Abstract
A nonlinear Maxwell fluid model consisting of a linear dashpot in series with a parallel arrangement of a linear spring and a second-order nonlinear spring, was developed. This configuration provides the flexibility necessary to describe both the stiffening and the softening responses of some viscoelastic materials. A noteworthy feature of the model is that under constant rate displacement, the force equation can be solved in closed form, thereby providing a continuous, exact general solution.
