Journal article Open Access
Guang Zou; Kian Banisoleiman; Arturo González
Crack initiation and propagation threatens structural integrity of welded joints and normally inspections are assigned based on crack propagation models. However, the approach based on crack propagation models may not be applicable for some high-quality welded joints, because the initial flaws in them may be so small that it may take long time for the flaws to develop into a detectable size. This raises a concern regarding the inspection planning of high-quality welded joins, as there is no generally acceptable approach for modeling the whole fatigue process that includes the crack initiation period. In order to address the issue, this paper reviews treatment methods for crack initiation period and initial crack size in crack propagation models applied to inspection planning. Generally, there are four approaches, by: 1) Neglecting the crack initiation period and fitting a probabilistic distribution for initial crack size based on statistical data; 2) Extrapolating the crack propagation stage to a very small fictitious initial crack size, so that the whole fatigue process can be modeled by crack propagation models; 3) Assuming a fixed detectable initial crack size and fitting a probabilistic distribution for crack initiation time based on specimen tests; and, 4) Modeling the crack initiation and propagation stage separately using small crack growth theories and Paris law or similar models. The conclusion is that in view of trade-off between accuracy and computation efforts, calibration of a small fictitious initial crack size to S-N curves is the most efficient approach.
DNV No. 30.6, Structural reliability analysis of marine structures. Det Norske Veritas, 1992.  I. Lotsberg, G. Sigurdsson, and P. T. Wold, "Probabilistic inspection planning of the Asgard A FPSO hull structure with respect to fatigue," Journal of Offshore Mechanics and Arctic Engineering, vol. 122, no. 2, pp. 134-140, 2000.  T. Moan and R. Song, "Implications of inspection updating on system fatigue reliability of offshore structures," Journal of Offshore Mechanics and Arctic Engineering, vol. 122, no. 3, pp. 173-180, 2000.  D. Straub and M. H. Faber, "System effects in generic risk-based inspection planning," Journal of Offshore Mechanics and Arctic Engineering, vol. 126, no. 3, pp. 265-271, 2004.  K. M. Engesvik and T. Moan, "Probabilistic analysis of the uncertainty in the fatigue capacity of welded joints," Engineering Fracture Mechanics, vol. 18, no. 4, pp. 743-762, 1983.  K. Yamada and S. Nagatsu, "Evaluation of scatter in fatigue life of welded details using fracture mechanics," Doboku Gakkai Ronbunshu, no. 404, pp. 35-43, 1989.  S. Hudak Jr, R. McClung, M. Bartlett, J. FitzGerald, and D. Russell, "A comparison of single-cycle versus multiple-cycle proof testing strategies," Contractor Report, no. 4318, 1990.  N. Z. Chen, G. Wang, and C. Guedes Soares, "Palmgren-Miner's rule and fracture mechanics-based inspection planning," Engineering Fracture Mechanics, vol. 78, no. 18, pp. 3166-3182, 2011.  L. L. Martinez and P. Korsgren, "Characterization of initial defect distribution and weld geometry in welded fatigue test specimens," Fatigue under Spectrum Loading and Corrosive Environment, pp. 3-21, 1993.  T. Moan, O. T. Vardal, N. C. Hellevig, and K. Skjoldli, "Initial crack depth and POD values inferred from in-service observations of cracks in North Sea jackets," Journal of Offshore Mechanics and Arctic Engineering, vol. 122, no. 3, pp. 157-162, 2000.  O. I. Darchuk, "Application of the Probabilistic Mechanics of Fatigue Fracture to the Evaluation of the Reliability of Welded Structures," Materials Science, vol. 39, no. 4, pp. 481-491, 2003.  A. Schumacher, "Fatigue behaviour of welded circular hollow section joints in bridges," PhD Thesis, Swill Feeral Institue of Technology, 2003.  S. Walbridge, "Fatigue analysis of post-weld fatigue improvement treatments using a strain-based fracture mechanics model," Engineering Fracture Mechanics, vol. 75, no. 18, pp. 5057-5071, 2008.  U. Zerbst et al., "Review on fracture and crack propagation in weldments - A fracture mechanics perspective," Engineering Fraccture Mechanics, vol. 132, pp. 200-276, 2014.  P. Lazzarin and P. Livieri, "Notch stress intensity factors and fatigue strength of aluminium and steel welded joints," International Journal of Fatigue, vol. 23, no. 3, pp. 225-232, 2001.  Y. Xiang, Z. Lu, and Y. Liu, "Crack growth-based fatigue life prediction using an equivalent initial flaw model. Part I: Uniaxial loading," International Journal of Fatigue, vol. 32, no. 2, pp. 341-349, 2010.  Z. Lu, Y. Xiang, and Y. Liu, "Crack growth-based fatigue-life prediction using an equivalent initial flaw model. Part II: Multiaxial loading," International Journal of Fatigue, vol. 32, no. 2, pp. 376-381, 2010.  A. S. F. Alves, L. M. C. M. V. Sampayo, J. A. F. O. Correia, A. M. P. De Jesus, P. M. G. P. Moreira, and P. J. S. Tavares, "Fatigue Life Prediction Based on Crack Growth Analysis Using an Equivalent Initial Flaw Size Model: Application to a Notched Geometry," Procedia Engineering, vol. 114, pp. 730-737, 2015.  N. Iyyer, S. Sarkar, R. Merrill, and N. Phan, "Aircraft life management using crack initiation and crack growth models – P-3C Aircraft experience," International Journal of Fatigue, vol. 29, no. 9, pp. 1584-1607, 2007.  J. A. F. O. Correia, S. Blasón, A. M. P. De Jesus, A. F. Canteli, P. M. G. P. Moreira, and P. J. Tavares, "Fatigue life prediction based on an equivalent initial flaw size approach and a new normalized fatigue crack growth model," Engineering Failure Analysis, vol. 69, pp. 15-28, 2016.  M. Tammer and M. L. Kaminski, "Fatigue oriented risk based inspection and structural health monitoring of FPSOs," in The Twenty-third International Offshore and Polar Engineering Conference, 2013: International Society of Offshore and Polar Engineers.  P. Darcis, D. Santarosa, N. Recho, and T. Lassen, "A fracture mechanics approach for the crack growth in welded joints with reference to BS 7910," in ECF15, Stockolm 2004, 2013.  T. Lassen, "The effect of the welding process on the fatigue crack growth," Welding Journal, vol. 69, pp. 75S-81S, 1990.  BS7910, "Guidance on methods for assessing the acceptability of flaws in metallic structures," British Standards Institution, 2000.  M. K. Chryssanthopoulos and T. D. Righiniotis, "Fatigue reliability of welded steel structures," Journal of Constructional Steel Research, vol. 62, no. 11, pp. 1199-1209, 2006.  BS5400, "Part 10, Code of practice for fatigue," British Standards Institution, 1980.  I. Lotsberg, G. Sigurdsson, A. Fjeldstad, and T. Moan, "Probabilistic methods for planning of inspection for fatigue cracks in offshore structures," Marine Structures, vol. 46, pp. 167-192, 2016.  DNVGL-RP-0005, "Fatigue design of offshore steel structures," Det Norske Veritas AS, Oslo, Norway, 2014.  I. Lotsberg, "Assessment of the size effect for use in design standards for fatigue analysis," International Journal of Fatigue, vol. 66, pp. 86-100, 2014.  T. Lassen and J. D. Sørensen, "A probabilistic damage tolerance concept for welded joints. Part 1: data base and stochastic modelling," Marine Structures, vol. 15, no. 6, pp. 599-613, 2002.  K. Engesvik and T. Lassen, "The effect of weld geometry on fatigue life," in Proceedings of the Third International OMAE Conference, Houston, Texas, 1988, pp. 440-446.  B. Palmberg, "Equivalent Initial Flaw Sizes by Different Methods," Swedish Defence Research Agency, Stockholm2001.  European Norm EN, "Eurocode 3: Design of steel structures," Part1-1: General Rules and Rules for Buildings," 1993.  T. Lassen, "Markov modelling of the fatigue damage in welded structures under in- service inspection," International Journal of Fatigue, Vol. 13, No. 5, pp. 417–422, 1991).  J. D. Sørensen and G. Ersdal, "Safety and inspection planning of older installations," Proceedings of the Institution of Mechanical Engineers, Part O: Journal of Risk and Reliability, vol. 222, no. 3, pp. 403-417, 2008.  M. H. Faber, J. D. Sørensen, J. Tychsen, and D. Straub, "Field implementation of RBI for jacket structures," Journal of Offshore Mechanics and Arctic Engineering, vol. 127, no. 3, pp. 220-226, 2005.  M. H. Faber, D. Straub, and J. Goyet, "Unified approach to risk-based inspection planning for offshore production facilities," Journal of Offshore Mechanics and Arctic Engineering, vol. 125, no. 2, pp. 126-131, 2003.  DNV GL, "DNVGL-RP-C210 Probabilistic methods for inspection planning for fatigue cracks in offshore structures," DNVGL rule, 2015.  J. A. James, "Application of probabilistic fracture mechanics for life prediction of metallic materials," PhD Thesis, Department of Aerospace Engineering, Wichita State University, 2007.  F. Lawrence, S. Dimitrakis, and W. Munse, "Factors influencing weldment fatigue," Fatigue and fracture, vol. 19, pp. 274-286, 1996.  T. Lassen and N. Recho, Fatigue Life Analyses of Welded Structures: Flaws. John Wiley & Sons, 2013.  D. F. Socie, J. Morrow, and W.-C. Chen, "A procedure for estimating the total fatigue life of notched and cracked members," Engineering Fracture Mechanics, vol. 11, no. 4, pp. 851-859, 1979.  N. Dowling, "Notched member fatigue life predictions combining crack initiation and propagation," Fatigue & Fracture of Engineering Materials & Structures, vol. 2, no. 2, pp. 129-138, 1979.  J. Schijve, "Fatigue of Structures and Materials in the 20th Century and the State of the Art," Materials Science, vol. 39, no. 3, pp. 307-333, 2003.  D. Radaj and M. Vormwald, "Ermüdungsfestigkeit: Grundlagen für Ingenieure," Springer-Verlag, 2007.  Americal Bureau of Shipping, "Guide for the fatigue assessment of offshore structures," ABS rule, 2003.  B. Journet, A. Lefrancois, and A. Pineau, "A crack closure study to predict the threshold behaviour of small cracks," Fatigue & Fracture of Engineering Materials & Structures, vol. 12, no. 3, pp. 237-246, 1989.  H. Chen, G. Y. Grondin, and R. G. Driver, Fatigue resistance of high performance steel. Department of Civil and Environmental Engineering, University of Alberta, 2005.  J. Y. Yung and F. Lawrence, "Analytical and graphical aids for the fatigue design of weldments," Fatigue & Fracture of Engineering Materials & Structures, vol. 8, no. 3, pp. 223-241, 1985.  A. M. P. de Jesus, A. L. L. da Silva, and J. Correia, "Fatigue of riveted and bolted joints made of puddle iron-A numerical approach," Journal of Constructional Steel Research, vol. 102, pp. 164-177, 2014.  R. F. Sanches, A. M. P. de Jesus, J. A. F. O. Correia, A. L. L. da Silva, and A. A. Fernandes, "A probabilistic fatigue approach for riveted joints using Monte Carlo simulation," Journal of Constructional Steel Research, vol. 110, pp. 149-162, 2015.
E. Ayala-Uraga and T. Moan, "Fatigue reliability-based assessment of welded joints applying consistent fracture mechanics formulations," International Journal of Fatigue, vol. 29, no. 3, pp. 444-456, 2007.
G. Josi, "Reliability-based management of fatigue failures," PhD Thesis, Department of Civil and Environmental Engineering, University of Alberta, pp. 340, 2010.
M. A. Valdebenito and G. I. Schuëller, "Design of maintenance schedules for fatigue-prone metallic components using reliability-based optimization," Computer Methods in Applied Mechanics and Engineering, vol. 199, no. 33, pp. 2305-2318, 2010.
M. Soliman, D. M. Frangopol, and A. Mondoro, "A probabilistic approach for optimizing inspection, monitoring, and maintenance actions against fatigue of critical ship details," Structural Safety, vol. 60, pp. 91-101, 2016.
S. Kim, M. Soliman, and D. M. Frangopol, "Generalized Probabilistic Framework for Optimum Inspection and Maintenance Planning," Journal of Structural Engineering, vol. 139, no. 3, pp. 435-447, 2013.
T. Bokalrud and A. Karlsen, "Probabilistic fracture mechanics evaluation of fatigue failure from weld defects in butt welded joints," Conference on Fitness for Purpose Validation of Welded Constructions, vol. 1, 1982.
T. Lassen and N. Recho, "Proposal for a more accurate physically based S– N curve for welded steel joints," International Journal of Fatigue, vol. 31, no. 1, pp. 70-78, 2009.
Y. Dong and D. M. Frangopol, "Incorporation of risk and updating in inspection of fatigue-sensitive details of ship structures," International Journal of Fatigue, vol. 82, pp. 676-688, 2016.