Stress intensity factor calculation for internal circumferential cracks in functionally graded cylinders using the weight function approach

• Weight function approach is applied to FG cylinders with internal cracks.
• A modified expression of the axisymmetric J integral in domain form is developed.
• A fitting technique is introduced to interpolate stress intensity values.
• Stress intensity factors from weight function agree very well with FE results.

In this work, we describe stress intensity factors obtained for functionally graded cylinders with internal circumferential cracks using the weight function method for different combinations of cylinder geometry, crack depth, and material gradation. A modified form of the J integral is employed to obtain reference stress intensity factors using finite element analysis results. Furthermore, a fitting technique is employed for calculating stress intensity factors not covered in the finite element modeling matrix. The results predicted by the weight function method along with the proposed fitting technique are in good agreement with the results directly obtained from the finite element analysis.