“…However in this study, the singularity index of the T-shaped structure is treated as λ ¼ 0:500 in consideration of the flexibility of the stress intensity factor. Also, in a magnesium alloy, a fatigue crack propagates in the rectangular direction to a maximum principal stress [22]. That is, the fatigue crack starting from the corner in the T-shaped structure follows the s θmax theory [23], propagating in the direction of the tangential adjusting stress s θ .…”