A transmission shaft of cold-drawn steel 27Mn² (Sᵤₜ = 500 N/mm², Sᵧₜ = 300 N/mm²) is subjected to a fluctuating torque which varies from -100 .m to +400 .m. The FOS is 2 . Corrected Endurance limit of the material is 150.58 /mm². Find the diameter of the shaft. Consider the distortion energy theory of failure.