Ermüdungskurve

Ermüdungskurve is a term used in materials science and engineering to describe the relationship between the stress applied to a material and the number of cycles it can withstand before failure due to fatigue. This curve, also known as an S-N curve (Stress-Number of cycles), is crucial for understanding the fatigue life of components under cyclic loading.

The curve is typically plotted on a logarithmic scale, with stress on the vertical axis and the number of cycles to failure on the horizontal axis. Generally, as the stress level decreases, the number of cycles a material can endure before fracturing increases. Conversely, higher stress levels lead to a significantly shorter fatigue life.

For some materials, particularly ferrous alloys like steel, a fatigue limit or endurance limit may be observed. This is a stress level below which the material can theoretically withstand an infinite number of cycles without failing. However, many non-ferrous metals and polymers do not exhibit a distinct fatigue limit and will eventually fail even at very low stress levels, albeit after a very large number of cycles.

The Ermüdungskurve is determined through laboratory testing where specimens are subjected to controlled cyclic stresses until fracture. The data points from these tests are then used to construct the curve. Understanding the Ermüdungskurve is essential for designing components that will be subjected to repeated loads, such as in aircraft, bridges, vehicles, and machinery, to ensure their safety and reliability over their intended service life.