Creep

CORE DEFINITION

Creep, also known as latent deformation, is the slow and permanent deformation of solid materials under stress. It occurs as a result of prolonged stress below the material's yield strength. Creep is more pronounced when materials are exposed to high temperatures or near their melting point for extended periods. The creep rate often increases with temperature. The creep rate depends on material properties, loading time, loading temperature, and applied structural stress. Depending on the applied stress and its duration, this deformation can become so significant that some components may fail. For example, creep in turbine blades can cause them to contact the casing, leading to blade failure. Creep is often a concern in engineering and metallurgy for components operating under high stress or high temperature. Creep may or may not be the deformation mechanism in a failure model. Moderate creep in concrete is sometimes beneficial because it relieves tensile stresses that might otherwise cause cracking. Unlike brittle fracture, creep deformation does not occur suddenly under stress. Instead, strain accumulates over time under sustained stress. Therefore, creep is a "time-dependent" deformation. The temperature range in which creep deformation occurs varies by material.