One of the key factors in the design of the spherical pressure vessels is the lack of study of the SIF in different modes of fracture. In the present research, the SIF evaluation in three modes of fracture was investigated in FGM spherical pressure vessel. The walls of the spherical vessel consisting of semi-elliptical and semi-circular cracks were considered. The simulation and numerical solutions of the problem were done in ABAQUS software. The modelling of FGM spherical vessel was done using the power function and the effect of crack angles on the SIF was evaluated under p, pd and ph . The obtained results illustrated that in homogeneous and FGM vessels, the variation of the SIF directly related to p, so that, with increasing p, the SIF also increases. Also, it was observed that the most variation in the SIF was associated with the ceramic phase of the wall of the vessel where the elastic modulus reduced. In addition, the minimum variation takes place in the steel phase of the wall where the elastic modulus increases. In addition, the results were indicated the minimum variation for this parameter relates to crack at = 90°.
