5. Testing Methods for Creep

The major techniques for collecting creep data are as follows: The results of the creep test are plotted as strain versus time to obtain a curve characterizing it. Often a creep power law relates creep strain to the applied stress. In ceramics a creep test at constant load and temperature is generally performed at prolonged times, because of the bond character in ceramics. Creep tests are often performed by compressive loading to eliminate growth of cavities and their opening and thus creep rate is slower compared to tension. In ceramics which are inherently brittle flexural tests are preferable since machining of test specimens is difficult and also because the tendency to break in the grips when test is performed by tension.