What factors contribute to the life limitations of rotating structures like disks and shafts?

The life limitations of rotating structures such as disks and shafts are primarily influenced by a combination of extreme mechanical loads and extreme thermodynamical loads. Rotating components experience significant stresses due to mechanical forces, which can lead to fatigue and failure over time. For instance, the dynamic loads during operation—such as those arising from rotation, acceleration, and deceleration—contribute to wear and possible fracturing of materials.

At the same time, thermodynamical factors, including temperature variations, can cause thermal expansion and thermal stresses in the material. These temperatures can vary widely, especially in high-performance applications, leading to fatigue and potential structural failure when materials are subjected to repeated thermal cycling. Therefore, both mechanical and thermodynamical loads must be considered to accurately assess the lifespan and reliability of these rotating structures. This comprehensive view helps engineers design components that can withstand the conditions they will face during operation, ultimately improving safety and performance.