A metal subjected to a constant tensile load at an elevated temperature will creep and undergo a time dependent increase
in length. In the present study, the so called structure parameters are firstly introduced to indicate their influence on Helmholtz free energy. The corresponding nonlinear
evolution equation is then derived based on the linear one proposed by Biot by means of
irreversible thermodynamics. As a worked example, the above nonlinear evolution equation is applied to an ideal viscoelastic solid rod to predict its uniaxial creep behaviour. Under the strain induced anisotropic effect due to the configurational structure changes, the rod gradually becomes transversely isotropic during the deformation process. The final results show that when the applied longitudinal stress is below a certain value, the creep strain will get towards an asymptotic value at a decreasing strain rate, and that when it is over this, the creep strain will initially increase at a decreasing strain rate and then it will increase at an accelerative rate.