gineering Design Folution Example 6-10 A 40-mm-diameter bar has been machined from an AISI 1050 cold-drawn bar. This part is to withstand a fluctuating tensile load varying from 0 to 70 kN. Because of the ends, and the fillet radius, a fatigue stress-concentration factor K, is 1.85 for 106 or larger life. Find Sa and Sm and the factor of safety guarding against fatigue and first-cycle yielding, using (a) the Gerber fatigue line and (b) the ASME-elliptic fatigue line. = 690 MPa and Sy = 580 MPa. We begin with some preliminaries. From Table A-20, Sut Note that Fa= Fm = 35 kN. The Marin factors are, deterministically, ka= 4.51(690)-0.265 = 0.798: Eq. (6-19), Table 6-2, p. 296 k = 1 (axial loading, see kc) ke=0.85: Eq. (6-26), p. 290 kd = ke = kf = 1 Se=0.798(1)0.850(1)(1)(1)0.5(690) = 234 MPa: Eqs. (6-8), (6-18), p. 290, p. 295