The GATE Grind

GATE 2024 ME – Question 26

Machine Design · Fatigue strength and S-N diagram · 1 mark · Multiple choice

Which one of the following failure theories is the most conservative design approach against fatigue failure?

  1. Soderberg line
  2. Modified Goodman line
  3. Gerber line
  4. Yield line

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Show answer and explanation

Correct answer: (A) Soderberg line

Explanation

The Soderberg line joins the endurance limit on the alternating stress axis to the yield strength on the mean stress axis, so it lies inside the Goodman and Gerber lines and allows the smallest stresses. It is the most conservative of the fatigue criteria. The yield line is a static criterion, not a fatigue criterion.