Stress concentration at cruciform welded joints under axial and bending loading modes
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RESEARCH PAPER
Stress concentration at cruciform welded joints under axial and bending loading modes Krzysztof L. Molski 1 & Piotr Tarasiuk 1
&
Grzegorz Glinka 2
Received: 5 November 2018 / Accepted: 15 July 2020 # The Author(s) 2020
Abstract The paper is concerned with the problem of stress concentration in cruciform fillet welded joints subjected to axial and bending load. Extended numerical analyses were carried out with the help of the finite element method. It made it possible to estimate stress concentration factors Kt for a variety of geometrical parameters defining the geometry of cruciform welded joints. It has been found that approximate Kt formulas, available in the literature, have two disadvantages, i.e. an unknown accuracy and small range of application with respect to geometrical parameters defining the weld shape. For these reasons, more general and accurate new formulas for stress concentration factors Kt have been derived. Even though the present approach is applicable to all types of welded joints, the analysis presented below has been conducted for a cruciform joint with the weld flank angle of θ = 45°. Final solutions have been given in the form of polynomial expressions, and they can be easily used in computer-aided design procedures. Keywords Cruciform welded joints . Stress concentration factor . Weld geometry . Finite element method . Axial and bending load . Fillets
List of symbols a Weld throat thickness Kt Theoretical elastic stress concentration factor Ktb Pure bending stress concentration factor Ktt Pure axial stress concentration factor h Attachment weld leg length hp Main plate leg length n=λ−1 Stress field exponent for a sharp corner N Number of loading cycles S Cyclic stress t Thickness of the main plate T Thickness of the attachment plate X=ρ/(ρ+a) Normalised weld toe radius parameter Y=a/(a+t) Normalised weld thickness parameter Recommended for publication by Commission XV - Design, Analysis, and Fabrication of Welded Structures * Piotr Tarasiuk [email protected] 1
Faculty of Mechanical Engineering, Bialystok University of Technology, Bialystok, Poland
2
Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo N0B 2H0, Canada
2α δx θ κ κb κt λ ρ σb σt
Total angle of the sharp corner Accuracy of the approximate Kt value Weld flank angle Correction function for the relative attachment thickness T/a Correction function for the relative attachment thickness T/a for pure bending load Correction function for the relative attachment thickness T/a for pure axial load Eigenvalue of the characteristic equation Weld toe radius Nominal bending stress Nominal axial stress
1 Introduction The linear elastic stress concentration factor Kt is one of the most important parameters used in predicting fatigue life of structural components with various types of stress raisers like holes, notches, grooves, and stiffeners. A variety of Kt solutions and approximated formulas can be found in the literature (e.g. [1–7]). Welded joints are often used in engineering practice,
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