A part is loaded with a combination of bending, axial and torsion such that the following stresses are created at a particular location:
Bending: Completely reversed with a maximum stress of 41MPa.
Axial: Constant stress of 18 MPa.
Torsion: Repeated load, varying from 0 MPa to 55 MPa.
Assume the varying stresses are in phase with each other. The part contains a notch such that Kf, bending = 1.3, Kf, axiel =1.1, and Kf, torsion = 2.0. The material properties are Sy = 300 MPa and Su = 400 MPa. The completely adjusted endurance limit is found to be Se = 200 MPa.
1. Using the Goodman criterion, find the factor of safety for fatigue based on infinite life. If the life is not infinite, estimate the number of cycles. Be sure to check for yielding. Round the answers to two decimal places.