Simulation of critical J-integral in functionally graded steels components weakened by U and blunt V-shape notches under Charpy test

► The effect of the notch opening angle on the failure resistance of FGS has been investigated. ► FGSs containing graded layers were fabricated via spot welding. ► Experimental values were measured by analyzing load-displacement curve recorded. ► The modified stress-strain curve was considered as the input parameter for the FEM simulation. ► The proposed FEM model agrees well with experimental results.