What does a “metal fatigue test” measure in sheet metal compliance?

A metal fatigue test is specifically designed to assess a metal's ability to endure cyclical loading or repeated stress and strain without failing. This is crucial in applications where materials are subject to fluctuations in stress due to operational conditions, such as in aircraft structures.

During the fatigue testing process, samples of metal undergo thousands or millions of stress cycles, which can lead to the initiation and propagation of cracks. The results help engineers determine the fatigue limit—the maximum stress that can be applied without leading to failure over a specified number of cycles. This information is vital in ensuring the safety and reliability of structures in real-world applications where components are continually subjected to varying loads.

While conductivity, weldability, and corrosion resistance are important properties of metals, they do not relate to how metals perform under repeated mechanical loading, which is the focus of a metal fatigue test. Therefore, the correct answer emphasizes the importance of fatigue resistance in ensuring the durability of structural components.