Questions & Answers of Fatigue Strength and The S-N Diagram

Weightage of Fatigue Strength and The S-N Diagram

Total 4 Questions have been asked from Fatigue Strength and The S-N Diagram topic of Machine Design subject in previous GATE papers. Average marks 1.50.

A machine element has an ultimate strength $\style{font-family:'Times New Roman'}{\left(\sigma_u\right)}$ of 600 N/mm2, and endurance limit $\style{font-family:'Times New Roman'}{\left(\sigma_{en}\right)}$ of 250 N/mm2. The fatigue curve for the element on a log-log plot is shown below. If the element is to be designed for a finite life of 10000 cycles, the maximum amplitude of a completely reversed operating stress is ____________ N/mm2.

 

In a structural member under fatigue loading, the minimum and maximum stresses developed at the critical point are 50 MPa and 150 MPa, respectively. The endurance, yield, and the ultimate strengths of the material are 200 MPa, 300 MPa and 400 MPa, respectively. The factor of safety using modified Goodman criterion is

In a structure subjected to fatigue loading, the minimum and maximum stresses developed in a cycle are 200 MPa and 400 MPa respectively. The value of stress amplitude (in MPa) is _______

An axial residual compressive stress due to a manufacturing process is present on the outer surface of a rotating shaft subjected to bending. Under a given bending load, the fatigue life of the shaft in the presence of the residual compressive stress is