PSI - Issue 60

Shreebanta Kumar Jena et al. / Procedia Structural Integrity 60 (2024) 115–122 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 8. Comparison between predicted fatigue life ( N p ) using critical plane model at characteristics distance and test fatigue life ( N i ) under remote pure axial and remote torsional loading conditions. 5. Conclusions The fatigue crack initiation study on C-Mn steel tubes having through thickness circular hole under remote torsional strain controlled conditions is summarized as below,  Test fatigue life reduces with increase in peak strain amplitude and increase in hole size indicating smaller strain gradient. This observation is in agreement with earlier studies by Jena et al. (2023) on same material under remote pure axial conditions.  The localized measured strains using digital image correlation and strain gauge compare well. Such techniques have been hardly used in literature for small strain amplitude (typically below 1%) fatigue tests for tube geometry.  The fatigue life of tube with hole has been predicted using point based critical distance and critical plane model of Arora et al. (2019, 2020). The predicted life compares well with test fatigue life for present remote torsional strain conditions and pure axial conditions. References Arora P., Gupta SK., Singh PK., Bhasin V., Vaze KK., Ghosh AK., Kushwaha HS., 2009. Fatigue crack initiation and crack growth studies for pipes made of carbon steel, 20th International Conference on Structural Mechanics In Reactor Technology (SMiRT 20), Espoo, Finland, August 9-14. Arora P., Gupta SK., Bhasin V., Singh RK., Sivaprasad S., Tarafder S., 2016.Testing and assessment of fatigue life prediction models for Indian PHWRs piping material under multi-axial load cycling, Int. J. Fatigue, 85, 98-113. Arora P., Samal MK., Gupta SK., Chattopadhyay J., 2019. Development of new critical plane model for assessment of fatigue life under multi-axial loading conditions, Int. J. Fatigue, 129, 105209. Arora P., Samal MK., Gupta SK., Chattopadhyay J., 2020. Validating generality of recently developed critical plane model for fatigue life assessments using multiaxial test database on seventeen different materials, Fatigue Fract. Eng. Mater. Struct., 43, 1327 – 1352. Arora P., Samal MK., Gupta SK., Chattopadhyay J., 2021. Proposing an improved cyclic plasticity material model for assessment of multiaxial response of low C-Mn steel, Int. J. Fatigue, 142, 105888. Arora P., Samal MK., Gupta SK., Chattopadhyay J., 2021. Assessment of Cyclic Plasticity Behaviour of Primary Piping Material of Indian PHWRs under Multiaxial Loading Scenario, Lect. Notes Mech. Eng., 227 – 247. E606 (ASTM), Standard Practice for Strain-Controlled Fatigue Testing, (Designation: E 606 – 04), American Society of Testing,” ASTM Compass. E2207-08(ASTM), 2009. Standard practice for strain-controlled axial torsional fatigue testing with thin-walled tubular specimens. 03.01, 1258 – 1265. Gates N., Fatemi A., 2014. Notched fatigue behavior and stress analysis under multiaxial states of stress, Int. J. Fatigue, 67, 2 – 14. Gates N., Fatemi A., 2016. Notch deformation and stress gradient effects in multiaxial fatigue, Theor. Appl. Fract. Mech., 84, 3 – 25. Gao Z., Qiu B., Wang X., Jiang Y., 2010. An investigation of fatigue of a notched member, Int. J. Fatigue, 32, 1960 – 1969.