PSI - Issue 14

Viswa Teja Vanapalli et al. / Procedia Structural Integrity 14 (2019) 521–528 Viswa Teja Vanapalli/ Structural Integrity Procedia 00 (2018) 000 – 000

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8” pipe having 60 0 crack angle denoted by SPBMTWC8-1.

Fig. 7. Comparison of Load vs CMOD for simulation results of different Z scores with experimental result for pipe components.

5. Conclusions

 One of the cohesive zone parameters called peak stress ‘T’ is a function of stress triaxiality ‘q’, beside the material.  Parameter ‘T’ increases with decrease in the value of ‘q’ and reaches a constant value asymptotically. Similarly, parameter ‘T’ decreases with the increase in ‘q’ and reaches a constant value asymptotically. Such variation of ‘T’ with ‘q’ may be represented by a sigmoidal curve.  For a constant value of ‘q’, there may be uncertainty in the value of peak stress ‘T’ for the same material due to microstructural changes at different points. Such uncertainty may be represented by a normal variation within two bounds.  For the material SA333 Gr6, variation of ‘T’ with ‘q’ as well as normal variation within two bounds have been quantified by numerical analyses of experimental results of TPBB and pipe specimens.  It is shown that experimental data on load-displacement of cracked pipe made up of SA333 Gr6 lies within the values calculated numerically assuming such normal variation of ‘T’ for a given value of ‘q’. References Anuradha, B., & Manivasagam, R. 2009. Triaxiality dependent cohesive zone model. Engineering Fracture Mechanics, 76 , 1761-1770. Barenblatt, G., 1962. The mathematical theory of equilibrium cracks in brittle fracture. Advanced Applied Mechanics, 7 , 55-129. Brocks, W., 2017. Plasticity and Fracture. Springer. Chen, C., O. Kolednik, J. Heerens, & F.D. Fischer., 2005. Three-dimensional modeling of ductile crack growth: Cohesive zone parameters and crack tip triaxiality. Engineering Fracture Mechanics, 72 , 2072-2094. CIEP/98/0055, P. N., 2000. Specimen size and constraint effects on J-R curves of SA333 Gr.6 Steel, TPB and C(T) geometries. Jamshedpur: National Metallurgical Laboratory. Cornec, A., Ingo Schieder, & Karl-Heinz Schwalbe., 2002. On the practical application of the cohesive model. Engineering fracture mechanics, 70 , 1963-1987. CSIR., 2014. Characterizing numerical SZW evaluation for determining material fracture toughness (Jszw). Bhopal: Board of Research on Nuclear Sciences (BRNS), Mumbai. Dugdale, D., 1960. Yielding of steel sheets containing slits. Journal of Mechanics and Physics of solids, 8 , 100-104. E1820-15a, A., 2015. Standard Test Method for Measurement of Fracture Toughness. ASTM International. Elices, M., G.V. Guinea, J. Gomez, & J. Planas., 2002. The cohesive zone model: advantages, limitations and challenges. Engineering Fracture Mechanics, 69 , 137-163. Healy, B., Arne Gullerud, Kyle Koppenhoefer, Arun Roy, Sushovan Roy Chowdhary, Jason Petti, . . . et al., 2016. Warp3D-Release 17.7.0 User's Guide. Mahler, M., & Jarir Aktaa., 2015. Approach for J-R curve determination based on sub-size specimens using a triaxiality dependent cohesive model on a (ferritic martensitic) steel. Engineering Fracture Mechanics, 1144 , 222-237. Needleman, A., Tvergaard V., & J.W. Hutchinson., 1992. Void growth in Plastic solids. . Topics in Fracture and Fatigue , 145-178. Schwalbe, K.-H., Ingo Scheider, & Alfred Cornec., 2013. Guidelines for applying cohesive models to the damage behaviorr of engineering materials and structures. Germany: Springer.