Q1: The fatigue resistance of a material is improved by the following technique.

ANS:D - Shot peening

The fatigue resistance of a material is typically improved by the technique of shot peening. Shot peening is a mechanical surface treatment process used to improve the fatigue strength and durability of materials, particularly metals. During shot peening, small spherical media, known as shot, are propelled at the surface of the material at high velocities. The impact of the shot induces compressive residual stresses in the surface layer of the material, which counteract the tensile stresses that develop during cyclic loading. This compression layer helps to prevent the initiation and propagation of cracks, thereby increasing the fatigue resistance of the material. Anodizing, carburizing, and ion nitriding are surface treatment processes that primarily focus on improving corrosion resistance, surface hardness, and wear resistance of materials, rather than specifically enhancing fatigue resistance. While these techniques may indirectly contribute to improved fatigue performance in certain cases, shot peening is specifically designed to enhance fatigue strength by introducing compressive stresses into the material surface.