Visual Testing (VT) Practice Exam

What term describes repeated fluctuating stress with a maximum value less than the tensile strength of the material?

1. A crack

2. Mechanical fatigue

3. Thermal fatigue

4. Stress corrosion cracking

The correct answer is: Mechanical fatigue

The term that describes repeated fluctuating stress with a maximum value less than the tensile strength of the material is mechanical fatigue. This phenomenon occurs when a material is subjected to cyclic loading, which can lead to the gradual deterioration of the material over time, even when the maximum stress experienced is below the material's tensile strength. Mechanical fatigue arises from the repetitive application of stress, resulting in microscopic damage that accumulates until it eventually leads to failure. This understanding is critical because it highlights the importance of considering not just the peak stress, but also how often and how cyclically the load is applied. Fatigue is a fundamental aspect in the analysis of materials, especially in engineering and design applications where components are expected to endure repeated stress cycles during their service life.