Høysyklusfatigue

Høysyklusfatigue refers to material failure that occurs after a large number of stress cycles, typically exceeding 10^4 or 10^5 cycles. This phenomenon is distinct from low-cycle fatigue, which involves fewer cycles but higher stress amplitudes. Materials subjected to high-cycle fatigue experience stress levels below the material's yield strength, but the cumulative effect of repeated loading and unloading leads to crack initiation and propagation. Common examples include components in aircraft, rotating machinery, and bridges where vibrations or operational stresses are constant and repetitive.

The initiation of fatigue cracks in high-cycle fatigue usually begins at stress concentrations, such as surface imperfections, sharp corners, or material defects. Once a crack forms, it grows incrementally with each subsequent stress cycle. The rate of crack growth is influenced by factors like the applied stress range, material properties (e.g., fracture toughness), and environmental conditions (e.g., corrosive environments can accelerate crack growth). Predicting and preventing high-cycle fatigue is crucial for ensuring the structural integrity and safety of many engineering applications. Techniques such as material selection, design optimization to minimize stress concentrations, surface treatments, and regular inspections are employed to mitigate the risk of high-cycle fatigue failure.