Investigation of the fracture problem of functionally graded materials with an inclined crack under strong transient thermal loading

•The Newmark method is employed to obtain the strong transient temperature field of functionally graded materials containing an inclined crack.•The transient interaction energy integral method (IEIM) is used to obtain the transient thermal stress intensity factors (TSIFs).•The IEIM is combined with the Newmark method so that TSIFs can be solved with high efficiency.•The effect of the profile of thermal relaxation parameter on the TSIFs, and the crack growth angle are studied.