(a) Draw the stress vs strain curve showing the different phases of change that occurs when an elastic material is subjected to load. (5)

(b) What is plastic deformation of material and how it is caused? Explain yield stress & how strain hardening is caused? where is this phenomenon successfully used? (6)

(c) Explain fatigue and how fatigue failure occurs? Suggest means in practice as to how fatigue failure can be avoided. (5)