A shaft is machined of cold drawn AISI 1020 steel. It is rotated at 500
rpm. The shaft is 100 mm long between supports. A 4.5 kN force is
applied continuously in the middle of the shaft for 10 hours. What is the
diameter that I need if a safety factor of 1.3 is used?
Take as load only the bending moment caused by the force into account
and use the SN diagram below.
Given: Shaft bending stress, s = M/Z
Z=section modulus of the bar = pD3
/32
the SN diagram is in PDF file, as well as the complete question