What term describes the permanent and cumulative deformation of the turbine blades in a turbojet engine?

Creep is the term that specifically refers to the permanent and cumulative deformation of materials, such as turbine blades in a turbojet engine, when they are subjected to high temperatures and stresses over an extended period. In a turbojet engine, parts like turbine blades operate in extreme conditions, including high thermal loads and mechanical stresses.

As the engine operates, these blades can continue to deform gradually, even if the stress levels remain below the yield strength of the material. This slow process can lead to significant shape changes and potential failures over time. Understanding creep is critical for turbine design and failure analysis, especially since it directly affects the longevity and performance of the engine components.

The other terms mentioned, while they relate to material failure or degradation, do not specifically capture the slow, time-dependent deformation associated with high-temperature applications like those found in turbine engines. For example, fatigue typically refers to the failure of materials due to cyclic loading, while wear involves the removal of material due to friction or contact. Yielding is associated with the point at which a material begins to deform plastically, but it does not encompass the gradual, time-related deformation that creep does.