Cyclically loaded structures are exposed to what type of stresses?

Cyclically loaded structures are primarily exposed to fatigue stresses. This type of stress arises from repeated loading and unloading of the material, which can lead to the development of microscopic cracks and ultimately result in failure after many cycles, even if the stresses are below the material's yield strength. This phenomenon is particularly important in structures that undergo varying loads over time, such as bridges, buildings subjected to wind forces, or machinery components.

While other stress types like static, thermal, and impact stresses exist, they do not capture the essence of what cyclic loading entails. Static stresses occur under constant loads without fluctuation, thermal stresses are due to temperature changes, and impact stresses arise from sudden forces. In contrast, fatigue stresses are a direct consequence of cyclic loading, making them the specific concern for the integrity of structures regularly subjected to variable forces.