As we have already noticed, the stress should exceed the strain as many times as the adopted factor-of-safety, or: Streess/Strain = factor-of-safety.

Or, stress = strain x factor-of-safety.

This holds good for all calculations, and can be expressed by the following simple fundamental formula: v = s.f (1)

Where v = the ultimate stress in pounds.

s= strain in pounds.

Fundamental Formula.

And where f= the factor-of-safety.