To increase the expected fatigue service life of a component, we can take the following measures besides the choice of a stronger material: (a) Improving the surface finish; (b) Decreasing stress concentration; (c) the structure shape; (d) All of the above

d). All the above

Explanation:

Smooth surface finish of a component improves fatique properties and increases the fatique life of the component subjected to any cyclic loading. Rough surface of any material leads to poor strength and increases the chance s for cracks ... So smooth finish is important and longer life of the component.

Stress concentration at any part of the component is the most weak part of the component where failure can take place. Stress concentration region is the most targeted region where cracks may developed due to external load. So decreasing the stress concentration at any part of the component would increase the fatique life of the component when subjected to any cyclic loading.

Fatigue failure also depends on the structure shape of the component which is indirectly related to the stress concentration at different sections of the component. For a component shape where there is sudden change in dimension or there is a hole or notches on the structures, such structural shape leads to stress concentration and thus leads to fatique failure subjected to cyclic loadings. To minimise stress concentration the structure should be simple and not complex type so to increase the fatique life.

Hence all the above factors results in increasing the fatique service life of a component.