The Maxwell model often fails to describe the relaxation behaviour of most real viscoelastic materials because it does not incorporate an equilibrium stress. This difficulty can be circumvented by coupling a Maxwell model with a spring in parallel which accounts for an equilibrium stress . On this basis, establish the general stress relaxation equation for this model explaining clearly your reasoning. [30\%] DATA for Question 4: The general solution of the Maxwell constitutive equation can be assumed without proof to be =e1(o+Go1e1dt)