Fatigue predictions of welded joints and the effective notch stress concept

Schijve, J.

doi:10.1016/j.ijfatigue.2012.06.016

Cited by 38 publications

(22 citation statements)

References 21 publications

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“…The subject of a suitable notch radius is still an ongoing debate despite the satisfactory results observed in the experiments. Some researchers 10,[23][24][25][26][27][28] argue that the notch radius should be a function of geometry (e.g., weld size and/or plate thickness) instead of being fixed at 1 mm.…”

mentioning

confidence: 99%

An extrapolation method to determine the effective notch stress in welded joints

Pradana

Qian

Swaddiwudhipong

2015

Fatigue Fract Eng Mat Struct

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This paper presents the development of an extrapolation method to estimate the notch stress in welded steel joints, in line with the effective notch stress concept described in the International Institute of Welding guideline. The proposed approach provides a convenient method to determine the local notch stress at the weld toes without the need to model a finite notch radius as required in engineering guidelines, which creates significant modeling challenges in the numerical procedure, especially for 3‐D joints with a complex topology. An experimental study validates the feasibility of this extrapolation method through strain measurements on cruciform joints. The numerical study then investigates two types of welded connections: (1) cruciform joints with full‐penetration welds and (2) tube‐to‐plate joints. The proposed extrapolation method provides accurate effective notch stress estimations on both joint types, compared with the effective notch stress calculated following the mesh requirement in the existing guidelines.

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confidence: 99%

An extrapolation method to determine the effective notch stress in welded joints

Pradana

Qian

Swaddiwudhipong

2015

Fatigue Fract Eng Mat Struct

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“…the relationship between the SIF and notch stress as well as crack tip of a reasonable local stress component (Sonsino et al 2012). Reference radius ρ r has already been proposed to be replaced by a relative one (Schijve 2012), although -at least for weld toe notches -involving the plate thickness seems a better solution than the weld leg length. At the same time the relative notch acuity becomes incorporated rather than the absolute one.…”

Section: Effective Notch Stress or Strain Criterionmentioning

confidence: 99%

Fatigue damage criteria classification, modelling developments and trends for welded joints in marine structures

Besten

2018

Ships and Offshore Structures

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Fatigue is typically a governing limit state for marine structures. Welded joints are the weakest links in that respect. Physics involve several resistance dimensions, a range of scales and distinct contributions in different stages of the accumulative damage process. Fatigue damage criteria developed over time have been classified with respect to type of information, geometry, parameter and process zone including plane and life region annotations. The criteria are evaluated regarding model (in)capabilities, showing up to what extent (governing) physics are taken into account. Modelling developments and trends towards complete strength, multi-scale and total life criteria have been identified. Incorporating all four (interacting) fatigue resistance dimensions: material, geometry, loading & response and environment translates into a complete strength fatigue damage criterion. Considering macro-, meso-and micro-scale information provides a multi-scale fatigue damage criterion. Correlation of crack initiation and growth requires matching intact and cracked geometry parameters, revealing a total life fatigue damage criterion. HIGHLIGHTS• Classification of fatigue damage criteria with respect to type of information, geometry, parameter and process zone including plane and life region annotations.• Identification of modelling developments and trends towards complete strength, multi-scale and total life fatigue damage criteria for welded joints in marine structures. NomenclatureA notch strain energy density process zone area C crack growth or fatigue resistance curve intercept (endurance coefficient) D fatigue damage E normal strain at macro-scale E Young's modulus J crack tip energy density J 1 hydrostatic stress or strain component J 2 deviatoric stress or strain component K σ crack tip stress intensity factor K ɛ crack tip strain intensity factor K' work hardening coefficient K N notch stress intensity factor K N I mode-I notch stress intensity factor K N III mode-III notch stress intensity factor K I mode-I stress intensity factor K I T total mode-I stress intensity factor K I r residual mode-I stress intensity factor K III mode-III stress intensity factor K * FE dimensionless FE based notch stress intensity factor N (total) number of cycles until failure N i number of cycles corresponding to initiation N g number of cycles corresponding to growth R notch strain energy density process zone radius S stress based fatigue damage criterion S B Battelle structural normal stress range S e effective notch stress range S eq (equivalent) Von Mises stress range S n nominal stress range S s hot spot structural stress range S T total stress range T temperature T B Battelle structural shear stress range T σS strength scatter band index W energy based fatigue damage criterion W N notch strain energy W N A notch strain energy density Y n notch factor Y f far field factor a crack size (i.e. length) a 0 critical defect size a d long-term corrosion pit size (i.e. depth) a i (real) defect or initial crack size a n (root) not...

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“…The information regarding the severity of stress concentration at the weld notch is the key to accurate fatigue assessment of welded joints. 1 With the computational power available today, the calculation of the local stress at the weld notch remains a manageable task, yet it requires the knowledge of the local weld geometry, specifically the weld notch radius, which is unknown prior to fabrication. In addition, this radius varies along the weld seam and also depends on other variables such as the workmanship and the welding method used.…”

Section: N O M E N C L a T U R Ementioning

confidence: 99%

An extrapolation method to determine the effective notch stress in circular hollow section X‐joints

Pradana

Qian

Swaddiwudhipong

et al. 2016

Fatigue Fract Eng Mat Struct

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This paper presents an extrapolation method to determine the effective notch stress (ENS) on the weld toes of welded circular hollow section (CHS) X‐joints in‐line with the extrapolation method to determine the structural hot‐spot stress in existing design guidelines. This investigation verifies and extends the recently proposed ENS extrapolation scheme to CHS X‐joints, which elevates significantly the difficulty in generating a weld toe radius along the brace‐to‐chord intersection as required in existing guidelines. An extensive numerical study then investigates the ENS extrapolation for CHS X‐joints under three loading conditions, namely, the brace axial load, the brace in‐plane bending load, and the brace out‐of‐plane bending load. The numerical study derives a set of recommended extrapolation parameters that ensures accurate ENS estimation for each loading condition. This paper demonstrates that the proposed extrapolation method for the CHS X‐joints yields good agreement with the standard ENS calculation procedure described in the International Institute of Welding (IIW) guideline.

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Fatigue predictions of welded joints and the effective notch stress concept

Cited by 38 publications

References 21 publications

An extrapolation method to determine the effective notch stress in welded joints

An extrapolation method to determine the effective notch stress in welded joints

Fatigue damage criteria classification, modelling developments and trends for welded joints in marine structures

An extrapolation method to determine the effective notch stress in circular hollow section X‐joints

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