Advanced Steel Construction

Vol. 12, No. 2, pp. 109-133 (2016)


STRESS INTENSITY FACTORS OF TUBULAR T/Y-JOINTS SUBJECTED TO THREE BASIC LOADING

S.T. Lie1,*, T. Li1 and Y.B. Shao2

1School of Civil and Environmental Engineering, Nanyang Technological University,

50 Nanyang Avenue, Singapore 639798

2School of Civil Engineering, Yantai University, Yantai City 264005, P. R. China
          *(Corresponding author: E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.)
Received: 30 July 2014; Revised: 17 June 2015; Accepted: 3 July 2015

 

DOI:10.18057/IJASC.2016.12.2.3

 

View Article   Export Citation: Plain Text | RIS | Endnote

ABSTRACT

This paper describes the determination of stress intensity factors (SIFs) of a 3D surface crack in acircular hollow section (CHS) T/Y-joint subjected to three basic loading. In order to achieve the main objective, anautomatic finite element (FE) mesh generator is designed whereby the mesh density and element type of the CrackTube zone can be controlled by the users. Extensive tests are carried out to check the accuracy and to test theconvergence of the mesh models. It is found that the generated mesh models are both accurate and robust.Subsequently, a total of 246 cracked CHS T/Y-joints subjected to axial loading; in-plane bending and out-of-planebending are analysed, and the influencing parameters β, γ, τ, θ, a/t0 and c/on the SIFs of a 3D surface crack areinvestigated in this study. The SIFs at the deepest point of a 3D surface crack are also determined using an indirectmethod incorporated in BS7910. It is found that the later underestimates the SIFs by as much as -36.9% under axialload for crack located at the crown and -32.9% under out-of-plane bending for crack located at the saddle,respectively. Hence, the indirect method is found to be unsafe in estimating the SIFs of a 3D surface crack in CHST/Y-joints under certain loading conditions and crack location.

 

KEYWORDS

Finite element analysis, Mesh generation, 3D Surface crack, Stress intensity factor, Tubular T/Y-joint


REFERENCES

[1] Shivakumar, K.N. and Raju, I.S., “Treatment of Singularities in Cracked Bodies,” International Journal of Fracture, 1990, Vol. 45, No. 3, pp. 159-178.

[2] Madia, M., Beretta, S., Schödel, M., Zerbst, U., Luke, M. and Varfolomeev, I., “Stress Intensity Factor Solutions for Cracks in Railway Axles,” Engineering Fracture Mechanics, 2011, Vol. 78, No. pp. 764-792.

[3] Hutař, P. and Náhlík, L., “Fatigue Crack Shape Prediction Based on Vertex Singularity,” Applied and Computational Mechanics, 2008, Vol. 2, No. pp. 45-52.

[4] Heyder, M., Kolk, K. and Kuhn, G., “Numerical and Experimental Investigations of the Influence of Corner Singularities on 3D Fatigue Crack Propagation,” Engineering Fracture Mechanics, 2005, Vol. 72, No. 13, pp. 2095-2105.

[5] Huang, X. and Hancock, J.W., “The Stress Intensity Factors for Semi-elliptical Cracks in a Tubular Welded T-joint Under Axial Loading,” Engineering Fracture Mechanics, 1988, Vol. 30, No. 1, pp. 25-35.

[6] Rhee, H.C., “Fatigue Crack Growth Analyses of Offshore Structural Tubular Joints,” Engineering Fracture Mechanics, 1989, Vol. 34, No. 5/6, pp. 1231-1239.

[7] Bowness, D. and Lee, M.M.K., “The Development of an Accurate Model for the Fatigue Assessment of Doubly Curved Cracks in Tubular Joints,” International Journal of Fracture, 1995, Vol. 73, No. 2, pp. 129-147.

[8] Bowness, D. and Lee, M.M.K., “Fatigue Crack Curvature under the Weld Toe in an Offshore Tubular Joint,” International Journal of Fatigue, 1998, Vol. 20, No. 6, pp. 481-490.

[9] Cao, J.J., Yang, G.J., Packer, J.A. and Burdekin, F.M., “Crack Modeling in FE Analysis of Circular Tubular Joints,” Engineering Fracture Mechanics, 1998, Vol. 61, No. 5-6, pp. 537-553.

[10] Lie, S.T., Lee, C.K. and Wong, S.M., “Model and Mesh Generation of Cracked Tubular Y-Joints,” Engineering Fracture Mechanics, 2003, Vol. 70, No. 2, pp. 161-184.

[11] Chiew, S.P., Lie, S.T., Lee, C.K. and Huang, Z.W., “Stress Intensity Factors for a Surface Crack in a Tubular T-Joint,” International Journal of Pressure Vessels and Pipes, 2001, Vol. 78, No. 10, pp. 677-685.

[12] Peter, T.M., Corrosion Fatigue and Fracture Mechanics of High Strength Jack Up Steels, PhD thesis, Department of Mechanical Engineering, University College London, UK, 1998.

[13] Shao, Y.B. and Lie, S.T., “Parametric Equation of Stress Intensity Factor for Tubular K-joint,” International Journal of Fatigue, 2005, Vol. 27, No. 6, pp. 666-679.

[14] BS7910-Amendment 1, Guide to Methods for Assessing the Acceptability of Flaws in Fusion Welded Structures, British Standards Institution, London, UK, 2005.

[15] Newman, J.C. and Raju, I.S., “An Empirical Stress Intensity Factors Equation for the Surface Crack,” Engineering Fracture Mechanics, 1981, Vol. 15, No. 1-2, pp. 185-192.

[16] Newman, J.C., Reuter, W.G. and Aveline, C.R., “Stress and Fracture Analysis of Semi-elliptical Surface Cracks,” 30th National Symposium of Fatigue and Fracture Mechanics, St. Louis, MO, USA, 1998, pp. 403-426.

[17] Lee, M.M.K. and Bowness, D., “Estimation of Stress Intensity Factor Solutions for Weld Toe Cracks in Offshore Tubular Joints,” International Journal of Fatigue, 2002, Vol. 24, No. 8, pp. 861-875.

[18] Lie, S.T., Li, T. and Shao, Y.B., “Estimation of Stress Intensity Factors in Tubular K-joints Using Direct and Indirect Methods”. International Journal of Advanced Steel Construction, 2012, Vol. 8, No. 2, pp. 17-37.

[19] America Petroleum Institute, Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms-Working Stress Design, API-RP-2A-WSD, Washington, USA, 2005.

[20] Lie, S.T., Li, T. and Shao, Y.B., “Plastic Collapse Load Prediction and Failure Assessment Diagram Analysis of Cracked Circular Hollow Section T-joint and Y-joint,” Fatigue & Fracture of Engineering Material & Structure, 2014, Vol. 37, No. 3, pp. 314-324.

[21] FEACrack™, User’s Manual, Version 3.2, Quest-reliability-LLC, USA, 2003.

[22] ABAQUS, (2009). Standard User’s Manual, Version 6.9. Hibbett, Karlsson & Sorensen, Inc. Providence, Rhode Island, USA.

[23] Ritchie, D., and Huijskens, H.A.M., “Fracture Mechanics Based Prediction of the Effect of Size of Tubular Joint Test Specimens on Their Fatigue Life,” The 8th International Conference on Offshore Mechanics and Arctic Engineering, The Hague, Netherlands, 1988, pp. 121-126.

[24] Shen, W. and Choo, Y.S., “Stress Intensity Factor for a Tubular T-joint with Grouted Chord,” Engineering Structures, 2012, Vol. 35, pp. 37-47.

[25] Connolly, M.P., Hellier, A.K., Dover, W.D. and Sutomo, J., “A Parametric Study of the Ratio of Bending to Membrane Stress in Tubular Y and T joints,” International Journal of Fatigue, 1990, Vol. 12, No. 1, pp. 3-11.