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