Which of the following is not a nondestructive testing method?

Fatigue testing is characterized as a destructive testing method, which assesses the material's strength and durability under cyclical loads until failure occurs. It determines the point at which a material will fail due to repeated stress, which inherently requires the material to be tested to the point of damage. This contrasts with the other methods listed—ultrasonic testing, eddy current testing, and radiographic testing—each of which objectively inspects materials without causing any harm. These nondestructive testing methods are essential for evaluating the integrity and quality of materials while preserving their usefulness and performance.