considered co-first authors.

“…The fatigue cracking defection issue has been the most prominent problem, blocking further application in actual engineering and attracting much attention to the fatigue failure mechanism of typically welded joints in OBD structures. [1][2][3][4] Numerous welding techniques are executed during the manufacturing process of OBD structures, including the long and multi-layer welding seams among U-rib, deck plate, flange, and crossbeam plates. In this case, through-thickness residual stress (RS) is inevitably introduced by the welding procedures because of the uneven temperature fields and local plastic deformations.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on the verification of adequate fatigue test specimen size of U‐rib‐to‐deck joints in orthotropic steel bridge decks

Yang

2022

In this study, the distribution of residual stress of the substructure model and small coupon specimens in orthotropic steel bridge structures is experimentally and numerically investigated to validate adequate specimen sizes. Blindhole drilling and X-ray diffraction methods are used to capture longitudinal and transverse residual stresses and evaluate the effects of the cutting process. The maximum LRS and TRS were reduced by 16.6% and 15.6% from those that existed before cutting, verifying the proper size of small voucher specimens. The width-to-thickness ratio of 6-6.25 of small coupon specimens has proven sufficient to capture the effects of stress triaxiality induced by the residual stress. In the spirit of master S-N curves in ASME standard, the role of residual stress was represented in the fatigue process and does not be additionally taken into account when predicting the fatigue performances of welded structures using prediction methods based on the S-N curves. K E Y W O R D Sadequate specimen size, blind-hole drilling and X-ray diffraction methods, orthotropic steel bridge decks, residual stress effect, thermo-structure coupling method