Page 378 - Shigley's Mechanical Engineering Design

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Fatigue Failure Resulting from Variable Loading 353
6–47* to For the problem specified in the table, build upon the results of the original problem to determine
6–50* the minimum factor of safety for fatigue based on infinite life. If the life is not infinite, estimate
the number of cycles. The force F is applied as a repeated load. The material is AISI 1018 CD
steel. The fillet radius at the wall is 0.1 in, with theoretical stress concentrations of 1.5 for bend-
ing, 1.2 for axial, and 2.1 for torsion.

Problem Number Original Problem, Page Number
6–47* 3–80, 139
6–48* 3–81, 140
6–49* 3–82, 140
6–50* 3–83, 140

6–51* to For the problem specified in the table, build upon the results of the original problem to determine
6–53* the minimum factor of safety for fatigue at point A, based on infinite life. If the life is not infi-
nite, estimate the number of cycles. The force F is applied as a repeated load. The material is AISI
1018 CD steel.

Problem Number Original Problem, Page Number
6–51* 3–84, 140
6–52* 3–85, 141
6–53* 3–86, 141

6–54 Solve Prob. 6–17 except include a steady torque of 2500 lbf · in being transmitted through the
shaft between the points of application of the forces.
6–55 Solve Prob. 6–18 except include a steady torque of 2200 lbf · in being transmitted through the
shaft between the points of application of the forces.
6–56 In the figure shown, shaft A, made ofAISI 1020 hot-rolled steel, is welded to a fixed support and is
subjected to loading by equal and opposite forces F via shaft B. A theoretical stress-concentration
1
factor K ts of 1.6 is induced by the -in fillet. The length of shaft A from the fixed support to the
8
connection at shaft B is 2 ft. The load F cycles from 150 to 500 lbf.
(a) For shaft A, find the factor of safety for infinite life using the modified Goodman fatigue fail-
ure criterion.
(b) Repeat part (a) using the Gerber fatigue failure criterion.

F
7 -in dia
8
1 in
Problem 6–56
10 mm
1 in
1 in
8
fillet
Shaft A Shaft B
F