Questions $(5$ points each$)$:

Describe the slip theory as it relates to fatigue phenomenon in metallic structure. Describe the elements of a "slip system." Define various kinds of slip. Define cross slip, Schmid Law and Burgers Circuit?

Draw a schematic of a cyclic loading and identify $S_{\text{m}\text{a}\text{x}},S_{\text{m}\text{i}\text{n}},S_a,S_m$ on your diagram. Also draw fatigue diagrams for mean stress effects and an S$-$N Curve; identify$/$label each item appropriately. Explain the effect of a notch on the fatigue diagram.

What is the Max $K_t$ for an open hole in a fuselage skin subject to pressure? What about in a plate subject to biaxial tension$/$compression of the same magnitude?

Use a schematic diagram to describe low$-$cycle fatigue and high$-$cycle fatigue. Explain their distinctive characteristics?

When is cold$-$working of a hole useful, and when is it not? What are the drawbacks of cold working of a hole?