SOLUTION

Fatigue strength is the ability to resist fracture when the stresses are variable and alternate through a cycle.

Fatigue tests are made by subjecting a test specimen to variable loads. Some tests bend the piece alternately in one direction, then in the other. Others apply and remove tensile loads. Still, others make a cycle of tension and compression by rotating a loaded specimen. In most cases, this value is approximately 40-50% of the tensile strength.

Fatigue strength is the ability of steel to resist stresses that are a reversal in nature.