1 the section of shaft shown in the figure is to be designed to a25403

Question

1) The section of shaft shown in the figure is to be designed to approximate relative sizes of d = 0.75D and r = D/20 with diameter d conforming to that of standard metric rolling-bearing bore sizes. The shaft is to be made of AISI 4140 steel, heat-treated to obtain minimum strengths in the shoulder area of 951 MPa ultimate tensile strength and 834 MPa yield strength with a Brinell hardness not less than285. At the shoulder the shaft is subjected to a completely reversed bending moment of 35 x 10 N.mm, accompanied by steady torsion of 22.5 x 103 N.mm.Surfaces are machined.
1. Choose a diameter at the root groove d, =? b. Find the size factor, k, = ? c. Find the Endurance limit S. = ? d. Find the notch sensitivities and static stress concentration factors q=?, q_{s}=?, K_{t}=?, K_{t s}=? Find the fatigue stress concentration factors Kf = ?,Kfs = ? Using a fatigue factor of safety according ASME-EIliptic, n =nASME = 3.5, estimate the diameter at the root groove, d, d=\left\{\frac{16 n}{\pi}\left[4\left(\frac{K_{f} M_{a}}{S_{e}}\right)^{2}+3\left(\frac{K_{f s} T_{a}}{S_{e}}\right)^{2}+4\left(\frac{K_{f} M_{m}}{S_{y}}\right)^{2}+3\left(\frac{K_{f s} T_{m}}{S_{y}}\right)^{2}\right]^{1 / 2}\right\}^{1 / 3} g. With this new calculated, d,, Loop through part b to part f, until you have a converged solution for the diameter at the root groove.