Creep & Stress Rupture
Creep is a slow failure mechanism that occurs in materials exposed to a constant load or stress, below the elastic limit of the material, for a protracted period of time. Temperature can significantly affect the rate of creep deformation in materials; the greater the temperature the greater the rate of deformation. It is important to quantify and understand this type of deformation to ensure the safety of components designed to operate at elevated temperatures.
Stress rupture testing can be considered to be a creep test without the use of extensometry, which is used on a creep test to monitor the deformation of the specimen throughout the duration of the test. As the name suggests, stress rupture testing is focused on measurement of the time taken for the specimen to rupture. Permanent plastic elongation can also be determined from the test.