This work pertains to investigate the values of the stress intensity factor (SIF) in a functionally graded spherical pressure vessel with an embedded surface defect (semi elliptical crack) under thermo-mechanical loading. The three dimensional finite element analysis is performed to evaluate the SIFs through the crack front for a wide range of crack profiles and the various layer thickness. It is assumed that the elastic modulus of sphere varies exponentially in the radial direction of the vessel.
The effect of non-uniform coefficient of thermal expansion (CTE) on the fracture parameters is also studied. The obtained results show that the material gradation of spherical pressure vessel can considerably affect the distribution of the SIFs along the crack front. The gradation of material, the wall thickness of spherical pressure vessel and the profile of crack front can affect the critical point through the crack front which is apt to the crack growth.