what is SI unit of fatigue and breaking strength?

Answer 1

Unit of force or force over area.

kg-m-sec SI unit of force is the Newton (kg-m/sec^2). Force over area is Newton/m^2 where the area is the cross-sectional area of the piece being broken.

Fatigue implies a wearing down (a fatiguing) of the structure (crystalline, molecular) of the piece tested until it breaks. So time must also be folded into the measure of fatigue. For this, mean time to failure (MTTF) is often used. This is found by taken a number of test pieces, stressing them repeatedly, and noting when they fail. The average time (in sec for SI) is the MTTF.

Answer 2

breaking strength unit : Kg / cm ^ 3