PSI - Issue 2_A

Nedeljko Vukojević et al. / Procedia Structural Integrity 2 (2016) 2982 – 2988 Author name / Structural Integrity Procedia 00 (2016) 000–000

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Fig. 1. (a) specimens from vessel middle "M"; (b) specimens from bottom vessel head "B"; (c) specimens from top vessel head "T".

2. Applied test procedure To determine the critical value of J-integral and critical crack tip opening CTOD respectively, the resistance curve of materials was necessary to perform the experiment, indicate references Vukojevic et al. (2014). Experimental determination of the J-integral and CTOD value is in accordance with standard, indicate reference ASTM E1820 (2011). Requirements for fulfilling the conditions of plane strain deformation are defined by formula: ܤ ൒ ʹǡͷ ቀ ௄ ಺೎  ೊೄ ቁ ଶ . (1) Since the requirements (1) are not met, it is necessary to use an elastic plastic fracture mechanics as defined by ASTM E1820-11. The aim of use elastic-plastic fracture mechanics is the determination of the critical stress intensity factor, K Ic , indirectly by means of the critical J-integral, J Ic : ܭ ூ௖ ൌ ට ௃ ಺೎ ଵିఔ ா మ . (2) Applying the basic formula of fracture mechanics, using yield strength of materials  max =  YS and assuming the shape factor Y=1,12, approximate values for the critical crack length, a c , was calculated according to the equation: ܽ ௖ ൌ గ ଵ ቀ ௄ ಺೎ ௒ήఙ ೘ೌೣ ቁ ଶ . (3)