Question

discuss metallurgical factors related to fatigue and methods of increasing cycles to failure

Answer 1

Cyclical and variable loading of a material leads to fatigue and can even lead to early failure. Failure can occur by multiple ways and fatigue failure is one of them.

Stress cycles that lead to fatigue-failure have following factors:

Mean stress

Stress ratio

Amplitude ratio

Stress range

For fatigue fracture to occur, we need following:

Maximum tensile strength, enough changes in stress and Multiple cycles.

Fatigue Factors:

Endurance ratio, fatigue strength, fatigue life and fatigue limit.

Cycles vs vs stress amplitude diagram is given here

Material will fail under fatigue if there are higher number of Stress cycles with lower applied stress.