Question

Which of the following methods can improve the fatigue strength of a circular mild steel (MS) shaft?

• A. Enhancing surface finish
• B. Shot peening of the shaft
• C. Increasing relative humidity
• D. Reducing relative humidity

Hint:

Improving surface finish, introducing compressive residual stresses through shot peening, and controlling environmental factors like humidity can significantly improve the fatigue strength of materials.

Answer 1

The Correct Option is A, B, D

The fatigue strength of a mild steel shaft can be significantly improved by methods that reduce surface defects and introduce compressive residual stresses. These methods include: - Enhancing surface finish: A smooth surface finish reduces the initiation of cracks and enhances the fatigue strength. Rough surfaces can act as stress concentrators, leading to premature failure. - Shot peening of the shaft: Shot peening is a mechanical process in which small spheres (shots) are blasted against the surface, creating compressive stresses. This helps to prevent crack formation and improve fatigue resistance by reducing the effects of tensile stresses at the surface. - Reducing relative humidity: In some environments, reducing humidity can limit corrosion, which can otherwise lead to crack initiation and premature failure. Thus, the correct answers are (A), (B), and (D).