As a student engineer illustrate what design consideration you would like to account for parts manufactured by machining and forging.

A circular bas of 500mm length is hinghed freely at its two ends. It is performed upon by a central concentrated cyclic load having a minimum value of 20 kN and maximum value of 50kN. Evaluate the diameter of bar by taking factor of safety of 1.5, size effect of 0.85, surface complete factor of 0.9. The material properties of bar are provided by: ultimate strength of 650 upa, yield strength of 500 MPa and endurance strength of 350 MPa.