A Study of Fatigue Striations in Weld Toe Cracks

2009 ◽  
pp. 197-197-21
Author(s):  
P Albrecht
Keyword(s):  
Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 546
Author(s):  
Krzysztof L. Molski ◽  
Piotr Tarasiuk

The paper deals with the problem of stress concentration at the weld toe of a plate T-joint subjected to axial, bending, and shearing loading modes. Theoretical stress concentration factors were obtained from numerical simulations using the finite element method for several thousand geometrical cases, where five of the most important geometrical parameters of the joint were considered to be independent variables. For each loading mode—axial, bending, and shearing—highly accurate closed form parametric expression has been derived with a maximum percentage error lower than 2% with respect to the numerical values. Validity of each approximating formula covers the range of dimensional proportions of welded plate T-joints used in engineering applications. Two limiting cases are also included in the solutions—when the weld toe radius tends to zero and the main plate thickness becomes infinite.


Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1249
Author(s):  
Yixun Wang ◽  
Yuxiao Luo ◽  
Yuki Kotani ◽  
Seiichiro Tsutsumi

The existing S-N curves by effective notch stress to assess the fatigue life of gusset welded joints can result in reduced accuracy due to the oversimplification of bead geometries. The present work proposes the parametric formulae of stress concentration factor (SCF) for as-welded gusset joints based on the spline model, by which the effective notch stress can be accurately calculated for fatigue resistance assessment. The spline model is also modified to make it applicable to the additional weld. The fatigue resistance of as-welded and additional-welded specimens is assessed considering the geometric effects and weld profiles. The results show that the error of SCFs by the proposed formulae is proven to be smaller than 5%. The additional weld can increase the fatigue life by as great as 9.4 times, mainly because the increasing weld toe radius and weld leg length lead to the smaller SCF. The proposed series of S-N curves, considering different SCFs, can be used to assess the welded joints with various geometric parameters and weld profiles.


2017 ◽  
Vol 94 ◽  
pp. 158-165 ◽  
Author(s):  
John H.L. Pang ◽  
Hsin Jen Hoh ◽  
Kin Shun Tsang ◽  
Jason Low ◽  
Shawn Caleb Kong ◽  
...  

2014 ◽  
Vol 633-634 ◽  
pp. 659-664 ◽  
Author(s):  
Zong Tao Fang ◽  
De Yu Tang ◽  
Yan Hua Hu ◽  
Hu Li Niu

This paper focus on fatigue problem of submarine pipelines, four points bending full scale fatigue experiment were conducted on X65 pipelines butt joints specimens, utilizing pipeline full scale fatigue test machine developed by CNPC. Meanwhile contrast test was also carried out on small specimens. The results show that the fatigue strength of full scale welded joints is lower than the small scale joints. Owing to having no regard for the influence of residual stress and size effect, the small test would provide dangerous results. The fatigue property of full scale welded joints only meets the requirement of DNV C203 W3 curve, and meets the needs of DNV C203 F3 curve basically while not meet BS 7608 F2 curve’s requirements which relatively demand higher. Weld toe and geometric discontinuous near weld root is the weak point for the whole welded joints.


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