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

## What is the Weightage of Fatigue Strength and The S-N Diagram in GATE Exam?

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