Please answer all questions very urgent!!! Many thanks a) Explain the three processes of fatigue initiation and Stage I

[answerhappygod]

Please answer all questions very urgent!!! Many
thanks
a) Explain the three processes of fatigue initiation and Stage I
and II crack growth in a specimen with an ideal surface (i.e no
pre-existing cracks). [6 marks]
b) Define what is meant by the R-ratio during a fatigue test.
Draw a schematic of stress vs time for a loading cycle where
R=-0.5. Indicate the stress range, peak stress and mean stress. [5
marks]
c) List three methods of improving the fatigue performance of a
component and describe the mechanism by which the improvement
occurs.