Ermüdungslebens

Ermüdungslebens, a term derived from German, translates to "fatigue life" in English. It refers to the number of stress cycles a material can withstand before it fails due to fatigue. Fatigue is a phenomenon where a material weakens and eventually fractures under repeated or fluctuating loads, even if the stress levels are well below the material's ultimate tensile strength.

The concept of fatigue life is crucial in engineering, particularly in the design of structures and components subjected to cyclic stresses. Examples include aircraft wings, bridges, engine parts, and rotating machinery. The higher the fatigue life of a material, the more cycles it can endure before failure, making it more reliable for applications requiring long-term durability.

Factors influencing fatigue life include the magnitude and nature of the applied stress (e.g., tension, compression, bending), the stress concentration at geometric discontinuities like holes or sharp corners, the material's properties (e.g., tensile strength, ductility, fracture toughness), and the presence of environmental factors such as temperature and corrosive substances. Surface finish also plays a significant role, as surface imperfections can act as initiation sites for fatigue cracks.

Engineers use various methods to estimate and predict fatigue life, including S-N curves (stress-life curves) which plot stress amplitude against the number of cycles to failure, and fracture mechanics approaches that consider crack propagation. Understanding and accounting for fatigue life is essential for ensuring the safety and longevity of mechanical systems.