5. A non-rotating shaft made of AISI 1018 CD steel is machined to the shape shown below. A load Fy = -250 lbf (pointing down) and F2 = F, = 0 lbf is repeatedly applied and removed. Determine the factor of safety for fatigue based on Goodman criterion. If the life is not infinite, estimate the number of cycles to failure (f= 0.9 for S-N curve). 2 in 9 in 1-in din -in R. B | 2 in 1-in dia. 1-in dia. -in dia. 12 in

The shaft shown in the figure is machined from AISI 1030 CD steel. The shaft rotates at a constant RPM and is supported by roller bearings at A and B. The profile keyway at F has static stress concentration factor of Ktb = 2.312 for bending. The applied forces at gears C, D and F are in the same plane as the bearing reactions and remain constant. a) b) Clearly draw and label shear and bending diagrams for the shaft. Determine the factor of safety against bending fatigue only at location F (centerline of Gear F) assuming 50% reliability and state in words if the shaft will have infinite life based on this location. T 1.500 1.25 Ø- BEARING 1.160 A E 4.5 0.375 & GEAR C 500 lbf C -1.75 Ø 3.0 & GEAR F 300 lbf FV -0.75 2.5 BEARING -0.50 0.0312 R- B 2.5 3/8 x 3/8 PROFILE KEYWAY -0.375 GEAR D 1.5625 KEYWAY DETAIL AT "F" 450 lbf D 1/4 x 1/4 PROFILE KEYWAY -1.25 Ø

7-3 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 rolling- bearing bore sizes. The shaft is to be made of SAE 2340 steel, heat-treated to obtain minimum strengths in the shoulder area of 175 kpsi ultimate tensile strength and 160 kpsi yield strength with a Brinell hardness not less than 370. At the shoulder the shaft is subjected to a completely reversed bending moment of 600 lbf • in, accompaniced by a steady torsion of 400 lbf · in. Use a design factor of 2.5 and size the shaft for an infinite life using the DE-Goodman criterion. Problem 7-3 Section of a shaft containing a grinding-relief groove. Unless otherwise specified, the diameter at the root of the groove d, =d - 2r, and though the section of diameter d is ground, the root of the groove is still a machined surface.

Figure below shows a rotating shaft simply supported in ball bearings at A and D and loaded by a nonrotating orce Fof 6.8 kN. Using ASTM "minimum" strengths, estimate the life of the part. 6T td7 (a) Shaft drawing showing all dimensions in millimeters; all fillets 3-mm radius. The shaft rotates and the load is stationary; material is machined from AISI 1050 cold-drawn steel. (b) Bending moment diagram.

Design