PSI - Issue 14

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Taslim D. Shikalgar et al. / Procedia Structural Integrity 14 (2019) 529–536 T.D.Shikalgar et al./ Structural Integrity Procedia 00 (2018) 000–000

536

Table 4: Comparison of numerical J-initiation with standard values Material

Fracture toughness J i (kJ/m 2 )

Elastic-Plastic FE analysis

FE analysis with conventional GTN model

FE analysis with GTN model with modified q 2

From ASTM E1820 standard test

20MnMoNi55

246.78 344.02

192.18 264.49

141.66 194.22

150 198

T91

4. Conclusions The following conclusions may be drawn from the present study: 1. Pre-cracked small punch test specimens can be used along with the finite element analysis to obtain fracture initiation toughness in case of limited availability of material. 2. Elastic-plastic FE analysis of p-SPT specimen does not indicate the crack initiation load. The computed value of J-initiation is significantly higher in case it is assumed that the crack initiation occurs near the value of peak load. 3. Conventional GTN damage mechanics analysis can be used to know the crack initiation load. The computed J-initiation by this method is still higher than the standard test value 4. By using the GTN method with the modification suggested by Dutta et al. (2008), the computed J-initiation is within 6% of the standard test value. 5. The methodology described in this paper has the potential to determine fracture initiation toughness (J i ) of aged nuclear materials, such as irradiated materials, using pre-cracked small punch test. ASTM E1820-01. Standard test method for measurement of fracture toughness. Annual Book of ASTM Standards, Vol. 03.01. American Society for Testing and Materials (2001). B. K. Dutta, S, Guin, M. K. Sahu, M. K. Samal. A phenomenological form of the q 2 parameter in the Gurson model. International Journal of Pressure Vessels and Piping, 85 (2008), 199-210. BARC technical report. In-House Finite Element Code MADAM (MAterial DAmage Modeling) Developed by Reactor Safety Division (RSD), 1999 (India). C.F. Shih, B. Moran, T. Nakamura. Energy release rate along a three-dimensional crack front in a thermally stressed body. International journal of fracture 30 (1986), 79-102. Contract report, Flaw and Fracture behaviour of 9%Cr-Ferrritic / Martensitic steels, SCK.CEN-R-4122, (2005). E. Cardenas, F. J. Belzunce, D. Rodriguez, I. Penuelas and C. Betegon. Application of the small punch test to determine the fracture toughness of metallic materials, Fatigue Fract. Engng. Mater. Struct. 00 (2011), 1–10. E. Martinez-Paneda, I. I. Cuesta, I Penuelas, A. Diaz, J. M. Alegre. Damage modeling in small punch test specimens. Theoretical and applied fracture mechanics 86 (2016), 51-60. Emilio Martinez-Paneda, Tomas E. Garcia, Cristina Rodriguez. Fracture characterization through notched small punch test specimens. Material Science and Engineering A 657 (2016), 422-430. J. M. Alegre, I. I. Cuesta, H. L. Barbachano. Determination of the fracture properties of metallic materials using pre-cracked small punch tests. Fatigue Fract. Engng. Mater. Struct. 38 (2014), 104–112. J. M. Alegre, R. Lacalle, I. I. Cuesta, J. A. Alvarez. Different methodologies to obtain the fracture properties of metallic materials using pre notched small punch test specimens. Theoretical and applied fracture mechanics 86 (2016), 11-18. M.S. E1-Fadaly, T.A. E1-Sarrage, A.M. Eleiche, W. Dahl. Fracture toughness of 20MnMoNi55 steel at different temperatures as affected by room-temperature pre-deformation. Journal of Materials Processing Technology 54 (1995), 159-165. Pradeep Kumar, B. K. Dutta, J. Chattopadhyay, R. S Shrivastaw. Numerical evaluation of J-R curve using small punch test data. Theoretical and applied fracture mechanics 86 (2016), 292-300. Small Punch Test Method for Metallic Materials, CWA 15627.Part A: A Code of Practice for Small Punch Creep Testing and Part B: A Code of Practice for Small Punch Testing for Tensile and Fracture Behaviour, Documents of CEN WS21, Brussels, (2007). T.E. Garcia, C. Rodriguez, F. J. Belzunce, I.I. Cuesta. Development of a new methodology for estimating the CTOD of structural steels using the small punch test. Eng Failure Analysis 50 (2015), 88-99. V. Tvergaard, A. Needleman. Analysis of cup-cone fracture in a round tensile bar. Acta Metall. 32 (1984), 157-169. V. Tvergaard. On localization in ductile materials containing spherical voids. Int. J. Fract. 18 (1982), 237-252. Z. L. Zhang, E. Niemi. A class of generalized mid-point algorithms for the Gurson- Tvergaard material model, International. Journals of Numerical Methods in Engg., 38 (1995), 2033-2053. References