The GATE Grind

GATE 2023 MT – Question 27

Mechanical Behaviour of Materials · Fatigue · 1 mark · Multiple select

Which of the following is/are responsible for reducing the high cycle fatigue life of a component?

  1. increasing the mean stress at constant amplitude
  2. increasing the surface roughness
  3. employing shot peening
  4. absence of sharp corners in the component

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Show answer and explanation

Correct answer: (A) increasing the mean stress at constant amplitude; (B) increasing the surface roughness

Explanation

Increasing tensile mean stress at fixed amplitude reduces fatigue resistance. Greater surface roughness creates local stress concentrations and favours crack initiation. Shot peening adds beneficial compressive residual stress, and removing sharp corners reduces concentration.

Thus the harmful choices are **A,B**.