Problem 3 A square prismatic bar shown in the figure with sides 0.05 m is subjected to axial tension, Fm = 90 kN. Apply the Soderberg criterion (see below) to determine the limiting value of completely reversed axial load Fa that can be superimposed on Fm at the midpoint of a side of the cross section without causing fatigue failure at 106 cycles. For the material in the bar, the fatigue strength for completely reversed stress at 106 cycles is 210 MPa, and the static tensile yield strength is 280MPa. 50 mm Fm Fatigue Goodman σa + Equation σ cr 6 m Soderberg σm = = 1 + 0. cr ур = Fa 50 mm Gerber SAE 2 6 a 0m + = 1 σ 1 m =1 + Ост Ост น Subscript notations: a = alternating, cr = completely reversed, f= fracture, m = mean, u = static tensile ultimate, yp = static tensile yield.