Generalized Maxwell model
The Generalized Maxwell model also known as the Maxwell–Wiechert model (after James Clerk Maxwell and E Wiechert) is the most general form of the linear model for viscoelasticity. In this model several Maxwell elements are assembled in parallel. It takes into account that the relaxation does not occur at a single time, but in a set of times. Due to the presence of molecular segments of different lengths, with shorter ones contributing less than longer ones, there is a varying time distribution. The Wiechert model shows this by having as many spring–dashpot Maxwell elements as  are necessary to accurately represent the distribution. The figure on the right shows the generalised Wiechert model. General model form. Solids. Given formula_1 elements with moduli formula_2, viscosities formula_3, and relaxation times formula_4 The general form for the model for solids is given by : </math> formula_5 formula_6 formula_7 </math> formula_8 formula_9 formula_10 formula_9 formula_12 formula_5 formula_6 formula_15 formula_16 formula_9 formula_18 formula_9 formula_20 Example: standard linear solid model. Following the above model with formula_21 elements yields the standard linear solid model: </math> Fluids. Given formula_1 elements with moduli formula_2, viscosities formula_3, and relaxation times formula_4  The general form for the model for fluids is given by: </math> formula_5 formula_27 </math> formula_8 formula_9 formula_10 formula_9 formula_12 formula_5 formula_34 formula_35 formula_9 formula_37 formula_9 formula_39 Example: three parameter fluid. The analogous model to the standard linear solid model is the three parameter fluid, also known as the Jeffreys model: </math>