THERMODYNAMIC APPROACH TO CREEP AND PLASTICITY

A solid subjected to a small load distorts rapidly in the manner predi cted by elasticity theory. On a much longer time scale, the solid will creep. This dissipative motion is an important consideration in the e ngineering design of, for example, aircraft engines, but the macroscop ic equations of motion describing this deformation are based on empiri cal observations. The principles of thermodynamics specify the dissipa tive fluxes appropriate to the classical equations of elasticity, whic h include one, unique to solids, which describes creep. The thermodyna mic theory is presented, and the insights into the underlying microsco pic mechanisms of creep, gleaned from the macroscopic formalism, are a lso discussed.