Thermodynamic modeling of creep mechanical behaviour by non linear relaxations

For some years, Cunat [1] has developed a formalism based on the thermodynamics of irreversible processes in order to describe the behaviour of continuous media which are not, in the equilibrium state. This thermodynamics of relaxation has led to a very general modeling called "Distribution of Non-Linear Relaxations" (DNLR) modeling. This theoretical approach is currently applied in solid mechanics for various ways and sequences of loading. In this paper, the application to primary and secondary unidirectional creep is presented. Only five parameters whose physical meaning is known are necessary. We analyze the role of each of them and indicate a process of identification from experimental data.