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Journal ArticleDOI

Fatigue life prediction of gas tungsten arc welded AISI 304L cruciform joints with different LOP sizes

TL;DR: In this article, an automatic crack monitoring system based on crack propagation gauges was used to find the crack initiation and propagation data during fatigue process, and the predicted lives were compared with the experimental values.
About: This article is published in International Journal of Fatigue.The article was published on 2003-01-01. It has received 41 citations till now. The article focuses on the topics: Crack growth resistance curve & Fracture mechanics.
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Journal ArticleDOI
TL;DR: In this article, the weld toe region is modelled as a sharp, zero radius, V-shaped notch and the intensity of asymptotic stress distributions obeying Williams' solution are quantified by means of the Notch Stress Intensity Factors (NSIFs).
Abstract: Weld bead geometry cannot, by its nature, be precisely defined. Parameters such as bead shape and toe radius vary from joint to joint even in well-controlled manufacturing operations. In the present paper the weld toe region is modelled as a sharp, zero radius, V-shaped notch and the intensity of asymptotic stress distributions obeying Williams’ solution are quantified by means of the Notch Stress Intensity Factors (NSIFs). When the constancy of the angle included between weld flanks and main plates is assured and the angle is large enough to make mode II contribution non-singular, mode I NSIF can be directly used to summarise the fatigue strength of welded joints having very different geometry. By using a large amount of experimental data taken from the literature and related to a V-notch angle of 135°, two NSIF-based bands are reported for steel and aluminium welded joints under a nominal load ratio about equal to zero. A third band is reported for steel welded joints with failures originated from the weld roots, where the lack of penetration zone is treated as a crack-like notch and units for NSIFs are the same as conventional SIF used in LEFM. Afterwards, in order to overcome the problem related to the variability of the V-notch opening angle, the synthesis is made by simply using a scalar quantity, i.e. the mean value of the strain energy averaged in the structural volume surrounding the notch tips. This energy is given in closed form on the basis of the relevant NSIFs for modes I and II and the radius RC of the averaging zone is carefully identified with reference to conventional arc welding processes. RC for welded joints made of steel and aluminium considered here is 0.28 mm and 0.12 mm, respectively. Different values of RC might characterise welded joints obtained from high-power processes, in particular from automated laser beam welding. The local-energy based criterion is applied to steel welded joints under prevailing mode I (with failures both at the weld root and toe) and to aluminium welded joints under mode I and mixed load modes (with mode II contribution prevailing on that ascribable to mode I). Surprising, the mean value of ΔW related to the two groups of welded materials was found practically coincident at 2 million cycles. More than 750 fatigue data have been considered in the analyses reported herein.

326 citations


Cites background from "Fatigue life prediction of gas tung..."

  • ...As recently underlined by Singh et al. (2003a) , British Standard BS 7910 (2001) gives stress intensity factor values according to Equations (B.1–B.3)....

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Journal ArticleDOI
TL;DR: In this paper, the authors considered full penetration T butt weld joints between a tube and its flange, subjected to pure bending, pure torsion and a combination of these loading modes.
Abstract: Full penetration T butt weld joints between a tube and its flange are considered, subjected to pure bending, pure torsion and a combination of these loading modes. The model treats the weld toe like a sharp V-notch, in which mode I and mode III stress distributions are combined to give an equivalent notch stress intensity factor (N-SIF) and assess the high cycle fatigue strength of the welded joints. The N-SIF-based approach is then extended to low/medium cycle fatigue, considering fatigue curves for pure bending and pure torsion having the same slope or, alternatively, different slopes. The expression for the equivalent N-SIF is justified on the basis of the variation of the deviatoric strain energy in a small volume of material surrounding the weld toe. The energy is averaged in a critical volume of radius R C and given in closed form as a function of the mode I and mode III N-SIFs. The value of R C is explicitly referred to high cycle fatigue conditions, the material being modelled as isotropic and linear elastic. R C is thought of as a material property, independent in principle of the nominal load ratio. To validate the proposal, several experimental data taken from the literature are re-analysed. Such data were obtained by testing under pure bending, pure torsion and combined bending and torsion, welded joints made of fine-grained Fe E 460 steel and of age-hardened AlSi1MgMn aluminium alloy. Under high cycle fatigue conditions the critical radius R C was found to be close to 0.40 mm for welded joints made of Fe E 460 steel and close to 0.10 mm for those made of AlSi1MgMn alloy. Under low/medium cycle fatigue, the expression for energy has been modified by using directly the experimental slopes of the pure bending and pure torsion fatigue curves.

178 citations

Journal ArticleDOI
TL;DR: In this paper, a notch stress intensity approach to the fatigue assessment of welded joints is presented, where the weld toe is modelled as a sharp V-notch and the local stress distributions in plane problems are given on the basis of the relevant mode I and mode II notch intensity factors (N-SIFs).

175 citations

Journal ArticleDOI
TL;DR: In this article, the welding optimization parameters and tensile strength of duplex stainless steel 2205 by tungsten inert gas welding based on Taguchi method and analysis of variance were discussed.
Abstract: The main criteria discussed in this paper concern the welding optimization parameters and tensile strength of duplex stainless steel 2205 by tungsten inert gas welding based on Taguchi method and analysis of variance Taguchi method of orthogonal L9 design experiment is carried out using orthogonal array for defining the problem occur on welding process and to reduce the error occurred in the neural network for the prediction of output The neural network is a mathematical prediction model for the optimization process using back propagation algorithm Analysis of variance (ANOVA) is a decision tool for detecting the variation of process parameters, it is a statistical technique for find out the optimal level of factors for the verification of the optimal design parameters through confirmation experiments The purpose of this paper to increase the tensile strength, hardness and depth of weld by varying the parameters such as current, time, speed, variation of oxide fluxes, electrode diameter and gas flow rate The Mat lab software is used for analyzing results and it shows that neural network coupled with Taguchi method and Anova is an effective method for optimizing the weld quality of material

101 citations

Journal ArticleDOI
TL;DR: In this paper, a number of fatigue cracks were found in many butt welds in the longitudinal ribs of the orthotropic deck of the Kinuura Bridge (Japan) in June 2003.

92 citations

References
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Book
29 Feb 1980

433 citations

Journal ArticleDOI
TL;DR: In this paper, a fracture mechanics model of the fatigue behavior of fillet welded cruciform joints is developed and correlated with experimental results, and design equations based on the model and a design example are presented.
Abstract: A method for determining the fatigue strength of fillet welded cruciform joints is presented. The inadequacy of the present fatigue specification is examined through comparison with experimental data. The significance of the lack of penetration occurring at the weld root upon experimental fatigue is presented. A fracture mechanics model of the fatigue behavior is developed and correlated with experimental results. Design equations based on the model and a design example are presented.

105 citations

Journal ArticleDOI
TL;DR: In this paper, a simple version of a more elaborate analytical model of the fatigue behavior of weldments is presented, which provides analytical and graphical design aids for design, as well as a detailed analysis of the fracture initiation and growth of the notch-root material.
Abstract: There are four important attributes of weldments which, together with the magnitude of the fluctuating stresses applied, determine their resistance to metallic fatigue: the ratio of the applied or self-induced axial and bending stresses; the severity of the discontinuity or notch which is an inherent property of the geometry of the joint; the notch-root residual stresses which result from fabrication and subsequent use of the weldment; and the mechanical properties of the notch-root material in which fatigue crack initiation and growth takes place. A simple version of a more elaborate analytical model of the fatigue behavior of weldments [1] is presented here which provides analytical and graphical design aids for design.

77 citations

Journal ArticleDOI
TL;DR: In this paper, a new formula for the fatigue crack initation life is developed based on recent progress in the study of fatigue damage and crack initiation, and is substantiated experimentally.

58 citations