Ermüdungsfähigkeit

Ermüdungsfähigkeit refers to the capacity of a material to withstand repeated or fluctuating stresses over time without failing. This phenomenon is distinct from static failure, which occurs under a single, sustained load. When a material is subjected to cyclic loading, microscopic damage can accumulate with each stress cycle. This damage can manifest as crack initiation and subsequent propagation. Eventually, if the number of cycles or the magnitude of stress is sufficiently high, the material can fracture, even if the applied stresses are well below its yield strength.

The concept of fatigue is crucial in engineering design, particularly for components subjected to dynamic loads, such as aircraft wings, bridges, rotating machinery, and vehicle parts. Understanding a material's fatigue resistance allows engineers to predict its lifespan and design components that are safe and reliable under anticipated service conditions. Factors influencing fatigue behavior include the material's properties (e.g., strength, ductility, microstructure), the stress amplitude and ratio, the presence of surface defects or stress concentrations, and the environmental conditions (e.g., temperature, corrosive agents).

The fatigue life of a material is often represented by an S-N curve (stress-number of cycles to failure curve). This curve plots the stress amplitude against the number of cycles a material can endure before failing. Some materials exhibit a fatigue limit, a stress level below which they can theoretically withstand an infinite number of cycles. However, many materials, especially metals, do not have a distinct fatigue limit and will eventually fail regardless of the stress level if subjected to enough cycles.