A thermodynamic analysis of the empirical power relationships for creep rate and rupture time

A correlation between the empirical parameters describing power law of creep and the creep-rupture properties of materials is shown based on the thermodynamics of the steady-state creep or creep damage. Analytical relationships are suggested to explain this correlation, assuming that the activation energy depends on the logarithm of-the stress. This approach relates the cohesive energy of material to the steady-state creep and rupture time data. As a result, the origin of the Monkman-Grant rule becomes clear. A simple formula is presented to estimate a priori the slope of the logarithm of rupture time vs the logarithm of rupture stress at a given temperature, using the melting temperature of the material.