Which method is used to test fatigue using an S-N curve?

The Wohler test is specifically designed to create an S-N curve, which is used to analyze fatigue in materials. The S-N curve, or Wöhler curve, plots the number of cycles (N) a material can withstand at varying stress levels (S) before failure. In this testing method, specimens are subjected to cyclic loading, and the results indicate how many cycles the material can endure at different stress amplitudes. This information is crucial in material selection and design, especially in fields where components experience repetitive loading.

The other testing methods do not specifically focus on generating an S-N curve or assessing fatigue in the same manner. Stress tests primarily evaluate a material's strength and failure under static loads, durability tests assess the performance of materials over time under various conditions but do not directly produce an S-N curve, and impact tests measure a material's response to a sudden force or shock rather than cyclic fatigue.