väsimusteste

Väsimusteste, in Estonian, refers to fatigue tests—procedures that evaluate how a material or component responds to repeated cyclic loading. The goal is to determine fatigue life, the number of cycles a material can withstand before failure, and to understand crack initiation and propagation under service-like conditions. Results are used to assess reliability, predict service life, and guide design and maintenance decisions.

Typical fatigue test setups include constant-amplitude axial, torsional, or bending tests, as well as rotating-bending tests. Samples are usually shaped as dog-bones or cylinders for axial tests, or discs and shafts for rotating-bending. Tests are conducted with servo-hydraulic or electric machines, often at controlled frequencies from fractions of a hertz to a few tens of hertz. Researchers record the stress or strain ranges and the corresponding number of cycles to failure, sometimes using special equipment to detect crack initiation or monitor crack growth in real time.

The resulting data are commonly presented as S-N curves (Wöhler curves), which relate stress range to the expected fatigue life. Other approaches include strain-life methods for materials that do not exhibit a clear endurance limit and fracture mechanics methods that describe crack initiation and growth rates (Paris law). Fatigue testing often combines mechanical results with nondestructive evaluation techniques to locate and characterize cracks.

Standards from organizations such as ASTM and ISO guide fatigue testing, including specimen preparation, testing procedures, and data interpretation. Applications span aerospace, automotive, energy, and construction sectors. Limitations include environmental effects (corrosion, temperature), mean-stress influences, notch sensitivity, and the challenge of extrapolating lab results to complex, real-world components.